MultiMC metadata: Support updating NeoForge version (#75)

Removed a deleteIfExists call - this should be handled by DownloadTask instead

.github/workflows/pr.yml

@@ -0,0 +1,27 @@
+name: Java Gradle Build
+
+on:
+  pull_request
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - name: Set up JDK 8
+        uses: actions/setup-java@v2
+        with:
+          java-version: '8'
+          distribution: 'temurin'
+          cache: gradle
+      - name: Build with Gradle
+        run: ./gradlew build
+      - name: Cleanup Gradle Cache
+        # Remove some files from the Gradle cache, so they aren't cached by GitHub Actions.
+        # Restoring these files from a GitHub Actions cache might cause problems for future builds.
+        run: |
+          rm -f ~/.gradle/caches/modules-2/modules-2.lock
+          rm -f ~/.gradle/caches/modules-2/gc.properties

.github/workflows/release.yml

@@ -0,0 +1,29 @@
+name: Java Gradle Release
+
+on:
+  push:
+    tags:
+      - 'v\d+.\d+.\d+'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - name: Set up JDK 8
+        uses: actions/setup-java@v2
+        with:
+          java-version: '8'
+          distribution: 'temurin'
+          cache: gradle
+      - name: Publish with Gradle
+        run: ./gradlew publish -Pgithub.token="${{ secrets.GITHUB_TOKEN }}" -Pbunnycdn.token="${{ secrets.BUNNYCDN_TOKEN }}" -Prelease=true
+      - name: Cleanup Gradle Cache
+        # Remove some files from the Gradle cache, so they aren't cached by GitHub Actions.
+        # Restoring these files from a GitHub Actions cache might cause problems for future builds.
+        run: |
+          rm -f ~/.gradle/caches/modules-2/modules-2.lock
+          rm -f ~/.gradle/caches/modules-2/gc.properties

.github/workflows/snapshot.yml

@@ -0,0 +1,29 @@
+name: Java Gradle Snapshot
+
+on:
+  push:
+    branches:
+      - 'main'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - name: Set up JDK 8
+        uses: actions/setup-java@v2
+        with:
+          java-version: '8'
+          distribution: 'temurin'
+          cache: gradle
+      - name: Publish with Gradle
+        run: ./gradlew publish -Pgithub.token="${{ secrets.GITHUB_TOKEN }}" -Pbunnycdn.token="${{ secrets.BUNNYCDN_TOKEN }}"
+      - name: Cleanup Gradle Cache
+        # Remove some files from the Gradle cache, so they aren't cached by GitHub Actions.
+        # Restoring these files from a GitHub Actions cache might cause problems for future builds.
+        run: |
+          rm -f ~/.gradle/caches/modules-2/modules-2.lock
+          rm -f ~/.gradle/caches/modules-2/gc.properties

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2019
+Copyright (c) 2021 comp500
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

build.gradle.kts

@@ -1,32 +1,50 @@
 plugins {
 	java
 	application
-	id("com.github.johnrengelman.shadow") version "5.0.0"
-	id("com.palantir.git-version") version "0.11.0"
-	id("com.github.breadmoirai.github-release") version "2.2.9"
-	kotlin("jvm") version "1.3.61"
+	id("com.github.johnrengelman.shadow") version "7.1.2"
+	id("com.palantir.git-version") version "0.13.0"
+	id("com.github.breadmoirai.github-release") version "2.4.1"
+	kotlin("jvm") version "1.7.10"
+	id("com.github.jk1.dependency-license-report") version "2.0"
+	`maven-publish`
 }
 
 java {
 	sourceCompatibility = JavaVersion.VERSION_1_8
 }
 
-dependencies {
-	implementation("commons-cli:commons-cli:1.4")
-	implementation("com.moandjiezana.toml:toml4j:0.7.2")
-	// TODO: Implement tests
-	//testImplementation "junit:junit:4.12"
-	implementation("com.google.code.gson:gson:2.8.1")
-	implementation("com.squareup.okio:okio:2.2.2")
-	implementation(kotlin("stdlib-jdk8"))
+repositories {
+	mavenCentral()
+	google()
+	maven {
+		url = uri("https://jitpack.io")
+	}
 }
 
-repositories {
-	jcenter()
+val r8 by configurations.creating
+val distJarOutput by configurations.creating {
+	isCanBeResolved = false
+	isCanBeConsumed = true
+
+	attributes {
+		attribute(Usage.USAGE_ATTRIBUTE, project.objects.named(Usage::class.java, Usage.JAVA_RUNTIME))
+		attribute(Bundling.BUNDLING_ATTRIBUTE, project.objects.named(Bundling::class.java, Bundling.EMBEDDED))
+	}
+}
+
+dependencies {
+	implementation("commons-cli:commons-cli:1.5.0")
+	implementation("com.google.code.gson:gson:2.9.0")
+	implementation("com.squareup.okio:okio:3.1.0")
+	implementation(kotlin("stdlib-jdk8"))
+	implementation("com.squareup.okhttp3:okhttp:4.10.0")
+	implementation("cc.ekblad:4koma:1.1.0")
+
+	r8("com.android.tools:r8:3.3.28")
 }
 
 application {
-	mainClassName = "link.infra.packwiz.installer.RequiresBootstrap"
+	mainClass.set("link.infra.packwiz.installer.RequiresBootstrap")
 }
 
 val gitVersion: groovy.lang.Closure<*> by extra
@@ -39,50 +57,150 @@ tasks.jar {
 	}
 }
 
-// Commons CLI and Minimal JSON are already included in packwiz-installer-bootstrap
+licenseReport {
+	renderers = arrayOf<com.github.jk1.license.render.ReportRenderer>(
+		com.github.jk1.license.render.InventoryMarkdownReportRenderer("licenses.md", "packwiz-installer")
+	)
+	filters = arrayOf<com.github.jk1.license.filter.DependencyFilter>(com.github.jk1.license.filter.LicenseBundleNormalizer())
+}
+
 tasks.shadowJar {
-	dependencies {
-		exclude(dependency("commons-cli:commons-cli:1.4"))
-		exclude(dependency("com.eclipsesource.minimal-json:minimal-json:0.9.5"))
+	// 4koma uses kotlin-reflect; requires Kotlin metadata
+	//exclude("**/*.kotlin_metadata")
+	//exclude("**/*.kotlin_builtins")
+	exclude("META-INF/maven/**/*")
+	exclude("META-INF/proguard/**/*")
+
+	// Relocate Commons CLI, so that it doesn't clash with old packwiz-installer-bootstrap (that shades it)
+	relocate("org.apache.commons.cli", "link.infra.packwiz.installer.deps.commons-cli")
+
+	// from Commons CLI
+	exclude("META-INF/LICENSE.txt")
+	exclude("META-INF/NOTICE.txt")
+}
+
+val shrinkJar by tasks.registering(JavaExec::class) {
+	val rules = file("src/main/proguard.txt")
+	val r8File = base.libsDirectory.file(provider {
+		base.archivesName.get() + "-" + project.version + "-all-shrink.jar"
+	})
+	dependsOn(configurations.named("runtimeClasspath"))
+	inputs.files(tasks.shadowJar, rules)
+	outputs.file(r8File)
+
+	classpath(r8)
+	mainClass.set("com.android.tools.r8.R8")
+	args = mutableListOf(
+		"--release",
+		"--classfile",
+		"--output", r8File.get().toString(),
+		"--pg-conf", rules.toString(),
+		"--lib", System.getProperty("java.home"),
+		*(if (System.getProperty("java.version").startsWith("1.")) {
+			// javax.crypto, necessary on <1.9 for compiling Okio
+			arrayOf("--lib", System.getProperty("java.home") + "/lib/jce.jar")
+		} else { arrayOf() }),
+		tasks.shadowJar.get().archiveFile.get().asFile.toString()
+	)
+}
+
+// MANIFEST.MF must be one of the first 2 entries in the zip for JarInputStream to see it
+// Gradle's JAR creation handles this whereas R8 doesn't, so the dist JAR is repacked
+val distJar by tasks.registering(Jar::class) {
+	from(shrinkJar.map { zipTree(it.outputs.files.singleFile) })
+	archiveClassifier.set("all-repacked")
+	manifest {
+		from(shrinkJar.map { zipTree(it.outputs.files.singleFile).matching {
+			include("META-INF/MANIFEST.MF")
+		}.singleFile })
+	}
+}
+
+artifacts {
+	add("distJarOutput", distJar) {
+		classifier = "dist"
 	}
 }
 
 // Used for vscode launch.json
-tasks.register<Copy>("copyJar") {
-	from(tasks.shadowJar)
+val copyJar by tasks.registering(Copy::class) {
+	from(distJar)
 	rename("packwiz-installer-(.*)\\.jar", "packwiz-installer.jar")
-	into("build/libs/")
+	into(layout.buildDirectory.dir("dist"))
+	outputs.file(layout.buildDirectory.dir("dist").map { it.file("packwiz-installer.jar") })
 }
 
 tasks.build {
-	dependsOn("copyJar")
+	dependsOn(copyJar)
 }
 
-if (project.hasProperty("github.token")) {
-	githubRelease {
-		owner("comp500")
-		repo("packwiz-installer")
-		tagName("${project.version}")
-		releaseName("Release ${project.version}")
-		draft(true)
-		token(findProperty("github.token") as String? ?: "")
-		releaseAssets(tasks.jar.get().destinationDirectory.file("packwiz-installer.jar").get())
-	}
+githubRelease {
+	owner("comp500")
+	repo("packwiz-installer")
+	tagName("${project.version}")
+	releaseName("Release ${project.version}")
+	draft(true)
+	token(findProperty("github.token") as String?)
+	releaseAssets(layout.buildDirectory.dir("dist").map { it.file("packwiz-installer.jar") }.get())
+}
 
-	tasks.githubRelease {
-		dependsOn(tasks.build)
-	}
+tasks.githubRelease {
+	dependsOn(copyJar)
+	enabled = project.hasProperty("github.token") && project.findProperty("release") == "true"
+}
+
+tasks.publish {
+	dependsOn(tasks.githubRelease)
 }
 
 tasks.compileKotlin {
 	kotlinOptions {
 		jvmTarget = "1.8"
-		freeCompilerArgs = listOf("-Xjvm-default=enable")
+		freeCompilerArgs = listOf("-Xjvm-default=all", "-Xallow-result-return-type", "-opt-in=kotlin.io.path.ExperimentalPathApi", "-Xlambdas=indy")
 	}
 }
 tasks.compileTestKotlin {
 	kotlinOptions {
 		jvmTarget = "1.8"
-		freeCompilerArgs = listOf("-Xjvm-default=enable")
+		freeCompilerArgs = listOf("-Xjvm-default=all", "-Xallow-result-return-type", "-opt-in=kotlin.io.path.ExperimentalPathApi", "-Xlambdas=indy")
 	}
 }
+
+val javaComponent = components["java"] as AdhocComponentWithVariants
+javaComponent.addVariantsFromConfiguration(distJarOutput) {
+	mapToMavenScope("runtime")
+	mapToOptional()
+}
+javaComponent.withVariantsFromConfiguration(configurations["shadowRuntimeElements"]) {
+	skip()
+}
+
+if (project.hasProperty("bunnycdn.token")) {
+	publishing {
+		publications {
+			create<MavenPublication>("maven") {
+				groupId = "link.infra.packwiz"
+				artifactId = "packwiz-installer"
+
+				from(components["java"])
+			}
+		}
+		repositories {
+			maven {
+				url = if (project.findProperty("release") == "true") {
+					uri("https://storage.bunnycdn.com/comp-maven/repository/release")
+				} else {
+					uri("https://storage.bunnycdn.com/comp-maven/repository/snapshot")
+				}
+				credentials(HttpHeaderCredentials::class) {
+					name = "AccessKey"
+					value = findProperty("bunnycdn.token") as String?
+				}
+				authentication {
+					create<HttpHeaderAuthentication>("header")
+				}
+			}
+		}
+	}
+}
+

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.4.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.5-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -1,13 +1,13 @@
-#!/usr/bin/env sh
+#!/bin/sh
 
 #
-# Copyright 2015 the original author or authors.
+# Copyright © 2015-2021 the original authors.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
-#      http://www.apache.org/licenses/LICENSE-2.0
+#      https://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
@@ -17,78 +17,113 @@
 #
 
 ##############################################################################
-##
-##  Gradle start up script for UN*X
-##
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
 ##############################################################################
 
 # Attempt to set APP_HOME
+
 # Resolve links: $0 may be a link
-PRG="$0"
-# Need this for relative symlinks.
-while [ -h "$PRG" ] ; do
-    ls=`ls -ld "$PRG"`
-    link=`expr "$ls" : '.*-> \(.*\)$'`
-    if expr "$link" : '/.*' > /dev/null; then
-        PRG="$link"
-    else
-        PRG=`dirname "$PRG"`"/$link"
-    fi
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
 done
-SAVED="`pwd`"
-cd "`dirname \"$PRG\"`/" >/dev/null
-APP_HOME="`pwd -P`"
-cd "$SAVED" >/dev/null
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
 
 APP_NAME="Gradle"
-APP_BASE_NAME=`basename "$0"`
+APP_BASE_NAME=${0##*/}
 
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
 DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
-MAX_FD="maximum"
+MAX_FD=maximum
 
 warn () {
     echo "$*"
-}
+} >&2
 
 die () {
     echo
     echo "$*"
     echo
     exit 1
-}
+} >&2
 
 # OS specific support (must be 'true' or 'false').
 cygwin=false
 msys=false
 darwin=false
 nonstop=false
-case "`uname`" in
-  CYGWIN* )
-    cygwin=true
-    ;;
-  Darwin* )
-    darwin=true
-    ;;
-  MINGW* )
-    msys=true
-    ;;
-  NONSTOP* )
-    nonstop=true
-    ;;
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
 esac
 
 CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
 
+
 # Determine the Java command to use to start the JVM.
 if [ -n "$JAVA_HOME" ] ; then
     if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
         # IBM's JDK on AIX uses strange locations for the executables
-        JAVACMD="$JAVA_HOME/jre/sh/java"
+        JAVACMD=$JAVA_HOME/jre/sh/java
     else
-        JAVACMD="$JAVA_HOME/bin/java"
+        JAVACMD=$JAVA_HOME/bin/java
     fi
     if [ ! -x "$JAVACMD" ] ; then
         die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
@@ -97,7 +132,7 @@ Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
     fi
 else
-    JAVACMD="java"
+    JAVACMD=java
     which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
@@ -105,84 +140,95 @@ location of your Java installation."
 fi
 
 # Increase the maximum file descriptors if we can.
-if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
-    MAX_FD_LIMIT=`ulimit -H -n`
-    if [ $? -eq 0 ] ; then
-        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
-            MAX_FD="$MAX_FD_LIMIT"
-        fi
-        ulimit -n $MAX_FD
-        if [ $? -ne 0 ] ; then
-            warn "Could not set maximum file descriptor limit: $MAX_FD"
-        fi
-    else
-        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
-    fi
-fi
-
-# For Darwin, add options to specify how the application appears in the dock
-if $darwin; then
-    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
-fi
-
-# For Cygwin, switch paths to Windows format before running java
-if $cygwin ; then
-    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
-    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
-    JAVACMD=`cygpath --unix "$JAVACMD"`
-
-    # We build the pattern for arguments to be converted via cygpath
-    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
-    SEP=""
-    for dir in $ROOTDIRSRAW ; do
-        ROOTDIRS="$ROOTDIRS$SEP$dir"
-        SEP="|"
-    done
-    OURCYGPATTERN="(^($ROOTDIRS))"
-    # Add a user-defined pattern to the cygpath arguments
-    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
-        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
-    fi
-    # Now convert the arguments - kludge to limit ourselves to /bin/sh
-    i=0
-    for arg in "$@" ; do
-        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
-        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
-
-        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
-            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
-        else
-            eval `echo args$i`="\"$arg\""
-        fi
-        i=$((i+1))
-    done
-    case $i in
-        (0) set -- ;;
-        (1) set -- "$args0" ;;
-        (2) set -- "$args0" "$args1" ;;
-        (3) set -- "$args0" "$args1" "$args2" ;;
-        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
-        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
-        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
-        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
-        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
-        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
 fi
 
-# Escape application args
-save () {
-    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
-    echo " "
-}
-APP_ARGS=$(save "$@")
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
 
-# Collect all arguments for the java command, following the shell quoting and substitution rules
-eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
 
-# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
-if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
-  cd "$(dirname "$0")"
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
 fi
 
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
 exec "$JAVACMD" "$@"

gradlew.bat

@@ -5,7 +5,7 @@
 @rem you may not use this file except in compliance with the License.
 @rem You may obtain a copy of the License at
 @rem
-@rem      http://www.apache.org/licenses/LICENSE-2.0
+@rem      https://www.apache.org/licenses/LICENSE-2.0
 @rem
 @rem Unless required by applicable law or agreed to in writing, software
 @rem distributed under the License is distributed on an "AS IS" BASIS,
@@ -29,6 +29,9 @@ if "%DIRNAME%" == "" set DIRNAME=.
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
 @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
 set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
 
@@ -37,7 +40,7 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto init
+if "%ERRORLEVEL%" == "0" goto execute
 
 echo.
 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
@@ -51,7 +54,7 @@ goto fail
 set JAVA_HOME=%JAVA_HOME:"=%
 set JAVA_EXE=%JAVA_HOME%/bin/java.exe
 
-if exist "%JAVA_EXE%" goto init
+if exist "%JAVA_EXE%" goto execute
 
 echo.
 echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
@@ -61,28 +64,14 @@ echo location of your Java installation.
 
 goto fail
 
-:init
-@rem Get command-line arguments, handling Windows variants
-
-if not "%OS%" == "Windows_NT" goto win9xME_args
-
-:win9xME_args
-@rem Slurp the command line arguments.
-set CMD_LINE_ARGS=
-set _SKIP=2
-
-:win9xME_args_slurp
-if "x%~1" == "x" goto execute
-
-set CMD_LINE_ARGS=%*
-
 :execute
 @rem Setup the command line
 
 set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
+
 @rem Execute Gradle
-"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
 
 :end
 @rem End local scope for the variables with windows NT shell

src/main/java/link/infra/packwiz/installer/RequiresBootstrap.java

@@ -8,8 +8,6 @@ public class RequiresBootstrap {
 	public static void main(String[] args) {
 		// Very small CLI implementation, because Commons CLI complains on unexpected
 		// options
-		// Also so that Commons CLI can be excluded from the shaded JAR, as it is
-		// included in the bootstrap
 		if (Arrays.stream(args).map(str -> {
 			if (str == null) return "";
 			if (str.startsWith("--")) {

src/main/kotlin/link/infra/packwiz/installer/DevMain.kt

@@ -0,0 +1,5 @@
+package link.infra.packwiz.installer
+
+fun main(args: Array<String>) {
+	Main(args)
+}

src/main/kotlin/link/infra/packwiz/installer/DownloadTask.kt

@@ -2,40 +2,57 @@ package link.infra.packwiz.installer
 
 import link.infra.packwiz.installer.metadata.IndexFile
 import link.infra.packwiz.installer.metadata.ManifestFile
-import link.infra.packwiz.installer.metadata.SpaceSafeURI
 import link.infra.packwiz.installer.metadata.hash.Hash
-import link.infra.packwiz.installer.metadata.hash.HashUtils.getHash
-import link.infra.packwiz.installer.metadata.hash.HashUtils.getHasher
-import link.infra.packwiz.installer.ui.ExceptionDetails
-import link.infra.packwiz.installer.ui.IOptionDetails
+import link.infra.packwiz.installer.metadata.hash.HashFormat
+import link.infra.packwiz.installer.request.RequestException
+import link.infra.packwiz.installer.target.ClientHolder
+import link.infra.packwiz.installer.target.Side
+import link.infra.packwiz.installer.target.path.PackwizFilePath
+import link.infra.packwiz.installer.ui.data.ExceptionDetails
+import link.infra.packwiz.installer.ui.data.IOptionDetails
+import link.infra.packwiz.installer.util.Log
 import okio.Buffer
 import okio.HashingSink
+import okio.blackholeSink
 import okio.buffer
 import java.io.IOException
 import java.nio.file.Files
-import java.nio.file.Paths
 import java.nio.file.StandardCopyOption
-import java.util.*
 
-internal class DownloadTask private constructor(val metadata: IndexFile.File, defaultFormat: String, private val downloadSide: UpdateManager.Options.Side) : IOptionDetails {
+internal class DownloadTask private constructor(val metadata: IndexFile.File, val index: IndexFile, private val downloadSide: Side) : IOptionDetails {
 	var cachedFile: ManifestFile.File? = null
+		private set
 
 	private var err: Exception? = null
 	val exceptionDetails get() = err?.let { e -> ExceptionDetails(name, e) }
 
 	fun failed() = err != null
 
-	private var alreadyUpToDate = false
+	var alreadyUpToDate = false
+		private set
 	private var metadataRequired = true
 	private var invalidated = false
 	// If file is new or isOptional changed to true, the option needs to be presented again
 	private var newOptional = true
+	var completionStatus = CompletionStatus.INCOMPLETE
+		private set
 
-	val isOptional get() = metadata.linkedFile?.isOptional ?: false
+	enum class CompletionStatus {
+		INCOMPLETE,
+		DOWNLOADED,
+		ALREADY_EXISTS_CACHED,
+		ALREADY_EXISTS_VALIDATED,
+		SKIPPED_DISABLED,
+		SKIPPED_WRONG_SIDE,
+		DELETED_DISABLED,
+		DELETED_WRONG_SIDE;
+	}
+
+	val isOptional get() = metadata.linkedFile?.option?.optional ?: false
 
 	fun isNewOptional() = isOptional && newOptional
 
-	fun correctSide() = metadata.linkedFile?.side?.hasSide(downloadSide) ?: true
+	fun correctSide() = metadata.linkedFile?.side?.let { downloadSide.hasSide(it) } ?: true
 
 	override val name get() = metadata.name
 
@@ -51,12 +68,6 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 
 	override val optionDescription get() = metadata.linkedFile?.option?.description ?: ""
 
-	init {
-		if (metadata.hashFormat?.isEmpty() != false) {
-			metadata.hashFormat = defaultFormat
-		}
-	}
-
 	fun invalidate() {
 		invalidated = true
 		alreadyUpToDate = false
@@ -72,7 +83,7 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 		this.cachedFile = cachedFile
 		if (!invalidated) {
 			val currHash = try {
-				getHash(metadata.hashFormat!!, metadata.hash!!)
+				metadata.getHashObj(index)
 			} catch (e: Exception) {
 				err = e
 				return
@@ -80,6 +91,7 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 			if (currHash == cachedFile.hash) { // Already up to date
 				alreadyUpToDate = true
 				metadataRequired = false
+				completionStatus = CompletionStatus.ALREADY_EXISTS_CACHED
 			}
 		}
 		if (cachedFile.isOptional) {
@@ -89,13 +101,13 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 		}
 	}
 
-	fun downloadMetadata(parentIndexFile: IndexFile, indexUri: SpaceSafeURI) {
+	fun downloadMetadata(clientHolder: ClientHolder) {
 		if (err != null) return
 
 		if (metadataRequired) {
 			try {
 				// Retrieve the linked metadata file
-				metadata.downloadMeta(parentIndexFile, indexUri)
+				metadata.downloadMeta(index, clientHolder)
 			} catch (e: Exception) {
 				err = e
 				return
@@ -103,70 +115,134 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 			cachedFile?.let { cachedFile ->
 				val linkedFile = metadata.linkedFile
 				if (linkedFile != null) {
-					linkedFile.option?.let { opt ->
-						if (opt.optional) {
-							if (cachedFile.isOptional) {
-								// isOptional didn't change
-								newOptional = false
-							} else {
-								// isOptional false -> true, set option to it's default value
-								// TODO: preserve previous option value, somehow??
-								cachedFile.optionValue = opt.defaultValue
-							}
+					if (linkedFile.option.optional) {
+						if (cachedFile.isOptional) {
+							// isOptional didn't change
+							newOptional = false
+						} else {
+							// isOptional false -> true, set option to it's default value
+							// TODO: preserve previous option value, somehow??
+							cachedFile.optionValue = linkedFile.option.defaultValue
 						}
 					}
-					cachedFile.isOptional = isOptional
-					cachedFile.onlyOtherSide = !correctSide()
 				}
+				cachedFile.isOptional = isOptional
+				cachedFile.onlyOtherSide = !correctSide()
 			}
 		}
 	}
 
