* add GooglePlayServices check

* implement wifi-reconnect feature for casting
* move wifiLock logic to abstract PSMP

app/src/main/java/de/danoeh/antennapod/preferences/PreferenceController.java

@@ -34,6 +34,8 @@ import android.widget.Toast;
 import android.widget.ListView;
 
 import com.afollestad.materialdialogs.MaterialDialog;
+import com.google.android.gms.common.ConnectionResult;
+import com.google.android.gms.common.GoogleApiAvailability;
 
 import org.apache.commons.lang3.ArrayUtils;
 
@@ -410,6 +412,22 @@ public class PreferenceController implements SharedPreferences.OnSharedPreferenc
             ui.getActivity().startActivity(Intent.createChooser(emailIntent, intentTitle));
             return true;
         });
+        //checks whether Google Play Services is installed on the device (condition necessary for Cast support)
+        ui.findPreference(UserPreferences.PREF_CAST_ENABLED).setOnPreferenceChangeListener((preference, o) -> {
+            if (o instanceof Boolean && ((Boolean) o)) {
+                final int googlePlayServicesCheck = GoogleApiAvailability.getInstance()
+                        .isGooglePlayServicesAvailable(ui.getActivity());
+                if (googlePlayServicesCheck == ConnectionResult.SUCCESS) {
+                    return true;
+                } else {
+                    GoogleApiAvailability.getInstance()
+                            .getErrorDialog(ui.getActivity(), googlePlayServicesCheck, 0)
+                            .show();
+                    return false;
+                }
+            }
+            return true;
+        });
         buildEpisodeCleanupPreference();
         buildSmartMarkAsPlayedPreference();
         buildAutodownloadSelectedNetworsPreference();

core/src/main/java/de/danoeh/antennapod/core/cast/CastManager.java

@@ -136,6 +136,7 @@ public class CastManager extends BaseCastManager implements OnFailedListener {
             if (ConnectionResult.SUCCESS != GoogleApiAvailability.getInstance()
                     .isGooglePlayServicesAvailable(context)) {
                 Log.e(TAG, "Couldn't find the appropriate version of Google Play Services");
+                //TODO check whether creating an instance without google play services installed actually gives an exception
             }
             INSTANCE = new CastManager(context, castConfiguration);
         }

core/src/main/java/de/danoeh/antennapod/core/service/playback/LocalPSMP.java

@@ -2,7 +2,6 @@ package de.danoeh.antennapod.core.service.playback;
 
 import android.content.Context;
 import android.media.AudioManager;
-import android.net.wifi.WifiManager;
 import android.os.PowerManager;
 import android.support.annotation.NonNull;
 import android.telephony.TelephonyManager;
@@ -56,11 +55,6 @@ public class LocalPSMP extends PlaybackServiceMediaPlayer {
 
     private final ThreadPoolExecutor executor;
 
-    /**
-     * A wifi-lock that is acquired if the media file is being streamed.
-     */
-    private WifiManager.WifiLock wifiLock;
-
     public LocalPSMP(@NonNull Context context,
                      @NonNull PSMPCallback callback) {
         super(context, callback);
@@ -805,21 +799,9 @@ public class LocalPSMP extends PlaybackServiceMediaPlayer {
         });
     }
 
-    private synchronized void acquireWifiLockIfNecessary() {
+    @Override
-        if (stream) {
+    protected boolean shouldLockWifi(){
-            if (wifiLock == null) {
+        return stream;
-                wifiLock = ((WifiManager) context.getSystemService(Context.WIFI_SERVICE))
-                        .createWifiLock(WifiManager.WIFI_MODE_FULL, TAG);
-                wifiLock.setReferenceCounted(false);
-            }
-            wifiLock.acquire();
-        }
-    }
-
-    private synchronized void releaseWifiLockIfNecessary() {
-        if (wifiLock != null && wifiLock.isHeld()) {
-            wifiLock.release();
-        }
     }
 
     private IPlayer setMediaPlayerListeners(IPlayer mp) {
@@ -878,13 +860,8 @@ public class LocalPSMP extends PlaybackServiceMediaPlayer {
         return callback.onMediaPlayerInfo(what);
     }
 
