Improve handling of manual downloads; "Continue" now rechecks files

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

@@ -182,13 +182,13 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 
 		// Ensure wrong-side or optional false files are removed
 		cachedFile?.let {
-			if (!it.optionValue || !correctSide()) {
-				if (it.cachedLocation == null) return
-
-				try {
-					Files.deleteIfExists(Paths.get(packFolder, it.cachedLocation))
-				} catch (e: IOException) {
-					Log.warn("Failed to delete file before downloading", e)
+			if ((it.isOptional && !it.optionValue) || !correctSide()) {
+				if (it.cachedLocation != null) {
+					try {
+						Files.deleteIfExists(Paths.get(packFolder, it.cachedLocation))
+					} catch (e: IOException) {
+						Log.warn("Failed to delete file before downloading", e)
+					}
 				}
 				it.cachedLocation = null
 			}
@@ -292,7 +292,7 @@ internal class DownloadTask private constructor(val metadata: IndexFile.File, de
 
 	companion object {
 		@JvmStatic
-		fun createTasksFromIndex(index: IndexFile, defaultFormat: String, downloadSide: Side): List<DownloadTask> {
+		fun createTasksFromIndex(index: IndexFile, defaultFormat: String, downloadSide: Side): MutableList<DownloadTask> {
 			val tasks = ArrayList<DownloadTask>()
 			for (file in Objects.requireNonNull(index.files)) {
 				tasks.add(DownloadTask(file, defaultFormat, downloadSide))

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

@@ -128,7 +128,9 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 		if (manifest.packFileHash?.let { packFileSource.hashIsEqual(it) } == true && invalidatedUris.isEmpty()) {
 			// todo: --force?
 			ui.submitProgress(InstallProgress("Modpack is already up to date!", 1, 1))
-			ui.awaitOptionalButton(false)
+			if (manifest.cachedFiles.any { it.value.isOptional }) {
+				ui.awaitOptionalButton(false)
+			}
 			if (!ui.optionsButtonPressed) {
 				return
 			}
@@ -186,7 +188,9 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 	private fun processIndex(indexUri: SpaceSafeURI, indexHash: Hash, hashFormat: String, manifest: ManifestFile, invalidatedUris: List<SpaceSafeURI>) {
 		if (manifest.indexFileHash == indexHash && invalidatedUris.isEmpty()) {
 			ui.submitProgress(InstallProgress("Modpack files are already up to date!", 1, 1))
-			ui.awaitOptionalButton(false)
+			if (manifest.cachedFiles.any { it.value.isOptional }) {
+				ui.awaitOptionalButton(false)
+			}
 			if (!ui.optionsButtonPressed) {
 				return
 			}
@@ -310,8 +314,8 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 		}
 
 		// TODO: task failed function?
-		val nonFailedFirstTasks = tasks.filter { t -> !t.failed() }.toList()
-		val optionTasks = nonFailedFirstTasks.filter(DownloadTask::correctSide).filter(DownloadTask::isOptional).toList()
+		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) {
@@ -335,35 +339,11 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 		// TODO: keep this enabled? then apply changes after download process?
 		ui.disableOptionsButton(optionTasks.isNotEmpty())
 
-		ui.submitProgress(InstallProgress("Validating existing files..."))
-
-		// Validate existing files
-		for (downloadTask in nonFailedFirstTasks.filter(DownloadTask::correctSide)) {
-			downloadTask.validateExistingFile(opts.packFolder)
-		}
-
-		// 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 == "metadata:curseforge" }.toList()
-		if (cfFiles.isNotEmpty()) {
-			ui.submitProgress(InstallProgress("Resolving CurseForge metadata..."))
-			val resolveFailures = resolveCfMetadata(cfFiles)
-			if (resolveFailures.isNotEmpty()) {
-				errorsOccurred = true
-				when (ui.showExceptions(resolveFailures, cfFiles.size, true)) {
-					ExceptionListResult.CONTINUE -> {}
-					ExceptionListResult.CANCEL -> {
-						cancelled = true
-						return
-					}
-					ExceptionListResult.IGNORE -> {
-						cancelledStartGame = true
-						return
-					}
-				}
+		while (true) {
+			when (validateAndResolve(tasks)) {
+				ResolveResult.RETRY -> {}
+				ResolveResult.QUIT -> return
+				ResolveResult.SUCCESS -> break
 			}
 		}
 
@@ -414,7 +394,7 @@ 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
 			when (ui.showExceptions(failedTasks2ElectricBoogaloo, tasks.size, false)) {
@@ -425,6 +405,49 @@ class UpdateManager internal constructor(private val opts: Options, val ui: IUse
 		}
 	}
 
+	enum class ResolveResult {
+		RETRY,
+		QUIT,
+		SUCCESS;
+	}
+
+	private fun validateAndResolve(nonFailedFirstTasks: List<DownloadTask>): ResolveResult {
+		ui.submitProgress(InstallProgress("Validating existing files..."))
+
+		// Validate existing files
+		for (downloadTask in nonFailedFirstTasks.filter(DownloadTask::correctSide)) {
+			downloadTask.validateExistingFile(opts.packFolder)
+		}
+
+		// 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 == "metadata:curseforge" }.toList()
+		if (cfFiles.isNotEmpty()) {
+			ui.submitProgress(InstallProgress("Resolving CurseForge metadata..."))
+			val resolveFailures = resolveCfMetadata(cfFiles)
+			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