Merge pull request #2954 from orionlee/bugfix_phantom_notification_rework_2716

Fix phantom service notification

4 files changed, 430 insertions, 127 deletions

diff --git a/core/src/main/java/de/danoeh/antennapod/core/service/playback/PlaybackService.java b/core/src/main/java/de/danoeh/antennapod/core/service/playback/PlaybackService.java
index 66cf7d244..c31dbc83d 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/service/playback/PlaybackService.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/service/playback/PlaybackService.java
@@ -25,6 +25,7 @@ import android.preference.PreferenceManager;
 import android.support.annotation.NonNull;
 import android.support.annotation.StringRes;
 import android.support.v4.app.NotificationCompat;
+import android.support.v4.content.ContextCompat;
 import android.support.v4.media.MediaBrowserCompat;
 import android.support.v4.media.MediaBrowserServiceCompat;
 import android.support.v4.media.MediaDescriptionCompat;
@@ -75,6 +76,11 @@ import de.greenrobot.event.EventBus;
 
 /**
  * Controls the MediaPlayer that plays a FeedMedia-file
+ *
+ * Callers should connect to the service with either:
+ * - .bindService()
+ * - ContextCompat.startForegroundService(), optionally with arguments, such as media to be played, in intent extras
+ *
  */
 public class PlaybackService extends MediaBrowserServiceCompat {
     /**
@@ -193,10 +199,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
      */
     public static boolean isRunning = false;
     /**
-     * Is true if service has received a valid start command.
-     */
-    public static boolean started = false;
-    /**
      * Is true if the service was running, but paused due to headphone disconnect
      */
     private static boolean transientPause = false;
@@ -264,9 +266,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
         Log.d(TAG, "Service created.");
         isRunning = true;
 
-        NotificationCompat.Builder notificationBuilder = createBasicNotification();
-        startForeground(NOTIFICATION_ID, notificationBuilder.build());
-
         registerReceiver(autoStateUpdated, new IntentFilter("com.google.android.gms.car.media.STATUS"));
         registerReceiver(headsetDisconnected, new IntentFilter(Intent.ACTION_HEADSET_PLUG));
         registerReceiver(shutdownReceiver, new IntentFilter(ACTION_SHUTDOWN_PLAYBACK_SERVICE));
@@ -344,7 +343,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
         Log.d(TAG, "Service is about to be destroyed");
         stopForeground(true);
         isRunning = false;
-        started = false;
         currentMediaType = MediaType.UNKNOWN;
 
         PreferenceManager.getDefaultSharedPreferences(this)
@@ -366,11 +364,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
         taskManager.shutdown();
     }
     
-    private void stopService() {
-        stopForeground(true);
-        stopSelf();
-    }
-
     @Override
     public BrowserRoot onGetRoot(@NonNull String clientPackageName, int clientUid, Bundle rootHints) {
         Log.d(TAG, "OnGetRoot: clientPackageName=" + clientPackageName +
@@ -464,37 +457,32 @@ public class PlaybackService extends MediaBrowserServiceCompat {
         final boolean castDisconnect = intent.getBooleanExtra(EXTRA_CAST_DISCONNECT, false);
         Playable playable = intent.getParcelableExtra(EXTRA_PLAYABLE);
         if (keycode == -1 && playable == null && !castDisconnect) {
-            Log.e(TAG, "PlaybackService was started with no arguments");
-            stopService();
+            // Typical cases when the service was started with no argument
+            // - when it is first bound, and then moved to startedState, as in <code>serviceManager.moveServiceToStartedState()</code>
+            // - callers (e.g., Controller) explicitly
+            Log.d(TAG, "PlaybackService was started with no arguments.");
             return Service.START_NOT_STICKY;
         }
 
