Made auto-cleanup and auto-download methods changeable

9 files changed, 527 insertions, 175 deletions

diff --git a/core/src/main/java/de/danoeh/antennapod/core/ClientConfig.java b/core/src/main/java/de/danoeh/antennapod/core/ClientConfig.java
index e5e609f5f..1a2671555 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/ClientConfig.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/ClientConfig.java
@@ -22,4 +22,6 @@ public class ClientConfig {
     public static FlattrCallbacks flattrCallbacks;
 
     public static StorageCallbacks storageCallbacks;
+
+    public static DBTasksCallbacks dbTasksCallbacks;
 }
diff --git a/core/src/main/java/de/danoeh/antennapod/core/DBTasksCallbacks.java b/core/src/main/java/de/danoeh/antennapod/core/DBTasksCallbacks.java
new file mode 100644
index 000000000..edf3e3199
--- /dev/null
+++ b/core/src/main/java/de/danoeh/antennapod/core/DBTasksCallbacks.java
@@ -0,0 +1,20 @@
+package de.danoeh.antennapod.core;
+
+import de.danoeh.antennapod.core.storage.AutomaticDownloadAlgorithm;
+import de.danoeh.antennapod.core.storage.EpisodeCleanupAlgorithm;
+
+/**
+ * Callbacks for the DBTasks class of the storage module.
+ */
+public interface DBTasksCallbacks {
+
+    /**
+     * Returns the client's implementation of the AutomaticDownloadAlgorithm interface.
+     */
+    public AutomaticDownloadAlgorithm getAutomaticDownloadAlgorithm();
+
+    /**
+     * Returns the client's implementation of the EpisodeCacheCleanupAlgorithm interface.
+     */
+    public EpisodeCleanupAlgorithm getEpisodeCacheCleanupAlgorithm();
+}
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/APCleanupAlgorithm.java b/core/src/main/java/de/danoeh/antennapod/core/storage/APCleanupAlgorithm.java
new file mode 100644
index 000000000..499fddf74
--- /dev/null
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/APCleanupAlgorithm.java
@@ -0,0 +1,103 @@
+package de.danoeh.antennapod.core.storage;
+
+import android.content.Context;
+import android.util.Log;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Date;
+import java.util.List;
+import java.util.concurrent.ExecutionException;
+
+import de.danoeh.antennapod.core.feed.FeedItem;
+import de.danoeh.antennapod.core.preferences.UserPreferences;
+import de.danoeh.antennapod.core.util.QueueAccess;
+
+/**
+ * Implementation of the EpisodeCleanupAlgorithm interface used by AntennaPod.
+ */
+public class APCleanupAlgorithm implements EpisodeCleanupAlgorithm<Integer> {
+    private static final String TAG = "APCleanupAlgorithm";
+
+    @Override
+    public int performCleanup(Context context, Integer episodeNumber) {
+        List<FeedItem> candidates = new ArrayList<FeedItem>();
+        List<FeedItem> downloadedItems = DBReader.getDownloadedItems(context);
+        QueueAccess queue = QueueAccess.IDListAccess(DBReader.getQueueIDList(context));
+        List<FeedItem> delete;
+        for (FeedItem item : downloadedItems) {
+            if (item.hasMedia() && item.getMedia().isDownloaded()
+                    && !queue.contains(item.getId()) && item.isRead()) {
+                candidates.add(item);
+            }
+
+        }
+
+        Collections.sort(candidates, new Comparator<FeedItem>() {
+            @Override
+            public int compare(FeedItem lhs, FeedItem rhs) {
+                Date l = lhs.getMedia().getPlaybackCompletionDate();
+                Date r = rhs.getMedia().getPlaybackCompletionDate();
+
+                if (l == null) {
+                    l = new Date(0);
+                }
+                if (r == null) {
