From 8471fa01070dfe80311630f22490c2ca749cb42a Mon Sep 17 00:00:00 2001
From: Luke Street <luke@street.dev>
Date: Tue, 14 Jul 2026 09:22:50 -0600
Subject: [PATCH] Android: Bundle in-tree mods into the APK

---
 .github/workflows/build.yml                   |  4 ++
 platforms/android/.gitignore                  |  1 +
 platforms/android/app/build.gradle            |  5 ++
 .../com/twilitrealm/dusk/DuskActivity.java    | 49 +++++++++++++++++++
 platforms/android/scripts/stage-jni-libs.sh   | 24 +++++++++
 5 files changed, 83 insertions(+)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 5a8c505c52..2f9f666700 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -205,6 +205,9 @@ jobs:
       - name: Build native library
         run: cmake --build --preset ${{matrix.preset}} --target dusklight
 
+      - name: Build bundled mods
+        run: cmake --build --preset ${{matrix.preset}} --target dusklight_mods
+
       - name: Stage stripped JNI library
         run: ANDROID_STAGE_ABIS="${{matrix.abi}}" platforms/android/scripts/stage-jni-libs.sh
 
@@ -289,5 +292,6 @@ jobs:
             build/install/*.dll
             build/install/*.symdb
             build/install/res/
+            build/install/mods/
             build/install/debug.7z
             build/install/sdk/
diff --git a/platforms/android/.gitignore b/platforms/android/.gitignore
index 7775e3c7f4..002aaa86aa 100644
--- a/platforms/android/.gitignore
+++ b/platforms/android/.gitignore
@@ -3,3 +3,4 @@ build/
 app/build/
 local.properties
 app/src/main/jniLibs/*/*.so
+app/src/main/bundled_mods/
diff --git a/platforms/android/app/build.gradle b/platforms/android/app/build.gradle
index 8527cd1f4d..c7a25e732b 100644
--- a/platforms/android/app/build.gradle
+++ b/platforms/android/app/build.gradle
@@ -12,6 +12,11 @@ def syncDuskAssets = tasks.register('syncDuskAssets', Sync) {
         into 'res'
         exclude '**/.DS_Store'
     }
+    // Staged by platforms/android/scripts/stage-jni-libs.sh
+    from(new File(projectDir, 'src/main/bundled_mods')) {
+        into 'mods'
+        include '*.dusk'
+    }
     into duskGeneratedAssetsDir
 }
 
diff --git a/platforms/android/app/src/main/java/com/twilitrealm/dusk/DuskActivity.java b/platforms/android/app/src/main/java/com/twilitrealm/dusk/DuskActivity.java
index 96fc302d9e..2fa6cbacb3 100644
--- a/platforms/android/app/src/main/java/com/twilitrealm/dusk/DuskActivity.java
+++ b/platforms/android/app/src/main/java/com/twilitrealm/dusk/DuskActivity.java
@@ -27,6 +27,10 @@ import org.libsdl.app.SDLActivity;
 import org.libsdl.app.SDLSurface;
 
 import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -90,10 +94,55 @@ public class DuskActivity extends SDLActivity {
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
+        extractBundledMods();
         super.onCreate(savedInstanceState);
         hideSystemBars();
     }
 
+    // Bundled mod packages ship as APK assets, which the native loader cannot read directly;
+    // mirror them into internal storage (the loader's CachePath/bundled_mods search dir)
+    // before SDL_main starts.
+    private void extractBundledMods() {
+        File outDir = new File(getFilesDir(), "bundled_mods");
+        try {
+            deleteRecursively(outDir); // drop packages removed by an app update
+            String[] names = getAssets().list("mods");
+            if (names == null || names.length == 0) {
+                return;
+            }
+            if (!outDir.mkdirs()) {
+                Log.w(TAG, "Unable to create " + outDir);
+                return;
+            }
+            byte[] buffer = new byte[65536];
+            for (String name : names) {
+                if (!name.endsWith(".dusk")) {
+                    continue;
+                }
+                try (InputStream in = getAssets().open("mods/" + name);
+                     OutputStream out = new FileOutputStream(new File(outDir, name)))
+                {
+                    int count;
+                    while ((count = in.read(buffer)) > 0) {
+                        out.write(buffer, 0, count);
+                    }
+                }
+            }
+        } catch (IOException e) {
+            Log.w(TAG, "Failed to extract bundled mods", e);
+        }
+    }
+
+    private static void deleteRecursively(File file) {
+        File[] children = file.listFiles();
+        if (children != null) {
+            for (File child : children) {
+                deleteRecursively(child);
+            }
+        }
+        file.delete();
+    }
+
     @Override
     protected SDLSurface createSDLSurface(Context context) {
         return new DuskSurface(context);
diff --git a/platforms/android/scripts/stage-jni-libs.sh b/platforms/android/scripts/stage-jni-libs.sh
index 42b08c13e6..a30d961156 100755
--- a/platforms/android/scripts/stage-jni-libs.sh
+++ b/platforms/android/scripts/stage-jni-libs.sh
@@ -70,3 +70,27 @@ for abi in $ANDROID_STAGE_ABIS; do
   esac
   copy_lib "$abi" "$src"
 done
+
+# Stage bundled mod packages into the app's assets source dir.
+MODS_STAGING_DIR="$ROOT_DIR/platforms/android/app/src/main/bundled_mods"
+rm -rf "$MODS_STAGING_DIR"
+mkdir -p "$MODS_STAGING_DIR"
+for abi in $ANDROID_STAGE_ABIS; do
+  case "$abi" in
+    arm64-v8a) build_dir="$ROOT_DIR/build/android-arm64" ;;
+    x86_64) build_dir="$ROOT_DIR/build/android-x86_64" ;;
+  esac
+  [[ -d "$build_dir/bundled_mods" ]] || continue
+  for pkg in "$build_dir/bundled_mods"/*.dusk; do
+    [[ -f "$pkg" ]] || continue
+    name="$(basename "$pkg")"
+    if [[ ! -f "$MODS_STAGING_DIR/$name" ]]; then
+      cp -f "$pkg" "$MODS_STAGING_DIR/$name"
+      echo "Staged bundled mod $pkg"
+    else
+      stage_dir="$build_dir/mods/${name%.dusk}/${name%.dusk}_stage"
+      (cd "$stage_dir" && zip -q -r "$MODS_STAGING_DIR/$name" lib)
+      echo "Appended $abi libraries to bundled mod $name"
+    fi
+  done
+done