-        if ((flags & Service.START_FLAG_REDELIVERY) != 0) {
-            Log.d(TAG, "onStartCommand is a redelivered intent, calling stopForeground now.");
-            stopForeground(true);
-        } else {
-            if (keycode != -1) {
-                Log.d(TAG, "Received media button event");
-                boolean handled = handleKeycode(keycode, true);
-                if (!handled) {
-                    stopService();
-                    return Service.START_NOT_STICKY;
-                }
-            } else if (!flavorHelper.castDisconnect(castDisconnect) && playable != null) {
-                started = true;
-                boolean stream = intent.getBooleanExtra(EXTRA_SHOULD_STREAM,
-                        true);
-                boolean startWhenPrepared = intent.getBooleanExtra(EXTRA_START_WHEN_PREPARED, false);
-                boolean prepareImmediately = intent.getBooleanExtra(EXTRA_PREPARE_IMMEDIATELY, false);
-                sendNotificationBroadcast(NOTIFICATION_TYPE_RELOAD, 0);
-                //If the user asks to play External Media, the casting session, if on, should end.
-                flavorHelper.castDisconnect(playable instanceof ExternalMedia);
-                if (playable instanceof FeedMedia) {
-                    playable = DBReader.getFeedMedia(((FeedMedia) playable).getId());
-                }
-                mediaPlayer.playMediaObject(playable, stream, startWhenPrepared, prepareImmediately);
+        if (keycode != -1) {
+            Log.d(TAG, "Received media button event");
+            boolean handled = handleKeycode(keycode, true);
+            if (!handled) {
+                // Just silently ignores unsupported keycode. Whether the service will
+                // continue to run is solely dependent on whether it is playing some media.
+                return Service.START_NOT_STICKY;
+            }
+        } else if (!flavorHelper.castDisconnect(castDisconnect) && playable != null) {
+            boolean stream = intent.getBooleanExtra(EXTRA_SHOULD_STREAM, true);
+            boolean startWhenPrepared = intent.getBooleanExtra(EXTRA_START_WHEN_PREPARED, false);
+            boolean prepareImmediately = intent.getBooleanExtra(EXTRA_PREPARE_IMMEDIATELY, false);
+            sendNotificationBroadcast(NOTIFICATION_TYPE_RELOAD, 0);
+            //If the user asks to play External Media, the casting session, if on, should end.
+            flavorHelper.castDisconnect(playable instanceof ExternalMedia);
+            if (playable instanceof FeedMedia) {
+                playable = DBReader.getFeedMedia(((FeedMedia) playable).getId());
             }
-            setupNotification(playable);
+            mediaPlayer.playMediaObject(playable, stream, startWhenPrepared, prepareImmediately);
         }
 
         return Service.START_NOT_STICKY;
@@ -568,12 +556,23 @@ public class PlaybackService extends MediaBrowserServiceCompat {
                 mediaPlayer.seekDelta(-UserPreferences.getRewindSecs() * 1000);
                 return true;
             case KeyEvent.KEYCODE_MEDIA_STOP:
+                // The logic gives UI illusion of stop by removing notification
+                // In the UI within AntennaPod, including widgets, it is seen as PAUSE, e.g.,
+                // users can still user on-screen widget to resume playing.
                 if (status == PlayerStatus.PLAYING) {
+                    // Implementation note: Use of a state in serviceManager to tell it to
+                    // show stop state UI (i.e., stopForeground(true)) is a bit awkward.
+                    //
+                    // More intuitive API would be for mediaPlayer.pause() returns a Future that
+                    // returns after pause, including the related async notification work completes.
+                    // However, it has its own complication, that mediaPlayer.pause() does not
+                    // really know when all the related work completes, as they are buried into
+                    // (asynchronous) callbacks.
+                    serviceManager.treatNextPauseAsStopOnUI();
                     mediaPlayer.pause(true, true);
-                    started = false;
+                } else {
+                    serviceManager.showUIForStopState();
                 }
-
-                stopForeground(true); // gets rid of persistent notification
                 return true;
             default:
                 Log.d(TAG, "Unhandled key code: " + keycode);
@@ -589,7 +588,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
         Playable playable = Playable.PlayableUtils.createInstanceFromPreferences(getApplicationContext());
         if (playable != null) {
             mediaPlayer.playMediaObject(playable, false, true, true);
-            started = true;
             PlaybackService.this.updateMediaSessionMetadata(playable);
         }
     }
@@ -604,10 +602,9 @@ public class PlaybackService extends MediaBrowserServiceCompat {
     }
 
     public void notifyVideoSurfaceAbandoned() {
+        Log.v(TAG, "notifyVideoSurfaceAbandoned()");
         mediaPlayer.pause(true, false);
         mediaPlayer.resetVideoSurface();
-        setupNotification(getPlayable());
-        stopForeground(!UserPreferences.isPersistNotify());
     }
 