-	fun download(packFolder: String, indexUri: SpaceSafeURI) {
+	/**
+	 * Check if the file in the destination location is already valid
+	 * Must be done after metadata retrieval
+	 */
+	fun validateExistingFile(packFolder: PackwizFilePath, clientHolder: ClientHolder) {
+		if (!alreadyUpToDate) {
+			try {
+				// TODO: only do this for files that didn't exist before or have been modified since last full update?
+				val destPath = metadata.destURI.rebase(packFolder)
+				destPath.source(clientHolder).use { src ->
+					// TODO: clean up duplicated code
+					val hash: Hash<*>
+					val fileHashFormat: HashFormat<*>
+					val linkedFile = metadata.linkedFile
+
+					if (linkedFile != null) {
+						hash = linkedFile.hash
+						fileHashFormat = linkedFile.download.hashFormat
+					} else {
+						hash = metadata.getHashObj(index)
+						fileHashFormat = metadata.hashFormat(index)
+					}
+
+					val fileSource = fileHashFormat.source(src)
+					fileSource.buffer().readAll(blackholeSink())
+					if (hash == fileSource.hash) {
+						alreadyUpToDate = true
+						completionStatus = CompletionStatus.ALREADY_EXISTS_VALIDATED
+
+						// Update the manifest file
+						cachedFile = (cachedFile ?: ManifestFile.File()).also {
+							try {
+								it.hash = metadata.getHashObj(index)
+							} catch (e: Exception) {
+								err = e
+								return
+							}
+							it.isOptional = isOptional
+							it.cachedLocation = metadata.destURI.rebase(packFolder)
+							metadata.linkedFile?.let { linked ->
+								try {
+									it.linkedFileHash = linked.hash
+								} catch (e: Exception) {
+									err = e
+								}
+							}
+						}
+					}
+				}
+			} catch (e: RequestException) {
+				// Ignore exceptions; if the file doesn't exist we'll be downloading it
+			} catch (e: IOException) {
+				// Ignore exceptions; if the file doesn't exist we'll be downloading it
+			}
+		}
+	}
+
+	fun download(packFolder: PackwizFilePath, clientHolder: ClientHolder) {
 		if (err != null) return
 
-		// Ensure it is removed
+		// Exclude wrong-side and optional false files
 		cachedFile?.let {
-			if (!it.optionValue || !correctSide()) {
-				if (it.cachedLocation == null) return
-
-				try {
-					Files.deleteIfExists(Paths.get(packFolder, it.cachedLocation))
-				} catch (e: IOException) {
-					// TODO: how much of a problem is this? use log4j/other log library to show warning?
-					e.printStackTrace()
+			if ((it.isOptional && !it.optionValue) || !correctSide()) {
+				if (it.cachedLocation != null) {
+					// Ensure wrong-side or optional false files are removed
+					try {
+						completionStatus = if (Files.deleteIfExists(it.cachedLocation!!.nioPath)) {
+							if (correctSide()) { CompletionStatus.DELETED_DISABLED } else { CompletionStatus.DELETED_WRONG_SIDE }
+						} else {
+							if (correctSide()) { CompletionStatus.SKIPPED_DISABLED } else { CompletionStatus.SKIPPED_WRONG_SIDE }
+						}
+					} catch (e: IOException) {
+						Log.warn("Failed to delete file", e)
+					}
+				} else {
+					completionStatus =
+						if (correctSide()) { CompletionStatus.SKIPPED_DISABLED }
+						else { CompletionStatus.SKIPPED_WRONG_SIDE }
 				}
 				it.cachedLocation = null
+				return
 			}
 		}
 		if (alreadyUpToDate) return
 
-		// TODO: should I be validating JSON properly, or this fine!!!!!!!??
-		assert(metadata.destURI != null)
-		val destPath = Paths.get(packFolder, metadata.destURI.toString())
+		val destPath = metadata.destURI.rebase(packFolder)
 
 		// Don't update files marked with preserve if they already exist on disk
 		if (metadata.preserve) {
-			if (destPath.toFile().exists()) {
+			if (destPath.nioPath.toFile().exists()) {
 				return
 			}
 		}
 
+		// TODO: add .disabled support?
+
 		try {
-			val hash: Hash
-			val fileHashFormat: String
+			val hash: Hash<*>
+			val fileHashFormat: HashFormat<*>
 			val linkedFile = metadata.linkedFile
 
 			if (linkedFile != null) {
 				hash = linkedFile.hash
-				fileHashFormat = Objects.requireNonNull(Objects.requireNonNull(linkedFile.download)!!.hashFormat)!!
+				fileHashFormat = linkedFile.download.hashFormat
 			} else {
-				hash = metadata.getHashObj()
-				fileHashFormat = Objects.requireNonNull(metadata.hashFormat)!!
+				hash = metadata.getHashObj(index)
+				fileHashFormat = metadata.hashFormat(index)
 			}
 
-			val src = metadata.getSource(indexUri)
-			val fileSource = getHasher(fileHashFormat).getHashingSource(src)
+			val src = metadata.getSource(clientHolder)
+			val fileSource = fileHashFormat.source(src)
 			val data = Buffer()
 
 			// Read all the data into a buffer (very inefficient for large files! but allows rollback if hash check fails)
@@ -175,20 +251,24 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 				it.readAll(data)
 			}
 
-			if (fileSource.hashIsEqual(hash)) {
+			if (hash == fileSource.hash) {
 				// isDirectory follows symlinks, but createDirectories doesn't
-				if (Files.isDirectory(destPath.parent)) {
-					Files.createDirectories(destPath.parent)
+				try {
+					Files.createDirectories(destPath.parent.nioPath)
+				} catch (e: java.nio.file.FileAlreadyExistsException) {
+					if (!Files.isDirectory(destPath.parent.nioPath)) {
+						throw e
+					}
 				}
-				Files.copy(data.inputStream(), destPath, StandardCopyOption.REPLACE_EXISTING)
+				Files.copy(data.inputStream(), destPath.nioPath, StandardCopyOption.REPLACE_EXISTING)
 				data.clear()
 			} else {
-				// TODO: no more PRINTLN!!!!!!!!!
+				// TODO: move println to something visible in the error window
 				println("Invalid hash for " + metadata.destURI.toString())
 				println("Calculated: " + fileSource.hash)
 				println("Expected:   $hash")
 				// Attempt to get the SHA256 hash
-				val sha256 = HashingSink.sha256(okio.blackholeSink())
+				val sha256 = HashingSink.sha256(blackholeSink())
 				data.readAll(sha256)
 				println("SHA256 hash value: " + sha256.hash)
 				err = Exception("Hash invalid!")
@@ -196,10 +276,10 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 				return
 			}
 			cachedFile?.cachedLocation?.let {
-				if (destPath != Paths.get(packFolder, it)) {
+				if (destPath != it) {
 					// Delete old file if location changes
 					try {
-						Files.delete(Paths.get(packFolder, cachedFile!!.cachedLocation))
+						Files.delete(cachedFile!!.cachedLocation!!.nioPath)
 					} catch (e: IOException) {
 						// Continue, as it was probably already deleted?
 						// TODO: log it
@@ -214,13 +294,13 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 		// Update the manifest file
 		cachedFile = (cachedFile ?: ManifestFile.File()).also {
 			try {
-				it.hash = metadata.getHashObj()
+				it.hash = metadata.getHashObj(index)
 			} catch (e: Exception) {
 				err = e
 				return
 			}
 			it.isOptional = isOptional
-			it.cachedLocation = metadata.destURI.toString()
+			it.cachedLocation = metadata.destURI.rebase(packFolder)
 			metadata.linkedFile?.let { linked ->
 				try {
 					it.linkedFileHash = linked.hash
@@ -229,14 +309,15 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 				}
 			}
 		}
+
+		completionStatus = CompletionStatus.DOWNLOADED
 	}
 
 	companion object {
-		@JvmStatic
-		fun createTasksFromIndex(index: IndexFile, defaultFormat: String, downloadSide: UpdateManager.Options.Side): List<DownloadTask> {
+		fun createTasksFromIndex(index: IndexFile, downloadSide: Side): MutableList<DownloadTask> {
 			val tasks = ArrayList<DownloadTask>()
-			for (file in Objects.requireNonNull(index.files)) {
-				tasks.add(DownloadTask(file, defaultFormat, downloadSide))
+			for (file in index.files) {
+				tasks.add(DownloadTask(file, index, downloadSide))
 			}
 			return tasks
 		}

src/main/kotlin/link/infra/packwiz/installer/LauncherUtils.kt

@@ -0,0 +1,142 @@
+package link.infra.packwiz.installer
+
+import com.google.gson.Gson
+import com.google.gson.JsonIOException
+import com.google.gson.JsonParser
+import com.google.gson.JsonSyntaxException
+import link.infra.packwiz.installer.metadata.PackFile
+import link.infra.packwiz.installer.ui.IUserInterface
+import link.infra.packwiz.installer.util.Log
+import kotlin.io.path.reader
+import kotlin.io.path.writeText
+
+class LauncherUtils internal constructor(private val opts: UpdateManager.Options, val ui: IUserInterface) {
+	enum class LauncherStatus {
+		SUCCESSFUL,
+		NO_CHANGES,
+		CANCELLED,
+		NOT_FOUND, // When there is no mmc-pack.json file found (i.e. MultiMC is not being used)
+	}
+
+	fun handleMultiMC(pf: PackFile, gson: Gson): LauncherStatus {
+		// MultiMC MC and loader version checker
+		val manifestPath = opts.multimcFolder / "mmc-pack.json"
+
+		if (!manifestPath.nioPath.toFile().exists()) {
+			return LauncherStatus.NOT_FOUND
+		}
+
+		val multimcManifest = manifestPath.nioPath.reader().use {
+			try {
+				JsonParser.parseReader(it)
+			} catch (e: JsonIOException) {
+				throw Exception("Cannot read the MultiMC pack file", e)
+			} catch (e: JsonSyntaxException) {
+				throw Exception("Invalid MultiMC pack file", e)
+			}.asJsonObject
+		}
+
+		Log.info("Loaded MultiMC config")
+
+		// We only support format 1, if it gets updated in the future we'll have to handle that
+		// There's only version 1 for now tho, so that's good
+		if (multimcManifest["formatVersion"]?.asInt != 1) {
+			throw Exception("Unsupported MultiMC format version ${multimcManifest["formatVersion"]}")
+		}
+
+		var manifestModified = false
+		val modLoaders = hashMapOf(
+			"net.minecraft" to "minecraft",
+			"net.minecraftforge" to "forge",
+			"net.neoforged" to "neoforge",
+			"net.fabricmc.fabric-loader" to "fabric",
+			"org.quiltmc.quilt-loader" to "quilt",
+			"com.mumfrey.liteloader" to "liteloader"
+		)
+		// MultiMC requires components to be sorted; this is defined in the MultiMC meta repo, but they seem to
+		// be the same for every version so they are just used directly here
+		val componentOrders = mapOf(
+			"net.minecraft" to -2,
+			"org.lwjgl" to -1,
+			"org.lwjgl3" to -1,
+			"net.minecraftforge" to 5,
+			"net.neoforged" to 5,
+			"net.fabricmc.fabric-loader" to 10,
+			"org.quiltmc.quilt-loader" to 10,
+			"com.mumfrey.liteloader" to 10,
+			"net.fabricmc.intermediary" to 11
+		)
+		val modLoadersClasses = modLoaders.entries.associate{(k,v)-> v to k}
+		val loaderVersionsFound = HashMap<String, String?>()
+		val outdatedLoaders = mutableSetOf<String>()
+		val components = multimcManifest["components"]?.asJsonArray ?: throw Exception("Invalid mmc-pack.json: no components key")
+		components.removeAll {
+			val component = it.asJsonObject
+
+			val version = component["version"]?.asString
+			// If we find any of the modloaders we support, we save it and check the version
+			if (modLoaders.containsKey(component["uid"]?.asString)) {
+				val modLoader = modLoaders.getValue(component["uid"]!!.asString)
+				loaderVersionsFound[modLoader] = version
+				if (version != pf.versions[modLoader]) {
+					outdatedLoaders.add(modLoader)
+					true // Delete component; cached metadata is invalid and will be re-added
+				} else {
+					false // Already up to date; cached metadata is valid
+				}
+			} else { false } // Not a known loader / MC
+		}
+
+		for ((_, loader) in modLoaders
+			.filter {
+				(!loaderVersionsFound.containsKey(it.value) || outdatedLoaders.contains(it.value)) && pf.versions.containsKey(it.value)
+			}
+		) {
+			manifestModified = true
+			components.add(gson.toJsonTree(
+				hashMapOf("uid" to modLoadersClasses[loader], "version" to pf.versions[loader]))
+			)
+		}
+
+		// If inconsistent Intermediary mappings version is found, delete it - MultiMC will add and re-dl the correct one
+		components.find { it.isJsonObject && it.asJsonObject["uid"]?.asString == "net.fabricmc.intermediary" }?.let {
+			if (it.asJsonObject["version"]?.asString != pf.versions["minecraft"]) {
+				components.remove(it)
+				manifestModified = true
+			}
+		}
+
+		if (manifestModified) {
+			// Sort manifest by component order
+			val sortedComponents = components.sortedWith(nullsLast(compareBy {
+				if (it.isJsonObject) {
+					componentOrders[it.asJsonObject["uid"]?.asString]
+				} else { null }
+			}))
+			components.removeAll { true }
+			sortedComponents.forEach { components.add(it) }
+
+			// The manifest has been modified, so before saving it we'll ask the user
+			// if they wanna update it, continue without updating it, or exit
+			val oldVers = loaderVersionsFound.map { Pair(it.key, it.value) }
+			val newVers = pf.versions.map { Pair(it.key, it.value) }
+
+			when (ui.showUpdateConfirmationDialog(oldVers, newVers)) {
+				IUserInterface.UpdateConfirmationResult.CANCELLED -> {
+					return LauncherStatus.CANCELLED
+				}
+				IUserInterface.UpdateConfirmationResult.CONTINUE -> {
+					return LauncherStatus.SUCCESSFUL
+				}
+				else -> {}
+			}
+
+			manifestPath.nioPath.writeText(gson.toJson(multimcManifest))
+			Log.info("Successfully updated mmc-pack.json based on version metadata")
+
+			return LauncherStatus.SUCCESSFUL
+		}
+
+		return LauncherStatus.NO_CHANGES
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/Main.kt

@@ -2,16 +2,23 @@
 
 package link.infra.packwiz.installer
 
-import link.infra.packwiz.installer.metadata.SpaceSafeURI
-import link.infra.packwiz.installer.ui.CLIHandler
-import link.infra.packwiz.installer.ui.InputStateHandler
-import link.infra.packwiz.installer.ui.InstallWindow
+import link.infra.packwiz.installer.target.Side
+import link.infra.packwiz.installer.target.path.HttpUrlPath
+import link.infra.packwiz.installer.target.path.PackwizFilePath
+import link.infra.packwiz.installer.ui.cli.CLIHandler
+import link.infra.packwiz.installer.ui.gui.GUIHandler
+import link.infra.packwiz.installer.ui.wrap
+import link.infra.packwiz.installer.util.Log
+import okhttp3.HttpUrl.Companion.toHttpUrl
+import okio.Path.Companion.toOkioPath
+import okio.Path.Companion.toPath
 import org.apache.commons.cli.DefaultParser
 import org.apache.commons.cli.Options
 import org.apache.commons.cli.ParseException
 import java.awt.EventQueue
 import java.awt.GraphicsEnvironment
-import java.net.URISyntaxException
+import java.net.URI
+import java.nio.file.Paths
 import javax.swing.JOptionPane
 import javax.swing.UIManager
 import kotlin.system.exitProcess
@@ -19,7 +26,7 @@ import kotlin.system.exitProcess
 @Suppress("unused")
 class Main(args: Array<String>) {
 	// Don't attempt to start a GUI if we are headless
-	var guiEnabled = !GraphicsEnvironment.isHeadless()
+	private var guiEnabled = !GraphicsEnvironment.isHeadless()
 
 	private fun startup(args: Array<String>) {
 		val options = Options()
@@ -30,7 +37,7 @@ class Main(args: Array<String>) {
 		val cmd = try {
 			parser.parse(options, args)
 		} catch (e: ParseException) {
-			e.printStackTrace()
+			Log.fatal("Failed to parse command line arguments", e)
 			if (guiEnabled) {
 				EventQueue.invokeAndWait {
 					try {
@@ -38,7 +45,8 @@ class Main(args: Array<String>) {
 					} catch (ignored: Exception) {
 						// Ignore the exceptions, just continue using the ugly L&F
 					}
-					JOptionPane.showMessageDialog(null, e.message, "packwiz-installer", JOptionPane.ERROR_MESSAGE)
+					JOptionPane.showMessageDialog(null, "Failed to parse command line arguments: $e",
+						"packwiz-installer", JOptionPane.ERROR_MESSAGE)
 				}
 			}
 			exitProcess(1)
@@ -48,46 +56,65 @@ class Main(args: Array<String>) {
 			guiEnabled = false
 		}
 
-		val ui = if (guiEnabled) InstallWindow() else CLIHandler()
+		val ui = if (guiEnabled) GUIHandler() else CLIHandler()
 
 		val unparsedArgs = cmd.args
 		if (unparsedArgs.size > 1) {
-			ui.handleExceptionAndExit(RuntimeException("Too many arguments specified!"))
+			ui.showErrorAndExit("Too many arguments specified!")
 		} else if (unparsedArgs.isEmpty()) {
-			ui.handleExceptionAndExit(RuntimeException("URI to install from must be specified!"))
+			ui.showErrorAndExit("pack.toml URI to install from must be specified!")
 		}
 
-		cmd.getOptionValue("title")?.also(ui::setTitle)
-
-		val inputStateHandler = InputStateHandler()
-		ui.show(inputStateHandler)
-
-		val uOptions = UpdateManager.Options().apply {
-			side = cmd.getOptionValue("side")?.let((UpdateManager.Options.Side)::from) ?: side
-			packFolder = cmd.getOptionValue("pack-folder") ?: packFolder
-			manifestFile = cmd.getOptionValue("meta-file") ?: manifestFile
+		val title = cmd.getOptionValue("title")
+		if (title != null) {
+			ui.title = title
 		}
 
-		try {
-			uOptions.downloadURI = SpaceSafeURI(unparsedArgs[0])
-		} catch (e: URISyntaxException) {
-			// TODO: better error message?
-			ui.handleExceptionAndExit(e)
+		ui.show()
+
+		val packFileRaw = unparsedArgs[0]
+
+		val packFile = when {
+			// HTTP(s) URLs
+			Regex("^https?://", RegexOption.IGNORE_CASE).containsMatchIn(packFileRaw) -> ui.wrap("Invalid HTTP/HTTPS URL for pack file: $packFileRaw") {
+				HttpUrlPath(packFileRaw.toHttpUrl().resolve(".")!!, packFileRaw.toHttpUrl().pathSegments.last())
+			}
+			// File URIs (uses same logic as old packwiz-installer, for backwards compat)
+			Regex("^file:", RegexOption.IGNORE_CASE).containsMatchIn(packFileRaw) -> {
+				ui.wrap("Failed to parse file path for pack file: $packFileRaw") {
+					val path = Paths.get(URI(packFileRaw)).toOkioPath()
+					PackwizFilePath(path.parent ?: ui.showErrorAndExit("Invalid pack file path: $packFileRaw"), path.name)
+				}
+			}
+			// Other URIs (unsupported)
+			Regex("^[a-z][a-z\\d+\\-.]*://", RegexOption.IGNORE_CASE).containsMatchIn(packFileRaw) -> ui.showErrorAndExit("Unsupported scheme for pack file: $packFileRaw")
+			// None of the above matches -> interpret as file path
+			else -> PackwizFilePath(packFileRaw.toPath().parent ?: ui.showErrorAndExit("Invalid pack file path: $packFileRaw"), packFileRaw.toPath().name)
+		}
+		val side = cmd.getOptionValue("side")?.let {
+			Side.from(it) ?: ui.showErrorAndExit("Unknown side name: $it")
+		} ?: Side.CLIENT
+		val packFolder = ui.wrap("Invalid pack folder path") {
+			cmd.getOptionValue("pack-folder")?.let{ PackwizFilePath(it.toPath()) } ?: PackwizFilePath(".".toPath())
+		}
+		val multimcFolder = ui.wrap("Invalid MultiMC folder path") {
+			cmd.getOptionValue("multimc-folder")?.let{ PackwizFilePath(it.toPath()) } ?: PackwizFilePath("..".toPath())
+		}
+		val manifestFile = ui.wrap("Invalid manifest file path") {
+			packFolder / (cmd.getOptionValue("meta-file") ?: "packwiz.json")
+		}
+		val timeout = ui.wrap("Invalid timeout value") {
+			cmd.getOptionValue("timeout")?.toLong() ?: 10
 		}
 
 		// Start update process!
-		// TODO: start in SwingWorker?
 		try {
-			ui.executeManager {
-				try {
-					UpdateManager(uOptions, ui, inputStateHandler)
-				} catch (e: Exception) { // TODO: better error message?
-					ui.handleExceptionAndExit(e)
-				}
-			}
-		} catch (e: Exception) { // TODO: better error message?
-			ui.handleExceptionAndExit(e)
+			UpdateManager(UpdateManager.Options(packFile, manifestFile, packFolder, multimcFolder, side, timeout), ui)
+		} catch (e: Exception) {
+			ui.showErrorAndExit("Update process failed", e)
 		}
+		println("Finished successfully!")
+		ui.dispose()
 	}
 
 	companion object {
@@ -97,7 +124,9 @@ class Main(args: Array<String>) {
 			options.addOption("s", "side", true, "Side to install mods from (client/server, defaults to client)")
 			options.addOption(null, "title", true, "Title of the installer window")
 			options.addOption(null, "pack-folder", true, "Folder to install the pack to (defaults to the JAR directory)")
+			options.addOption(null, "multimc-folder", true, "The MultiMC pack folder (defaults to the parent of the pack directory)")
 			options.addOption(null, "meta-file", true, "JSON file to store pack metadata, relative to the pack folder (defaults to packwiz.json)")
+			options.addOption("t", "timeout", true, "Seconds to wait before automatically launching when asking about optional mods (defaults to 10)")
 		}
 
 		// TODO: link these somehow so they're only defined once?
@@ -110,6 +139,12 @@ class Main(args: Array<String>) {
 			options.addOption("g", "no-gui", false, "Don't display a GUI to show update progress")
 			options.addOption("h", "help", false, "Display this message") // Implemented in packwiz-installer-bootstrap!
 		}
+
+		@JvmStatic
+		fun main(args: Array<String>) {
+			Log.info("packwiz-installer was started without packwiz-installer-bootstrap. Use the bootstrapper for automatic updates! (Disregard this message if you have your own update mechanism)")
+			Main(args)
+		}
 	}
 
 	// Actual main() is in RequiresBootstrap!
@@ -118,17 +153,17 @@ class Main(args: Array<String>) {
 		try {
 			startup(args)
 		} catch (e: Exception) {
-			e.printStackTrace()
+			Log.fatal("Error from main", e)
 			if (guiEnabled) {
 				EventQueue.invokeLater {
 					JOptionPane.showMessageDialog(null,
-						"A fatal error occurred: \n" + e.javaClass.canonicalName + ": " + e.message,
+						"A fatal error occurred: \n$e",
 						"packwiz-installer", JOptionPane.ERROR_MESSAGE)
 					exitProcess(1)
 				}
+				// In case the EventQueue is broken, exit after 1 minute
+				Thread.sleep(60 * 1000.toLong())
 			}
-			// In case the EventQueue is broken, exit after 1 minute
-			Thread.sleep(60 * 1000.toLong())
 			exitProcess(1)
 		}
 	}

src/main/kotlin/link/infra/packwiz/installer/UpdateManager.kt

@@ -1,40 +1,39 @@
 package link.infra.packwiz.installer
 
+import cc.ekblad.toml.decode
 import com.google.gson.GsonBuilder
 import com.google.gson.JsonIOException
 import com.google.gson.JsonSyntaxException
-import com.google.gson.annotations.SerializedName
-import com.moandjiezana.toml.Toml
 import link.infra.packwiz.installer.DownloadTask.Companion.createTasksFromIndex
+import link.infra.packwiz.installer.metadata.DownloadMode
 import link.infra.packwiz.installer.metadata.IndexFile
 import link.infra.packwiz.installer.metadata.ManifestFile
 import link.infra.packwiz.installer.metadata.PackFile
-import link.infra.packwiz.installer.metadata.SpaceSafeURI
+import link.infra.packwiz.installer.metadata.curseforge.resolveCfMetadata
 import link.infra.packwiz.installer.metadata.hash.Hash
-import link.infra.packwiz.installer.metadata.hash.HashUtils.getHash
-import link.infra.packwiz.installer.metadata.hash.HashUtils.getHasher
-import link.infra.packwiz.installer.request.HandlerManager.getFileSource
-import link.infra.packwiz.installer.request.HandlerManager.getNewLoc
+import link.infra.packwiz.installer.metadata.hash.HashFormat
+import link.infra.packwiz.installer.request.RequestException
+import link.infra.packwiz.installer.target.ClientHolder
+import link.infra.packwiz.installer.target.Side
+import link.infra.packwiz.installer.target.path.PackwizFilePath
+import link.infra.packwiz.installer.target.path.PackwizPath
 import link.infra.packwiz.installer.ui.IUserInterface
 import link.infra.packwiz.installer.ui.IUserInterface.CancellationResult
 import link.infra.packwiz.installer.ui.IUserInterface.ExceptionListResult
-import link.infra.packwiz.installer.ui.InputStateHandler
-import link.infra.packwiz.installer.ui.InstallProgress
+import link.infra.packwiz.installer.ui.data.InstallProgress
+import link.infra.packwiz.installer.util.Log
 import okio.buffer
-import java.io.FileNotFoundException
-import java.io.FileReader
-import java.io.FileWriter
 import java.io.IOException
+import java.io.InputStreamReader
+import java.nio.charset.StandardCharsets
 import java.nio.file.Files
-import java.nio.file.Paths
-import java.util.*
 import java.util.concurrent.CompletionService
 import java.util.concurrent.ExecutionException
 import java.util.concurrent.ExecutorCompletionService
 import java.util.concurrent.Executors
 import kotlin.system.exitProcess
 
