Suppress checking for messages on application foreground.

app/src/main/java/org/thoughtcrime/securesms/jobs/MessageFetchJob.java

@@ -1,5 +1,6 @@
 package org.thoughtcrime.securesms.jobs;
 
+import android.content.Context;
 import android.os.Build;
 
 import androidx.annotation.NonNull;
@@ -7,19 +8,20 @@ import androidx.annotation.Nullable;
 
 import org.signal.core.util.logging.Log;
 import org.thoughtcrime.securesms.R;
+import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
 import org.thoughtcrime.securesms.jobmanager.Job;
 import org.thoughtcrime.securesms.jobmanager.impl.NetworkConstraint;
 import org.thoughtcrime.securesms.messages.WebSocketDrainer;
 import org.thoughtcrime.securesms.notifications.NotificationChannels;
-import org.thoughtcrime.securesms.service.DelayedNotificationController;
 import org.thoughtcrime.securesms.service.GenericForegroundService;
-import org.thoughtcrime.securesms.service.NotificationController;
+import org.thoughtcrime.securesms.util.AppForegroundObserver;
 import org.whispersystems.signalservice.api.push.exceptions.PushNetworkException;
 
 import java.io.IOException;
+import java.util.concurrent.atomic.AtomicReference;
 
 /**
- * Fetches messages from the service, posting a foreground service if possible.
+ * Fetches messages from the service, posting a foreground service if possible if the app is in the background.
  */
 public final class MessageFetchJob extends BaseJob {
 
@@ -54,19 +56,8 @@ public final class MessageFetchJob extends BaseJob {
   public void onRun() throws IOException {
     boolean success;
 
-    if (Build.VERSION.SDK_INT < 31) {
-      try (DelayedNotificationController unused = GenericForegroundService.startForegroundTaskDelayed(context, context.getString(R.string.BackgroundMessageRetriever_checking_for_messages), 300, R.drawable.ic_signal_refresh)) {
-        success = WebSocketDrainer.blockUntilDrainedAndProcessed();
-      }
-    } else {
-      try {
-        try (NotificationController unused = GenericForegroundService.startForegroundTask(context, context.getString(R.string.BackgroundMessageRetriever_checking_for_messages), NotificationChannels.getInstance().OTHER, R.drawable.ic_signal_refresh)) {
-          success = WebSocketDrainer.blockUntilDrainedAndProcessed();
-        }
-      } catch (UnableToStartException e) {
-        Log.w(TAG, "Failed to start foreground service. Running in the background.");
-        success = WebSocketDrainer.blockUntilDrainedAndProcessed();
-      }
+    try (ForegroundServiceController controller = ForegroundServiceController.create(context)) {
+      success = controller.awaitResult();
     }
 
     if (success) {
@@ -86,6 +77,92 @@ public final class MessageFetchJob extends BaseJob {
   public void onFailure() {
   }
 
+  /**
+   * Controls whether or not the ForegroundService is started, based off of whether the application process is
+   * in the foreground or background.
+   */
+  private static final class ForegroundServiceController implements AppForegroundObserver.Listener, AutoCloseable {
+
+    private final @NonNull Context context;
+    private final @NonNull AtomicReference<AutoCloseable> notificationController = new AtomicReference<>();
+
+    private volatile boolean isRunning;
+
+    private ForegroundServiceController(@NonNull Context context) {
+      this.context = context;
+    }
+
+    @Override
+    public void onForeground() {
+      if (!isRunning) {
+        return;
+      }
+
+      closeNotificationController();
+    }
+
+    @Override
+    public void onBackground() {
+      if (!isRunning) {
+        return;
+      }
+
+      if (notificationController.get() != null) {
+        Log.w(TAG, "Already displaying or displayed a foreground notification.");
+        return;
+      }
+
+      if (Build.VERSION.SDK_INT < 31) {
+        notificationController.set(GenericForegroundService.startForegroundTaskDelayed(context, context.getString(R.string.BackgroundMessageRetriever_checking_for_messages), 300, R.drawable.ic_signal_refresh));
+      } else {
+        try {
+          notificationController.set(GenericForegroundService.startForegroundTask(context, context.getString(R.string.BackgroundMessageRetriever_checking_for_messages), NotificationChannels.getInstance().OTHER, R.drawable.ic_signal_refresh));
+        } catch (UnableToStartException e) {
+          Log.w(TAG, "Failed to start foreground service. Running without a foreground service.");
+        }
+      }
+    }
+
+    @Override
+    public void close() {
+      ApplicationDependencies.getAppForegroundObserver().removeListener(this);
+      closeNotificationController();
+    }
+
+    public boolean awaitResult() {
+      isRunning = true;
+
+      boolean success;
+      try {
+        success = WebSocketDrainer.blockUntilDrainedAndProcessed();
+      } finally {
+        isRunning = false;
+      }
+
+      return success;
+    }
+
+    private void closeNotificationController() {
+      AutoCloseable controller = notificationController.get();
+      if (controller == null) {
+        return;
+      }
+
+      try {
+        controller.close();
+      } catch (Exception e) {
+        Log.w(TAG, "Exception thrown while closing notification controller", e);
+      }
+    }
+
+    static ForegroundServiceController create(@NonNull Context context) {
+      ForegroundServiceController instance = new ForegroundServiceController(context);
+      ApplicationDependencies.getAppForegroundObserver().addListener(instance);
+
+      return instance;
+    }
+  }
+
   public static final class Factory implements Job.Factory<MessageFetchJob> {
     @Override
     public @NonNull MessageFetchJob create(@NonNull Parameters parameters, @Nullable byte[] serializedData) {