     private final PlaybackServiceTaskManager.PSTMCallback taskManagerCallback = new PlaybackServiceTaskManager.PSTMCallback() {
@@ -670,27 +667,15 @@ public class PlaybackService extends MediaBrowserServiceCompat {
                     break;
 
                 case PAUSED:
-                    if ((UserPreferences.isPersistNotify() || isCasting) &&
-                            android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
-                        // do not remove notification on pause based on user pref and whether android version supports expanded notifications
-                        // Change [Play] button to [Pause]
-                        setupNotification(newInfo);
-                    } else if (!UserPreferences.isPersistNotify() && !isCasting) {
-                        // remove notification on pause
-                        stopForeground(true);
-                    }
                     writePlayerStatusPlaybackPreferences();
                     break;
 
                 case STOPPED:
                     //writePlaybackPreferencesNoMediaPlaying();
-                    //stopService();
                     break;
 
                 case PLAYING:
                     writePlayerStatusPlaybackPreferences();
-                    setupNotification(newInfo);
-                    started = true;
                     // set sleep timer if auto-enabled
                     if (newInfo.oldPlayerStatus != null && newInfo.oldPlayerStatus != PlayerStatus.SEEKING &&
                             SleepTimerPreferences.autoEnable() && !sleepTimerActive()) {
@@ -701,7 +686,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
 
                 case ERROR:
                     writePlaybackPreferencesNoMediaPlaying();
-                    stopService();
                     break;
 
             }
@@ -714,7 +698,7 @@ public class PlaybackService extends MediaBrowserServiceCompat {
 
         @Override
         public void shouldStop() {
-            stopService();
+            serviceManager.stopService();
         }
 
         @Override
@@ -763,7 +747,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
             }
             sendNotificationBroadcast(NOTIFICATION_TYPE_ERROR, what);
             writePlaybackPreferencesNoMediaPlaying();
-            stopService();
             return true;
         }
 
@@ -847,9 +830,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
         if (stopPlaying) {
             taskManager.cancelPositionSaver();
             writePlaybackPreferencesNoMediaPlaying();
-            if (!isCasting) {
-                stopForeground(true);
-            }
         }
         if (mediaType == null) {
             sendNotificationBroadcast(NOTIFICATION_TYPE_PLAYBACK_END, 0);
@@ -1063,6 +1043,7 @@ public class PlaybackService extends MediaBrowserServiceCompat {
     private void updateMediaSession(final PlayerStatus playerStatus) {
         PlaybackStateCompat.Builder sessionState = new PlaybackStateCompat.Builder();
 
+        @PlaybackStateCompat.State
         int state;
         if (playerStatus != null) {
             switch (playerStatus) {
@@ -1126,7 +1107,9 @@ public class PlaybackService extends MediaBrowserServiceCompat {
 
         flavorHelper.mediaSessionSetExtraForWear(mediaSession);
 
-        mediaSession.setPlaybackState(sessionState.build());
+        final PlaybackStateCompat sessionStateBuilt = sessionState.build();
+        mediaSession.setPlaybackState(sessionStateBuilt);
+        serviceManager.onPlaybackStateChange(sessionStateBuilt);
     }
 
     private static boolean useSkipToPreviousForRewindInLockscreen() {
@@ -1180,7 +1163,7 @@ public class PlaybackService extends MediaBrowserServiceCompat {
                     builder.putString(MediaMetadataCompat.METADATA_KEY_DISPLAY_ICON_URI, imageLocation);
                 }
             }
-            if (!Thread.currentThread().isInterrupted() && started) {
+            if (!Thread.currentThread().isInterrupted() && isStarted()) {
                 mediaSession.setSessionActivity(PendingIntent.getActivity(this, 0,
                         PlaybackService.getPlayerActivityIntent(this),
                         PendingIntent.FLAG_UPDATE_CURRENT));
@@ -1203,21 +1186,14 @@ public class PlaybackService extends MediaBrowserServiceCompat {
      */
     private Thread notificationSetupThread;
 