-class UpdateManager internal constructor(private val opts: Options, val ui: IUserInterface, private val stateHandler: InputStateHandler) {
+class UpdateManager internal constructor(private val opts: Options, val ui: IUserInterface) {
 	private var cancelled = false
 	private var cancelledStartGame = false
 	private var errorsOccurred = false
@@ -44,171 +43,153 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 	}
 
 	data class Options(
-			var downloadURI: SpaceSafeURI? = null,
-			var manifestFile: String = "packwiz.json", // TODO: make configurable
-			var packFolder: String = ".",
-			var side: Side = Side.CLIENT
-	) {
-		enum class Side {
-			@SerializedName("client")
-			CLIENT("client"),
-			@SerializedName("server")
-			SERVER("server"),
-			@SerializedName("both")
-			@Suppress("unused")
-			BOTH("both", arrayOf(CLIENT, SERVER));
-
-			private val sideName: String
-			private val depSides: Array<Side>?
-
-			constructor(sideName: String) {
-				this.sideName = sideName.toLowerCase()
-				depSides = null
-			}
-
-			constructor(sideName: String, depSides: Array<Side>) {
-				this.sideName = sideName.toLowerCase()
-				this.depSides = depSides
-			}
-
-			override fun toString() = sideName
-
-			fun hasSide(tSide: Side): Boolean {
-				if (this == tSide) {
-					return true
-				}
-				if (depSides != null) {
-					for (depSide in depSides) {
-						if (depSide == tSide) {
-							return true
-						}
-					}
-				}
-				return false
-			}
-
-			companion object {
-				fun from(name: String): Side? {
-					val lowerName = name.toLowerCase()
-					for (side in values()) {
-						if (side.sideName == lowerName) {
-							return side
-						}
-					}
-					return null
-				}
-			}
-		}
-	}
+		val packFile: PackwizPath<*>,
+		val manifestFile: PackwizFilePath,
+		val packFolder: PackwizFilePath,
+		val multimcFolder: PackwizFilePath,
+		val side: Side,
+		val timeout: Long,
+	)
 
+	// TODO: make this return a value based on results?
 	private fun start() {
-		checkOptions()
+		val clientHolder = ClientHolder()
+		ui.cancelCallback = {
+			clientHolder.close()
+		}
 
 		ui.submitProgress(InstallProgress("Loading manifest file..."))
-		val gson = GsonBuilder().registerTypeAdapter(Hash::class.java, Hash.TypeHandler()).create()
+		val gson = GsonBuilder()
+			.registerTypeAdapter(Hash::class.java, Hash.TypeHandler())
+			.registerTypeAdapter(PackwizFilePath::class.java, PackwizPath.adapterRelativeTo(opts.packFolder))
+			.enableComplexMapKeySerialization()
+			.create()
 		val manifest = try {
-			gson.fromJson(FileReader(Paths.get(opts.packFolder, opts.manifestFile).toString()),
-					ManifestFile::class.java)
-		} catch (e: FileNotFoundException) {
+			// TODO: kotlinx.serialisation?
+			InputStreamReader(opts.manifestFile.source(clientHolder).inputStream(), StandardCharsets.UTF_8).use { reader ->
+				gson.fromJson(reader, ManifestFile::class.java)
+			}
+		} catch (e: RequestException.Response.File.FileNotFound) {
+			ui.firstInstall = true
 			ManifestFile()
 		} catch (e: JsonSyntaxException) {
-			ui.handleExceptionAndExit(e)
-			return
+			ui.showErrorAndExit("Invalid local manifest file, try deleting ${opts.manifestFile}", e)
 		} catch (e: JsonIOException) {
-			ui.handleExceptionAndExit(e)
-			return
+			ui.showErrorAndExit("Failed to read local manifest file, try deleting ${opts.manifestFile}", e)
 		}
 
-		if (stateHandler.cancelButton) {
+		if (ui.cancelButtonPressed) {
 			showCancellationDialog()
 			handleCancellation()
 		}
 
 		ui.submitProgress(InstallProgress("Loading pack file..."))
 		val packFileSource = try {
-			val src = getFileSource(opts.downloadURI!!)
-			getHasher("sha256").getHashingSource(src)
+			val src = opts.packFile.source(clientHolder)
+			HashFormat.SHA256.source(src)
 		} catch (e: Exception) {
-			// TODO: run cancellation window?
-			ui.handleExceptionAndExit(e)
-			return
+			// TODO: ensure suppressed/caused exceptions are shown?
+			ui.showErrorAndExit("Failed to download pack.toml", e)
 		}
 		val pf = packFileSource.buffer().use {
 			try {
-				Toml().read(it.inputStream()).to(PackFile::class.java)
+				PackFile.mapper(opts.packFile).decode<PackFile>(it.inputStream())
 			} catch (e: IllegalStateException) {
-				ui.handleExceptionAndExit(e)
-				return
+				ui.showErrorAndExit("Failed to parse pack.toml", e)
 			}
 		}
 
-		if (stateHandler.cancelButton) {
+		if (ui.cancelButtonPressed) {
+			showCancellationDialog()
+			handleCancellation()
+		}
+
+		// Launcher checks
+		val lu = LauncherUtils(opts, ui)
+
+		// MultiMC MC and loader version checker
+		ui.submitProgress(InstallProgress("Loading MultiMC pack file..."))
+		try {
+			when (lu.handleMultiMC(pf, gson)) {
+				LauncherUtils.LauncherStatus.CANCELLED -> cancelled = true
+				LauncherUtils.LauncherStatus.NOT_FOUND -> Log.info("MultiMC not detected")
+				else -> {}
+			}
+			handleCancellation()
+		} catch (e: Exception) {
+			ui.showErrorAndExit(e.message!!, e)
+		}
+
+		if (ui.cancelButtonPressed) {
 			showCancellationDialog()
 			handleCancellation()
 		}
 
 		ui.submitProgress(InstallProgress("Checking local files..."))
 
-		// Invalidation checking must be done here, as it must happen before pack/index hashes are checked
-		val invalidatedUris: MutableList<SpaceSafeURI> = ArrayList()
-		for ((fileUri, file) in manifest.cachedFiles) {
-			// ignore onlyOtherSide files
-			if (file.onlyOtherSide) {
-				continue
-			}
+		// If the side changes, invalidate EVERYTHING (even when the index hasn't changed)
+		val invalidateAll = opts.side != manifest.cachedSide
+		val invalidatedUris: MutableList<PackwizFilePath> = ArrayList()
+		if (!invalidateAll) {
+			// Invalidation checking must be done here, as it must happen before pack/index hashes are checked
+			for ((fileUri, file) in manifest.cachedFiles) {
+				// ignore onlyOtherSide files
+				if (file.onlyOtherSide) {
+					continue
+				}
 
-			var invalid = false
-			// if isn't optional, or is optional but optionValue == true
-			if (!file.isOptional || file.optionValue) {
-				if (file.cachedLocation != null) {
-					if (!Paths.get(opts.packFolder, file.cachedLocation).toFile().exists()) {
+				var invalid = false
+				// if isn't optional, or is optional but optionValue == true
+				if (!file.isOptional || file.optionValue) {
+					if (file.cachedLocation != null) {
+						if (!file.cachedLocation!!.nioPath.toFile().exists()) {
+							invalid = true
+						}
+					} else {
+						// if cachedLocation == null, should probably be installed!!
 						invalid = true
 					}
-				} else {
-					// if cachedLocation == null, should probably be installed!!
-					invalid = true
+				}
+				if (invalid) {
+					Log.info("File ${fileUri.filename} invalidated, marked for redownloading")
+					invalidatedUris.add(fileUri)
 				}
 			}
-			if (invalid) {
-				println("File $fileUri invalidated, marked for redownloading")
-				invalidatedUris.add(fileUri)
+
+			if (manifest.packFileHash?.let { it == packFileSource.hash } == true && invalidatedUris.isEmpty()) {
+				// todo: --force?
+				ui.submitProgress(InstallProgress("Modpack is already up to date!", 1, 1))
+				if (manifest.cachedFiles.any { it.value.isOptional }) {
+					ui.awaitOptionalButton(false, opts.timeout)
+				}
+				if (!ui.optionsButtonPressed) {
+					return
+				}
 			}
 		}
 
-		if (manifest.packFileHash?.let { packFileSource.hashIsEqual(it) } == true && invalidatedUris.isEmpty()) {
-			println("Modpack is already up to date!")
-			// todo: --force?
-			if (!stateHandler.optionsButton) {
-				return
-			}
-		}
+		Log.info("Modpack name: ${pf.name}")
 
-		println("Modpack name: " + pf.name)
-
-		if (stateHandler.cancelButton) {
+		if (ui.cancelButtonPressed) {
 			showCancellationDialog()
 			handleCancellation()
 		}
 		try {
-			val index = pf.index!!
-			getNewLoc(opts.downloadURI, index.file)?.let { newLoc ->
-				index.hashFormat?.let { hashFormat ->
-					processIndex(
-						newLoc,
-						getHash(index.hashFormat!!, index.hash!!),
-						hashFormat,
-						manifest,
-						invalidatedUris
-					)
-				}
-			}
+			processIndex(
+				pf.index.file,
+				pf.index.hashFormat.fromString(pf.index.hash),
+				pf.index.hashFormat,
+				manifest,
+				invalidatedUris,
+				invalidateAll,
+				clientHolder
+			)
 		} catch (e1: Exception) {
-			ui.handleExceptionAndExit(e1)
+			ui.showErrorAndExit("Failed to process index file", e1)
 		}
 
 		handleCancellation()
 
-		// TODO: update MMC params, java args etc
 
 		// If there were errors, don't write the manifest/index hashes, to ensure they are rechecked later
 		if (errorsOccurred) {
@@ -220,82 +201,69 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 
 		manifest.cachedSide = opts.side
 		try {
-			FileWriter(Paths.get(opts.packFolder, opts.manifestFile).toString()).use { writer -> gson.toJson(manifest, writer) }
+			Files.newBufferedWriter(opts.manifestFile.nioPath, StandardCharsets.UTF_8).use { writer -> gson.toJson(manifest, writer) }
 		} catch (e: IOException) {
-			// TODO: add message?
-			ui.handleException(e)
+			ui.showErrorAndExit("Failed to save local manifest file", e)
 		}
 	}
 
-	private fun checkOptions() {
-		// TODO: implement
-	}
-
-	private fun processIndex(indexUri: SpaceSafeURI, indexHash: Hash, hashFormat: String, manifest: ManifestFile, invalidatedUris: List<SpaceSafeURI>) {
-		if (manifest.indexFileHash == indexHash && invalidatedUris.isEmpty()) {
-			println("Modpack files are already up to date!")
-			if (!stateHandler.optionsButton) {
-				return
+	private fun processIndex(indexUri: PackwizPath<*>, indexHash: Hash<*>, hashFormat: HashFormat<*>, manifest: ManifestFile, invalidatedFiles: List<PackwizFilePath>, invalidateAll: Boolean, clientHolder: ClientHolder) {
+		if (!invalidateAll) {
+			if (manifest.indexFileHash == indexHash && invalidatedFiles.isEmpty()) {
+				ui.submitProgress(InstallProgress("Modpack files are already up to date!", 1, 1))
+				if (manifest.cachedFiles.any { it.value.isOptional }) {
+					ui.awaitOptionalButton(false, opts.timeout)
+				}
+				if (!ui.optionsButtonPressed) {
+					return
+				}
+				if (ui.cancelButtonPressed) {
+					showCancellationDialog()
+					return
+				}
 			}
 		}
 		manifest.indexFileHash = indexHash
 
 		val indexFileSource = try {
-			val src = getFileSource(indexUri)
-			getHasher(hashFormat).getHashingSource(src)
+			val src = indexUri.source(clientHolder)
+			hashFormat.source(src)
 		} catch (e: Exception) {
-			// TODO: run cancellation window?
-			ui.handleExceptionAndExit(e)
-			return
+			ui.showErrorAndExit("Failed to download index file", e)
 		}
+
 		val indexFile = try {
-			Toml().read(indexFileSource.buffer().inputStream()).to(IndexFile::class.java)
+			IndexFile.mapper(indexUri).decode<IndexFile>(indexFileSource.buffer().inputStream())
 		} catch (e: IllegalStateException) {
-			ui.handleExceptionAndExit(e)
-			return
+			ui.showErrorAndExit("Failed to parse index file", e)
 		}
-		if (!indexFileSource.hashIsEqual(indexHash)) {
-			ui.handleExceptionAndExit(RuntimeException("Your index hash is invalid! Please run packwiz refresh on the pack again"))
-			return
+		if (indexHash != indexFileSource.hash) {
+			ui.showErrorAndExit("Your index file hash is invalid! The pack developer should packwiz refresh on the pack again")
 		}
-		if (stateHandler.cancelButton) {
+
+		if (ui.cancelButtonPressed) {
 			showCancellationDialog()
 			return
 		}
 
 		ui.submitProgress(InstallProgress("Checking local files..."))
-		// TODO: use kotlin filtering/FP rather than an iterator?
-		val it: MutableIterator<Map.Entry<SpaceSafeURI, ManifestFile.File>> = manifest.cachedFiles.entries.iterator()
+		val it: MutableIterator<Map.Entry<PackwizFilePath, ManifestFile.File>> = manifest.cachedFiles.entries.iterator()
 		while (it.hasNext()) {
 			val (uri, file) = it.next()
 			if (file.cachedLocation != null) {
-				var alreadyDeleted = false
-				// Delete if option value has been set to false
-				if (file.isOptional && !file.optionValue) {
+				if (indexFile.files.none { it.file.rebase(opts.packFolder) == uri }) { // File has been removed from the index
 					try {
-						Files.deleteIfExists(Paths.get(opts.packFolder, file.cachedLocation))
+						Files.deleteIfExists(file.cachedLocation!!.nioPath)
 					} catch (e: IOException) {
-						// TODO: should this be shown to the user in some way?
-						e.printStackTrace()
-					}
-					// Set to null, as it doesn't exist anymore
-					file.cachedLocation = null
-					alreadyDeleted = true
-				}
-				if (indexFile.files.none { it.file == uri }) { // File has been removed from the index
-					if (!alreadyDeleted) {
-						try {
-							Files.deleteIfExists(Paths.get(opts.packFolder, file.cachedLocation))
-						} catch (e: IOException) { // TODO: should this be shown to the user in some way?
-							e.printStackTrace()
-						}
+						Log.warn("Failed to delete file removed from index", e)
 					}
+					Log.info("Deleted ${file.cachedLocation!!.filename} (removed from pack)")
 					it.remove()
 				}
 			}
 		}
 
-		if (stateHandler.cancelButton) {
+		if (ui.cancelButtonPressed) {
 			showCancellationDialog()
 			return
 		}
@@ -303,51 +271,38 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 
 		// TODO: progress bar?
 		if (indexFile.files.isEmpty()) {
-			println("Warning: Index is empty!")
+			Log.warn("Index is empty!")
 		}
-		val tasks = createTasksFromIndex(indexFile, indexFile.hashFormat, opts.side)
-		// If the side changes, invalidate EVERYTHING just in case
-		// Might not be needed, but done just to be safe
-		val invalidateAll = opts.side != manifest.cachedSide
+		val tasks = createTasksFromIndex(indexFile, opts.side)
 		if (invalidateAll) {
-			println("Side changed, invalidating all mods")
+			Log.info("Side changed, invalidating all mods")
 		}
 		tasks.forEach{ f ->
 			// TODO: should linkedfile be checked as well? should this be done in the download section?
 			if (invalidateAll) {
 				f.invalidate()
-			} else if (invalidatedUris.contains(f.metadata.file)) {
+			} else if (invalidatedFiles.contains(f.metadata.file.rebase(opts.packFolder))) {
 				f.invalidate()
 			}
-			val file = manifest.cachedFiles[f.metadata.file]
+			val file = manifest.cachedFiles[f.metadata.file.rebase(opts.packFolder)]
 			// Ensure the file can be reverted later if necessary - the DownloadTask modifies the file so if it fails we need the old version back
 			file?.backup()
 			// If it is null, the DownloadTask will make a new empty cachedFile
 			f.updateFromCache(file)
 		}
 
-		if (stateHandler.cancelButton) {
+		if (ui.cancelButtonPressed) {
 			showCancellationDialog()
 			return
 		}
 
 		// Let's hope downloadMetadata is a pure function!!!
-		tasks.parallelStream().forEach { f -> f.downloadMetadata(indexFile, indexUri) }
+		tasks.parallelStream().forEach { f -> f.downloadMetadata(clientHolder) }
 
 		val failedTaskDetails = tasks.asSequence().map(DownloadTask::exceptionDetails).filterNotNull().toList()
 		if (failedTaskDetails.isNotEmpty()) {
 			errorsOccurred = true
-			val exceptionListResult: ExceptionListResult
-			exceptionListResult = try {
-				ui.showExceptions(failedTaskDetails, tasks.size, true).get()
-			} catch (e: InterruptedException) { // Interrupted means cancelled???
-				ui.handleExceptionAndExit(e)
-				return
-			} catch (e: ExecutionException) {
-				ui.handleExceptionAndExit(e)
-				return
-			}
-			when (exceptionListResult) {
+			when (ui.showExceptions(failedTaskDetails, tasks.size, true)) {
 				ExceptionListResult.CONTINUE -> {}
 				ExceptionListResult.CANCEL -> {
 					cancelled = true
@@ -360,80 +315,94 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 			}
 		}
 
-		if (stateHandler.cancelButton) {
+		if (ui.cancelButtonPressed) {
 			showCancellationDialog()
 			return
 		}
 
 		// TODO: task failed function?
-		val nonFailedFirstTasks = tasks.filter { t -> !t.failed() }.toList()
-		val optionTasks = nonFailedFirstTasks.filter(DownloadTask::correctSide).filter(DownloadTask::isOptional).toList()
-		// If options changed, present all options again
-		if (stateHandler.optionsButton || optionTasks.any(DownloadTask::isNewOptional)) {
-			// new ArrayList is required so it's an IOptionDetails rather than a DownloadTask list
-			val cancelledResult = ui.showOptions(ArrayList(optionTasks))
-			try {
-				if (cancelledResult.get()) {
-					cancelled = true
-					// TODO: Should the UI be closed somehow??
+		tasks.removeAll { it.failed() }
+		val optionTasks = tasks.filter(DownloadTask::correctSide).filter(DownloadTask::isOptional).toList()
+		val optionsChanged = optionTasks.any(DownloadTask::isNewOptional)
+		if (optionTasks.isNotEmpty() && !optionsChanged) {
+			if (!ui.optionsButtonPressed) {
+				// TODO: this is so ugly
+				ui.submitProgress(InstallProgress("Reconfigure optional mods?", 0,1))
+				ui.awaitOptionalButton(true, opts.timeout)
+				if (ui.cancelButtonPressed) {
+					showCancellationDialog()
 					return
 				}
-			} catch (e: InterruptedException) {
-				// Interrupted means cancelled???
-				ui.handleExceptionAndExit(e)
-			} catch (e: ExecutionException) {
-				ui.handleExceptionAndExit(e)
 			}
 		}
-		ui.disableOptionsButton()
+		// If options changed, present all options again
+		if (ui.optionsButtonPressed || optionsChanged) {
+			// new ArrayList is required so it's an IOptionDetails rather than a DownloadTask list
+			if (ui.showOptions(ArrayList(optionTasks))) {
+				cancelled = true
+				handleCancellation()
+			}
+		}
+		// TODO: keep this enabled? then apply changes after download process?
+		ui.disableOptionsButton(optionTasks.isNotEmpty())
+
+		while (true) {
+			when (validateAndResolve(tasks, clientHolder)) {
+				ResolveResult.RETRY -> {}
+				ResolveResult.QUIT -> return
+				ResolveResult.SUCCESS -> break
+			}
+		}
 
 		// TODO: different thread pool type?
 		val threadPool = Executors.newFixedThreadPool(10)
 		val completionService: CompletionService<DownloadTask> = ExecutorCompletionService(threadPool)
 		tasks.forEach { t ->
 			completionService.submit {
-				t.download(opts.packFolder, indexUri)
+				t.download(opts.packFolder, clientHolder)
 				t
 			}
 		}
 		for (i in tasks.indices) {
-			var task: DownloadTask?
-			task = try {
+			val task: DownloadTask = try {
 				completionService.take().get()
 			} catch (e: InterruptedException) {
-				ui.handleException(e)
-				null
+				ui.showErrorAndExit("Interrupted when consuming download tasks", e)
 			} catch (e: ExecutionException) {
-				ui.handleException(e)
-				null
+				ui.showErrorAndExit("Failed to execute download task", e)
 			}
 			// Update manifest - If there were no errors cachedFile has already been modified in place (good old pass by reference)
-			task?.cachedFile?.let { file ->
+			task.cachedFile?.let { file ->
 				if (task.failed()) {
 					val oldFile = file.revert
 					if (oldFile != null) {
-						task.metadata.file?.let { uri -> manifest.cachedFiles.putIfAbsent(uri, oldFile) }
+						manifest.cachedFiles.putIfAbsent(task.metadata.file.rebase(opts.packFolder), oldFile)
 					} else { null }
 				} else {
-					task.metadata.file?.let { uri -> manifest.cachedFiles.putIfAbsent(uri, file) }
+					manifest.cachedFiles.putIfAbsent(task.metadata.file.rebase(opts.packFolder), file)
 				}
 			}
 
-			var progress: String
-			if (task != null) {
-				val exDetails = task.exceptionDetails
-				if (exDetails != null) {
-					progress = "Failed to download ${exDetails.name}: ${exDetails.exception.message}"
-					exDetails.exception.printStackTrace()
-				} else {
-					progress = "Downloaded ${task.name}"
-				}
+			val exDetails = task.exceptionDetails
+			val progress = if (exDetails != null) {
+				"Failed to download ${exDetails.name}: ${exDetails.exception.message}"
 			} else {
-				progress = "Failed to download, unknown reason"
+				when (task.completionStatus) {
+					DownloadTask.CompletionStatus.INCOMPLETE -> "${task.name} pending (you should never see this...)"
+					DownloadTask.CompletionStatus.DOWNLOADED -> "Downloaded ${task.name}"
+					DownloadTask.CompletionStatus.ALREADY_EXISTS_CACHED -> "${task.name} already exists (cached)"
+					DownloadTask.CompletionStatus.ALREADY_EXISTS_VALIDATED -> "${task.name} already exists (validated)"
+					DownloadTask.CompletionStatus.SKIPPED_DISABLED -> "Skipped ${task.name} (disabled)"
+					DownloadTask.CompletionStatus.SKIPPED_WRONG_SIDE -> "Skipped ${task.name} (wrong side)"
+					DownloadTask.CompletionStatus.DELETED_DISABLED -> "Deleted ${task.name} (disabled)"
+					DownloadTask.CompletionStatus.DELETED_WRONG_SIDE -> "Deleted ${task.name} (wrong side)"
+				}
 			}
 			ui.submitProgress(InstallProgress(progress, i + 1, tasks.size))
 
-			if (stateHandler.cancelButton) { // Stop all tasks, don't launch the game (it's in an invalid state!)
+			if (ui.cancelButtonPressed) { // Stop all tasks, don't launch the game (it's in an invalid state!)
+				// TODO: close client holder in more places?
+				clientHolder.close()
 				threadPool.shutdown()
 				cancelled = true
 				return
@@ -443,21 +412,10 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 		// Shut down the thread pool when the update is done
 		threadPool.shutdown()
 
-		val failedTasks2ElectricBoogaloo = nonFailedFirstTasks.asSequence().map(DownloadTask::exceptionDetails).filterNotNull().toList()
+		val failedTasks2ElectricBoogaloo = tasks.asSequence().map(DownloadTask::exceptionDetails).filterNotNull().toList()
 		if (failedTasks2ElectricBoogaloo.isNotEmpty()) {
 			errorsOccurred = true
-			val exceptionListResult: ExceptionListResult
-			exceptionListResult = try {
-				ui.showExceptions(failedTasks2ElectricBoogaloo, tasks.size, false).get()
-			} catch (e: InterruptedException) {
-				// Interrupted means cancelled???
-				ui.handleExceptionAndExit(e)
-				return
-			} catch (e: ExecutionException) {
-				ui.handleExceptionAndExit(e)
-				return
-			}
-			when (exceptionListResult) {
+			when (ui.showExceptions(failedTasks2ElectricBoogaloo, tasks.size, false)) {
 				ExceptionListResult.CONTINUE -> {}
 				ExceptionListResult.CANCEL -> cancelled = true
 				ExceptionListResult.IGNORE -> cancelledStartGame = true
@@ -465,24 +423,57 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 		}
 	}
 