+                    r = new Date(0);
+                }
+                return l.compareTo(r);
+            }
+        });
+
+        if (candidates.size() > episodeNumber) {
+            delete = candidates.subList(0, episodeNumber);
+        } else {
+            delete = candidates;
+        }
+
+        for (FeedItem item : delete) {
+            try {
+                DBWriter.deleteFeedMediaOfItem(context, item.getMedia().getId()).get();
+            } catch (InterruptedException | ExecutionException e) {
+                e.printStackTrace();
+            }
+        }
+
+        int counter = delete.size();
+
+
+        Log.i(TAG, String.format(
+                "Auto-delete deleted %d episodes (%d requested)", counter,
+                episodeNumber));
+
+        return counter;
+    }
+
+    @Override
+    public Integer getDefaultCleanupParameter(Context context) {
+        return 0;
+    }
+
+    @Override
+    public Integer getPerformCleanupParameter(Context context, List<FeedItem> items) {
+        return getPerformAutoCleanupArgs(context, items.size());
+    }
+
+    static int getPerformAutoCleanupArgs(Context context,
+                                         final int episodeNumber) {
+        if (episodeNumber >= 0
+                && UserPreferences.getEpisodeCacheSize() != UserPreferences
+                .getEpisodeCacheSizeUnlimited()) {
+            int downloadedEpisodes = DBReader
+                    .getNumberOfDownloadedEpisodes(context);
+            if (downloadedEpisodes + episodeNumber >= UserPreferences
+                    .getEpisodeCacheSize()) {
+
+                return downloadedEpisodes + episodeNumber
+                        - UserPreferences.getEpisodeCacheSize();
+            }
+        }
+        return 0;
+    }
+}
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/APDownloadAlgorithm.java b/core/src/main/java/de/danoeh/antennapod/core/storage/APDownloadAlgorithm.java
new file mode 100644
index 000000000..c5f871f48
--- /dev/null
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/APDownloadAlgorithm.java
@@ -0,0 +1,133 @@
+package de.danoeh.antennapod.core.storage;
+
+import android.content.Context;
+import android.util.Log;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import de.danoeh.antennapod.core.BuildConfig;
+import de.danoeh.antennapod.core.feed.FeedItem;
+import de.danoeh.antennapod.core.preferences.UserPreferences;
+import de.danoeh.antennapod.core.util.NetworkUtils;
+import de.danoeh.antennapod.core.util.PowerUtils;
+
+/**
+ * Implements the automatic download algorithm used by AntennaPod. This class assumes that
+ * the client uses the APEpisodeCleanupAlgorithm.
+ */
+public class APDownloadAlgorithm implements AutomaticDownloadAlgorithm {
+    private static final String TAG = "APDownloadAlgorithm";
+
+    private final APCleanupAlgorithm cleanupAlgorithm = new APCleanupAlgorithm();
+
+    /**
+     * Looks for undownloaded episodes in the queue or list of unread items and request a download if
+     * 1. Network is available
+     * 2. The device is charging or the user allows auto download on battery
+     * 3. There is free space in the episode cache
+     * This method is executed on an internal single thread executor.
+     *
+     * @param context  Used for accessing the DB.
+     * @param mediaIds If this list is not empty, the method will only download a candidate for automatic downloading if
+     *                 its media ID is in the mediaIds list.
+     * @return A Runnable that will be submitted to an ExecutorService.
