1 files changed, 177 insertions, 0 deletions
diff --git a/app/src/main/java/de/danoeh/antennapod/asynctask/DownloadObserver.java b/app/src/main/java/de/danoeh/antennapod/asynctask/DownloadObserver.java
new file mode 100644
index 000000000..21ae5291e
--- /dev/null
+++ b/app/src/main/java/de/danoeh/antennapod/asynctask/DownloadObserver.java
@@ -0,0 +1,177 @@
+package de.danoeh.antennapod.asynctask;
+
+import android.app.Activity;
+import android.content.*;
+import android.os.Handler;
+import android.os.IBinder;
+import android.util.Log;
+
+import org.apache.commons.lang3.Validate;
+
+import de.danoeh.antennapod.BuildConfig;
+import de.danoeh.antennapod.service.download.DownloadService;
+import de.danoeh.antennapod.service.download.Downloader;
+
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * Provides access to the DownloadService's list of items that are currently being downloaded.
+ * The DownloadObserver object should be created in the activity's onCreate() method. resume() and pause()
+ * should be called in the activity's onResume() and onPause() methods
+ */
+public class DownloadObserver {
+    private static final String TAG = "DownloadObserver";
+
+    /**
+     * Time period between update notifications.
+     */
+    public static final int WAITING_INTERVAL_MS = 3000;
+
+    private volatile Activity activity;
+    private final Handler handler;
+    private final Callback callback;
+
+    private DownloadService downloadService = null;
+    private AtomicBoolean mIsBound = new AtomicBoolean(false);
+
+    private Thread refresherThread;
+    private AtomicBoolean refresherThreadRunning = new AtomicBoolean(false);
+
+
+    /**
+     * Creates a new download observer.
+     *
+     * @param activity Used for registering receivers
+     * @param handler  All callback methods are executed on this handler. The handler MUST run on the GUI thread.
+     * @param callback Callback methods for posting content updates
+     * @throws java.lang.IllegalArgumentException if one of the arguments is null.
+     */
+    public DownloadObserver(Activity activity, Handler handler, Callback callback) {
+        Validate.notNull(activity);
+        Validate.notNull(handler);
+        Validate.notNull(callback);
+
+        this.activity = activity;
+        this.handler = handler;
+        this.callback = callback;
+    }
+
+    public void onResume() {
+        if (BuildConfig.DEBUG) Log.d(TAG, "DownloadObserver resumed");
+        activity.registerReceiver(contentChangedReceiver, new IntentFilter(DownloadService.ACTION_DOWNLOADS_CONTENT_CHANGED));
+        connectToDownloadService();
+    }
+
+    public void onPause() {
+        if (BuildConfig.DEBUG) Log.d(TAG, "DownloadObserver paused");
+        try {
+            activity.unregisterReceiver(contentChangedReceiver);
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        }
+        try {
+            activity.unbindService(mConnection);
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        }
+        stopRefresher();
+    }
+
+    private BroadcastReceiver contentChangedReceiver = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            // reconnect to DownloadService if connection has been closed
+            if (downloadService == null) {
+                connectToDownloadService();
+            }
+            callback.onContentChanged();
+            startRefresher();
+        }
+    };
+
+    public interface Callback {
+        void onContentChanged();
+
+        void onDownloadDataAvailable(List<Downloader> downloaderList);
+    }
+
+    private void connectToDownloadService() {
+        activity.bindService(new Intent(activity, DownloadService.class), mConnection, 0);
+    }
+
+    private ServiceConnection mConnection = new ServiceConnection() {
+        public void onServiceDisconnected(ComponentName className) {
+            downloadService = null;
+            mIsBound.set(false);
+            stopRefresher();
+            Log.i(TAG, "Closed connection with DownloadService.");
+        }
+
+        public void onServiceConnected(ComponentName name, IBinder service) {
+            downloadService = ((DownloadService.LocalBinder) service)
+                    .getService();
+            mIsBound.set(true);
+            if (BuildConfig.DEBUG)
+                Log.d(TAG, "Connection to service established");
+            List<Downloader> downloaderList = downloadService.getDownloads();
+            if (downloaderList != null && !downloaderList.isEmpty()) {
+                callback.onDownloadDataAvailable(downloaderList);
+                startRefresher();
+            }
+        }
+    };
+
+    private void stopRefresher() {
+        if (refresherThread != null) {
+            refresherThread.interrupt();
+        }
+    }
+
+    private void startRefresher() {
+        if (refresherThread == null || refresherThread.isInterrupted()) {
+            refresherThread = new Thread(new RefresherThread());
+            refresherThread.start();
+        }
+    }
+
+    private class RefresherThread implements Runnable {
+
+        public void run() {
+            refresherThreadRunning.set(true);
+            while (!Thread.interrupted()) {
+                try {
+                    Thread.sleep(WAITING_INTERVAL_MS);
+                } catch (InterruptedException e) {
+                    Log.d(TAG, "Refresher thread was interrupted");
+                }
+                if (mIsBound.get()) {
+                    postUpdate();
+                }
+            }
+            refresherThreadRunning.set(false);
+        }
+
+        private void postUpdate() {
+            handler.post(new Runnable() {
+                @Override
+                public void run() {
+                    callback.onContentChanged();
+                    if (downloadService != null) {
+                        List<Downloader> downloaderList = downloadService.getDownloads();
+                        if (downloaderList == null || downloaderList.isEmpty()) {
+                            Thread.currentThread().interrupt();
+                        }
+                    }
+                }
+            });
+        }
+    }
+
+    public void setActivity(Activity activity) {
+        Validate.notNull(activity);
+        this.activity = activity;
+    }
+
+}
+