-    /**
-     * Prepares notification and starts the service in the foreground.
-     */
-    private void setupNotification(final PlaybackServiceMediaPlayer.PSMPInfo info) {
-        setupNotification(info.playable);
-    }
-
-    private synchronized void setupNotification(final Playable playable) {
+    private synchronized void setupNotification(final Playable playable, boolean treatPauseAsStop) {
         if (notificationSetupThread != null) {
             notificationSetupThread.interrupt();
         }
         if (playable == null) {
             Log.d(TAG, "setupNotification: playable is null");
-            if (!started) {
-                stopService();
+            if (!isStarted()) {
+                serviceManager.stopService();
             }
             return;
         }
@@ -1226,12 +1202,12 @@ public class PlaybackService extends MediaBrowserServiceCompat {
 
             @Override
             public void run() {
-                Log.d(TAG, "Starting background work");
+                Log.d(TAG, "notificationSetupTask: Starting background work");
 
                 if (mediaPlayer == null) {
                     Log.d(TAG, "notificationSetupTask: mediaPlayer is null");
-                    if (!started) {
-                        stopService();
+                    if (!isStarted()) {
+                        serviceManager.stopService();
                     }
                     return;
                 }
@@ -1256,8 +1232,9 @@ public class PlaybackService extends MediaBrowserServiceCompat {
                 }
 
                 PlayerStatus playerStatus = mediaPlayer.getPlayerStatus();
+                Log.v(TAG, "notificationSetupTask: playerStatus=" + playerStatus);
 
-                if (!Thread.currentThread().isInterrupted() && started) {
+                if (!Thread.currentThread().isInterrupted() && isStarted()) {
                     String contentText = playable.getEpisodeTitle();
                     String contentTitle = playable.getFeedTitle();
                     Notification notification;
@@ -1349,15 +1326,33 @@ public class PlaybackService extends MediaBrowserServiceCompat {
                             playerStatus == PlayerStatus.PREPARING ||
                             playerStatus == PlayerStatus.SEEKING ||
                             isCasting) {
+                        Log.v(TAG, "notificationSetupTask: make service foreground");
                         startForeground(NOTIFICATION_ID, notification);
+                    } else if (playerStatus == PlayerStatus.PAUSED) {
+                        if (treatPauseAsStop) {
+                            stopForeground(true);
+                        } else if ((UserPreferences.isPersistNotify() || isCasting) &&
+                                android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
+                            // do not remove notification on pause based on user pref and whether android version supports expanded notifications
+                            // Change [Play] button to [Pause]
+                            leaveNotificationAsBackground(notification);
+                        } else if (!UserPreferences.isPersistNotify() && !isCasting) {
+                            // remove notification on pause
+                            stopForeground(true);
+                        }
                     } else {
-                        stopForeground(false);
-                        NotificationManager mNotificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
-                        mNotificationManager.notify(NOTIFICATION_ID, notification);
+                        leaveNotificationAsBackground(notification);
                     }
                     Log.d(TAG, "Notification set up");
                 }
             }
+
+            private void leaveNotificationAsBackground(@NonNull Notification notification) {
+                stopForeground(false);
+                NotificationManager mNotificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
+                mNotificationManager.notify(NOTIFICATION_ID, notification);
+            }
+
         };
         notificationSetupThread = new Thread(notificationSetupTask);
         notificationSetupThread.start();
@@ -1552,7 +1547,7 @@ public class PlaybackService extends MediaBrowserServiceCompat {
         @Override
         public void onReceive(Context context, Intent intent) {
             if (TextUtils.equals(intent.getAction(), ACTION_SHUTDOWN_PLAYBACK_SERVICE)) {
-                stopService();
+                serviceManager.stopService();
             }
         }
 
@@ -1850,8 +1845,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
 
         void saveCurrentPosition(boolean fromMediaPlayer, Playable playable, int position);
 
-        void setupNotification(boolean connected, PlaybackServiceMediaPlayer.PSMPInfo info);
-
         MediaSessionCompat getMediaSession();
 
         Intent registerReceiver(BroadcastReceiver receiver, IntentFilter filter);
@@ -1891,24 +1884,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
         }
 