+     */
+    @Override
+    public Runnable autoDownloadUndownloadedItems(final Context context, final long... mediaIds) {
+        return new Runnable() {
+            @Override
+            public void run() {
+
+                // true if we should auto download based on network status
+                boolean networkShouldAutoDl = NetworkUtils.autodownloadNetworkAvailable(context)
+                        && UserPreferences.isEnableAutodownload();
+
+                // true if we should auto download based on power status
+                boolean powerShouldAutoDl = PowerUtils.deviceCharging(context)
+                        || UserPreferences.isEnableAutodownloadOnBattery();
+
+                // we should only auto download if both network AND power are happy
+                if (networkShouldAutoDl && powerShouldAutoDl) {
+
+                    Log.d(TAG, "Performing auto-dl of undownloaded episodes");
+
+                    final List<FeedItem> queue = DBReader.getQueue(context);
+                    final List<FeedItem> unreadItems = DBReader
+                            .getUnreadItemsList(context);
+
+                    int undownloadedEpisodes = DBTasks.getNumberOfUndownloadedEpisodes(queue,
+                            unreadItems);
+                    int downloadedEpisodes = DBReader
+                            .getNumberOfDownloadedEpisodes(context);
+                    int deletedEpisodes = cleanupAlgorithm.performCleanup(context,
+                            APCleanupAlgorithm.getPerformAutoCleanupArgs(context, undownloadedEpisodes));
+                    int episodeSpaceLeft = undownloadedEpisodes;
+                    boolean cacheIsUnlimited = UserPreferences.getEpisodeCacheSize() == UserPreferences
+                            .getEpisodeCacheSizeUnlimited();
+
+                    if (!cacheIsUnlimited
+                            && UserPreferences.getEpisodeCacheSize() < downloadedEpisodes
+                            + undownloadedEpisodes) {
+                        episodeSpaceLeft = UserPreferences.getEpisodeCacheSize()
+                                - (downloadedEpisodes - deletedEpisodes);
+                    }
+
+                    Arrays.sort(mediaIds);    // sort for binary search
+                    final boolean ignoreMediaIds = mediaIds.length == 0;
+                    List<FeedItem> itemsToDownload = new ArrayList<FeedItem>();
+
+                    if (episodeSpaceLeft > 0 && undownloadedEpisodes > 0) {
+                        for (int i = 0; i < queue.size(); i++) { // ignore playing item
+                            FeedItem item = queue.get(i);
+                            long mediaId = (item.hasMedia()) ? item.getMedia().getId() : -1;
+                            if ((ignoreMediaIds || Arrays.binarySearch(mediaIds, mediaId) >= 0)
+                                    && item.hasMedia()
+                                    && !item.getMedia().isDownloaded()
+                                    && !item.getMedia().isPlaying()
+                                    && item.getFeed().getPreferences().getAutoDownload()) {
+                                itemsToDownload.add(item);
+                                episodeSpaceLeft--;
+                                undownloadedEpisodes--;
+                                if (episodeSpaceLeft == 0 || undownloadedEpisodes == 0) {
+                                    break;
+                                }
+                            }
+                        }
+                    }
+
+                    if (episodeSpaceLeft > 0 && undownloadedEpisodes > 0) {
+                        for (FeedItem item : unreadItems) {
+                            long mediaId = (item.hasMedia()) ? item.getMedia().getId() : -1;
+                            if ((ignoreMediaIds || Arrays.binarySearch(mediaIds, mediaId) >= 0)
+                                    && item.hasMedia()
+                                    && !item.getMedia().isDownloaded()
+                                    && item.getFeed().getPreferences().getAutoDownload()) {
+                                itemsToDownload.add(item);
+                                episodeSpaceLeft--;
+                                undownloadedEpisodes--;
+                                if (episodeSpaceLeft == 0 || undownloadedEpisodes == 0) {
+                                    break;
+                                }
+                            }
+                        }
+                    }
+                    if (BuildConfig.DEBUG)
+                        Log.d(TAG, "Enqueueing " + itemsToDownload.size()
+                                + " items for download");
+
+                    try {
+                        DBTasks.downloadFeedItems(false, context,
+                                itemsToDownload.toArray(new FeedItem[itemsToDownload
+                                        .size()])
+                        );
+                    } catch (DownloadRequestException e) {
+                        e.printStackTrace();
+                    }
+
+                }
+            }
+        };
+    }
+}
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/APSPCleanupAlgorithm.java b/core/src/main/java/de/danoeh/antennapod/core/storage/APSPCleanupAlgorithm.java
new file mode 100644
index 000000000..b53645d93
--- /dev/null
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/APSPCleanupAlgorithm.java
@@ -0,0 +1,136 @@
+package de.danoeh.antennapod.core.storage;
+
+import android.content.Context;
+import android.util.Log;
+
+import org.apache.commons.io.FileUtils;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.List;
+import java.util.concurrent.ExecutionException;
+
+import de.danoeh.antennapod.core.BuildConfig;
+import de.danoeh.antennapod.core.feed.FeedItem;
+
+/**
+ * Implementation of the EpisodeCleanupAlgorithm interface used by AntennaPodSP apps.