-	private fun showCancellationDialog() {
-		val cancellationResult: CancellationResult
-		cancellationResult = try {
-			ui.showCancellationDialog().get()
-		} catch (e: InterruptedException) {
-			// Interrupted means cancelled???
-			ui.handleExceptionAndExit(e)
-			return
-		} catch (e: ExecutionException) {
-			ui.handleExceptionAndExit(e)
-			return
+	enum class ResolveResult {
+		RETRY,
+		QUIT,
+		SUCCESS;
+	}
+
+	private fun validateAndResolve(nonFailedFirstTasks: List<DownloadTask>, clientHolder: ClientHolder): ResolveResult {
+		ui.submitProgress(InstallProgress("Validating existing files..."))
+
+		// Validate existing files
+		for (downloadTask in nonFailedFirstTasks.filter(DownloadTask::correctSide)) {
+			downloadTask.validateExistingFile(opts.packFolder, clientHolder)
 		}
-		when (cancellationResult) {
+
+		// Resolve CurseForge metadata
+		val cfFiles = nonFailedFirstTasks.asSequence().filter { !it.alreadyUpToDate }
+			.filter(DownloadTask::correctSide)
+			.map { it.metadata }
+			.filter { it.linkedFile != null }
+			.filter { it.linkedFile!!.download.mode == DownloadMode.CURSEFORGE }.toList()
+		if (cfFiles.isNotEmpty()) {
+			ui.submitProgress(InstallProgress("Resolving CurseForge metadata..."))
+			val resolveFailures = resolveCfMetadata(cfFiles, opts.packFolder, clientHolder)
+			if (resolveFailures.isNotEmpty()) {
+				errorsOccurred = true
+				return when (ui.showExceptions(resolveFailures, cfFiles.size, true)) {
+					ExceptionListResult.CONTINUE -> {
+						ResolveResult.RETRY
+					}
+					ExceptionListResult.CANCEL -> {
+						cancelled = true
+						ResolveResult.QUIT
+					}
+					ExceptionListResult.IGNORE -> {
+						cancelledStartGame = true
+						ResolveResult.QUIT
+					}
+				}
+			}
+		}
+		return ResolveResult.SUCCESS
+	}
+
+	private fun showCancellationDialog() {
+		when (ui.showCancellationDialog()) {
 			CancellationResult.QUIT -> cancelled = true
 			CancellationResult.CONTINUE -> cancelledStartGame = true
 		}
 	}
 
+	// TODO: move to UI?
 	private fun handleCancellation() {
 		if (cancelled) {
 			println("Update cancelled by user!")
@@ -492,4 +483,5 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 			exitProcess(0)
 		}
 	}
+
 }

src/main/kotlin/link/infra/packwiz/installer/metadata/DownloadMode.kt

@@ -0,0 +1,19 @@
+package link.infra.packwiz.installer.metadata
+
+import cc.ekblad.toml.model.TomlValue
+import cc.ekblad.toml.tomlMapper
+
+enum class DownloadMode {
+	URL,
+	CURSEFORGE;
+
+	companion object {
+		fun mapper() = tomlMapper {
+			decoder { it: TomlValue.String -> when (it.value) {
+				"", "url" -> URL
+				"metadata:curseforge" -> CURSEFORGE
+				else -> throw Exception("Unsupported download mode ${it.value}")
+			} }
+		}
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/EfficientBooleanAdapter.kt

@@ -17,7 +17,7 @@ class EfficientBooleanAdapter : TypeAdapter<Boolean?>() {
 	}
 
 	@Throws(IOException::class)
-	override fun read(reader: JsonReader): Boolean? {
+	override fun read(reader: JsonReader): Boolean {
 		if (reader.peek() == JsonToken.NULL) {
 			reader.nextNull()
 			return false

src/main/kotlin/link/infra/packwiz/installer/metadata/IndexFile.kt

@@ -1,99 +1,97 @@
 package link.infra.packwiz.installer.metadata
 
-import com.google.gson.annotations.SerializedName
-import com.moandjiezana.toml.Toml
+import cc.ekblad.toml.decode
+import cc.ekblad.toml.tomlMapper
 import link.infra.packwiz.installer.metadata.hash.Hash
-import link.infra.packwiz.installer.metadata.hash.HashUtils.getHash
-import link.infra.packwiz.installer.metadata.hash.HashUtils.getHasher
-import link.infra.packwiz.installer.request.HandlerManager.getFileSource
-import link.infra.packwiz.installer.request.HandlerManager.getNewLoc
+import link.infra.packwiz.installer.metadata.hash.HashFormat
+import link.infra.packwiz.installer.target.ClientHolder
+import link.infra.packwiz.installer.target.path.PackwizPath
+import link.infra.packwiz.installer.util.delegateTransitive
 import okio.Source
 import okio.buffer
-import java.nio.file.Paths
 
-class IndexFile {
-	@SerializedName("hash-format")
-	var hashFormat: String = "sha-256"
-	var files: MutableList<File> = ArrayList()
-
-	class File {
-		var file: SpaceSafeURI? = null
-		@SerializedName("hash-format")
-		var hashFormat: String? = null
-		var hash: String? = null
-		var alias: SpaceSafeURI? = null
-		var metafile = false
-		var preserve = false
-
-		@Transient
+data class IndexFile(
+	val hashFormat: HashFormat<*>,
+	val files: List<File> = listOf()
+) {
+	data class File(
+		val file: PackwizPath<*>,
+		private val hashFormat: HashFormat<*>? = null,
+		val hash: String,
+		val alias: PackwizPath<*>?,
+		val metafile: Boolean = false,
+		val preserve: Boolean = false,
+	) {
 		var linkedFile: ModFile? = null
-		@Transient
-		var linkedFileURI: SpaceSafeURI? = null
+
+		fun hashFormat(index: IndexFile) = hashFormat ?: index.hashFormat
+		@Throws(Exception::class)
+		fun getHashObj(index: IndexFile): Hash<*> {
+			// TODO: more specific exceptions?
+			return hashFormat(index).fromString(hash)
+		}
 
 		@Throws(Exception::class)
-		fun downloadMeta(parentIndexFile: IndexFile, indexUri: SpaceSafeURI?) {
+		fun downloadMeta(index: IndexFile, clientHolder: ClientHolder) {
 			if (!metafile) {
 				return
 			}
-			if (hashFormat?.length ?: 0 == 0) {
-				hashFormat = parentIndexFile.hashFormat
-			}
-			// TODO: throw a proper exception instead of allowing NPE?
-			val fileHash = getHash(hashFormat!!, hash!!)
-			linkedFileURI = getNewLoc(indexUri, file)
-			val src = getFileSource(linkedFileURI!!)
-			val fileStream = getHasher(hashFormat!!).getHashingSource(src)
-			linkedFile = Toml().read(fileStream.buffer().inputStream()).to(ModFile::class.java)
-			if (!fileStream.hashIsEqual(fileHash)) {
+			val fileHash = getHashObj(index)
+			val src = file.source(clientHolder)
+			val fileStream = hashFormat(index).source(src)
+			linkedFile = ModFile.mapper(file).decode<ModFile>(fileStream.buffer().inputStream())
+			if (fileHash != fileStream.hash) {
+				// TODO: propagate details about hash, and show better error!
 				throw Exception("Invalid mod file hash")
 			}
 		}
 
 		@Throws(Exception::class)
-		fun getSource(indexUri: SpaceSafeURI?): Source {
+		fun getSource(clientHolder: ClientHolder): Source {
 			return if (metafile) {
 				if (linkedFile == null) {
 					throw Exception("Linked file doesn't exist!")
 				}
-				linkedFile!!.getSource(linkedFileURI)
+				linkedFile!!.getSource(clientHolder)
 			} else {
-				val newLoc = getNewLoc(indexUri, file) ?: throw Exception("Index file URI is invalid")
-				getFileSource(newLoc)
+				file.source(clientHolder)
 			}
 		}
 
-		@Throws(Exception::class)
-		fun getHashObj(): Hash {
-			if (hash == null) { // TODO: should these be more specific exceptions (e.g. IndexFileException?!)
-				throw Exception("Index file doesn't have a hash")
-			}
-			if (hashFormat == null) {
-				throw Exception("Index file doesn't have a hash format")
-			}
-			return getHash(hashFormat!!, hash!!)
-		}
-
-		// TODO: throw some kind of exception?
 		val name: String
 			get() {
 				if (metafile) {
-					return linkedFile?.name ?: linkedFile?.filename ?:
-					file?.run { Paths.get(path).fileName.toString() } ?: "Invalid file"
+					return linkedFile?.name ?: file.filename
 				}
-				return file?.run { Paths.get(path).fileName.toString() } ?: "Invalid file"
+				return file.filename
 			}
 
-		// TODO: URIs are bad
-		val destURI: SpaceSafeURI?
+		val destURI: PackwizPath<*>
 			get() {
 				if (alias != null) {
 					return alias
 				}
-				return if (metafile && linkedFile != null) {
-					linkedFile?.filename?.let { file?.resolve(it) }
+				return if (metafile) {
+					linkedFile!!.filename
 				} else {
 					file
 				}
 			}
+
+		companion object {
+			fun mapper(base: PackwizPath<*>) = tomlMapper {
+				mapping<File>("hash-format" to "hashFormat")
+				delegateTransitive<HashFormat<*>>(HashFormat.mapper())
+				delegateTransitive<PackwizPath<*>>(PackwizPath.mapperRelativeTo(base))
+			}
+		}
+	}
+
+	companion object {
+		fun mapper(base: PackwizPath<*>) = tomlMapper {
+			mapping<IndexFile>("hash-format" to "hashFormat")
+			delegateTransitive<HashFormat<*>>(HashFormat.mapper())
+			delegateTransitive<File>(File.mapper(base))
+		}
 	}
 }

src/main/kotlin/link/infra/packwiz/installer/metadata/ManifestFile.kt

@@ -1,25 +1,25 @@
 package link.infra.packwiz.installer.metadata
 
 import com.google.gson.annotations.JsonAdapter
-import link.infra.packwiz.installer.UpdateManager
 import link.infra.packwiz.installer.metadata.hash.Hash
+import link.infra.packwiz.installer.target.Side
+import link.infra.packwiz.installer.target.path.PackwizFilePath
 
 class ManifestFile {
-	var packFileHash: Hash? = null
-	var indexFileHash: Hash? = null
-	var cachedFiles: MutableMap<SpaceSafeURI, File> = HashMap()
+	var packFileHash: Hash<*>? = null
+	var indexFileHash: Hash<*>? = null
+	var cachedFiles: MutableMap<PackwizFilePath, File> = HashMap()
 	// If the side changes, EVERYTHING invalidates. FUN!!!
-	var cachedSide = UpdateManager.Options.Side.CLIENT
+	var cachedSide = Side.CLIENT
 
-	// TODO: switch to Kotlin-friendly JSON/TOML libs?
 	class File {
 		@Transient
 		var revert: File? = null
 			private set
 
-		var hash: Hash? = null
-		var linkedFileHash: Hash? = null
-		var cachedLocation: String? = null
+		var hash: Hash<*>? = null
+		var linkedFileHash: Hash<*>? = null
+		var cachedLocation: PackwizFilePath? = null
 
 		@JsonAdapter(EfficientBooleanAdapter::class)
 		var isOptional = false

src/main/kotlin/link/infra/packwiz/installer/metadata/ModFile.kt

@@ -1,57 +1,96 @@
 package link.infra.packwiz.installer.metadata
 
-import com.google.gson.annotations.SerializedName
-import link.infra.packwiz.installer.UpdateManager
+import cc.ekblad.toml.delegate
+import cc.ekblad.toml.model.TomlValue
+import cc.ekblad.toml.tomlMapper
+import link.infra.packwiz.installer.metadata.curseforge.UpdateData
 import link.infra.packwiz.installer.metadata.hash.Hash
-import link.infra.packwiz.installer.metadata.hash.HashUtils.getHash
-import link.infra.packwiz.installer.request.HandlerManager.getFileSource
-import link.infra.packwiz.installer.request.HandlerManager.getNewLoc
+import link.infra.packwiz.installer.metadata.hash.HashFormat
+import link.infra.packwiz.installer.target.ClientHolder
+import link.infra.packwiz.installer.target.Side
+import link.infra.packwiz.installer.target.path.HttpUrlPath
+import link.infra.packwiz.installer.target.path.PackwizPath
+import link.infra.packwiz.installer.util.delegateTransitive
+import okhttp3.HttpUrl.Companion.toHttpUrl
 import okio.Source
+import kotlin.reflect.KType
 
-class ModFile {
-	var name: String? = null
-	var filename: String? = null
-	var side: UpdateManager.Options.Side? = null
-	var download: Download? = null
+data class ModFile(
+	val name: String,
+	val filename: PackwizPath<*>,
+	val side: Side = Side.BOTH,
+	val download: Download,
+	val update: Map<String, UpdateData> = mapOf(),
+	val option: Option = Option(false)
+) {
+	data class Download(
+		val url: PackwizPath<*>?,
+		val hashFormat: HashFormat<*>,
+		val hash: String,
+		val mode: DownloadMode = DownloadMode.URL
+	) {
+		companion object {
+			fun mapper() = tomlMapper {
+				decoder<TomlValue.String, PackwizPath<*>> { it -> HttpUrlPath(it.value.toHttpUrl()) }
+				mapping<Download>("hash-format" to "hashFormat")
 
-	class Download {
-		var url: SpaceSafeURI? = null
-		@SerializedName("hash-format")
-		var hashFormat: String? = null
-		var hash: String? = null
+				delegateTransitive<HashFormat<*>>(HashFormat.mapper())
+				delegate<DownloadMode>(DownloadMode.mapper())
+			}
+		}
 	}
 
-	var update: Map<String, Any>? = null
-	var option: Option? = null
+	@Transient
+	val resolvedUpdateData = mutableMapOf<String, PackwizPath<*>>()
 
-	class Option {
-		var optional = false
-		var description: String? = null
-		@SerializedName("default")
-		var defaultValue = false
+	data class Option(
+		val optional: Boolean,
+		val description: String = "",
+		val defaultValue: Boolean = false
+	) {
+		companion object {
+			fun mapper() = tomlMapper {
+				mapping<Option>("default" to "defaultValue")
+			}
+		}
 	}
 
 	@Throws(Exception::class)
-	fun getSource(baseLoc: SpaceSafeURI?): Source {
-		download?.let {
-			if (it.url == null) {
-				throw Exception("Metadata file doesn't have a download URI")
+	fun getSource(clientHolder: ClientHolder): Source {
+		return when (download.mode) {
+			DownloadMode.URL -> {
+				(download.url ?: throw Exception("No download URL provided")).source(clientHolder)
 			}
-			val newLoc = getNewLoc(baseLoc, it.url) ?: throw Exception("Metadata file URI is invalid")
-			return getFileSource(newLoc)
-		} ?: throw Exception("Metadata file doesn't have download")
+			DownloadMode.CURSEFORGE -> {
+				if (!resolvedUpdateData.contains("curseforge")) {
+					throw Exception("Metadata file specifies CurseForge mode, but is missing metadata")
+				}
+				return resolvedUpdateData["curseforge"]!!.source(clientHolder)
+			}
+		}
 	}
 
 	@get:Throws(Exception::class)
-	val hash: Hash
-		get() {
-			download?.let {
-				return getHash(
-						it.hashFormat ?: throw Exception("Metadata file doesn't have a hash format"),
-						it.hash ?: throw Exception("Metadata file doesn't have a hash")
-				)
-			} ?: throw Exception("Metadata file doesn't have download")
-		}
+	val hash: Hash<*>
+		get() = download.hashFormat.fromString(download.hash)
 
-	val isOptional: Boolean get() = option?.optional ?: false
+	companion object {
+		fun mapper(base: PackwizPath<*>) = tomlMapper {
+			delegateTransitive<PackwizPath<*>>(PackwizPath.mapperRelativeTo(base))
+
+			delegateTransitive<Option>(Option.mapper())
+			delegateTransitive<Download>(Download.mapper())
+
+			delegateTransitive<Side>(Side.mapper())
+
+			val updateDataMapper = UpdateData.mapper()
+			decoder { type: KType, it: TomlValue.Map ->
+				if (type.arguments[1].type?.classifier == UpdateData::class) {
+					updateDataMapper.decode<Map<String, UpdateData>>(it)
+				} else {
+					pass()
+				}
+			}
+		}
+	}
 }

src/main/kotlin/link/infra/packwiz/installer/metadata/PackFile.kt

@@ -1,19 +1,37 @@
 package link.infra.packwiz.installer.metadata
 
-import com.google.gson.annotations.SerializedName
+import cc.ekblad.toml.model.TomlValue
+import cc.ekblad.toml.tomlMapper
+import link.infra.packwiz.installer.metadata.hash.HashFormat
+import link.infra.packwiz.installer.target.path.PackwizPath
+import link.infra.packwiz.installer.util.delegateTransitive
 
-class PackFile {
-	var name: String? = null
-	var index: IndexFileLoc? = null
-
-	class IndexFileLoc {
-		var file: SpaceSafeURI? = null
-		@SerializedName("hash-format")
-		var hashFormat: String? = null
-		var hash: String? = null
+data class PackFile(
+	val name: String,
+	val packFormat: PackFormat = PackFormat.DEFAULT,
+	val index: IndexFileLoc,
+	val versions: Map<String, String> = mapOf()
+) {
+	data class IndexFileLoc(
+		val file: PackwizPath<*>,
+		val hashFormat: HashFormat<*>,
+		val hash: String,
+	) {
+		companion object {
+			fun mapper(base: PackwizPath<*>) = tomlMapper {
+				mapping<IndexFileLoc>("hash-format" to "hashFormat")
+				delegateTransitive<PackwizPath<*>>(PackwizPath.mapperRelativeTo(base))
+				delegateTransitive<HashFormat<*>>(HashFormat.mapper())
+			}
+		}
 	}
 
-	var versions: Map<String, String>? = null
-	var client: Map<String, Any>? = null
-	var server: Map<String, Any>? = null
+	companion object {
+		fun mapper(base: PackwizPath<*>) = tomlMapper {
+			mapping<PackFile>("pack-format" to "packFormat")
+			decoder { it: TomlValue.String -> PackFormat(it.value) }
+			encoder { it: PackFormat -> TomlValue.String(it.format) }
+			delegateTransitive<IndexFileLoc>(IndexFileLoc.mapper(base))
+		}
+	}
 }

src/main/kotlin/link/infra/packwiz/installer/metadata/PackFormat.kt

@@ -0,0 +1,10 @@
+package link.infra.packwiz.installer.metadata
+
+@JvmInline
+value class PackFormat(val format: String) {
+	companion object {
+		val DEFAULT = PackFormat("packwiz:1.0.0")
+	}
+
+	// TODO: implement validation, errors for too new / invalid versions
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/SpaceSafeURI.kt

@@ -1,61 +0,0 @@
-package link.infra.packwiz.installer.metadata
-
-import com.google.gson.annotations.JsonAdapter
-import java.io.Serializable
-import java.net.MalformedURLException
-import java.net.URI
-import java.net.URISyntaxException
-import java.net.URL
-
-// The world's worst URI wrapper
-@JsonAdapter(SpaceSafeURIParser::class)
-class SpaceSafeURI : Comparable<SpaceSafeURI>, Serializable {
-	private val u: URI
-
-	@Throws(URISyntaxException::class)
-	constructor(str: String) {
-		u = URI(str.replace(" ", "%20"))
-	}
-
-	constructor(uri: URI) {
-		u = uri
-	}
-
-	@Throws(URISyntaxException::class)
-	constructor(scheme: String?, authority: String?, path: String?, query: String?, fragment: String?) { // TODO: do all components need to be replaced?
-		u = URI(
-				scheme?.replace(" ", "%20"),
-				authority?.replace(" ", "%20"),
-				path?.replace(" ", "%20"),
-				query?.replace(" ", "%20"),
-				fragment?.replace(" ", "%20")
-		)
-	}
-
-	val path: String get() = u.path.replace("%20", " ")
-
-	override fun toString(): String = u.toString().replace("%20", " ")
-
-	fun resolve(path: String): SpaceSafeURI = SpaceSafeURI(u.resolve(path.replace(" ", "%20")))
-
-	fun resolve(loc: SpaceSafeURI): SpaceSafeURI = SpaceSafeURI(u.resolve(loc.u))
-
-	fun relativize(loc: SpaceSafeURI): SpaceSafeURI = SpaceSafeURI(u.relativize(loc.u))
-
-	override fun equals(other: Any?): Boolean {
-		return if (other is SpaceSafeURI) {
-			u == other.u
-		} else false
-	}
-
-	override fun hashCode() = u.hashCode()
-
-	override fun compareTo(other: SpaceSafeURI): Int = u.compareTo(other.u)
-
-	val scheme: String get() = u.scheme
-	val authority: String get() = u.authority
-	val host: String get() = u.host
-
-	@Throws(MalformedURLException::class)
-	fun toURL(): URL = u.toURL()
-}

src/main/kotlin/link/infra/packwiz/installer/metadata/SpaceSafeURIParser.kt

@@ -1,25 +0,0 @@
-package link.infra.packwiz.installer.metadata
-
-import com.google.gson.JsonDeserializationContext
-import com.google.gson.JsonDeserializer
-import com.google.gson.JsonElement
-import com.google.gson.JsonParseException
-import java.lang.reflect.Type
-import java.net.URISyntaxException
-
-/**
- * This class encodes spaces before parsing the URI, so the URI can actually be
- * parsed.
- */
-internal class SpaceSafeURIParser : JsonDeserializer<SpaceSafeURI> {
-	@Throws(JsonParseException::class)
-	override fun deserialize(json: JsonElement, typeOfT: Type, context: JsonDeserializationContext): SpaceSafeURI {
-		return try {
-			SpaceSafeURI(json.asString)
-		} catch (e: URISyntaxException) {
-			throw JsonParseException("Failed to parse URI", e)
-		}
-	}
-
-	// TODO: replace this with a better solution?
-}

src/main/kotlin/link/infra/packwiz/installer/metadata/curseforge/CurseForgeSourcer.kt