         @Override
-        public void setupNotification(boolean connected, PlaybackServiceMediaPlayer.PSMPInfo info) {
-            if (connected) {
-                PlaybackService.this.setupNotification(info);
-            } else {
-                PlayerStatus status = info.playerStatus;
-                if ((status == PlayerStatus.PLAYING ||
-                        status == PlayerStatus.SEEKING ||
-                        status == PlayerStatus.PREPARING ||
-                        UserPreferences.isPersistNotify()) &&
-                        android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
-                    PlaybackService.this.setupNotification(info);
-                } else if (!UserPreferences.isPersistNotify()) {
-                    PlaybackService.this.stopForeground(true);
-                }
-            }
-        }
-
-        @Override
         public MediaSessionCompat getMediaSession() {
             return PlaybackService.this.mediaSession;
         }
@@ -1923,4 +1898,116 @@ public class PlaybackService extends MediaBrowserServiceCompat {
             PlaybackService.this.unregisterReceiver(receiver);
         }
     };
+
+    private boolean isStarted() {
+        return serviceManager.serviceInStartedState;
+    }
+
+    /**
+     * The helper that manages PlaybackService's foreground service life cycle and the associated
+     * notification control.
+     *
+     * The logic is adapted from a sample app from The Android Open Source Project.
+     * See https://github.com/googlesamples/android-MediaBrowserService/blob/6cf01be9ef82ca2dd653f03e2a4af0b075cc0021/Application/src/main/java/com/example/android/mediasession/service/MusicService.java#L211
+     *
+     */
+    private class ServiceManager {
+        private boolean serviceInStartedState;
+        private boolean toTreatNextPauseAsStopOnUI = false;
+
+        /**
+         *
+         * Entry point method for callers. Upon PlaybackState changes,
+         * the manager start/stop the PlaybackService as well as relevant notification
+         */
+        void onPlaybackStateChange(PlaybackStateCompat state) {
+            // Report the state to the MediaSession.
+
+            Log.v(TAG, "onPlaybackStateChange(" + (state != null ? state.getState() : "null") + ")");
+            try {
+                // Manage the started state of this service.
+                switch (state.getState()) {
+                    case PlaybackStateCompat.STATE_CONNECTING:
+                        // move the service to started, aka, making it foreground
+                        // upon STATE_CONNECTING, i.e., in preparing to play a media.
+                        // This is done so that in case the preparation takes a long time, e.g.,
+                        // streaming over a slow network,
+                        // the service won't be killed by the system prematurely.
+                        moveServiceToStartedState(state);
+                        break;
+                    case PlaybackStateCompat.STATE_PLAYING:
+                        moveServiceToStartedState(state);
+                        break;
+                    case PlaybackStateCompat.STATE_PAUSED:
+                        updateNotificationForPause(state);
+                        break;
+                    case PlaybackStateCompat.STATE_STOPPED:
+                        moveServiceOutOfStartedState(state);
+                        break;
+                    case PlaybackStateCompat.STATE_ERROR:
+                        moveServiceOutOfStartedState(state);
+                        break;
+                }
+            } finally {
+                if (toTreatNextPauseAsStopOnUI) {
+                    Log.v(TAG, "onPlaybackStateChange() - toTreatNextPauseAsStopOnUI enabled. The actual state (should be PAUSED, aka 2): " + state.getState());
+                    toTreatNextPauseAsStopOnUI = false;
+                }
+            }
+        }
+
+        /**
+         * Tell service manager that on the next state change, if the state is STATE_PAUSED,
+         * give UI treatment as if it is stopped.
+         *
+         * @see #handleKeycode(int, boolean) the use case
+         */
+        public void treatNextPauseAsStopOnUI() {
+            this.toTreatNextPauseAsStopOnUI = true;
+        }
+
+        public void showUIForStopState() {
+            Log.v(TAG, "serviceManager.showUIForStopState()");
+            stopForeground(true); // gets rid of persistent notification, to give the UI illusion of STOP
+        }
+
+        public void stopService() {
+            stopForeground(true);
+            stopSelf();
+            serviceInStartedState = false;
+        }
+
+        private void moveServiceToStartedState(PlaybackStateCompat state) {
+            if (!serviceInStartedState) {
+                ContextCompat.startForegroundService(
+                        PlaybackService.this,
+                        new Intent(PlaybackService.this, PlaybackService.class));
+                serviceInStartedState = true;
+            }
+
+            doSetupNotification();
+        }
+
+        private void updateNotificationForPause(PlaybackStateCompat state) {
+            doSetupNotification();
+        }
+
+        private void moveServiceOutOfStartedState(PlaybackStateCompat state) {
+            stopService();
+        }
+
+        private void doSetupNotification() {
+            if (mediaPlayer != null && mediaPlayer.getPlayable() != null) {
+                // it updates notification and set foreground status
+                // based on player status (similar to PlaybackState)
+                setupNotification(mediaPlayer.getPlayable(), toTreatNextPauseAsStopOnUI);
+            } else {
+                // should not happen unless there are bugs.
+                Log.e(TAG, "doSetupNotification() - unexpectedly there is no playable. No notification setup done. mediaPlayer." + mediaPlayer);
+            }
+        }
+    }
+
+    private final ServiceManager serviceManager = new ServiceManager();
+
 }
diff --git a/core/src/main/java/de/danoeh/antennapod/core/util/Optional.java b/core/src/main/java/de/danoeh/antennapod/core/util/Optional.java
new file mode 100644
index 000000000..0fe11ec53
--- /dev/null
+++ b/core/src/main/java/de/danoeh/antennapod/core/util/Optional.java
@@ -0,0 +1,213 @@
+/*
+ * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package de.danoeh.antennapod.core.util;
+
+import java.util.NoSuchElementException;
+import java.util.Objects;
+
+// AntennaPod's stripped-down version of Java/Android platform's java.util.Optional
+// so that it can be used on lower API level (API level 14)
+
+// Android-changed: removed ValueBased paragraph.
+/**
+ * A container object which may or may not contain a non-null value.
+ * If a value is present, {@code isPresent()} will return {@code true} and
