Restore subscriptions when the app is first started

Perform a subscription list restore when the app is started for the
first time. Use a preference setting to figure out if the app is freshly
installed or not.

res/values/strings.xml

@@ -354,6 +354,9 @@
     <string name="new_episodes_count_label">Number of new episodes</string>
     <string name="in_progress_episodes_count_label">Number of episodes you have started listening to</string>
 
+    <!-- OPML backup -->
+    <string name="backup_restored">"Restored feed subscriptions from backup"</string>
+
     <!-- AntennaPodSP -->
 
     <string name="sp_apps_importing_feeds_msg">Importing subscriptions from single-purpose apps&#8230;</string>

src/de/danoeh/antennapod/activity/MainActivity.java

@@ -4,6 +4,8 @@ import java.util.ArrayList;
 
 import android.app.SearchManager;
 import android.app.SearchableInfo;
+import android.app.backup.BackupManager;
+import android.app.backup.RestoreObserver;
 import android.content.Context;
 import android.content.Intent;
 import android.media.AudioManager;
@@ -22,6 +24,8 @@ import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.Window;
+import android.widget.Toast;
+
 import de.danoeh.antennapod.AppConfig;
 import de.danoeh.antennapod.R;
 import de.danoeh.antennapod.feed.EventDistributor;
@@ -114,6 +118,26 @@ public class MainActivity extends ActionBarActivity {
 		updateProgressBarVisibility();
 		EventDistributor.getInstance().register(contentUpdate);
 
+		// Possibly restore feed subscriptions from backup
+		if (UserPreferences.isFreshInstall()) {
+			new BackupManager(this).requestRestore(new BackupRestoreObserver(this));
+			UserPreferences.setIsFreshInstall(false);
+		}
+	}
+
+	private static class BackupRestoreObserver extends RestoreObserver {
+		private final Context mContext;
+
+		public BackupRestoreObserver(final Context context) {
+			mContext = context;
+		}
+
+		@Override
+		public void restoreFinished(int error) {
+			if (error == 0) {
+				Toast.makeText(mContext, R.string.backup_restored, Toast.LENGTH_SHORT).show();
+			}
+		}
 	}
 
 	private EventDistributor.EventListener contentUpdate = new EventDistributor.EventListener() {

src/de/danoeh/antennapod/preferences/UserPreferences.java

@@ -50,6 +50,7 @@ public class UserPreferences implements
 	private static final String PREF_PLAYBACK_SPEED = "prefPlaybackSpeed";
 	private static final String PREF_PLAYBACK_SPEED_ARRAY = "prefPlaybackSpeedArray";
 	public static final String PREF_PAUSE_PLAYBACK_FOR_FOCUS_LOSS = "prefPauseForFocusLoss";
+	private static final String PREF_IS_FRESH_INSTALL = "prefIsFreshInstall";
 
     // TODO: Make this value configurable
     private static final double PLAYED_DURATION_AUTOFLATTR_THRESHOLD = 0.8;
@@ -76,6 +77,7 @@ public class UserPreferences implements
 	private String playbackSpeed;
 	private String[] playbackSpeedArray;
 	private boolean pauseForFocusLoss;
+	private boolean isFreshInstall;
 
 	private UserPreferences(Context context) {
 		this.context = context;
@@ -130,6 +132,7 @@ public class UserPreferences implements
 		playbackSpeedArray = readPlaybackSpeedArray(sp.getString(
 				PREF_PLAYBACK_SPEED_ARRAY, null));
 		pauseForFocusLoss = sp.getBoolean(PREF_PAUSE_PLAYBACK_FOR_FOCUS_LOSS, false);
+		isFreshInstall = sp.getBoolean(PREF_IS_FRESH_INSTALL, true);
 	}
 
 	private int readThemeValue(String valueFromPrefs) {
@@ -284,6 +287,11 @@ public class UserPreferences implements
 		return instance.pauseForFocusLoss;
 	}
 
+	public static boolean isFreshInstall() {
+		instanceAvailable();
+		return instance.isFreshInstall;
+	}
+
 	@Override
 	public void onSharedPreferenceChanged(SharedPreferences sp, String key) {
 		if (AppConfig.DEBUG)
@@ -334,6 +342,8 @@ public class UserPreferences implements
 			pauseForFocusLoss = sp.getBoolean(PREF_PAUSE_PLAYBACK_FOR_FOCUS_LOSS, false);
 		} else if (key.equals(PREF_PAUSE_ON_HEADSET_DISCONNECT)) {
             pauseOnHeadsetDisconnect = sp.getBoolean(PREF_PAUSE_ON_HEADSET_DISCONNECT, true);
+        } else if (key.equals(PREF_IS_FRESH_INSTALL)) {
+            isFreshInstall = sp.getBoolean(PREF_IS_FRESH_INSTALL, true);
         }
 	}
 
@@ -526,4 +536,11 @@ public class UserPreferences implements
         instanceAvailable();
         return PLAYED_DURATION_AUTOFLATTR_THRESHOLD;
     }
+
+    public static void setIsFreshInstall(boolean isFreshInstall) {
+        instanceAvailable();
+        PreferenceManager.getDefaultSharedPreferences(instance.context).edit()
+                .putBoolean(PREF_IS_FRESH_INSTALL, isFreshInstall)
+                .apply();
+    }
 }