@@ -0,0 +1,159 @@
+package link.infra.packwiz.installer.metadata.curseforge
+
+import com.google.gson.Gson
+import com.google.gson.JsonIOException
+import com.google.gson.JsonSyntaxException
+import link.infra.packwiz.installer.metadata.IndexFile
+import link.infra.packwiz.installer.target.ClientHolder
+import link.infra.packwiz.installer.target.path.HttpUrlPath
+import link.infra.packwiz.installer.target.path.PackwizFilePath
+import link.infra.packwiz.installer.ui.data.ExceptionDetails
+import okhttp3.HttpUrl.Companion.toHttpUrl
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.Request
+import okhttp3.RequestBody.Companion.toRequestBody
+import okhttp3.internal.closeQuietly
+import okio.ByteString.Companion.decodeBase64
+import java.nio.charset.StandardCharsets
+import kotlin.io.path.absolute
+
+private class GetFilesRequest(val fileIds: List<Int>)
+private class GetModsRequest(val modIds: List<Int>)
+
+private class GetFilesResponse {
+	class CfFile {
+		var id = 0
+		var modId = 0
+		var downloadUrl: String? = null
+	}
+	val data = mutableListOf<CfFile>()
+}
+
+private class GetModsResponse {
+	class CfMod {
+		var id = 0
+		var name = ""
+		var links: CfLinks? = null
+	}
+	class CfLinks {
+		var websiteUrl = ""
+	}
+	val data = mutableListOf<CfMod>()
+}
+
+private const val APIServer = "api.curseforge.com"
+// If you fork/derive from packwiz, I request that you obtain your own API key.
+private val APIKey = "JDJhJDEwJHNBWVhqblU1N0EzSmpzcmJYM3JVdk92UWk2NHBLS3BnQ2VpbGc1TUM1UGNKL0RYTmlGWWxh".decodeBase64()!!
+	.string(StandardCharsets.UTF_8)
+
+@Throws(JsonSyntaxException::class, JsonIOException::class)
+fun resolveCfMetadata(mods: List<IndexFile.File>, packFolder: PackwizFilePath, clientHolder: ClientHolder): List<ExceptionDetails> {
+	val failures = mutableListOf<ExceptionDetails>()
+	val fileIdMap = mutableMapOf<Int, List<IndexFile.File>>()
+
+	for (mod in mods) {
+		if (!mod.linkedFile!!.update.contains("curseforge")) {
+			failures.add(ExceptionDetails(mod.linkedFile!!.name, Exception("Failed to resolve CurseForge metadata: no CurseForge update section")))
+			continue
+		}
+		val fileId = (mod.linkedFile!!.update["curseforge"] as CurseForgeUpdateData).fileId
+		fileIdMap[fileId] = (fileIdMap[fileId] ?: listOf()) + mod
+	}
+
+	val reqData = GetFilesRequest(fileIdMap.keys.toList())
+	val req = Request.Builder()
+		.url("https://${APIServer}/v1/mods/files")
+		.header("Accept", "application/json")
+		.header("User-Agent", "packwiz-installer")
+		.header("X-API-Key", APIKey)
+		.post(Gson().toJson(reqData, GetFilesRequest::class.java).toRequestBody("application/json".toMediaType()))
+		.build()
+	val res = clientHolder.okHttpClient.newCall(req).execute()
+	if (!res.isSuccessful || res.body == null) {
+		res.closeQuietly()
+		failures.add(ExceptionDetails("Other", Exception("Failed to resolve CurseForge metadata for file data: error code ${res.code}")))
+		return failures
+	}
+
+	val resData = Gson().fromJson(res.body!!.charStream(), GetFilesResponse::class.java)
+	res.closeQuietly()
+
+	val manualDownloadMods = mutableMapOf<Int, List<Int>>()
+	for (file in resData.data) {
+		if (!fileIdMap.contains(file.id)) {
+			failures.add(ExceptionDetails(file.id.toString(),
+				Exception("Failed to find file from result: ID ${file.id}, Project ID ${file.modId}")))
+			continue
+		}
+		if (file.downloadUrl == null) {
+			manualDownloadMods[file.modId] = (manualDownloadMods[file.modId] ?: listOf()) + file.id
+			continue
+		}
+		try {
+			for (indexFile in fileIdMap[file.id]!!) {
+				indexFile.linkedFile!!.resolvedUpdateData["curseforge"] =
+					HttpUrlPath(file.downloadUrl!!.toHttpUrl())
+			}
+		} catch (e: IllegalArgumentException) {
+			failures.add(ExceptionDetails(file.id.toString(),
+				Exception("Failed to parse URL: ${file.downloadUrl} for ID ${file.id}, Project ID ${file.modId}", e)))
+		}
+	}
+
+	// Some file types don't show up in the API at all! (e.g. shaderpacks)
+	// Add unresolved files to manualDownloadMods
+	for ((fileId, indexFiles) in fileIdMap) {
+		for (file in indexFiles) {
+			if (file.linkedFile != null) {
+				if (file.linkedFile!!.resolvedUpdateData["curseforge"] == null) {
+					val projectId = (file.linkedFile!!.update["curseforge"] as CurseForgeUpdateData).projectId
+					manualDownloadMods[projectId] = (manualDownloadMods[projectId] ?: listOf()) + fileId
+				}
+			}
+		}
+	}
+
+	if (manualDownloadMods.isNotEmpty()) {
+		val reqModsData = GetModsRequest(manualDownloadMods.keys.toList())
+		val reqMods = Request.Builder()
+			.url("https://${APIServer}/v1/mods")
+			.header("Accept", "application/json")
+			.header("User-Agent", "packwiz-installer")
+			.header("X-API-Key", APIKey)
+			.post(Gson().toJson(reqModsData, GetModsRequest::class.java).toRequestBody("application/json".toMediaType()))
+			.build()
+		val resMods = clientHolder.okHttpClient.newCall(reqMods).execute()
+		if (!resMods.isSuccessful || resMods.body == null) {
+			resMods.closeQuietly()
+			failures.add(ExceptionDetails("Other", Exception("Failed to resolve CurseForge metadata for mod data: error code ${resMods.code}")))
+			return failures
+		}
+
+		val resModsData = Gson().fromJson(resMods.body!!.charStream(), GetModsResponse::class.java)
+		resMods.closeQuietly()
+
+		for (mod in resModsData.data) {
+			if (!manualDownloadMods.contains(mod.id)) {
+				failures.add(ExceptionDetails(mod.name,
+					Exception("Failed to find project from result: ID ${mod.id}")))
+				continue
+			}
+
+			for (fileId in manualDownloadMods[mod.id]!!) {
+				if (!fileIdMap.contains(fileId)) {
+					failures.add(ExceptionDetails(mod.name,
+						Exception("Failed to find file from result: file ID $fileId")))
+					continue
+				}
+
+				for (indexFile in fileIdMap[fileId]!!) {
+					var modUrl = "${mod.links?.websiteUrl}/files/${fileId}"
+					failures.add(ExceptionDetails(indexFile.name, Exception("This mod is excluded from the CurseForge API and must be downloaded manually.\n" +
+						"Please go to ${modUrl} and save this file to ${indexFile.destURI.rebase(packFolder).nioPath.absolute()}"), modUrl))
+				}
+			}
+		}
+	}
+
+	return failures
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/curseforge/CurseForgeUpdateData.kt

@@ -0,0 +1,14 @@
+package link.infra.packwiz.installer.metadata.curseforge
+
+import cc.ekblad.toml.tomlMapper
+
+data class CurseForgeUpdateData(
+	val fileId: Int,
+	val projectId: Int,
+): UpdateData {
+	companion object {
+		fun mapper() = tomlMapper {
+			mapping<CurseForgeUpdateData>("file-id" to "fileId", "project-id" to "projectId")
+		}
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/curseforge/UpdateData.kt

@@ -0,0 +1,17 @@
+package link.infra.packwiz.installer.metadata.curseforge
+
+import cc.ekblad.toml.model.TomlValue
+import cc.ekblad.toml.tomlMapper
+
+interface UpdateData {
+	companion object {
+		fun mapper() = tomlMapper {
+			val cfMapper = CurseForgeUpdateData.mapper()
+			decoder { it: TomlValue.Map ->
+				if (it.properties.contains("curseforge")) {
+					mapOf("curseforge" to cfMapper.decode<CurseForgeUpdateData>(it.properties["curseforge"]!!))
+				} else { mapOf() }
+			}
+		}
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/curseforge/UpdateDeserializer.kt

@@ -0,0 +1,22 @@
+package link.infra.packwiz.installer.metadata.curseforge
+
+import com.google.gson.JsonDeserializationContext
+import com.google.gson.JsonDeserializer
+import com.google.gson.JsonElement
+import java.lang.reflect.Type
+
+class UpdateDeserializer: JsonDeserializer<Map<String, UpdateData>> {
+	override fun deserialize(
+		json: JsonElement?,
+		typeOfT: Type?,
+		context: JsonDeserializationContext?
+	): Map<String, UpdateData> {
+		val out = mutableMapOf<String, UpdateData>()
+		for ((k, v) in json!!.asJsonObject.entrySet()) {
+			if (k == "curseforge") {
+				out[k] = context!!.deserialize(v, CurseForgeUpdateData::class.java)
+			}
+		}
+		return out
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/GeneralHashingSource.kt

@@ -1,10 +0,0 @@
-package link.infra.packwiz.installer.metadata.hash
-
-import okio.ForwardingSource
-import okio.Source
-
-abstract class GeneralHashingSource(delegate: Source) : ForwardingSource(delegate) {
-	abstract val hash: Hash
-
-	fun hashIsEqual(compareTo: Any) = compareTo == hash
-}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/Hash.kt

@@ -1,20 +1,62 @@
 package link.infra.packwiz.installer.metadata.hash
 
 import com.google.gson.*
+import link.infra.packwiz.installer.metadata.hash.Hash.SourceProvider
+import okio.ByteString
+import okio.ByteString.Companion.decodeHex
+import okio.ForwardingSource
+import okio.HashingSource
+import okio.Source
 import java.lang.reflect.Type
 
-abstract class Hash {
-	protected abstract val stringValue: String
-	protected abstract val type: String
+data class Hash<T>(val type: HashFormat<T>, val value: T) {
+	interface Encoding<T> {
+		fun encodeToString(value: T): String
+		fun decodeFromString(str: String): T
 
-	class TypeHandler : JsonDeserializer<Hash>, JsonSerializer<Hash> {
-		override fun serialize(src: Hash, typeOfSrc: Type, context: JsonSerializationContext): JsonElement = JsonObject().apply {
-			add("type", JsonPrimitive(src.type))
-			add("value", JsonPrimitive(src.stringValue))
+		object Hex: Encoding<ByteString> {
+			override fun encodeToString(value: ByteString) = value.hex()
+			override fun decodeFromString(str: String) = str.decodeHex()
+		}
+
+		object UInt: Encoding<kotlin.UInt> {
+			override fun encodeToString(value: kotlin.UInt) = value.toString()
+			override fun decodeFromString(str: String) =
+				try {
+					str.toUInt()
+				} catch (e: NumberFormatException) {
+					// Old packwiz.json values are signed; if they are negative they should be parsed as signed integers
+					// and reinterpreted as unsigned integers
+					str.toInt().toUInt()
+				}
+		}
+	}
+
+	fun interface SourceProvider<T> {
+		fun source(type: HashFormat<T>, delegate: Source): HasherSource<T>
+
+		companion object {
+			fun fromOkio(provider: ((Source) -> HashingSource)): SourceProvider<ByteString> {
+				return SourceProvider { type, delegate ->
+					val delegateHashing = provider.invoke(delegate)
+					object : ForwardingSource(delegateHashing), HasherSource<ByteString> {
+						override val hash: Hash<ByteString> by lazy(LazyThreadSafetyMode.NONE) { Hash(type, delegateHashing.hash) }
+					}
+				}
+			}
+		}
+	}
+
+	class TypeHandler : JsonDeserializer<Hash<*>>, JsonSerializer<Hash<*>> {
+		override fun serialize(src: Hash<*>, typeOfSrc: Type, context: JsonSerializationContext): JsonElement = JsonObject().apply {
+			add("type", JsonPrimitive(src.type.formatName))
+			// Local function for generics
+			fun <T> addValue(src: Hash<T>) = add("value", JsonPrimitive(src.type.encodeToString(src.value)))
+			addValue(src)
 		}
 
 		@Throws(JsonParseException::class)
-		override fun deserialize(json: JsonElement, typeOfT: Type, context: JsonDeserializationContext): Hash {
+		override fun deserialize(json: JsonElement, typeOfT: Type, context: JsonDeserializationContext): Hash<*> {
 			val obj = json.asJsonObject
 			val type: String
 			val value: String
@@ -25,7 +67,7 @@ abstract class Hash {
 				throw JsonParseException("Invalid hash JSON data")
 			}
 			return try {
-				HashUtils.getHash(type, value)
+				(HashFormat.fromName(type) ?: throw JsonParseException("Unknown hash type $type")).fromString(value)
 			} catch (e: Exception) {
 				throw JsonParseException("Failed to create hash object", e)
 			}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/HashFormat.kt

@@ -0,0 +1,39 @@
+package link.infra.packwiz.installer.metadata.hash
+
+import cc.ekblad.toml.model.TomlValue
+import cc.ekblad.toml.tomlMapper
+import link.infra.packwiz.installer.metadata.hash.Hash.Encoding
+import link.infra.packwiz.installer.metadata.hash.Hash.SourceProvider
+import link.infra.packwiz.installer.metadata.hash.Hash.SourceProvider.Companion.fromOkio
+import okio.ByteString
+import okio.Source
+import okio.HashingSource.Companion as OkHashes
+
+sealed class HashFormat<T>(val formatName: String): Encoding<T>, SourceProvider<T> {
+	object SHA1: HashFormat<ByteString>("sha1"),
+		Encoding<ByteString> by Encoding.Hex, SourceProvider<ByteString> by fromOkio(OkHashes::sha1)
+	object SHA256: HashFormat<ByteString>("sha256"),
+		Encoding<ByteString> by Encoding.Hex, SourceProvider<ByteString> by fromOkio(OkHashes::sha256)
+	object SHA512: HashFormat<ByteString>("sha512"),
+		Encoding<ByteString> by Encoding.Hex, SourceProvider<ByteString> by fromOkio(OkHashes::sha512)
+	object MD5: HashFormat<ByteString>("md5"),
+		Encoding<ByteString> by Encoding.Hex, SourceProvider<ByteString> by fromOkio(OkHashes::md5)
+	object MURMUR2: HashFormat<UInt>("murmur2"),
+		Encoding<UInt> by Encoding.UInt, SourceProvider<UInt> by SourceProvider(::Murmur2HasherSource)
+
+	fun source(delegate: Source): HasherSource<T> = source(this, delegate)
+	fun fromString(str: String) = Hash(this, decodeFromString(str))
+	override fun toString() = formatName
+
+	companion object {
+		// lazy used to prevent initialisation issues!
+		private val values by lazy { listOf(SHA1, SHA256, SHA512, MD5, MURMUR2) }
+		fun fromName(formatName: String) = values.find { formatName == it.formatName }
+
+		fun mapper() = tomlMapper {
+			// TODO: better exception?
+			decoder { it: TomlValue.String -> fromName(it.value) ?: throw Exception("Hash format ${it.value} not supported") }
+			encoder { it: HashFormat<*> -> TomlValue.String(it.formatName) }
+		}
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/HashUtils.kt

@@ -1,21 +0,0 @@
-package link.infra.packwiz.installer.metadata.hash
-
-object HashUtils {
-	private val hashTypeConversion: Map<String, IHasher> = mapOf(
-			"sha256" to HashingSourceHasher("sha256"),
-			"sha512" to HashingSourceHasher("sha512"),
-			"murmur2" to Murmur2Hasher()
-	)
-
-	@JvmStatic
-	@Throws(Exception::class)
-	fun getHasher(type: String): IHasher {
-		return hashTypeConversion[type] ?: throw Exception("Hash type not supported: $type")
-	}
-
-	@JvmStatic
-	@Throws(Exception::class)
-	fun getHash(type: String, value: String): Hash {
-		return hashTypeConversion[type]?.getHash(value) ?: throw Exception("Hash type not supported: $type")
-	}
-}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/HasherSource.kt

@@ -0,0 +1,7 @@
+package link.infra.packwiz.installer.metadata.hash
+
+import okio.Source
+
+interface HasherSource<T>: Source {
+	val hash: Hash<T>
+}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/HashingSourceHasher.kt

@@ -1,45 +0,0 @@
-package link.infra.packwiz.installer.metadata.hash
-
-import okio.HashingSource
-import okio.Source
-
-class HashingSourceHasher internal constructor(private val type: String) : IHasher {
-	// i love naming things
-	private inner class HashingSourceGeneralHashingSource internal constructor(val delegateHashing: HashingSource) : GeneralHashingSource(delegateHashing) {
-		override val hash: Hash by lazy(LazyThreadSafetyMode.NONE) {
-			HashingSourceHash(delegateHashing.hash.hex())
-		}
-	}
-
-	// this some funky inner class stuff
-	// each of these classes is specific to the instance of the HasherHashingSource
-	// therefore HashingSourceHashes from different parent instances will be not instanceof each other
-	private inner class HashingSourceHash(val value: String) : Hash() {
-		override val stringValue get() = value
-
-		override fun equals(other: Any?): Boolean {
-			if (other !is HashingSourceHash) {
-				return false
-			}
-			return stringValue.equals(other.stringValue, ignoreCase = true)
-		}
-
-		override fun toString(): String = "$type: $stringValue"
-		override fun hashCode(): Int = value.hashCode()
-
-		override val type: String get() = this@HashingSourceHasher.type
-	}
-
-	override fun getHashingSource(delegate: Source): GeneralHashingSource {
-		when (type) {
-			"md5" -> return HashingSourceGeneralHashingSource(HashingSource.md5(delegate))
-			"sha256" -> return HashingSourceGeneralHashingSource(HashingSource.sha256(delegate))
-			"sha512" -> return HashingSourceGeneralHashingSource(HashingSource.sha512(delegate))
-		}
-		throw RuntimeException("Invalid hash type provided")
-	}
-
-	override fun getHash(value: String): Hash {
-		return HashingSourceHash(value)
-	}
-}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/IHasher.kt

@@ -1,8 +0,0 @@
-package link.infra.packwiz.installer.metadata.hash
-
-import okio.Source
-
-interface IHasher {
-	fun getHashingSource(delegate: Source): GeneralHashingSource
-	fun getHash(value: String): Hash
-}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/Murmur2Hasher.kt

@@ -1,91 +0,0 @@
-package link.infra.packwiz.installer.metadata.hash
-
-import okio.Buffer
-import okio.Source
-import java.io.IOException
-
-class Murmur2Hasher : IHasher {
-	private inner class Murmur2GeneralHashingSource(delegate: Source) : GeneralHashingSource(delegate) {
-		val internalBuffer = Buffer()
-		val tempBuffer = Buffer()
-
-		override val hash: Hash by lazy(LazyThreadSafetyMode.NONE) {
-			val data = internalBuffer.readByteArray()
-			Murmur2Hash(Murmur2Lib.hash32(data, data.size, 1))
-		}
-
-		@Throws(IOException::class)
-		override fun read(sink: Buffer, byteCount: Long): Long {
-			val out = delegate.read(tempBuffer, byteCount)
-			if (out > -1) {
-				sink.write(tempBuffer.clone(), out)
-				computeNormalizedBufferFaster(tempBuffer, internalBuffer)
-			}
-			return out
-		}
-
-		// Credit to https://github.com/modmuss50/CAV2/blob/master/murmur.go
-//		private fun computeNormalizedArray(input: ByteArray): ByteArray {
-//			val output = ByteArray(input.size)
-//			var index = 0
-//			for (b in input) {
-//				when (b) {
-//					9.toByte(), 10.toByte(), 13.toByte(), 32.toByte() -> {}
-//					else -> {
-//						output[index] = b
-//						index++
-//					}
-//				}
-//			}
-//			val outputTrimmed = ByteArray(index)
-//			System.arraycopy(output, 0, outputTrimmed, 0, index)
-//			return outputTrimmed
-//		}
-
-		private fun computeNormalizedBufferFaster(input: Buffer, output: Buffer) {
-			var index = 0
-			val arr = input.readByteArray()
-			for (b in arr) {
-				when (b) {
-					9.toByte(), 10.toByte(), 13.toByte(), 32.toByte() -> {}
-					else -> {
-						arr[index] = b
-						index++
-					}
-				}
-			}
-			output.write(arr, 0, index)
-		}
-
-	}
-
-	private class Murmur2Hash : Hash {
-		val value: Int
-
-		constructor(value: String) {
-			// Parsing as long then casting to int converts values gt int max value but lt uint max value
-			// into negatives. I presume this is how the murmur2 code handles this.
-			this.value = value.toLong().toInt()
-		}
-
-		constructor(value: Int) {
-			this.value = value
-		}
-
-		override val stringValue get() = value.toString()
-		override val type get() = "murmur2"
-
-		override fun equals(other: Any?): Boolean {
-			if (other !is Murmur2Hash) {
-				return false
-			}
-			return value == other.value
-		}
-
-		override fun toString(): String = "murmur2: $value"
-		override fun hashCode(): Int = value
-	}
-
-	override fun getHashingSource(delegate: Source): GeneralHashingSource = Murmur2GeneralHashingSource(delegate)
-	override fun getHash(value: String): Hash = Murmur2Hash(value)
-}

src/main/kotlin/link/infra/packwiz/installer/metadata/hash/Murmur2HasherSource.kt

@@ -0,0 +1,43 @@
+package link.infra.packwiz.installer.metadata.hash
+
+import okio.Buffer
+import okio.ForwardingSource
+import okio.Source
+import java.io.IOException
+
+class Murmur2HasherSource(type: HashFormat<UInt>, delegate: Source) : ForwardingSource(delegate), HasherSource<UInt> {
+	private val internalBuffer = Buffer()
+	private val tempBuffer = Buffer()
+
+	override val hash: Hash<UInt> by lazy(LazyThreadSafetyMode.NONE) {
+		// TODO: remove internal buffering?
+		val data = internalBuffer.readByteArray()
+		Hash(type, Murmur2Lib.hash32(data, data.size, 1).toUInt())
+	}
+
+	@Throws(IOException::class)
+	override fun read(sink: Buffer, byteCount: Long): Long {
+		val out = delegate.read(tempBuffer, byteCount)
+		if (out > -1) {
+			sink.write(tempBuffer.clone(), out)
+			computeNormalizedBufferFaster(tempBuffer, internalBuffer)
+		}
+		return out
+	}
+
+	// Credit to https://github.com/modmuss50/CAV2/blob/master/murmur.go
+	private fun computeNormalizedBufferFaster(input: Buffer, output: Buffer) {
+		var index = 0
+		val arr = input.readByteArray()
+		for (b in arr) {
+			when (b) {
+				9.toByte(), 10.toByte(), 13.toByte(), 32.toByte() -> {}
+				else -> {
+					arr[index] = b
+					index++
+				}
+			}
+		}
+		output.write(arr, 0, index)
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/request/HandlerManager.kt

@@ -1,49 +0,0 @@
-package link.infra.packwiz.installer.request
-
-import link.infra.packwiz.installer.metadata.SpaceSafeURI
-import link.infra.packwiz.installer.request.handlers.RequestHandlerFile
-import link.infra.packwiz.installer.request.handlers.RequestHandlerGithub
-import link.infra.packwiz.installer.request.handlers.RequestHandlerHTTP
-import okio.Source
-
-object HandlerManager {
-
-	private val handlers: List<IRequestHandler> = listOf(
-			RequestHandlerGithub(),
-			RequestHandlerHTTP(),
-			RequestHandlerFile()
-	)
-
-	@JvmStatic
-	fun getNewLoc(base: SpaceSafeURI?, loc: SpaceSafeURI?): SpaceSafeURI? {
-		if (loc == null) {
-			return null
-		}
-		val dest = base?.run { resolve(loc) } ?: loc
-		for (handler in handlers) with (handler) {
-			if (matchesHandler(dest)) {
-				return getNewLoc(dest)
-			}
-		}
-		return dest
-	}
-
-	// TODO: What if files are read multiple times??
-	// Zip handler discards once read, requesting multiple times on other handlers would cause multiple downloads
-	// Caching system? Copy from already downloaded files?
-
-	@JvmStatic
-	@Throws(Exception::class)
-	fun getFileSource(loc: SpaceSafeURI): Source {
-		for (handler in handlers) {
-			if (handler.matchesHandler(loc)) {
-				return handler.getFileSource(loc) ?: throw Exception("Couldn't find URI: $loc")
-			}
-		}
-		throw Exception("No handler available for URI: $loc")
-	}
-
-	// TODO: github toml resolution?
-	// e.g. https://github.com/comp500/Demagnetize -> demagnetize.toml
-	// https://github.com/comp500/Demagnetize/blob/master/demagnetize.toml
-}

src/main/kotlin/link/infra/packwiz/installer/request/IRequestHandler.kt

@@ -1,24 +0,0 @@
-package link.infra.packwiz.installer.request
-
-import link.infra.packwiz.installer.metadata.SpaceSafeURI
-import okio.Source
-
-/**
- * IRequestHandler handles requests for locations specified in modpack metadata.
- */
-interface IRequestHandler {
-	fun matchesHandler(loc: SpaceSafeURI): Boolean
-
-	fun getNewLoc(loc: SpaceSafeURI): SpaceSafeURI {
-		return loc
-	}
-
-	/**
-	 * Gets the Source for a location. Must be threadsafe.
-	 * It is assumed that each location is read only once for the duration of an IRequestHandler.
-	 * @param loc The location to be read
-	 * @return The Source containing the data of the file
-	 * @throws Exception Exception if it failed to download a file!!!
-	 */
-	fun getFileSource(loc: SpaceSafeURI): Source?
-}

src/main/kotlin/link/infra/packwiz/installer/request/RequestExceptions.kt

@@ -0,0 +1,67 @@
+package link.infra.packwiz.installer.request
+
+import okio.IOException
+
+sealed class RequestException: Exception {
+	constructor(message: String, cause: Throwable) : super(message, cause)
+	constructor(message: String) : super(message)
+
+	/**
+	 * Internal errors that should not be shown to the user when the code is correct
+	 */
+	sealed class Internal: RequestException {
+		constructor(message: String, cause: Throwable) : super(message, cause)
+		constructor(message: String) : super(message)
+
+		sealed class HTTP: Internal {
+			constructor(message: String, cause: Throwable) : super(message, cause)
+			constructor(message: String) : super(message)
+
+			class NoResponseBody: HTTP("HTTP response in onResponse must have a response body")
+			class RequestFailed(cause: IOException): HTTP("HTTP request failed", cause)
+			class IllegalState(cause: IllegalStateException): HTTP("Internal fatal HTTP request error", cause)
+		}
+	}
+
+	/**
+	 * Errors indicating that the request is malformed
+	 */
+	sealed class Validation: RequestException {
+		constructor(message: String, cause: Throwable) : super(message, cause)
+		constructor(message: String) : super(message)
+
+		// TODO: move out of RequestException?
+		class PathContainsNUL(path: String): Validation("Invalid path; contains NUL bytes: ${path.replace("\u0000", "")}")
+		class PathContainsVolumeLetter(path: String): Validation("Invalid path; contains volume letter: $path")
+	}
+
+	/**
+	 * Errors relating to the response from the server
+	 */
+	sealed class Response: RequestException {
+		constructor(message: String, cause: Throwable) : super(message, cause)
+		constructor(message: String) : super(message)
+
+		// TODO: fancier way of displaying this?
+		sealed class HTTP: Response {
+			val res: okhttp3.Response
+
+			constructor(req: okhttp3.Request, res: okhttp3.Response, message: String, cause: Throwable) : super("Failed to make HTTP request to ${req.url}: $message", cause) {
+				this.res = res
+			}
+			constructor(req: okhttp3.Request, res: okhttp3.Response, message: String) : super("Failed to make HTTP request to ${req.url}: $message") {
+				this.res = res
+			}
+
+			class ErrorCode(req: okhttp3.Request, res: okhttp3.Response): HTTP(req, res, "Non-successful error code from HTTP request: ${res.code}")
+		}
+
+		sealed class File: RequestException {
+			constructor(message: String, cause: Throwable) : super(message, cause)
+			constructor(message: String) : super(message)
+
+			class FileNotFound(file: String): File("File path not found: $file")
+			class Other(cause: Throwable): File("Failed to read file", cause)
+		}
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/request/handlers/RequestHandlerFile.kt