-    private final MediaPlayer.OnSpeedAdjustmentAvailableChangedListener
+    private final MediaPlayer.OnSpeedAdjustmentAvailableChangedListener audioSetSpeedAbilityListener =
-            audioSetSpeedAbilityListener = new MediaPlayer.OnSpeedAdjustmentAvailableChangedListener() {
+            (arg0, speedAdjustmentAvailable) -> callback.setSpeedAbilityChanged();
-        @Override
-        public void onSpeedAdjustmentAvailableChanged(MediaPlayer arg0, boolean speedAdjustmentAvailable) {
-            callback.setSpeedAbilityChanged();
-        }
-    };
 
 
     private final MediaPlayer.OnErrorListener audioErrorListener =

core/src/main/java/de/danoeh/antennapod/core/service/playback/PlaybackService.java

@@ -15,6 +15,8 @@ import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.media.AudioManager;
 import android.media.MediaPlayer;
+import android.net.NetworkInfo;
+import android.net.wifi.WifiManager;
 import android.os.Binder;
 import android.os.Build;
 import android.os.IBinder;
@@ -60,6 +62,7 @@ import de.danoeh.antennapod.core.receiver.MediaButtonReceiver;
 import de.danoeh.antennapod.core.storage.DBTasks;
 import de.danoeh.antennapod.core.storage.DBWriter;
 import de.danoeh.antennapod.core.util.IntList;
+import de.danoeh.antennapod.core.util.NetworkUtils;
 import de.danoeh.antennapod.core.util.QueueAccess;
 import de.danoeh.antennapod.core.util.flattr.FlattrUtils;
 import de.danoeh.antennapod.core.util.playback.ExternalMedia;
@@ -167,6 +170,12 @@ public class PlaybackService extends Service implements SharedPreferences.OnShar
      */
     public static final int INVALID_TIME = -1;
 
+    /**
+     * Time in seconds during which the CastManager will try to reconnect to the Cast Device after
+     * the Wifi Connection is regained.
+     */
+    private static final int RECONNECTION_ATTEMPT_PERIOD_S = 15;
+
     /**
      * Is true if service is running.
      */
@@ -188,6 +197,9 @@ public class PlaybackService extends Service implements SharedPreferences.OnShar
      */
     private volatile PlaybackServiceMediaPlayer.PSMPInfo infoBeforeCastDisconnection;
 
+    private boolean mWifiConnectivity = true;
+    private BroadcastReceiver mWifiBroadcastReceiver;
+
     private static final int NOTIFICATION_ID = 1;
 
     private PlaybackServiceMediaPlayer mediaPlayer;
@@ -318,6 +330,7 @@ public class PlaybackService extends Service implements SharedPreferences.OnShar
         unregisterReceiver(pausePlayCurrentEpisodeReceiver);
         unregisterReceiver(pauseResumeCurrentEpisodeReceiver);
         CastManager.getInstance().removeCastConsumer(castConsumer);
+        unregisterWifiBroadcastReceiver();
         mediaPlayer.shutdown();
         taskManager.shutdown();
     }
@@ -1561,6 +1574,7 @@ public class PlaybackService extends Service implements SharedPreferences.OnShar
                     (mediaPlayer != null) ? mediaPlayer.getPSMPInfo() :
                             new PlaybackServiceMediaPlayer.PSMPInfo(PlayerStatus.STOPPED, null));
             sendNotificationBroadcast(NOTIFICATION_TYPE_RELOAD, EXTRA_CODE_CAST);
+            registerWifiBroadcastReceiver();
         }
 
         @Override
@@ -1602,6 +1616,7 @@ public class PlaybackService extends Service implements SharedPreferences.OnShar
                 Log.d(TAG, "Cast session disconnected, but no current media");
                 sendNotificationBroadcast(NOTIFICATION_TYPE_PLAYBACK_END, 0);
             }
+            unregisterWifiBroadcastReceiver();
         }
     };
 