+ * {@code get()} will return the value.
+ *
+ * <p>Additional methods that depend on the presence or absence of a contained
+ * value are provided, such as {@link #orElse(java.lang.Object) orElse()}
+ * (return a default value if value not present) and
+ * {@link #ifPresent(java.util.function.Consumer) ifPresent()} (execute a block
+ * of code if the value is present).
+ *
+ * @since 1.8
+ */
+public final class Optional<T> {
+    /**
+     * Common instance for {@code empty()}.
+     */
+    private static final Optional<?> EMPTY = new Optional<>();
+
+    /**
+     * If non-null, the value; if null, indicates no value is present
+     */
+    private final T value;
+
+    /**
+     * Constructs an empty instance.
+     *
+     * @implNote Generally only one empty instance, {@link Optional#EMPTY},
+     * should exist per VM.
+     */
+    private Optional() {
+        this.value = null;
+    }
+
+    /**
+     * Returns an empty {@code Optional} instance.  No value is present for this
+     * Optional.
+     *
+     * @apiNote Though it may be tempting to do so, avoid testing if an object
+     * is empty by comparing with {@code ==} against instances returned by
+     * {@code Option.empty()}. There is no guarantee that it is a singleton.
+     * Instead, use {@link #isPresent()}.
+     *
+     * @param <T> Type of the non-existent value
+     * @return an empty {@code Optional}
+     */
+    public static<T> Optional<T> empty() {
+        @SuppressWarnings("unchecked")
+        Optional<T> t = (Optional<T>) EMPTY;
+        return t;
+    }
+
+    /**
+     * Constructs an instance with the value present.
+     *
+     * @param value the non-null value to be present
+     * @throws NullPointerException if value is null
+     */
+    private Optional(T value) {
+        this.value = Objects.requireNonNull(value);
+    }
+
+    /**
+     * Returns an {@code Optional} with the specified present non-null value.
+     *
+     * @param <T> the class of the value
+     * @param value the value to be present, which must be non-null
+     * @return an {@code Optional} with the value present
+     * @throws NullPointerException if value is null
+     */
+    public static <T> Optional<T> of(T value) {
+        return new Optional<>(value);
+    }
+
+    /**
+     * Returns an {@code Optional} describing the specified value, if non-null,
+     * otherwise returns an empty {@code Optional}.
+     *
+     * @param <T> the class of the value
+     * @param value the possibly-null value to describe
+     * @return an {@code Optional} with a present value if the specified value
+     * is non-null, otherwise an empty {@code Optional}
+     */
+    public static <T> Optional<T> ofNullable(T value) {
+        return value == null ? empty() : of(value);
+    }
+
+    /**
+     * If a value is present in this {@code Optional}, returns the value,
+     * otherwise throws {@code NoSuchElementException}.
+     *
+     * @return the non-null value held by this {@code Optional}
+     * @throws NoSuchElementException if there is no value present
+     *
+     * @see Optional#isPresent()
+     */
+    public T get() {
+        if (value == null) {
+            throw new NoSuchElementException("No value present");
+        }
+        return value;
+    }
+
+    /**
+     * Return {@code true} if there is a value present, otherwise {@code false}.
+     *
+     * @return {@code true} if there is a value present, otherwise {@code false}
+     */
+    public boolean isPresent() {
+        return value != null;
+    }
+
+
+    /**
+     * Return the value if present, otherwise return {@code other}.
+     *
+     * @param other the value to be returned if there is no value present, may
+     * be null
+     * @return the value, if present, otherwise {@code other}
+     */
+    public T orElse(T other) {
+        return value != null ? value : other;
+    }
+
+    /**
+     * Indicates whether some other object is "equal to" this Optional. The
+     * other object is considered equal if:
+     * <ul>
+     * <li>it is also an {@code Optional} and;
+     * <li>both instances have no value present or;
+     * <li>the present values are "equal to" each other via {@code equals()}.
+     * </ul>
+     *
+     * @param obj an object to be tested for equality
+     * @return {code true} if the other object is "equal to" this object
+     * otherwise {@code false}
+     */
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (!(obj instanceof Optional)) {
+            return false;
+        }
+
+        Optional<?> other = (Optional<?>) obj;
+        return (value == other.value) || (value != null && value.equals(other.value));
+    }
+
+    /**
+     * Returns the hash code value of the present value, if any, or 0 (zero) if
+     * no value is present.
+     *
+     * @return hash code value of the present value or 0 if no value is present
+     */
+    @Override
+    public int hashCode() {
+        return value != null ? value.hashCode() : 0;
+    }
+
+    /**
+     * Returns a non-empty string representation of this Optional suitable for
+     * debugging. The exact presentation format is unspecified and may vary
+     * between implementations and versions.
+     *
+     * @implSpec If a value is present the result must include its string
+     * representation in the result. Empty and present Optionals must be
+     * unambiguously differentiable.
+     *
+     * @return the string representation of this instance
+     */
+    @Override
+    public String toString() {
+        return value != null
+                ? String.format("Optional[%s]", value)
+                : "Optional.empty";
+    }
+}
diff --git a/core/src/main/java/de/danoeh/antennapod/core/util/playback/PlaybackController.java b/core/src/main/java/de/danoeh/antennapod/core/util/playback/PlaybackController.java
index bc047bda5..6498b9ff1 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/util/playback/PlaybackController.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/util/playback/PlaybackController.java
@@ -12,8 +12,6 @@ import android.media.MediaPlayer;
 import android.os.Build;
 import android.os.IBinder;
 import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
-import android.support.v4.content.ContextCompat;
 import android.text.TextUtils;
 import android.util.Log;
 import android.util.Pair;
@@ -37,6 +35,7 @@ import de.danoeh.antennapod.core.service.playback.PlaybackServiceMediaPlayer;
 import de.danoeh.antennapod.core.service.playback.PlayerStatus;
 import de.danoeh.antennapod.core.storage.DBTasks;
 import de.danoeh.antennapod.core.util.Converter;
+import de.danoeh.antennapod.core.util.Optional;
 import de.danoeh.antennapod.core.util.playback.Playable.PlayableUtils;
 import io.reactivex.Maybe;
 import io.reactivex.MaybeOnSubscribe;
@@ -105,6 +104,7 @@ public abstract class PlaybackController {
     }
 