@@ -1,18 +0,0 @@
-package link.infra.packwiz.installer.request.handlers
-
-import link.infra.packwiz.installer.metadata.SpaceSafeURI
-import link.infra.packwiz.installer.request.IRequestHandler
-import okio.Source
-import okio.source
-import java.nio.file.Paths
-
-open class RequestHandlerFile : IRequestHandler {
-	override fun matchesHandler(loc: SpaceSafeURI): Boolean {
-		return "file" == loc.scheme
-	}
-
-	override fun getFileSource(loc: SpaceSafeURI): Source? {
-		val path = Paths.get(loc.toURL().toURI())
-		return path.source()
-	}
-}

src/main/kotlin/link/infra/packwiz/installer/request/handlers/RequestHandlerGithub.kt

@@ -1,71 +0,0 @@
-package link.infra.packwiz.installer.request.handlers
-
-import link.infra.packwiz.installer.metadata.SpaceSafeURI
-import java.util.*
-import java.util.concurrent.locks.ReentrantReadWriteLock
-import java.util.regex.Pattern
-import kotlin.concurrent.read
-import kotlin.concurrent.write
-
-class RequestHandlerGithub : RequestHandlerZip(true) {
-	override fun getNewLoc(loc: SpaceSafeURI): SpaceSafeURI {
-		return loc
-	}
-
-	companion object {
-		private val repoMatcherPattern = Pattern.compile("/([\\w.-]+/[\\w.-]+).*")
-		private val branchMatcherPattern = Pattern.compile("/[\\w.-]+/[\\w.-]+/blob/([\\w.-]+).*")
-	}
-
-	// TODO: is caching really needed, if HTTPURLConnection follows redirects correctly?
-	private val zipUriMap: MutableMap<String, SpaceSafeURI> = HashMap()
-	private val zipUriLock = ReentrantReadWriteLock()
-	private fun getRepoName(loc: SpaceSafeURI): String? {
-		val matcher = repoMatcherPattern.matcher(loc.path)
-		return if (matcher.matches()) {
-			matcher.group(1)
-		} else {
-			null
-		}
-	}
-
-	override fun getZipUri(loc: SpaceSafeURI): SpaceSafeURI {
-		val repoName = getRepoName(loc)
-		val branchName = getBranch(loc)
-
-		zipUriLock.read {
-			zipUriMap["$repoName/$branchName"]
-		}?.let { return it }
-
-		var zipUri = SpaceSafeURI("https://api.github.com/repos/$repoName/zipball/$branchName")
-		zipUriLock.write {
-			// If another thread sets the value concurrently, use the existing value from the
-			// thread that first acquired the lock.
-			zipUri = zipUriMap.putIfAbsent("$repoName/$branchName", zipUri) ?: zipUri
-		}
-		return zipUri
-	}
-
-	private fun getBranch(loc: SpaceSafeURI): String? {
-		val matcher = branchMatcherPattern.matcher(loc.path)
-		return if (matcher.matches()) {
-			matcher.group(1)
-		} else {
-			null
-		}
-	}
-
-	override fun getLocationInZip(loc: SpaceSafeURI): SpaceSafeURI {
-		val path = "/" + getRepoName(loc) + "/blob/" + getBranch(loc)
-		return SpaceSafeURI(loc.scheme, loc.authority, path, null, null).relativize(loc)
-	}
-
-	override fun matchesHandler(loc: SpaceSafeURI): Boolean {
-		val scheme = loc.scheme
-		if (!("http" == scheme || "https" == scheme)) {
-			return false
-		}
-		// TODO: more match testing?
-		return "github.com" == loc.host && branchMatcherPattern.matcher(loc.path).matches()
-	}
-}

src/main/kotlin/link/infra/packwiz/installer/request/handlers/RequestHandlerHTTP.kt

@@ -1,29 +0,0 @@
-package link.infra.packwiz.installer.request.handlers
-
-import link.infra.packwiz.installer.metadata.SpaceSafeURI
-import link.infra.packwiz.installer.request.IRequestHandler
-import okio.Source
-import okio.source
-import java.net.HttpURLConnection
-
-open class RequestHandlerHTTP : IRequestHandler {
-	override fun matchesHandler(loc: SpaceSafeURI): Boolean {
-		val scheme = loc.scheme
-		return "http" == scheme || "https" == scheme
-	}
-
-	override fun getFileSource(loc: SpaceSafeURI): Source? {
-		val conn = loc.toURL().openConnection() as HttpURLConnection
-		// TODO: when do we send specific headers??? should there be a way to signal this?
-		conn.addRequestProperty("Accept", "application/octet-stream")
-		// TODO: include version?
-		conn.addRequestProperty("User-Agent", "packwiz-installer")
-
-		conn.apply {
-			// 30 second read timeout
-			readTimeout = 30 * 1000
-			requestMethod = "GET"
-		}
-		return conn.inputStream.source()
-	}
-}

src/main/kotlin/link/infra/packwiz/installer/request/handlers/RequestHandlerZip.kt

@@ -1,123 +0,0 @@
-package link.infra.packwiz.installer.request.handlers
-
-import link.infra.packwiz.installer.metadata.SpaceSafeURI
-import okio.Buffer
-import okio.Source
-import okio.buffer
-import okio.source
-import java.util.*
-import java.util.concurrent.locks.ReentrantLock
-import java.util.concurrent.locks.ReentrantReadWriteLock
-import java.util.function.Predicate
-import java.util.zip.ZipEntry
-import java.util.zip.ZipInputStream
-import kotlin.concurrent.read
-import kotlin.concurrent.withLock
-import kotlin.concurrent.write
-
-abstract class RequestHandlerZip(private val modeHasFolder: Boolean) : RequestHandlerHTTP() {
-	private fun removeFolder(name: String): String {
-		return if (modeHasFolder) {
-			// TODO: replace with proper path checks once switched to Path??
-			name.substring(name.indexOf("/") + 1)
-		} else {
-			name
-		}
-	}
-
-	private inner class ZipReader internal constructor(zip: Source) {
-		private val zis = ZipInputStream(zip.buffer().inputStream())
-		private val readFiles: MutableMap<SpaceSafeURI, Buffer> = HashMap()
-		// Write lock implies access to ZipInputStream - only 1 thread must read at a time!
-		val filesLock = ReentrantLock()
-		private var entry: ZipEntry? = null
-
-		private val zipSource = zis.source().buffer()
-
-		// File lock must be obtained before calling this function
-		private fun readCurrFile(): Buffer {
-			val fileBuffer = Buffer()
-			zipSource.readFully(fileBuffer, entry!!.size)
-			return fileBuffer
-		}
-
-		// File lock must be obtained before calling this function
-		private fun findFile(loc: SpaceSafeURI): Buffer? {
-			while (true) {
-				entry = zis.nextEntry
-				entry?.also {
-					val data = readCurrFile()
-					val fileLoc = SpaceSafeURI(removeFolder(it.name))
-					if (loc == fileLoc) {
-						return data
-					} else {
-						readFiles[fileLoc] = data
-					}
-				} ?: return null
-			}
-		}
-
-		fun getFileSource(loc: SpaceSafeURI): Source? {
-			filesLock.withLock {
-				// Assume files are only read once, allow GC by removing
-				readFiles.remove(loc)?.also { return it }
-				return findFile(loc)
-			}
-		}
-
-		fun findInZip(matches: Predicate<SpaceSafeURI>): SpaceSafeURI? {
-			filesLock.withLock {
-				readFiles.keys.find { matches.test(it) }?.let { return it }
-
-				do {
-					val entry = zis.nextEntry?.also {
-						val data = readCurrFile()
-						val fileLoc = SpaceSafeURI(removeFolder(it.name))
-						readFiles[fileLoc] = data
-						if (matches.test(fileLoc)) {
-							return fileLoc
-						}
-					}
-				} while (entry != null)
-				return null
-			}
-		}
-	}
-
-	private val cache: MutableMap<SpaceSafeURI, ZipReader> = HashMap()
-	private val cacheLock = ReentrantReadWriteLock()
-
-	protected abstract fun getZipUri(loc: SpaceSafeURI): SpaceSafeURI
-	protected abstract fun getLocationInZip(loc: SpaceSafeURI): SpaceSafeURI
-	abstract override fun matchesHandler(loc: SpaceSafeURI): Boolean
-
-	override fun getFileSource(loc: SpaceSafeURI): Source? {
-		val zipUri = getZipUri(loc)
-		var zr = cacheLock.read { cache[zipUri] }
-		if (zr == null) {
-			cacheLock.write {
-				// Recheck, because unlocking read lock allows another thread to modify it
-				zr = cache[zipUri]
-
-				if (zr == null) {
-					val src = super.getFileSource(zipUri) ?: return null
-					zr = ZipReader(src).also { cache[zipUri] = it }
-				}
-			}
-		}
-		return zr?.getFileSource(getLocationInZip(loc))
-	}
-
-	protected fun findInZip(loc: SpaceSafeURI, matches: Predicate<SpaceSafeURI>): SpaceSafeURI? {
-		val zipUri = getZipUri(loc)
-		return (cacheLock.read { cache[zipUri] } ?: cacheLock.write {
-			// Recheck, because unlocking read lock allows another thread to modify it
-			cache[zipUri] ?: run {
-				// Create the ZipReader if it doesn't exist, return null if getFileSource returns null
-				super.getFileSource(zipUri)?.let { ZipReader(it) }
-						?.also { cache[zipUri] = it }
-			}
-		})?.findInZip(matches)
-	}
-
-}

src/main/kotlin/link/infra/packwiz/installer/target/CachedTarget.kt

@@ -0,0 +1,23 @@
+package link.infra.packwiz.installer.target
+
+import link.infra.packwiz.installer.metadata.hash.Hash
+import java.nio.file.Path
+
+data class CachedTarget(
+	/**
+	 * @see Target.name
+	 */
+	val name: String,
+	/**
+	 * The location where the target was last downloaded to.
+	 * This is used for removing old files when the destination path changes.
+	 * This shouldn't be set to the .disabled path (that is manually appended and checked)
+	 */
+	val cachedLocation: Path,
+	val enabled: Boolean,
+	val hash: Hash<*>,
+	/**
+	 * For detecting when a target transitions non-optional -> optional and showing the option selection screen
+	 */
+	val isOptional: Boolean
+)

src/main/kotlin/link/infra/packwiz/installer/target/CachedTargetValidation.kt

@@ -0,0 +1,95 @@
+package link.infra.packwiz.installer.target
+
+import java.io.IOException
+import java.nio.file.*
+import java.nio.file.attribute.BasicFileAttributes
+import kotlin.io.path.relativeTo
+
+data class CachedTargetStatus(val target: CachedTarget, var isValid: Boolean, var markDisabled: Boolean)
+
+fun validate(targets: List<CachedTarget>, baseDir: Path) = runCatching {
+	val results = targets.map {
+		CachedTargetStatus(it, isValid = false, markDisabled = false)
+	}
+	val tree = buildTree(results, baseDir)
+
+	// Efficient file exists checking using directory listing, several orders of magnitude faster than Files.exists calls
+	Files.walkFileTree(baseDir, setOf(FileVisitOption.FOLLOW_LINKS), Int.MAX_VALUE, object : FileVisitor<Path> {
+		var currentNode: PathNode<CachedTargetStatus> = tree
+
+		override fun preVisitDirectory(dir: Path?, attrs: BasicFileAttributes?): FileVisitResult {
+			if (dir == null) {
+				return FileVisitResult.SKIP_SUBTREE
+			}
+			val subdirNode = currentNode.subdirs[dir.getName(dir.nameCount - 1)]
+			return if (subdirNode != null) {
+				currentNode = subdirNode
+				FileVisitResult.CONTINUE
+			} else {
+				FileVisitResult.SKIP_SUBTREE
+			}
+		}
+
+		override fun visitFile(file: Path?, attrs: BasicFileAttributes?): FileVisitResult {
+			if (file == null) {
+				return FileVisitResult.CONTINUE
+			}
+			// TODO: these are relative paths to baseDir
+			// TODO: strip the .disabled for lookup
+			val target = currentNode.files[file.getName(file.nameCount - 1)]
+			if (target != null) {
+				val disabledFile = file.endsWith(".disabled")
+				// If a .disabled file and the actual file both exist, mark as invalid if the target is disabled
+				if ((disabledFile )) {
+
+				}
+			}
+			return FileVisitResult.CONTINUE
+		}
+
+		@Throws(IOException::class)
+		override fun visitFileFailed(file: Path?, exc: IOException?): FileVisitResult {
+			if (exc != null) {
+				throw exc
+			}
+			throw IOException("visitFileFailed called with no exception")
+		}
+
+		@Throws(IOException::class)
+		override fun postVisitDirectory(dir: Path?, exc: IOException?): FileVisitResult {
+			if (exc != null) {
+				throw exc
+			} else {
+				val parent = currentNode.parent
+				if (parent != null) {
+					currentNode = parent
+				} else {
+					throw IOException("Invalid visitor tree structure")
+				}
+				return FileVisitResult.CONTINUE
+			}
+		}
+	})
+
+	results
+}
+
+fun buildTree(targets: List<CachedTargetStatus>, baseDir: Path): PathNode<CachedTargetStatus> {
+	val root = PathNode<CachedTargetStatus>()
+	for (target in targets) {
+		val relPath = target.target.cachedLocation.relativeTo(baseDir)
+		var node = root
+		// Traverse all the directory components, except for the last one
+		for (i in 0 until (relPath.nameCount - 1)) {
+			node = node.createSubdir(relPath.getName(i))
+		}
+		node.files[relPath.getName(relPath.nameCount - 1)] = target
+	}
+	return root
+}
+
+data class PathNode<T>(val subdirs: MutableMap<Path, PathNode<T>>, val files: MutableMap<Path, T>, val parent: PathNode<T>?) {
+	constructor() : this(mutableMapOf(), mutableMapOf(), null)
+
+	fun createSubdir(nextComponent: Path) = subdirs.getOrPut(nextComponent, { PathNode(mutableMapOf(), mutableMapOf(), this) })
+}

src/main/kotlin/link/infra/packwiz/installer/target/ClientHolder.kt

@@ -0,0 +1,57 @@
+package link.infra.packwiz.installer.target
+
+import link.infra.packwiz.installer.util.Log
+import okhttp3.OkHttpClient
+import okhttp3.Response
+import okio.FileSystem
+import java.net.SocketTimeoutException
+import java.util.concurrent.TimeUnit
+
+class ClientHolder {
+	// Tries 10s timeouts (default), then 15s timeouts, then 60s timeouts
+	private val retryTimes = arrayOf(15, 60)
+
+	// TODO: a button to increase timeouts temporarily when retrying? manual retry button?
+	val okHttpClient by lazy { OkHttpClient.Builder()
+		// Retry requests according to retryTimes list
+		.addInterceptor {
+			val req = it.request()
+
+			var lastException: SocketTimeoutException? = null
+			var res: Response? = null
+
+			try {
+				res = it.proceed(req)
+			} catch (e: SocketTimeoutException) {
+				lastException = e
+			}
+
+			var tryCount = 0
+			while (res == null && tryCount < retryTimes.size) {
+				Log.info("OkHttp connection to ${req.url} timed out; retrying... (${tryCount + 1}/${retryTimes.size})")
+
+				val longerTimeoutChain = it
+					.withConnectTimeout(retryTimes[tryCount], TimeUnit.SECONDS)
+					.withReadTimeout(retryTimes[tryCount], TimeUnit.SECONDS)
+					.withWriteTimeout(retryTimes[tryCount], TimeUnit.SECONDS)
+				try {
+					res = longerTimeoutChain.proceed(req)
+				} catch (e: SocketTimeoutException) {
+					lastException = e
+				}
+
+				tryCount++
+			}
+
+			res ?: throw lastException!!
+		}
+		.build() }
+
+	val fileSystem = FileSystem.SYSTEM
+
+	fun close() {
+		okHttpClient.dispatcher.cancelAll()
+		okHttpClient.dispatcher.executorService.shutdown()
+		okHttpClient.connectionPool.evictAll()
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/target/OverwriteMode.kt

@@ -0,0 +1,13 @@
+package link.infra.packwiz.installer.target
+
+enum class OverwriteMode {
+	/**
+	 * Overwrite the destination with the source file, if the source file has changed.
+	 */
+	IF_SRC_CHANGED,
+
+	/**
+	 * Never overwrite the destination; if it exists, it should not be written to.
+	 */
+	NEVER
+}

src/main/kotlin/link/infra/packwiz/installer/target/Side.kt

@@ -0,0 +1,48 @@
+package link.infra.packwiz.installer.target
+
+import cc.ekblad.toml.model.TomlValue
+import cc.ekblad.toml.tomlMapper
+import com.google.gson.annotations.SerializedName
+
+enum class Side(sideName: String) {
+	@SerializedName("client")
+	CLIENT("client"),
+	@SerializedName("server")
+	SERVER("server"),
+	@SerializedName("both")
+	@Suppress("unused")
+	BOTH("both") {
+		override fun hasSide(tSide: Side): Boolean {
+			return true
+		}
+	};
+
+	private val sideName: String
+
+	init {
+		this.sideName = sideName.lowercase()
+	}
+
+	override fun toString() = sideName
+
+	open fun hasSide(tSide: Side): Boolean {
+		return this == tSide || tSide == BOTH
+	}
+
+	companion object {
+		fun from(name: String): Side? {
+			val lowerName = name.lowercase()
+			for (side in values()) {
+				if (side.sideName == lowerName) {
+					return side
+				}
+			}
+			return null
+		}
+
+		fun mapper() = tomlMapper {
+			encoder { it: Side -> TomlValue.String(it.sideName) }
+			decoder { it: TomlValue.String -> from(it.value) ?: throw Exception("Invalid side name ${it.value}") }
+		}
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/target/Target.kt

@@ -0,0 +1,45 @@
+package link.infra.packwiz.installer.target
+
+import link.infra.packwiz.installer.target.path.PackwizPath
+
+// TODO: rename to avoid conflicting with @Target
+interface Target {
+	val src: PackwizPath<*>
+	val dest: PackwizPath<*>
+	val validityToken: ValidityToken
+
+	/**
+	 * Token interface for types used to compare Target identity. Implementations should use equals to indicate that
+	 * these tokens represent the same file; used to preserve optional target choices between file renames.
+	 */
+	interface IdentityToken
+
+	/**
+	 * Default implementation of IdentityToken that assumes files are not renamed; so optional choices do not need to
+	 * be preserved across renames.
+	 */
+	@JvmInline
+	value class PathIdentityToken(val path: PackwizPath<*>): IdentityToken
+
+	val ident: IdentityToken
+		get() = PathIdentityToken(dest) // TODO: should use local-rebased path?
+
+	/**
+	 * A user-friendly name; defaults to the destination path of the file.
+	 */
+	val name: String
+		get() = dest.filename
+	val side: Side
+		get() = Side.BOTH
+	val overwriteMode: OverwriteMode
+		get() = OverwriteMode.IF_SRC_CHANGED
+
+	interface Optional: Target {
+		val optional: Boolean
+		val optionalDefaultValue: Boolean
+	}
+
+	interface OptionalDescribed: Optional {
+		val optionalDescription: String
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/target/ValidityToken.kt

@@ -0,0 +1,16 @@
+package link.infra.packwiz.installer.target
+
+import link.infra.packwiz.installer.metadata.hash.Hash
+
+/**
+ * A token used to determine if the source or destination file is changed, and ensure that the destination file is valid.
+ */
+interface ValidityToken {
+	// TODO: functions to allow validating this from file metadata, from file, or during the download process
+
+	/**
+	 * Default implementation of ValidityToken based on a single hash.
+	 */
+	@JvmInline
+	value class HashValidityToken(val hash: Hash<*>): ValidityToken
+}

src/main/kotlin/link/infra/packwiz/installer/target/path/HttpUrlPath.kt

@@ -0,0 +1,69 @@
+package link.infra.packwiz.installer.target.path
+
+import link.infra.packwiz.installer.request.RequestException
+import link.infra.packwiz.installer.target.ClientHolder
+import okhttp3.HttpUrl
+import okhttp3.Request
+import okio.BufferedSource
+import okio.IOException
+
+class HttpUrlPath(private val url: HttpUrl, path: String? = null): PackwizPath<HttpUrlPath>(path) {
+	private fun build() = if (path == null) { url } else { url.newBuilder().addPathSegments(path).build() }
+
+	@Throws(RequestException::class)
+	override fun source(clientHolder: ClientHolder): BufferedSource {
+		val req = Request.Builder()
+			.url(build())
+			.header("Accept", "application/octet-stream")
+			.header("User-Agent", "packwiz-installer")
+			.get()
+			.build()
+		try {
+			val res = clientHolder.okHttpClient.newCall(req).execute()
+			// Can't use .use since it would close the response body before returning it to the caller
+			try {
+				if (!res.isSuccessful) {
+					throw RequestException.Response.HTTP.ErrorCode(req, res)
+				}
+
+				val body = res.body ?: throw RequestException.Internal.HTTP.NoResponseBody()
+				return body.source()
+			} catch (e: Exception) {
+				// If an exception is thrown, close the response and rethrow
+				res.close()
+				throw e
+			}
+		} catch (e: IOException) {
+			throw RequestException.Internal.HTTP.RequestFailed(e)
+		} catch (e: IllegalStateException) {
+			throw RequestException.Internal.HTTP.IllegalState(e)
+		}
+	}
+
+	override fun construct(path: String): HttpUrlPath = HttpUrlPath(url, path)
+
+	override val folder: Boolean
+		get() = pathFolder ?: (url.pathSegments.last() == "")
+	override val filename: String
+		get() = pathFilename ?: url.pathSegments.last()
+
+	override fun equals(other: Any?): Boolean {
+		if (this === other) return true
+		if (javaClass != other?.javaClass) return false
+		if (!super.equals(other)) return false
+
+		other as HttpUrlPath
+
+		if (url != other.url) return false
+
+		return true
+	}
+
+	override fun hashCode(): Int {
+		var result = super.hashCode()
+		result = 31 * result + url.hashCode()
+		return result
+	}
+
+	override fun toString() = build().toString()
+}

src/main/kotlin/link/infra/packwiz/installer/target/path/PackwizFilePath.kt

@@ -0,0 +1,51 @@
+package link.infra.packwiz.installer.target.path
+
+import link.infra.packwiz.installer.request.RequestException
+import link.infra.packwiz.installer.target.ClientHolder
+import okio.*
+
+class PackwizFilePath(private val base: Path, path: String? = null): PackwizPath<PackwizFilePath>(path) {
+	@Throws(RequestException::class)
+	override fun source(clientHolder: ClientHolder): BufferedSource {
+		val resolved = if (path == null) { base } else { this.base.resolve(path, true) }
+		try {
+			return clientHolder.fileSystem.source(resolved).buffer()
+		} catch (e: FileNotFoundException) {
+			throw RequestException.Response.File.FileNotFound(resolved.toString())
+		} catch (e: IOException) {
+			throw RequestException.Response.File.Other(e)
+		}
+	}
+
+	val nioPath: java.nio.file.Path get() {
+		val resolved = if (path == null) { base } else { this.base.resolve(path, true) }
+		return resolved.toNioPath()
+	}
+
+	override fun construct(path: String): PackwizFilePath = PackwizFilePath(base, path)
+
+	override val folder: Boolean
+		get() = pathFolder ?: (base.segments.last() == "")
+	override val filename: String
+		get() = pathFilename ?: base.segments.last()
+
+	override fun equals(other: Any?): Boolean {
+		if (this === other) return true
+		if (javaClass != other?.javaClass) return false
+		if (!super.equals(other)) return false
+
+		other as PackwizFilePath
+
+		if (base != other.base) return false
+
+		return true
+	}
+
+	override fun hashCode(): Int {
+		var result = super.hashCode()
+		result = 31 * result + base.hashCode()
+		return result
+	}
+
+	override fun toString() = nioPath.toString()
+}

