Improvements to MultiMC metadata updating

Reformatted and refactored names to fit Kotlin conventions
Closed manifest file reader properly
Fixed switching between loaders, improved intermediary logic
Improved error messages

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

@@ -12,10 +12,10 @@ import java.nio.file.Paths
 
 class LauncherUtils internal constructor(private val opts: UpdateManager.Options, val ui: IUserInterface) {
 	enum class LauncherStatus {
-        Succesful,
-        NoChanges,
-        Cancelled,
-        NotFound, // We'll use the NotFound as the neutral return type for now
+		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 {
@@ -24,85 +24,96 @@ class LauncherUtils internal constructor(private val opts: UpdateManager.Options
 		val manifestFile = File(manifestPath)
 
 		if (!manifestFile.exists()) {
-            return LauncherStatus.NotFound
+			return LauncherStatus.NOT_FOUND
 		}
 
-        val multimcManifest = try {
-            JsonParser.parseReader(manifestFile.reader())
+		val multimcManifest = manifestFile.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("Invalid MultiMC format version")
+		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.fabricmc.fabric-loader" to "fabric", "org.quiltmc.quilt-loader" to "quilt", "com.mumfrey.liteloader" to "liteloader")
+		val modLoaders = hashMapOf(
+			"net.minecraft" to "minecraft",
+			"net.minecraftforge" to "forge",
+			"net.fabricmc.fabric-loader" to "fabric",
+			"org.quiltmc.quilt-loader" to "quilt",
+			"com.mumfrey.liteloader" to "liteloader")
 		val modLoadersClasses = modLoaders.entries.associate{(k,v)-> v to k}
-        var modLoaderFound = false
-        val modLoadersFound = HashMap<String, String>() // Key: modLoader, Value: Version
-        val components = multimcManifest["components"].asJsonArray
-        for (componentObj in components) {
-            val component = componentObj.asJsonObject
+		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
+			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)
-                if (modLoader != "minecraft")
-                    modLoaderFound = true // Only set to true if modLoader isn't Minecraft
-                modLoadersFound[modLoader] = version
+			if (modLoaders.containsKey(component["uid"]?.asString)) {
+				val modLoader = modLoaders.getValue(component["uid"]!!.asString)
+				loaderVersionsFound[modLoader] = version
 				if (version != pf.versions?.get(modLoader)) {
-                    manifestModified = true
-                    component.addProperty("version", pf.versions?.get(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
 		}
 
-        // If we can't find the mod loader in the MultiMC file, we add it
-        if (!modLoaderFound) {
-            // Using this filter and loop to handle multiple handlers
 		for ((_, loader) in modLoaders
-                    .filter { it.value != "minecraft" && !modLoadersFound.containsKey(it.value) && pf.versions?.containsKey(it.value) == true }
+			.filter {
+				(!loaderVersionsFound.containsKey(it.value) || outdatedLoaders.contains(it.value))
+					&& pf.versions?.containsKey(it.value) == true }
 		) {
-                components.add(gson.toJsonTree(hashMapOf("uid" to modLoadersClasses.get(loader), "version" to pf.versions?.get(loader))))
-            }
+			manifestModified = true
+			components.add(gson.toJsonTree(
+				hashMapOf("uid" to modLoadersClasses[loader], "version" to pf.versions?.get(loader)))
+			)
 		}
 
-        // If mc version change detected, and fabric mappings are found, delete them, MultiMC will add and re-dl the correct one
-        if (modLoadersFound["minecraft"] != pf.versions?.getValue("minecraft"))
-            components.find { it.asJsonObject["uid"].asString == "net.fabricmc.intermediary" }?.asJsonObject?.let { components.remove(it) }
+		// 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?.get("minecraft")) {
+				components.remove(it)
+				manifestModified = true
+			}
+		}
 
 		if (manifestModified) {
 			// 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 = modLoadersFound.map { Pair(it.key, it.value) }
+			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
+					return LauncherStatus.CANCELLED
 				}
 				IUserInterface.UpdateConfirmationResult.CONTINUE -> {
-                    return LauncherStatus.Succesful // Returning succesful as... Well, the user is telling us to continue
+					return LauncherStatus.SUCCESSFUL
 				}
-                else -> {} // Compiler is giving warning about "non-exhaustive when", so i'll just add an empty one
+				else -> {}
 			}
 
 			manifestFile.writeText(gson.toJson(multimcManifest))
-            Log.info("Updated modpack Minecrafts and/or the modloaders version")
+			Log.info("Successfully updated mmc-pack.json based on version metadata")
 
-            return LauncherStatus.Succesful
+			return LauncherStatus.SUCCESSFUL
 		}
 
-        return LauncherStatus.NoChanges
+		return LauncherStatus.NO_CHANGES
 	}
 }

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

@@ -105,8 +105,9 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 		ui.submitProgress(InstallProgress("Loading MultiMC pack file..."))
 		try {
 			when (lu.handleMultiMC(pf, gson)) {
-				LauncherUtils.LauncherStatus.Cancelled -> cancelled = true
-				LauncherUtils.LauncherStatus.NotFound -> Log.info("MultiMC not detected")
+				LauncherUtils.LauncherStatus.CANCELLED -> cancelled = true
+				LauncherUtils.LauncherStatus.NOT_FOUND -> Log.info("MultiMC not detected")
+				else -> {}
 			}
 			handleCancellation()
 		} catch (e: Exception) {

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

@@ -202,10 +202,9 @@ class GUIHandler : IUserInterface {
 
 
 			val options = arrayOf("Cancel", "Continue anyways", "Update")
-			val result = JOptionPane.showOptionDialog(frmPackwizlauncher,
-					message,
+			val result = JOptionPane.showOptionDialog(frmPackwizlauncher, message,
 					"Updating MultiMC versions",
-					JOptionPane.YES_NO_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE, null, options, options[0])
+					JOptionPane.YES_NO_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE, null, options, options[2])
 			future.complete(
 				when (result) {
 					JOptionPane.CLOSED_OPTION, 0 -> IUserInterface.UpdateConfirmationResult.CANCELLED