     private synchronized void initServiceRunning() {
+        Log.v(TAG, "initServiceRunning()");
         if (initialized) {
             return;
         }
@@ -187,22 +187,15 @@ public abstract class PlaybackController {
         serviceBinder = Observable.fromCallable(this::getPlayLastPlayedMediaIntent)
                 .subscribeOn(Schedulers.io())
                 .observeOn(AndroidSchedulers.mainThread())
-                .subscribe(intent -> {
+                .subscribe(optionalIntent -> {
                     boolean bound = false;
-                    if (!PlaybackService.started) {
-                        if (intent != null) {
-                            Log.d(TAG, "Calling start service");
-                            ContextCompat.startForegroundService(activity, intent);
-                            bound = activity.bindService(intent, mConnection, 0);
-                        } else {
-                            status = PlayerStatus.STOPPED;
-                            setupGUI();
-                            handleStatus();
-                        }
+                    if (optionalIntent.isPresent()) {
+                        Log.d(TAG, "Calling bind service");
+                        bound = activity.bindService(optionalIntent.get(), mConnection, 0);
                     } else {
-                        Log.d(TAG, "PlaybackService is running, trying to connect without start command.");
-                        bound = activity.bindService(new Intent(activity, PlaybackService.class),
-                                mConnection, 0);
+                        status = PlayerStatus.STOPPED;
+                        setupGUI();
+                        handleStatus();
                     }
                     Log.d(TAG, "Result for service binding: " + bound);
                 }, error -> Log.e(TAG, Log.getStackTraceString(error)));
@@ -212,24 +205,26 @@ public abstract class PlaybackController {
      * Returns an intent that starts the PlaybackService and plays the last
      * played media or null if no last played media could be found.
      */
-    @Nullable private Intent getPlayLastPlayedMediaIntent() {
+    @NonNull
+    private Optional<Intent> getPlayLastPlayedMediaIntent() {
         Log.d(TAG, "Trying to restore last played media");
         Playable media = PlayableUtils.createInstanceFromPreferences(activity);
         if (media == null) {
             Log.d(TAG, "No last played media found");
-            return null;
+            return Optional.empty();
         }
 