src/main/kotlin/link/infra/packwiz/installer/target/path/PackwizPath.kt

@@ -0,0 +1,128 @@
+package link.infra.packwiz.installer.target.path
+
+import cc.ekblad.toml.model.TomlValue
+import cc.ekblad.toml.tomlMapper
+import com.google.gson.TypeAdapter
+import com.google.gson.stream.JsonReader
+import com.google.gson.stream.JsonWriter
+import link.infra.packwiz.installer.request.RequestException
+import link.infra.packwiz.installer.target.ClientHolder
+import okio.BufferedSource
+
+abstract class PackwizPath<T: PackwizPath<T>>(path: String? = null) {
+	protected val path: String?
+
+	init {
+		if (path != null) {
+			// Check for NUL bytes
+			if (path.contains('\u0000')) { throw RequestException.Validation.PathContainsNUL(path) }
+			// Normalise separator, to prevent differences between Unix/Windows
+			val pathNorm = path.replace('\\', '/')
+			// Split, create new lists for output
+			val split = pathNorm.split('/')
+			val canonicalised = mutableListOf<String>()
+
+			// Backward pass: collapse ".." components, remove "." components and empty components (except an empty component at the end; indicating a folder)
+			var parentComponentCount = 0
+			var first = true
+			for (component in split.asReversed()) {
+				if (first) {
+					first = false
+					if (component == "") {
+						canonicalised += component
+					}
+				}
+				// URL-encoded . is normalised
+				val componentNorm = component.replace("%2e", ".")
+				if (componentNorm == "." || componentNorm == "") {
+					// Do nothing
+				} else if (componentNorm == "..") {
+					parentComponentCount++
+				} else if (parentComponentCount > 0) {
+					parentComponentCount--
+				} else {
+					canonicalised += componentNorm
+					// Don't allow volume letters (allows traversal to the root on Windows)
+					if (componentNorm.length == 2) {
+						if (componentNorm[0] in 'a'..'z' || componentNorm[0] in 'A'..'Z') {
+							if (componentNorm[1] == ':') {
+								throw RequestException.Validation.PathContainsVolumeLetter(path)
+							}
+						}
+					}
+				}
+			}
+
+			if (canonicalised.isEmpty()) {
+				this.path = null
+			} else {
+				// Join path
+				this.path = canonicalised.asReversed().joinToString("/")
+			}
+		} else {
+			this.path = null
+		}
+	}
+
+	protected abstract fun construct(path: String): T
+
+	protected val pathFolder: Boolean? get() = path?.endsWith("/")
+	abstract val folder: Boolean
+	protected val pathFilename: String? get() = path?.split("/")?.last()
+	abstract val filename: String
+
+	fun resolve(path: String): T {
+		return if (path.startsWith('/') || path.startsWith('\\')) {
+			// Absolute (but still relative to base of pack)
+			construct(path)
+		} else if (folder) {
+			// File in folder; append
+			construct((this.path ?: "") + path)
+		} else {
+			// File in parent folder; append with parent component
+			construct((this.path ?: "") + "/../" + path)
+		}
+	}
+
+	operator fun div(path: String) = resolve(path)
+
+	fun <U: PackwizPath<U>> rebase(path: U) = path.resolve(this.path ?: "")
+
+	val parent: T get() = resolve(if (folder) { ".." } else { "." })
+
+	/**
+	 * Obtain a BufferedSource for this path
+	 * @throws RequestException When resolving the file failed
+	 */
+	@Throws(RequestException::class)
+	abstract fun source(clientHolder: ClientHolder): BufferedSource
+
+	override fun equals(other: Any?): Boolean {
+		if (this === other) return true
+		if (javaClass != other?.javaClass) return false
+
+		other as PackwizPath<*>
+
+		if (path != other.path) return false
+
+		return true
+	}
+
+	override fun hashCode() = path.hashCode()
+
+	companion object {
+		fun mapperRelativeTo(base: PackwizPath<*>) = tomlMapper {
+			encoder { it: PackwizPath<*> -> TomlValue.String(it.path ?: "") }
+			decoder { it: TomlValue.String -> base.resolve(it.value) }
+		}
+
+		fun <T: PackwizPath<T>> adapterRelativeTo(base: T) = object : TypeAdapter<T>() {
+			override fun write(writer: JsonWriter, value: T?) {
+				writer.value(value?.path)
+			}
+			override fun read(reader: JsonReader) = base.resolve(reader.nextString())
+		}
+	}
+
+	override fun toString() = "(Unknown base) $path"
+}

src/main/kotlin/link/infra/packwiz/installer/task/CacheKey.kt

@@ -0,0 +1,3 @@
+package link.infra.packwiz.installer.task
+
+data class CacheKey<T>(val key: String, val version: Int)

src/main/kotlin/link/infra/packwiz/installer/task/CacheManager.kt

@@ -0,0 +1,22 @@
+package link.infra.packwiz.installer.task
+
+import kotlin.reflect.KProperty
+
+class CacheManager {
+	class CacheValue<T> {
+		operator fun getValue(thisVal: Any?, property: KProperty<*>): T {
+			TODO("Not yet implemented")
+		}
+
+		operator fun setValue(thisVal: Any?, property: KProperty<*>, value: T) {
+			TODO("Not yet implemented")
+		}
+
+	}
+
+	operator fun <T> get(cacheKey: CacheKey<T>): CacheValue<T> {
+		return CacheValue()
+	}
+
+
+}

src/main/kotlin/link/infra/packwiz/installer/task/Task.kt

@@ -0,0 +1,20 @@
+package link.infra.packwiz.installer.task
+
+import kotlin.reflect.KMutableProperty0
+
+// TODO: task processing on 1 background thread; actual resolving of values calls out to a thread group
+// TODO: progress bar is updated from each of these tasks
+// TODO: have everything be lazy so there's no need to determine task ordering upfront? a bit like rust async - task results must be queried to occur
+
+abstract class Task<T>(protected val ctx: TaskContext): TaskInput<T> {
+	// TODO: lazy wrapper for fallible results
+	// TODO: multithreaded fanout subclass/helper
+
+	protected fun <T> wasUpdated(value: KMutableProperty0<T>, newValue: T): Boolean {
+		if (value.get() == newValue) {
+			return false
+		}
+		value.set(newValue)
+		return true
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/task/TaskCombinedResult.kt

@@ -0,0 +1,6 @@
+package link.infra.packwiz.installer.task
+
+/**
+ * An object for storing results where result and upToDate are calculated simultaneously
+ */
+data class TaskCombinedResult<T>(val result: T, val upToDate: Boolean)

src/main/kotlin/link/infra/packwiz/installer/task/TaskContext.kt

@@ -0,0 +1,12 @@
+package link.infra.packwiz.installer.task
+
+import link.infra.packwiz.installer.target.ClientHolder
+
+class TaskContext {
+	// TODO: thread pools, protocol roots
+	// TODO: cache management
+
+	val cache = CacheManager()
+
+	val clients = ClientHolder()
+}

src/main/kotlin/link/infra/packwiz/installer/task/TaskInput.kt

@@ -0,0 +1,29 @@
+package link.infra.packwiz.installer.task
+
+import kotlin.reflect.KProperty
+
+interface TaskInput<T> {
+	/**
+	 * The value of this task input. May be lazily evaluated; must be threadsafe.
+	 */
+	val value: T
+
+	/**
+	 * True if the effective value of this input has changed since the task was last run.
+	 * Doesn't require evaluation of the input value; should use cached data if possible.
+	 * May be lazily evaluated; must be threadsafe.
+	 */
+	val upToDate: Boolean
+
+	operator fun getValue(thisVal: Any?, property: KProperty<*>): T = value
+
+	companion object {
+		fun <T> raw(value: T): TaskInput<T> {
+			return object: TaskInput<T> {
+				override val value = value
+				override val upToDate: Boolean
+					get() = false
+			}
+		}
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/task/formats/packwizv1/PackwizV1PackFile.kt

@@ -0,0 +1,6 @@
+package link.infra.packwiz.installer.task.formats.packwizv1
+
+import link.infra.packwiz.installer.metadata.hash.Hash
+import link.infra.packwiz.installer.target.path.PackwizPath
+
+data class PackwizV1PackFile(val name: String, val indexPath: PackwizPath<*>, val indexHash: Hash<*>)

src/main/kotlin/link/infra/packwiz/installer/task/formats/packwizv1/PackwizV1PackTomlTask.kt

@@ -0,0 +1,48 @@
+package link.infra.packwiz.installer.task.formats.packwizv1
+
+import com.google.gson.annotations.SerializedName
+import link.infra.packwiz.installer.metadata.hash.Hash
+import link.infra.packwiz.installer.metadata.hash.HashFormat
+import link.infra.packwiz.installer.target.path.PackwizPath
+import link.infra.packwiz.installer.task.CacheKey
+import link.infra.packwiz.installer.task.Task
+import link.infra.packwiz.installer.task.TaskCombinedResult
+import link.infra.packwiz.installer.task.TaskContext
+
+class PackwizV1PackTomlTask(ctx: TaskContext, val path: PackwizPath<*>): Task<PackwizV1PackFile>(ctx) {
+	// TODO: make hierarchically defined by caller? - then changing the pack format type doesn't leave junk in the cache
+	private var cache by ctx.cache[CacheKey<Hash<*>>("packwiz.v1.packtoml.hash", 1)]
+
+	private class PackFile {
+		var name: String? = null
+		var index: IndexFileLoc? = null
+
+		class IndexFileLoc {
+			var file: String? = null
+			@SerializedName("hash-format")
+			var hashFormat: HashFormat<*>? = null
+			var hash: String? = null
+		}
+
+		var versions: Map<String, String>? = null
+	}
+
+	private val internalResult by lazy {
+		// TODO: query, parse JSON
+		val packFile = PackFile()
+			//Toml().read(InputStreamReader(path.source(ctx.clients).inputStream(), "UTF-8")).to(PackFile::class.java)
+
+		val hashFormat = (packFile.index?.hashFormat ?: throw RuntimeException("Hash format required"))
+		val resolved = PackwizV1PackFile(
+			packFile.name ?: throw RuntimeException("Name required"), // TODO: better exception handling
+			path.resolve(packFile.index?.file ?: throw RuntimeException("File required")),
+			hashFormat.fromString(packFile.index?.hash ?: throw RuntimeException("Hash required"))
+		)
+		val hash = hashFormat.fromString("whatever was just read")
+
+		TaskCombinedResult(resolved, wasUpdated(::cache, hash))
+	}
+
+	override val value by internalResult::result
+	override val upToDate by internalResult::upToDate
+}

src/main/kotlin/link/infra/packwiz/installer/ui/CLIHandler.kt

@@ -1,47 +0,0 @@
-package link.infra.packwiz.installer.ui
-
-import link.infra.packwiz.installer.ui.IUserInterface.ExceptionListResult
-import java.util.concurrent.CompletableFuture
-import java.util.concurrent.Future
-
-class CLIHandler : IUserInterface {
-	override fun handleException(e: Exception) {
-		e.printStackTrace()
-	}
-
-	override fun show(handler: InputStateHandler) {}
-	override fun submitProgress(progress: InstallProgress) {
-		val sb = StringBuilder()
-		if (progress.hasProgress) {
-			sb.append('(')
-			sb.append(progress.progress)
-			sb.append('/')
-			sb.append(progress.progressTotal)
-			sb.append(") ")
-		}
-		sb.append(progress.message)
-		println(sb.toString())
-	}
-
-	override fun executeManager(task: () -> Unit) {
-		task()
-		println("Finished successfully!")
-	}
-
-	override fun showOptions(options: List<IOptionDetails>): Future<Boolean> {
-		for (opt in options) {
-			opt.optionValue = true
-			// TODO: implement option choice in the CLI?
-			println("Warning: accepting option " + opt.name + " as option choosing is not implemented in the CLI")
-		}
-		return CompletableFuture<Boolean>().apply {
-			complete(false) // Can't be cancelled!
-		}
-	}
-
-	override fun showExceptions(exceptions: List<ExceptionDetails>, numTotal: Int, allowsIgnore: Boolean): Future<ExceptionListResult> {
-		val future = CompletableFuture<ExceptionListResult>()
-		future.complete(ExceptionListResult.CANCEL)
-		return future
-	}
-}

src/main/kotlin/link/infra/packwiz/installer/ui/ExceptionDetails.kt

@@ -1,6 +0,0 @@
-package link.infra.packwiz.installer.ui
-
-data class ExceptionDetails(
-		val name: String,
-		val exception: Exception
-)

src/main/kotlin/link/infra/packwiz/installer/ui/IUserInterface.kt

@@ -1,36 +1,35 @@
 package link.infra.packwiz.installer.ui
 
-import java.util.concurrent.CompletableFuture
-import java.util.concurrent.Future
-import kotlin.system.exitProcess
+import link.infra.packwiz.installer.ui.data.ExceptionDetails
+import link.infra.packwiz.installer.ui.data.IOptionDetails
+import link.infra.packwiz.installer.ui.data.InstallProgress
 
 interface IUserInterface {
-	fun show(handler: InputStateHandler)
-	fun handleException(e: Exception)
-	@JvmDefault
-	fun handleExceptionAndExit(e: Exception) {
-		handleException(e)
-		exitProcess(1)
-	}
+	fun show()
+	fun dispose()
 
-	@JvmDefault
-	fun setTitle(title: String) {}
+	fun showErrorAndExit(message: String): Nothing {
+		showErrorAndExit(message, null)
+	}
+	fun showErrorAndExit(message: String, e: Exception?): Nothing
+
+	var title: String
 	fun submitProgress(progress: InstallProgress)
-	fun executeManager(task: () -> Unit)
 	// Return true if the installation was cancelled!
-	fun showOptions(options: List<IOptionDetails>): Future<Boolean>
+	fun showOptions(options: List<IOptionDetails>): Boolean
 
-	fun showExceptions(exceptions: List<ExceptionDetails>, numTotal: Int, allowsIgnore: Boolean): Future<ExceptionListResult>
-	@JvmDefault
-	fun disableOptionsButton() {}
+	fun showExceptions(exceptions: List<ExceptionDetails>, numTotal: Int, allowsIgnore: Boolean): ExceptionListResult
+	fun disableOptionsButton(hasOptions: Boolean) {}
 
-	@JvmDefault
-	fun showCancellationDialog(): Future<CancellationResult> {
-		return CompletableFuture<CancellationResult>().apply {
-			complete(CancellationResult.QUIT)
-		}
+	fun showCancellationDialog(): CancellationResult = CancellationResult.QUIT
+
+	fun showUpdateConfirmationDialog(oldVersions: List<Pair<String, String?>>, newVersions: List<Pair<String, String?>>): UpdateConfirmationResult {
+		// Always update metadata when using the CLI
+		return UpdateConfirmationResult.UPDATE
 	}
 
+	fun awaitOptionalButton(showCancel: Boolean, timeout: Long)
+
 	enum class ExceptionListResult {
 		CONTINUE, CANCEL, IGNORE
 	}
@@ -38,4 +37,23 @@ interface IUserInterface {
 	enum class CancellationResult {
 		QUIT, CONTINUE
 	}
+
+	enum class UpdateConfirmationResult {
+		CANCELLED, CONTINUE, UPDATE
+	}
+
+	var optionsButtonPressed: Boolean
+	var cancelButtonPressed: Boolean
+	var cancelCallback: (() -> Unit)?
+
+	var firstInstall: Boolean
+
+}
+
+inline fun <T> IUserInterface.wrap(message: String, inner: () -> T): T {
+	return try {
+		inner.invoke()
+	} catch (e: Exception) {
+		showErrorAndExit(message, e)
+	}
 }

src/main/kotlin/link/infra/packwiz/installer/ui/InputStateHandler.kt

@@ -1,21 +0,0 @@
-package link.infra.packwiz.installer.ui
-
-class InputStateHandler {
-	// TODO: convert to coroutines/locks?
-	@get:Synchronized
-	var optionsButton = false
-		private set
-	@get:Synchronized
-	var cancelButton = false
-		private set
-
-	@Synchronized
-	fun pressCancelButton() {
-		cancelButton = true
-	}
-
-	@Synchronized
-	fun pressOptionsButton() {
-		optionsButton = true
-	}
-}

src/main/kotlin/link/infra/packwiz/installer/ui/InstallWindow.kt

@@ -1,228 +0,0 @@
-package link.infra.packwiz.installer.ui
-
-import link.infra.packwiz.installer.ui.IUserInterface.ExceptionListResult
-import java.awt.*
-import java.util.concurrent.CompletableFuture
-import java.util.concurrent.Future
-import java.util.concurrent.atomic.AtomicBoolean
-import javax.swing.*
-import javax.swing.border.EmptyBorder
-import kotlin.system.exitProcess
-
-class InstallWindow : IUserInterface {
-	private lateinit var frmPackwizlauncher: JFrame
-	private lateinit var lblProgresslabel: JLabel
-	private lateinit var progressBar: JProgressBar
-	private lateinit var btnOptions: JButton
-
-	private var inputStateHandler: InputStateHandler? = null
-	private var title = "Updating modpack..."
-	private var worker: SwingWorkerButWithPublicPublish<Unit, InstallProgress>? = null
-	private val aboutToCrash = AtomicBoolean()
-
-	// TODO: separate JFrame junk from IUserInterface junk?
-
-	init {
-		EventQueue.invokeAndWait {
-			frmPackwizlauncher = JFrame().apply {
-				title = this@InstallWindow.title
-				setBounds(100, 100, 493, 95)
-				defaultCloseOperation = JFrame.EXIT_ON_CLOSE
-				setLocationRelativeTo(null)
-
-				// Progress bar and loading text
-				add(JPanel().apply {
-					border = EmptyBorder(10, 10, 10, 10)
-					layout = BorderLayout(0, 0)
-
-					progressBar = JProgressBar().apply {
-						isIndeterminate = true
-					}
-					add(progressBar, BorderLayout.CENTER)
-
-					lblProgresslabel = JLabel("Loading...")
-					add(lblProgresslabel, BorderLayout.SOUTH)
-				}, BorderLayout.CENTER)
-
-				// Buttons
-				add(JPanel().apply {
-					border = EmptyBorder(0, 5, 0, 5)
-					layout = GridBagLayout()
-
-					btnOptions = JButton("Optional mods...").apply {
-						alignmentX = Component.CENTER_ALIGNMENT
-
-						addActionListener {
-							text = "Loading..."
-							isEnabled = false
-							inputStateHandler?.pressOptionsButton()
-						}
-					}
-					add(btnOptions, GridBagConstraints().apply {
-						gridx = 0
-						gridy = 0
-					})
-
-					add(JButton("Cancel").apply {
-						addActionListener {
-							isEnabled = false
-							inputStateHandler?.pressCancelButton()
-						}
-					}, GridBagConstraints().apply {
-						gridx = 0
-						gridy = 1
-					})
-				}, BorderLayout.EAST)
-			}
-		}
-	}
-
-	override fun show(handler: InputStateHandler) {
-		inputStateHandler = handler
-		EventQueue.invokeLater {
-			try {
-				UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName())
-				frmPackwizlauncher.isVisible = true
-			} catch (e: Exception) {
-				e.printStackTrace()
-			}
-		}
-	}
-
-	override fun handleException(e: Exception) {
-		e.printStackTrace()
-		EventQueue.invokeLater {
-			JOptionPane.showMessageDialog(null,
-					"An error occurred: \n" + e.javaClass.canonicalName + ": " + e.message,
-					title, JOptionPane.ERROR_MESSAGE)
-		}
-	}
-
-	override fun handleExceptionAndExit(e: Exception) {
-		e.printStackTrace()
-		// TODO: Fix this mess
-		// Used to prevent the done() handler of SwingWorker executing if the invokeLater hasn't happened yet
-		aboutToCrash.set(true)
-		EventQueue.invokeLater {
-			JOptionPane.showMessageDialog(null,
-					"A fatal error occurred: \n" + e.javaClass.canonicalName + ": " + e.message,
-					title, JOptionPane.ERROR_MESSAGE)
-			exitProcess(1)
-		}
-		// Pause forever, so it blocks while we wait for System.exit to take effect
-		try {
-			Thread.currentThread().join()
-		} catch (ex: InterruptedException) { // no u
-		}
-	}
-
-	override fun setTitle(title: String) {
-		this.title = title
-		frmPackwizlauncher.let { frame ->
-			EventQueue.invokeLater { frame.title = title }
-		}
-	}
-
-	override fun submitProgress(progress: InstallProgress) {
-		val sb = StringBuilder()
-		if (progress.hasProgress) {
-			sb.append('(')
-			sb.append(progress.progress)
-			sb.append('/')
-			sb.append(progress.progressTotal)
-			sb.append(") ")
-		}
-		sb.append(progress.message)
-		// TODO: better logging library?
-		println(sb.toString())
-		worker?.publishPublic(progress)
-	}
-
-	override fun executeManager(task: Function0<Unit>) {
-		EventQueue.invokeLater {
-			// TODO: rewrite this stupidity to use channels??!!!
-			worker = object : SwingWorkerButWithPublicPublish<Unit, InstallProgress>() {
-				override fun doInBackground() {
-					task.invoke()
-				}
-
-				override fun process(chunks: List<InstallProgress>) {
-					// Only process last chunk
-					if (chunks.isNotEmpty()) {
-						val (message, hasProgress, progress, progressTotal) = chunks[chunks.size - 1]
-						if (hasProgress) {
-							progressBar.isIndeterminate = false
-							progressBar.value = progress
-							progressBar.maximum = progressTotal
-						} else {
-							progressBar.isIndeterminate = true
-							progressBar.value = 0
-						}
-						lblProgresslabel.text = message
-					}
-				}
-
-				override fun done() {
-					if (aboutToCrash.get()) {
-						return
-					}
-					// TODO: a better way to do this?
-					frmPackwizlauncher.dispose()
-					println("Finished successfully!")
-					exitProcess(0)
-				}
-			}.also {
-				it.execute()
-			}
-		}
-	}
-
-	override fun showOptions(options: List<IOptionDetails>): Future<Boolean> {
-		val future = CompletableFuture<Boolean>()
-		EventQueue.invokeLater {
-			if (options.isEmpty()) {
-				JOptionPane.showMessageDialog(null,
-					"This modpack has no optional mods!",
-					"Optional mods", JOptionPane.INFORMATION_MESSAGE)
-				future.complete(false)
-			} else {
-				OptionsSelectWindow(options, future, frmPackwizlauncher).apply {
-					defaultCloseOperation = JDialog.DISPOSE_ON_CLOSE
-					isVisible = true
-				}
-			}
-		}
-		return future
-	}
-
-	override fun showExceptions(exceptions: List<ExceptionDetails>, numTotal: Int, allowsIgnore: Boolean): Future<ExceptionListResult> {
-		val future = CompletableFuture<ExceptionListResult>()
-		EventQueue.invokeLater {
-			ExceptionListWindow(exceptions, future, numTotal, allowsIgnore, frmPackwizlauncher).apply {
-				defaultCloseOperation = JDialog.DISPOSE_ON_CLOSE
-				isVisible = true
-			}
-		}
-		return future
-	}
-
-	override fun disableOptionsButton() {
-		btnOptions.apply {
-			text = "No optional mods"
-			isEnabled = false
-		}
-	}
-
-	override fun showCancellationDialog(): Future<IUserInterface.CancellationResult> {
-		val future = CompletableFuture<IUserInterface.CancellationResult>()
-		EventQueue.invokeLater {
-			val buttons = arrayOf("Quit", "Ignore")
-			val result = JOptionPane.showOptionDialog(frmPackwizlauncher,
-					"The installation was cancelled. Would you like to quit the game, or ignore the update and start the game?",
-					"Cancelled installation",
-					JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE, null, buttons, buttons[0])
-			future.complete(if (result == 0) IUserInterface.CancellationResult.QUIT else IUserInterface.CancellationResult.CONTINUE)
-		}
-		return future
-	}
-}

src/main/kotlin/link/infra/packwiz/installer/ui/SwingWorkerButWithPublicPublish.kt

