From 951b35ca5f785c9935002ed8ef4ba997706d46e6 Mon Sep 17 00:00:00 2001
From: alexytomi <60690056+alexytomi@users.noreply.github.com>
Date: Sun, 8 Jun 2025 17:31:30 +0800
Subject: [PATCH] fix[MinecraftDownloader]: Fix local profile and offline
 handling so they can actually launch the game

---
 .../tasks/MinecraftDownloader.java            | 37 +++++++++++++++----
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/app_pojavlauncher/src/main/java/net/kdt/pojavlaunch/tasks/MinecraftDownloader.java b/app_pojavlauncher/src/main/java/net/kdt/pojavlaunch/tasks/MinecraftDownloader.java
index db34eee3e..40abf1723 100644
--- a/app_pojavlauncher/src/main/java/net/kdt/pojavlaunch/tasks/MinecraftDownloader.java
+++ b/app_pojavlauncher/src/main/java/net/kdt/pojavlaunch/tasks/MinecraftDownloader.java
@@ -72,7 +72,7 @@ public class MinecraftDownloader {
      * @param listener The download status listener
      */
     public void start(@Nullable Activity activity, @Nullable JMinecraftVersionList.Version version,
-                      @NonNull String realVersion, // this was there for a reason
+                      @NonNull String realVersion,
                       @NonNull AsyncMinecraftDownloader.DoneListener listener) {
         if(activity != null){
             isLocalProfile = Tools.isLocalProfile(activity);
@@ -86,11 +86,32 @@ public class MinecraftDownloader {
 
         sExecutorService.execute(() -> {
             try {
-                if(isLocalProfile){
-                    throw new RuntimeException("Download failed. Please make sure you are logged in with a Microsoft Account.");
-                }
+                if(isLocalProfile || !isOnline) {
+                    String versionMessage = realVersion; // Use provided version unless we find its a modded instance
+
+                    // See if provided version is a modded version and if that version depends on another jar, check for presence of both jar's .json.
+                    try {
+                        // This reads the .json associated with the provided version. If it fails, we can assume it's not installed.
+                        File providedJsonFile = new File(Tools.DIR_HOME_VERSION + "/" + realVersion + "/" + realVersion + ".json");
+                        JMinecraftVersionList.Version providedJson = Tools.GLOBAL_GSON.fromJson(Tools.read(providedJsonFile.getAbsolutePath()), JMinecraftVersionList.Version.class);
+
+                        // This checks if running modded version that depends on other jars, so we use that for the error message.
+                        File vanillaJsonFile = new File(Tools.DIR_HOME_VERSION + "/" + providedJson.inheritsFrom + "/" + providedJson.inheritsFrom + ".json");
+                        versionMessage = providedJson.inheritsFrom != null ? providedJson.inheritsFrom : versionMessage;
+
+                        // Ensure they're both not some 0 byte corrupted json
+                        if (providedJsonFile.length() == 0 || vanillaJsonFile.exists() && vanillaJsonFile.length() == 0){
+                            throw new RuntimeException("Minecraft "+versionMessage+ " is needed by " +realVersion); }
+
+                        listener.onDownloadDone();
+                    } catch (Exception e) {
+                        String tryagain = !isOnline ? "Please ensure you have an internet connection" : "Please try again on your Microsoft Account";
+                        Tools.showErrorRemote(versionMessage + " is not currently installed. "+ tryagain, e);
+                    }
+                }else {
                 downloadGame(activity, version, realVersion);
                 listener.onDownloadDone();
+                }
             }catch (Exception e) {
                 listener.onDownloadFailed(e);
             }
@@ -484,18 +505,18 @@ public class MinecraftDownloader {
             File cacheFile = new File(sha1CacheDir.getAbsolutePath() + FileUtils.getFileName(mTargetUrl) + ".sha");
 
             // Only use cache when its offline. No point in having cache invalidation now!
-            if (!isOnline) {
+            if (!isOnline || !LauncherPreferences.PREF_CHECK_LIBRARY_SHA) { // Well not only offlines..this setting speeds up launch times at least!
                 try (BufferedReader cacheFileReader = new BufferedReader(new FileReader(cacheFile))) {
                     mTargetSha1 = cacheFileReader.readLine();
                     if (mTargetSha1 != null) {
-                        Log.i("MinecraftDownloader", "(No internet found) Reading Hash: " + mTargetSha1 + " from " + cacheFile);
+                        Log.i("MinecraftDownloader", "Reading Hash from cache: " + mTargetSha1 + " from " + cacheFile);
                     } else if (cacheFile.exists()) {
-                        Log.i("MinecraftDownloader", "(No internet found) Deleting invalid hash from cache: " + cacheFile);
+                        Log.i("MinecraftDownloader", "Deleting invalid hash from cache: " + cacheFile);
                         cacheFile.delete();
                     }
                 } catch (FileNotFoundException ignored) {
                     mTargetSha1 = null;
-                    Log.w("MinecraftDownloader", "(No internet found) Failed to read hash for " + cacheFile);
+                    Log.w("MinecraftDownloader", "Failed to read hash for " + cacheFile);
                 }
                 return;
             }