@@ -1620,4 +1635,37 @@ public class PlaybackService extends Service implements SharedPreferences.OnShar
                     info.playerStatus.isAtLeast(PlayerStatus.PREPARING));
         }
     }
+
+    private void registerWifiBroadcastReceiver() {
+        if (mWifiBroadcastReceiver != null) {
+            return;
+        }
+        mWifiBroadcastReceiver = new BroadcastReceiver() {
+            @Override
+            public void onReceive(Context context, Intent intent) {
+                if (intent.getAction().equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)) {
+                    NetworkInfo info = intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
+                    boolean isConnected = info.isConnected();
+                    //apparently this method gets called twice when a change happens, but one run is enough.
+                    if (isConnected && !mWifiConnectivity) {
+                        mWifiConnectivity = true;
+                        CastManager castMgr = CastManager.getInstance();
+                        castMgr.startCastDiscovery();
+                        castMgr.reconnectSessionIfPossible(RECONNECTION_ATTEMPT_PERIOD_S, NetworkUtils.getWifiSsid());
+                    } else {
+                        mWifiConnectivity = isConnected;
+                    }
+                }
+            }
+        };
+        registerReceiver(mWifiBroadcastReceiver,
+                new IntentFilter(WifiManager.NETWORK_STATE_CHANGED_ACTION));
+    }
+
+    private void unregisterWifiBroadcastReceiver() {
+        if (mWifiBroadcastReceiver != null) {
+            unregisterReceiver(mWifiBroadcastReceiver);
+            mWifiBroadcastReceiver = null;
+        }
+    }
 }

core/src/main/java/de/danoeh/antennapod/core/service/playback/PlaybackServiceMediaPlayer.java

@@ -1,6 +1,7 @@
 package de.danoeh.antennapod.core.service.playback;
 
 import android.content.Context;
+import android.net.wifi.WifiManager;
 import android.support.annotation.NonNull;
 import android.util.Log;
 import android.util.Pair;
@@ -33,6 +34,11 @@ public abstract class PlaybackServiceMediaPlayer {
 
     protected volatile PlayerStatus playerStatus;
 
+    /**
+     * A wifi-lock that is acquired if the media file is being streamed.
+     */
+    private WifiManager.WifiLock wifiLock;
+
     protected final PSMPCallback callback;
     protected final Context context;
 
@@ -237,6 +243,28 @@ public abstract class PlaybackServiceMediaPlayer {
      */
     public abstract void stop();
 
+    /**
+     * @return {@code true} if the WifiLock feature should be used, {@code false} otherwise.
+     */
+    protected abstract boolean shouldLockWifi();
+
+    protected final synchronized void acquireWifiLockIfNecessary() {
+        if (shouldLockWifi()) {
+            if (wifiLock == null) {
+                wifiLock = ((WifiManager) context.getSystemService(Context.WIFI_SERVICE))
+                        .createWifiLock(WifiManager.WIFI_MODE_FULL, TAG);
+                wifiLock.setReferenceCounted(false);
+            }
+            wifiLock.acquire();
+        }
+    }
+
+    protected final synchronized void releaseWifiLockIfNecessary() {
+        if (wifiLock != null && wifiLock.isHeld()) {
+            wifiLock.release();
+        }
+    }
+
     /**
      * Sets the player status of the PSMP object. PlayerStatus and media attributes have to be set at the same time
      * so that getPSMPInfo can't return an invalid state (e.g. status is PLAYING, but media is null).

core/src/main/java/de/danoeh/antennapod/core/service/playback/RemotePSMP.java

@@ -450,4 +450,9 @@ public class RemotePSMP extends PlaybackServiceMediaPlayer {
     public void stop() {
         //TODO
     }
+
+    @Override
+    protected boolean shouldLockWifi() {
+        return false;
+    }
 }

core/src/main/java/de/danoeh/antennapod/core/util/NetworkUtils.java

@@ -92,6 +92,18 @@ public class NetworkUtils {
 		return mWifi.isConnected();
 	}
 
+    /**
+     * Returns the SSID of the wifi connection, or <code>null</code> if there is no wifi.
+     */
+    public static String getWifiSsid() {
+        WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
+        WifiInfo wifiInfo = wifiManager.getConnectionInfo();
+        if (wifiInfo != null) {
+            return wifiInfo.getSSID();
+        }
+        return null;
+    }
+
 	public static Observable<Long> getFeedMediaSizeObservable(FeedMedia media) {
         return Observable.create(new Observable.OnSubscribe<Long>() {
             @Override