@@ -1,13 +0,0 @@
-package link.infra.packwiz.installer.ui
-
-import javax.swing.SwingWorker
-
-// Q: AAA WHAT HAVE YOU DONE THIS IS DISGUSTING
-// A: it just makes things easier, so i can easily have one interface for CLI/GUI
-//    if someone has a better way to do this please PR it
-abstract class SwingWorkerButWithPublicPublish<T, V> : SwingWorker<T, V>() {
-	@SafeVarargs
-	fun publishPublic(vararg chunks: V) {
-		publish(*chunks)
-	}
-}

src/main/kotlin/link/infra/packwiz/installer/ui/cli/CLIHandler.kt

@@ -0,0 +1,69 @@
+package link.infra.packwiz.installer.ui.cli
+
+import link.infra.packwiz.installer.ui.IUserInterface
+import link.infra.packwiz.installer.ui.IUserInterface.ExceptionListResult
+import link.infra.packwiz.installer.ui.data.ExceptionDetails
+import link.infra.packwiz.installer.ui.data.IOptionDetails
+import link.infra.packwiz.installer.ui.data.InstallProgress
+import link.infra.packwiz.installer.util.Log
+import kotlin.system.exitProcess
+
+class CLIHandler : IUserInterface {
+	@Volatile
+	override var optionsButtonPressed = false
+	// TODO: treat ctrl+c as cancel?
+	@Volatile
+	override var cancelButtonPressed = false
+	@Volatile
+	override var cancelCallback: (() -> Unit)? = null
+	@Volatile
+	override var firstInstall = false
+
+	override var title: String = ""
+
+	override fun showErrorAndExit(message: String, e: Exception?): Nothing {
+		if (e != null) {
+			Log.fatal(message, e)
+		} else {
+			Log.fatal(message)
+		}
+		exitProcess(1)
+	}
+
+	override fun show() {}
+	override fun dispose() {}
+	override fun submitProgress(progress: InstallProgress) {
+		val sb = StringBuilder()
+		if (progress.hasProgress) {
+			sb.append('(')
+			sb.append(progress.progress)
+			sb.append('/')
+			sb.append(progress.progressTotal)
+			sb.append(") ")
+		}
+		sb.append(progress.message)
+		println(sb.toString())
+	}
+
+	override fun showOptions(options: List<IOptionDetails>): Boolean {
+		for (opt in options) {
+			opt.optionValue = true
+			// TODO: implement option choice in the CLI?
+			Log.warn("Accepting option ${opt.name} as option choosing is not implemented in the CLI")
+		}
+		return false // Can't be cancelled!
+	}
+
+	override fun showExceptions(exceptions: List<ExceptionDetails>, numTotal: Int, allowsIgnore: Boolean): ExceptionListResult {
+		println("Failed to download modpack, the following errors were encountered:")
+		for (ex in exceptions) {
+			print(ex.name + ": ")
+			ex.exception.printStackTrace()
+		}
+		return ExceptionListResult.CANCEL
+	}
+
+	override fun awaitOptionalButton(showCancel: Boolean, timeout: Long) {
+		// Do nothing
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/ui/data/ExceptionDetails.kt

@@ -0,0 +1,7 @@
+package link.infra.packwiz.installer.ui.data
+
+data class ExceptionDetails(
+		val name: String,
+		val exception: Exception,
+		val modUrl: String? = null
+)

src/main/kotlin/link/infra/packwiz/installer/ui/data/IOptionDetails.kt

@@ -1,4 +1,4 @@
-package link.infra.packwiz.installer.ui
+package link.infra.packwiz.installer.ui.data
 
 interface IOptionDetails {
 	val name: String

src/main/kotlin/link/infra/packwiz/installer/ui/data/InstallProgress.kt

@@ -1,4 +1,4 @@
-package link.infra.packwiz.installer.ui
+package link.infra.packwiz.installer.ui.data
 
 data class InstallProgress(
 		val message: String,

src/main/kotlin/link/infra/packwiz/installer/ui/gui/ExceptionListWindow.kt

@@ -1,5 +1,8 @@
-package link.infra.packwiz.installer.ui
+package link.infra.packwiz.installer.ui.gui
 
+import link.infra.packwiz.installer.util.Log
+import link.infra.packwiz.installer.ui.IUserInterface
+import link.infra.packwiz.installer.ui.data.ExceptionDetails
 import java.awt.BorderLayout
 import java.awt.Desktop
 import java.awt.event.WindowAdapter
@@ -16,12 +19,30 @@ import javax.swing.border.EmptyBorder
 class ExceptionListWindow(eList: List<ExceptionDetails>, future: CompletableFuture<IUserInterface.ExceptionListResult>, numTotal: Int, allowsIgnore: Boolean, parentWindow: JFrame?) : JDialog(parentWindow, "Failed file downloads", true) {
 	private val lblExceptionStacktrace: JTextArea
 
-	private class ExceptionListModel internal constructor(private val details: List<ExceptionDetails>) : AbstractListModel<String>() {
+	private class ExceptionListModel(private val details: List<ExceptionDetails>) : AbstractListModel<String>() {
 		override fun getSize() = details.size
 		override fun getElementAt(index: Int) = details[index].name
 		fun getExceptionAt(index: Int) = details[index].exception
 	}
 
+	private fun openUrl(url: String) {
+		try {
+			if (Desktop.isDesktopSupported() && Desktop.getDesktop().isSupported(Desktop.Action.BROWSE)) {
+				Desktop.getDesktop().browse(URI(url))
+			} else {
+				val process = Runtime.getRuntime().exec(arrayOf("xdg-open", url));
+				val exitValue = process.waitFor()
+				if (exitValue > 0) {
+					Log.warn("Failed to open $url: xdg-open exited with code $exitValue")
+				}
+			}
+		} catch (e: IOException) {
+			Log.warn("Failed to open $url", e)
+		} catch (e: URISyntaxException) {
+			Log.warn("Failed to open $url", e)
+		}
+	}
+
 	/**
 	 * Create the dialog.
 	 */
@@ -110,6 +131,19 @@ class ExceptionListWindow(eList: List<ExceptionDetails>, future: CompletableFutu
 							this@ExceptionListWindow.dispose()
 						}
 					})
+
+					val missingMods = eList.filter { it.modUrl != null }.map { it.modUrl!! }.toSet()
+
+					if (!missingMods.isEmpty()) {
+						add(JButton("Open missing mods").apply {
+							toolTipText = "Open missing mods in your browser"
+							addActionListener {
+								missingMods.forEach {
+									openUrl(it)
+								}
+							}
+						})
+					}
 				}, BorderLayout.EAST)
 
 				// Errored label
@@ -120,16 +154,8 @@ class ExceptionListWindow(eList: List<ExceptionDetails>, future: CompletableFutu
 				// Left buttons
 				add(JPanel().apply {
 					add(JButton("Report issue").apply {
-						if (Desktop.isDesktopSupported() && Desktop.getDesktop().isSupported(Desktop.Action.BROWSE)) {
-							addActionListener {
-								try {
-									Desktop.getDesktop().browse(URI("https://github.com/comp500/packwiz-installer/issues/new"))
-								} catch (e: IOException) {
-									// lol the button just won't work i guess
-								} catch (e: URISyntaxException) {}
-							}
-						} else {
-							isEnabled = false
+						addActionListener {
+							openUrl("https://github.com/packwiz/packwiz-installer/issues/new")
 						}
 					})
 				}, BorderLayout.WEST)

src/main/kotlin/link/infra/packwiz/installer/ui/gui/GUIHandler.kt

@@ -0,0 +1,251 @@
+package link.infra.packwiz.installer.ui.gui
+
+import link.infra.packwiz.installer.ui.IUserInterface
+import link.infra.packwiz.installer.ui.IUserInterface.ExceptionListResult
+import link.infra.packwiz.installer.ui.data.ExceptionDetails
+import link.infra.packwiz.installer.ui.data.IOptionDetails
+import link.infra.packwiz.installer.ui.data.InstallProgress
+import link.infra.packwiz.installer.util.Log
+import java.awt.EventQueue
+import java.util.Timer
+import java.util.concurrent.CompletableFuture
+import java.util.concurrent.CountDownLatch
+import javax.swing.JDialog
+import javax.swing.JOptionPane
+import javax.swing.UIManager
+import kotlin.concurrent.timer
+import kotlin.system.exitProcess
+
+class GUIHandler : IUserInterface {
+	private lateinit var frmPackwizlauncher: InstallWindow
+
+	@Volatile
+	override var optionsButtonPressed = false
+		set(value) {
+			optionalSelectedLatch.countDown()
+			field = value
+		}
+	@Volatile
+	override var cancelButtonPressed = false
+		set(value) {
+			optionalSelectedLatch.countDown()
+			field = value
+			cancelCallback?.invoke()
+		}
+	@Volatile
+	override var cancelCallback: (() -> Unit)? = null
+	var okButtonPressed = false
+		set(value) {
+			optionalSelectedLatch.countDown()
+			field = value
+		}
+	@Volatile
+	override var firstInstall = false
+
+	override var title = "packwiz-installer"
+		set(value) {
+			field = value
+			EventQueue.invokeLater { frmPackwizlauncher.title = value }
+		}
+
+	init {
+		EventQueue.invokeAndWait {
+			try {
+				UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName())
+			} catch (e: Exception) {
+				Log.warn("Failed to set look and feel", e)
+			}
+			frmPackwizlauncher = InstallWindow(this).apply {
+				title = this@GUIHandler.title
+			}
+		}
+	}
+
+	private val visibleCountdownLatch = CountDownLatch(1)
+	private val optionalSelectedLatch = CountDownLatch(1)
+
+	override fun show() = EventQueue.invokeLater {
+		frmPackwizlauncher.isVisible = true
+		visibleCountdownLatch.countDown()
+	}
+
+	override fun dispose() = EventQueue.invokeAndWait {
+		frmPackwizlauncher.dispose()
+	}
+
+	override fun showErrorAndExit(message: String, e: Exception?): Nothing {
+		val buttons = arrayOf("Quit", if (firstInstall) "Continue without installing" else "Continue without updating")
+		if (e != null) {
+			Log.fatal(message, e)
+			EventQueue.invokeAndWait {
+				val result = JOptionPane.showOptionDialog(frmPackwizlauncher,
+					"$message: $e",
+					title,
+					JOptionPane.YES_NO_OPTION, JOptionPane.ERROR_MESSAGE, null, buttons, buttons[0])
+				if (result == 1) {
+					Log.info("User selected to continue without installing/updating, exiting with code 0...")
+					exitProcess(0)
+				} else {
+					Log.info("User selected to quit, exiting with code 1...")
+					exitProcess(1)
+				}
+			}
+		} else {
+			Log.fatal(message)
+			EventQueue.invokeAndWait {
+				val result = JOptionPane.showOptionDialog(frmPackwizlauncher,
+					message,
+					title,
+					JOptionPane.YES_NO_OPTION, JOptionPane.ERROR_MESSAGE, null, buttons, buttons[0])
+				if (result == 1) {
+					Log.info("User selected to continue without installing/updating, exiting with code 0...")
+					exitProcess(0)
+				} else {
+					Log.info("User selected to quit, exiting with code 1...")
+					exitProcess(1)
+				}
+			}
+		}
+		exitProcess(1)
+	}
+
+	override fun submitProgress(progress: InstallProgress) {
+		val sb = StringBuilder()
+		if (progress.hasProgress) {
+			sb.append('(')
+			sb.append(progress.progress)
+			sb.append('/')
+			sb.append(progress.progressTotal)
+			sb.append(") ")
+		}
+		sb.append(progress.message)
+		Log.info(sb.toString())
+		EventQueue.invokeLater {
+			frmPackwizlauncher.displayProgress(progress)
+		}
+	}
+
+	override fun showOptions(options: List<IOptionDetails>): Boolean {
+		val future = CompletableFuture<Boolean>()
+		EventQueue.invokeAndWait {
+			if (options.isEmpty()) {
+				JOptionPane.showMessageDialog(null,
+					"This modpack has no optional mods!",
+					"Optional mods", JOptionPane.INFORMATION_MESSAGE)
+				future.complete(false)
+			} else {
+				OptionsSelectWindow(options, future, frmPackwizlauncher).apply {
+					defaultCloseOperation = JDialog.DISPOSE_ON_CLOSE
+					isVisible = true
+				}
+			}
+		}
+		return future.get()
+	}
+
+	override fun showExceptions(exceptions: List<ExceptionDetails>, numTotal: Int, allowsIgnore: Boolean): ExceptionListResult {
+		val future = CompletableFuture<ExceptionListResult>()
+		EventQueue.invokeLater {
+			ExceptionListWindow(exceptions, future, numTotal, allowsIgnore, frmPackwizlauncher).apply {
+				defaultCloseOperation = JDialog.DISPOSE_ON_CLOSE
+				isVisible = true
+			}
+		}
+		return future.get()
+	}
+
+	override fun disableOptionsButton(hasOptions: Boolean) = EventQueue.invokeLater {
+		frmPackwizlauncher.disableOptionsButton(hasOptions)
+	}
+
+	override fun showCancellationDialog(): IUserInterface.CancellationResult {
+		val future = CompletableFuture<IUserInterface.CancellationResult>()
+		EventQueue.invokeLater {
+			val buttons = arrayOf("Quit", "Ignore")
+			val result = JOptionPane.showOptionDialog(frmPackwizlauncher,
+					"The installation was cancelled. Would you like to quit the game, or ignore the update and start the game?",
+					"Cancelled installation",
+					JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE, null, buttons, buttons[0])
+			future.complete(if (result == 0) IUserInterface.CancellationResult.QUIT else IUserInterface.CancellationResult.CONTINUE)
+		}
+		return future.get()
+	}
+
+	override fun showUpdateConfirmationDialog(oldVersions: List<Pair<String, String?>>, newVersions: List<Pair<String, String?>>): IUserInterface.UpdateConfirmationResult {
+		assert(newVersions.isNotEmpty())
+		val future = CompletableFuture<IUserInterface.UpdateConfirmationResult>()
+		EventQueue.invokeLater {
+			val oldVersIndex = oldVersions.map { it.first to it.second }.toMap()
+			val newVersIndex = newVersions.map { it.first to it.second }.toMap()
+			val message = StringBuilder()
+			message.append("<html>" +
+					"This modpack uses newer versions of the following:<br>" +
+					"<ul>")
+
+			for (oldVer in oldVersions) {
+				val correspondingNewVer = newVersIndex[oldVer.first]
+				message.append("<li>")
+				message.append(oldVer.first.replaceFirstChar { it.uppercase() })
+				message.append(": <font color=${if (oldVer.second != correspondingNewVer) "#ff0000" else "#000000"}>")
+				message.append(oldVer.second ?: "Not found")
+				message.append("</font></li>")
+			}
+			message.append("</ul>")
+
+			message.append("New versions:" +
+					"<ul>")
+			for (newVer in newVersions) {
+				val correspondingOldVer = oldVersIndex[newVer.first]
+				message.append("<li>")
+				message.append(newVer.first.replaceFirstChar { it.uppercase() })
+				message.append(": <font color=${if (newVer.second != correspondingOldVer) "#00ff00" else "#000000"}>")
+				message.append(newVer.second ?: "Not found")
+				message.append("</font></li>")
+			}
+			message.append("</ul><br>" +
+					"Would you like to update the versions, launch without updating, or cancel the launch?")
+
+
+			val options = arrayOf("Cancel", "Continue anyways", "Update")
+			val result = JOptionPane.showOptionDialog(frmPackwizlauncher, message,
+					"Updating MultiMC versions",
+					JOptionPane.YES_NO_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE, null, options, options[2])
+			future.complete(
+				when (result) {
+					JOptionPane.CLOSED_OPTION, 0 -> IUserInterface.UpdateConfirmationResult.CANCELLED
+					1 -> IUserInterface.UpdateConfirmationResult.CONTINUE
+					2 -> IUserInterface.UpdateConfirmationResult.UPDATE
+					else -> IUserInterface.UpdateConfirmationResult.CANCELLED
+				}
+			)
+		}
+		return future.get()
+	}
+
+	override fun awaitOptionalButton(showCancel: Boolean, timeout: Long) {
+		EventQueue.invokeAndWait {
+			frmPackwizlauncher.showOk(!showCancel)
+		}
+		visibleCountdownLatch.await()
+
+		var closeTimer: Timer? = null
+		if (timeout >= 0) {
+			var count = 0
+			closeTimer = timer("timeout", true, 0, 1000) {
+				if (count >= timeout) {
+					optionalSelectedLatch.countDown()
+					cancel()
+				} else {
+					frmPackwizlauncher.timeoutOk(timeout - count)
+					count += 1
+				}
+			};
+		}
+
+		optionalSelectedLatch.await()
+		closeTimer?.cancel()
+		EventQueue.invokeLater {
+			frmPackwizlauncher.hideOk()
+		}
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/ui/gui/InstallWindow.kt

@@ -0,0 +1,128 @@
+package link.infra.packwiz.installer.ui.gui
+
+import link.infra.packwiz.installer.ui.data.InstallProgress
+import java.awt.BorderLayout
+import java.awt.Component
+import java.awt.GridBagConstraints
+import java.awt.GridBagLayout
+import javax.swing.*
+import javax.swing.border.EmptyBorder
+
+class InstallWindow(private val handler: GUIHandler) : JFrame() {
+	private var lblProgresslabel: JLabel
+	private var progressBar: JProgressBar
+	private var btnOptions: JButton
+	private val btnCancel: JButton
+	private val btnOk: JButton
+	private val buttonsPanel: JPanel
+
+	init {
+		setBounds(100, 100, 493, 95)
+		// Works better with tiling window managers - there isn't any reason to change window size currently anyway
+		isResizable = false
+		defaultCloseOperation = EXIT_ON_CLOSE
+		setLocationRelativeTo(null)
+
+		// Progress bar and loading text
+		add(JPanel().apply {
+			border = EmptyBorder(10, 10, 10, 10)
+			layout = BorderLayout(0, 0)
+
+			progressBar = JProgressBar().apply {
+				isIndeterminate = true
+			}
+			add(progressBar, BorderLayout.CENTER)
+
+			lblProgresslabel = JLabel("Loading...")
+			add(lblProgresslabel, BorderLayout.SOUTH)
+		}, BorderLayout.CENTER)
+
+		// Buttons
+		buttonsPanel = JPanel().apply {
+			border = EmptyBorder(0, 5, 0, 5)
+			layout = GridBagLayout()
+
+			btnOptions = JButton("Optional mods...").apply {
+				alignmentX = Component.CENTER_ALIGNMENT
+
+				addActionListener {
+					text = "Loading..."
+					isEnabled = false
+					handler.optionsButtonPressed = true
+				}
+			}
+			add(btnOptions, GridBagConstraints().apply {
+				gridx = 1
+				gridy = 0
+			})
+
+			btnCancel = JButton("Cancel").apply {
+				addActionListener {
+					isEnabled = false
+					handler.cancelButtonPressed = true
+				}
+			}
+			add(btnCancel, GridBagConstraints().apply {
+				gridx = 1
+				gridy = 1
+			})
+		}
+
+		btnOk = JButton("Continue").apply {
+			addActionListener {
+				handler.okButtonPressed = true
+			}
+		}
+		add(buttonsPanel, BorderLayout.EAST)
+	}
+
+	fun displayProgress(progress: InstallProgress) {
+		if (progress.hasProgress) {
+			progressBar.isIndeterminate = false
+			progressBar.value = progress.progress
+			progressBar.maximum = progress.progressTotal
+		} else {
+			progressBar.isIndeterminate = true
+			progressBar.value = 0
+		}
+		lblProgresslabel.text = progress.message
+	}
+
+	fun disableOptionsButton(hasOptions: Boolean) {
+		btnOptions.apply {
+			text = if (hasOptions) { "Optional mods..." } else { "No optional mods" }
+ 			isEnabled = false
+		}
+	}
+
+	fun showOk(hideCancel: Boolean) {
+		if (hideCancel) {
+			buttonsPanel.add(btnOk, GridBagConstraints().apply {
+				gridx = 1
+				gridy = 1
+			})
+			buttonsPanel.remove(btnCancel)
+		} else {
+			buttonsPanel.add(btnOk, GridBagConstraints().apply {
+				gridx = 0
+				gridy = 1
+			})
+		}
+		buttonsPanel.revalidate()
+	}
+
+	fun hideOk() {
+		buttonsPanel.remove(btnOk)
+		if (!buttonsPanel.components.contains(btnCancel)) {
+			buttonsPanel.add(btnCancel, GridBagConstraints().apply {
+				gridx = 1
+				gridy = 1
+			})
+		}
+		buttonsPanel.revalidate()
+	}
+
+	fun timeoutOk(remaining: Long) {
+		btnOk.text = "Continue ($remaining)"
+	}
+}

src/main/kotlin/link/infra/packwiz/installer/ui/gui/OptionTempHandler.kt

@@ -1,4 +1,6 @@
-package link.infra.packwiz.installer.ui
+package link.infra.packwiz.installer.ui.gui
+
+import link.infra.packwiz.installer.ui.data.IOptionDetails
 
 // Serves as a proxy for IOptionDetails, so that setOptionValue isn't called until OK is clicked
 internal class OptionTempHandler(private val opt: IOptionDetails) : IOptionDetails {

src/main/kotlin/link/infra/packwiz/installer/ui/gui/OptionsSelectWindow.kt

@@ -1,5 +1,6 @@
-package link.infra.packwiz.installer.ui
+package link.infra.packwiz.installer.ui.gui
 
+import link.infra.packwiz.installer.ui.data.IOptionDetails
 import java.awt.BorderLayout
 import java.awt.FlowLayout
 import java.awt.event.ActionEvent
@@ -18,7 +19,7 @@ class OptionsSelectWindow internal constructor(optList: List<IOptionDetails>, fu
 	private val tableModel: OptionTableModel
 	private val future: CompletableFuture<Boolean>
 
-	private class OptionTableModel internal constructor(givenOpts: List<IOptionDetails>) : TableModel {
+	private class OptionTableModel(givenOpts: List<IOptionDetails>) : TableModel {
 		private val opts: List<OptionTempHandler>
 
 		init {

src/main/kotlin/link/infra/packwiz/installer/util/4KDelegation.kt

@@ -0,0 +1,10 @@
+package link.infra.packwiz.installer.util
+
+import cc.ekblad.toml.TomlMapper
+import cc.ekblad.toml.configuration.TomlMapperConfigurator
+import cc.ekblad.toml.model.TomlValue
+
+inline fun <reified T: Any> TomlMapperConfigurator.delegateTransitive(mapper: TomlMapper) {
+	decoder { it: TomlValue -> mapper.decode<T>(it) }
+	encoder { it: T -> mapper.encode(it) }
+}

src/main/kotlin/link/infra/packwiz/installer/util/Log.kt

@@ -0,0 +1,16 @@
+package link.infra.packwiz.installer.util
+
+object Log {
+	fun info(message: String) = println(message)
+
+	fun warn(message: String) = println("[Warning] $message")
+	fun warn(message: String, exception: Exception) = println("[Warning] $message: $exception")
+
+	fun fatal(message: String) {
+		println("[FATAL] $message")
+	}
+	fun fatal(message: String, exception: Exception) {
+		println("[FATAL] $message: ")
+		exception.printStackTrace()
+	}
+}

src/main/proguard.txt

@@ -0,0 +1,19 @@
+-dontoptimize
+-dontobfuscate
+
+# Used by Okio and OkHttp
+-dontwarn org.codehaus.mojo.animal_sniffer.*
+-dontwarn okhttp3.internal.platform.**
+-dontwarn org.conscrypt.**
+-dontwarn org.bouncycastle.**
+-dontwarn org.openjsse.**
+
+-keep class !link.infra.packwiz.installer.deps.**,link.infra.packwiz.installer.** { *; }
+
+-keep class com.google.gson.reflect.TypeToken { *; }
+-keep class * extends com.google.gson.reflect.TypeToken
+
+-keep @interface kotlin.Metadata { *; }
+
+-renamesourcefileattribute SourceFile
+-keepattributes *Annotation*,SourceFile,LineNumberTable,Signature

src/main/resources/META-INF/LICENSES.md

@@ -0,0 +1,264 @@
+# Licenses
+
+packwiz-installer itself is under the MIT license ([Source](https://github.com/packwiz/packwiz-installer)), except for Murmur2Lib and bundled dependencies as follows:
+
+- Murmur2Lib: Apache 2.0 ([Source](https://github.com/prasanthj/hasher/blob/master/src/main/java/hasher/Murmur2.java))
+  - Copyright 2014 Prasanth Jayachandran
+- Google Gson 2.9.0: Apache 2.0 ([Source](https://github.com/google/gson))
+  - Copyright 2008 Google Inc.
+- Okio 3.1.0: Apache 2.0 ([Source](https://github.com/square/okio/))
+  - Copyright 2013 Square, Inc.
+- Commons CLI 1.5: Apache 2.0 ([Source](http://commons.apache.org/proper/commons-cli/))
+- Jetbrains Annotations 13.0: Apache 2.0 ([Source](https://github.com/JetBrains/java-annotations))
+  - Copyright 2000-2016 JetBrains s.r.o.
+- Kotlin Standard Library 1.7.10: Apache 2.0 ([Source](https://github.com/JetBrains/kotlin))
+  - Copyright 2010-2020 JetBrains s.r.o and respective authors and developers
+- 4koma 1.1.0: MIT ([Source](https://github.com/valderman/4koma))
+  - Copyright (c) 2021 Anton Ekblad
+
+## Associated notices
+
+### Commons CLI
+Apache Commons CLI
+Copyright 2001-2017 The Apache Software Foundation
+
+This product includes software developed at
+The Apache Software Foundation (http://www.apache.org/).
+
+## Full license texts
+
+### MIT
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+### Apache 2.0
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+1. Definitions.
+
+   "License" shall mean the terms and conditions for use, reproduction,
+   and distribution as defined by Sections 1 through 9 of this document.
+
+   "Licensor" shall mean the copyright owner or entity authorized by
+   the copyright owner that is granting the License.
+
+   "Legal Entity" shall mean the union of the acting entity and all
+   other entities that control, are controlled by, or are under common
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+   direction or management of such entity, whether by contract or
+   otherwise, or (ii) ownership of fifty percent (50%) or more of the
+   outstanding shares, or (iii) beneficial ownership of such entity.
+
+   "You" (or "Your") shall mean an individual or Legal Entity
+   exercising permissions granted by this License.
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+   including but not limited to software source code, documentation
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+
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+
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