Drastically improve module download service

app/src/main/java/com/topjohnwu/magisk/App.java

@@ -33,7 +33,7 @@ public class App extends Application implements Application.ActivityLifecycleCal
     public SharedPreferences prefs;
     public MagiskDB mDB;
     public RepoDatabaseHelper repoDB;
-    public BaseActivity foreground;
+    private volatile BaseActivity foreground;
 
     static {
         Shell.Config.setFlags(Shell.FLAG_MOUNT_MASTER | Shell.FLAG_USE_MAGISK_BUSYBOX);
@@ -68,6 +68,10 @@ public class App extends Application implements Application.ActivityLifecycleCal
         LocaleManager.setLocale(this);
     }
 
+    public static BaseActivity foreground() {
+        return self.foreground;
+    }
+
     @Override
     public void onActivityCreated(@NonNull Activity activity, @Nullable Bundle bundle) {}
 
@@ -75,12 +79,12 @@ public class App extends Application implements Application.ActivityLifecycleCal
     public void onActivityStarted(@NonNull Activity activity) {}
 
     @Override
-    public void onActivityResumed(@NonNull Activity activity) {
+    public synchronized void onActivityResumed(@NonNull Activity activity) {
         foreground = (BaseActivity) activity;
     }
 
     @Override
-    public void onActivityPaused(@NonNull Activity activity) {
+    public synchronized void onActivityPaused(@NonNull Activity activity) {
         foreground = null;
     }
 

app/src/main/java/com/topjohnwu/magisk/components/DownloadModuleService.java

@@ -1,20 +1,20 @@
 package com.topjohnwu.magisk.components;
 
+import android.app.PendingIntent;
 import android.app.Service;
 import android.content.Intent;
 import android.net.Uri;
 import android.os.IBinder;
-import android.widget.Toast;
 
 import androidx.annotation.Nullable;
 
+import com.topjohnwu.magisk.App;
 import com.topjohnwu.magisk.ClassMap;
 import com.topjohnwu.magisk.Const;
 import com.topjohnwu.magisk.FlashActivity;
-import com.topjohnwu.magisk.R;
 import com.topjohnwu.magisk.container.Repo;
+import com.topjohnwu.magisk.uicomponents.Notifications;
 import com.topjohnwu.magisk.uicomponents.ProgressNotification;
-import com.topjohnwu.magisk.utils.Utils;
 import com.topjohnwu.net.Networking;
 import com.topjohnwu.superuser.Shell;
 import com.topjohnwu.superuser.ShellUtils;
@@ -25,13 +25,15 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipInputStream;
 import java.util.zip.ZipOutputStream;
 
 public class DownloadModuleService extends Service {
 
-    private boolean running = false;
+    private List<ProgressNotification> notifications;
 
     @Nullable
     @Override
@@ -39,46 +41,82 @@ public class DownloadModuleService extends Service {
         return null;
     }
 
+    @Override
+    public void onCreate() {
+        notifications = new ArrayList<>();
+    }
+
     @Override
     public int onStartCommand(Intent intent, int flags, int startId) {
-        if (flags == 0 && running) {
-            Utils.toast(R.string.dl_one_module, Toast.LENGTH_LONG);
-        } else {
-            running = true;
         Shell.EXECUTOR.execute(() -> {
             Repo repo = intent.getParcelableExtra("repo");
             boolean install = intent.getBooleanExtra("install", false);
             dlProcessInstall(repo, install);
-                stopSelf();
         });
-        }
         return START_REDELIVER_INTENT;
     }
 
+    @Override
+    public synchronized void onTaskRemoved(Intent rootIntent) {
+        for (ProgressNotification n : notifications) {
+            Notifications.mgr.cancel(n.hashCode());
+        }
+        notifications.clear();
+    }
+
+    private synchronized void addNotification(ProgressNotification n) {
+        if (notifications.isEmpty()) {
+            // Start foreground
+            startForeground(n.hashCode(), n.getNotification());
+        }
+        notifications.add(n);
+    }
+
+    private synchronized void removeNotification(ProgressNotification n) {
+        notifications.remove(n);
+        if (notifications.isEmpty()) {
+            // No more tasks, stop service
+            stopForeground(true);
+            stopSelf();
+        } else {
+            // Pick another notification as our foreground notification
+            n = notifications.get(0);
+            startForeground(n.hashCode(), n.getNotification());
+        }
+    }
+
     private void dlProcessInstall(Repo repo, boolean install) {
         File output = new File(Const.EXTERNAL_PATH, repo.getDownloadFilename());
         ProgressNotification progress = new ProgressNotification(output.getName());
-        startForeground(progress.hashCode(), progress.getNotification());
+        addNotification(progress);
         try {
             InputStream in = Networking.get(repo.getZipUrl())
                     .setDownloadProgressListener(progress)
                     .execForInputStream().getResult();
             OutputStream out = new BufferedOutputStream(new FileOutputStream(output));
             processZip(in, out, repo.isNewInstaller());
-            if (install) {
-                progress.dismiss();
             Intent intent = new Intent(this, ClassMap.get(FlashActivity.class));
             intent.setData(Uri.fromFile(output))
                     .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
                     .putExtra(Const.Key.FLASH_ACTION, Const.Value.FLASH_ZIP);
-                startActivity(intent);
+            synchronized (getApplication()) {
+                if (install && App.foreground() != null &&
+                        !(App.foreground() instanceof FlashActivity)) {
+                    /* Only start flashing if there is a foreground activity and the
+                     * user is not also flashing another module at the same time */
+                    App.foreground().startActivity(intent);
                 } else {
-                progress.dlDone();
+                    /* Or else we preset a notification notifying that we are done */
+                    PendingIntent pi = PendingIntent.getActivity(this, progress.hashCode(), intent,
+                            PendingIntent.FLAG_UPDATE_CURRENT);
+                    progress.dlDone(pi);
+                }
             }
         } catch (Exception e) {
             e.printStackTrace();
             progress.dlFail();
         }
+        removeNotification(progress);
     }
 
     private void processZip(InputStream in, OutputStream out, boolean inject)

app/src/main/java/com/topjohnwu/magisk/components/UpdateCheckService.java

@@ -15,7 +15,7 @@ public class UpdateCheckService extends DelegateWorker {
     @NonNull
     @Override
     public ListenableWorker.Result doWork() {
-        if (App.self.foreground == null) {
+        if (App.foreground() == null) {
             Shell.getShell();
             CheckUpdates.check(this::onCheckDone);
         }

app/src/main/java/com/topjohnwu/magisk/uicomponents/ProgressNotification.java

@@ -1,6 +1,8 @@
 package com.topjohnwu.magisk.uicomponents;
 
 import android.app.Notification;
+import android.app.PendingIntent;
+import android.content.Intent;
 import android.widget.Toast;
 
 import androidx.core.app.NotificationCompat;
@@ -55,10 +57,17 @@ public class ProgressNotification implements DownloadProgressListener {
     }
 
     public void dlDone() {
+        dlDone(PendingIntent.getActivity(App.self, hashCode(),
+                new Intent(), PendingIntent.FLAG_UPDATE_CURRENT));
+    }
+
+    public void dlDone(PendingIntent intent) {
         builder.setProgress(0, 0, false)
                 .setContentText(App.self.getString(R.string.download_complete))
                 .setSmallIcon(android.R.drawable.stat_sys_download_done)
-                .setOngoing(false);
+                .setContentIntent(intent)
+                .setOngoing(false)
+                .setAutoCancel(true);
         lastUpdate();
     }