+
         boolean fileExists = media.localFileAvailable();
         boolean lastIsStream = PlaybackPreferences.getCurrentEpisodeIsStream();
         if (!fileExists && !lastIsStream && media instanceof FeedMedia) {
             DBTasks.notifyMissingFeedMediaFile(activity, (FeedMedia) media);
         }
 
-        return new PlaybackServiceStarter(activity, media)
+        return Optional.of(new PlaybackServiceStarter(activity, media)
                 .startWhenPrepared(false)
                 .shouldStream(lastIsStream || !fileExists)
-                .getIntent();
+                .getIntent());
     }
 
 
@@ -587,7 +582,8 @@ public abstract class PlaybackController {
                     .startWhenPrepared(true)
                     .streamIfLastWasStream()
                     .start();
-            Log.w(TAG, "Play/Pause button was pressed, but playbackservice was null!");
+            Log.d(TAG, "Play/Pause button was pressed, but playbackservice was null - " +
+                    "it is likely to have been released by Android system. Restarting it.");
             return;
         }
         switch (status) {
@@ -764,6 +760,7 @@ public abstract class PlaybackController {
     }
 
     public void notifyVideoSurfaceAbandoned() {
+        Log.v(TAG, "notifyVideoSurfaceAbandoned() - hasPlaybackService=" + (playbackService != null));
         if (playbackService != null) {
             playbackService.notifyVideoSurfaceAbandoned();
         }
@@ -784,6 +781,7 @@ public abstract class PlaybackController {
     }
 
     private void initServiceNotRunning() {
+        Log.v(TAG, "initServiceNotRunning()");
         mediaLoader = Maybe.create((MaybeOnSubscribe<Playable>) emitter -> {
             Playable media = getMedia();
             if (media != null) {
diff --git a/core/src/main/java/de/danoeh/antennapod/core/util/playback/PlaybackServiceStarter.java b/core/src/main/java/de/danoeh/antennapod/core/util/playback/PlaybackServiceStarter.java
index f7d2ee409..64cf61457 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/util/playback/PlaybackServiceStarter.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/util/playback/PlaybackServiceStarter.java
@@ -2,14 +2,15 @@ package de.danoeh.antennapod.core.util.playback;
 
 import android.content.Context;
 import android.content.Intent;
-import android.media.MediaPlayer;
-import android.support.annotation.NonNull;
 import android.support.v4.content.ContextCompat;
+import android.util.Log;
 
 import de.danoeh.antennapod.core.preferences.PlaybackPreferences;
 import de.danoeh.antennapod.core.service.playback.PlaybackService;
 
 public class PlaybackServiceStarter {
+    private static final String TAG = "PlaybackServiceStarter";
+
     private final Context context;
     private final Playable media;
     private boolean startWhenPrepared = false;
@@ -66,6 +67,10 @@ public class PlaybackServiceStarter {
         launchIntent.putExtra(PlaybackService.EXTRA_SHOULD_STREAM, shouldStream);
         launchIntent.putExtra(PlaybackService.EXTRA_PREPARE_IMMEDIATELY, prepareImmediately);
 
+        if (media == null) {
+            Log.e(TAG, "getIntent() - media is unexpectedly null. intent:" + launchIntent);
+        }
+
         return launchIntent;
     }