+ */
+public class APSPCleanupAlgorithm implements EpisodeCleanupAlgorithm<Integer> {
+    private static final String TAG = "APSPCleanupAlgorithm";
+
+    final int numberOfNewAutomaticallyDownloadedEpisodes;
+
+    public APSPCleanupAlgorithm(int numberOfNewAutomaticallyDownloadedEpisodes) {
+        this.numberOfNewAutomaticallyDownloadedEpisodes = numberOfNewAutomaticallyDownloadedEpisodes;
+    }
+
+    /**
+     * Performs an automatic cleanup. Episodes that have been downloaded first will also be deleted first.
+     * The episode that is currently playing as well as the n most recent episodes (the exact value is determined
+     * by AppPreferences.numberOfNewAutomaticallyDownloadedEpisodes) will never be deleted.
+     *
+     * @param context
+     * @param episodeSize The maximum amount of space that should be freed by this method
+     * @return The number of episodes that have been deleted
+     */
+    @Override
+    public int performCleanup(Context context, Integer episodeSize) {
+        if (BuildConfig.DEBUG) Log.d(TAG, String.format("performAutoCleanup(%d)", episodeSize));
+        if (episodeSize <= 0) {
+            return 0;
+        }
+
+        List<FeedItem> candidates = getAutoCleanupCandidates(context);
+        List<FeedItem> deleteList = new ArrayList<FeedItem>();
+        long deletedEpisodesSize = 0;
+        Collections.sort(candidates, new Comparator<FeedItem>() {
+            @Override
+            public int compare(FeedItem lhs, FeedItem rhs) {
+                File lFile = new File(lhs.getMedia().getFile_url());
+                File rFile = new File(rhs.getMedia().getFile_url());
+                if (!lFile.exists() || !rFile.exists()) {
+                    return 0;
+                }
+                if (FileUtils.isFileOlder(lFile, rFile)) {
+                    return -1;
+                } else {
+                    return 1;
+                }
+            }
+        });
+        // listened episodes will be deleted first
+        Iterator<FeedItem> it = candidates.iterator();
+        for (FeedItem i = it.next(); it.hasNext() && deletedEpisodesSize <= episodeSize; i = it.next()) {
+            if (!i.getMedia().isPlaying() && i.getMedia().getPlaybackCompletionDate() != null) {
+                it.remove();
+                deleteList.add(i);
+                deletedEpisodesSize += i.getMedia().getSize();
+            }
+        }
+        // delete unlistened old episodes if necessary
+        it = candidates.iterator();
+        for (FeedItem i = it.next(); it.hasNext() && deletedEpisodesSize <= episodeSize; i = it.next()) {
+            if (!i.getMedia().isPlaying()) {
+                it.remove();
+                deleteList.add(i);
+                deletedEpisodesSize += i.getMedia().getSize();
+            }
+        }
+        for (FeedItem item : deleteList) {
+            try {
+                DBWriter.deleteFeedMediaOfItem(context, item.getMedia().getId()).get();
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            } catch (ExecutionException e) {
+                e.printStackTrace();
+            }
+        }
+        if (BuildConfig.DEBUG)
+            Log.d(TAG, String.format("performAutoCleanup(%d) deleted %d episodes and free'd %d bytes of memory",
+                    episodeSize, deleteList.size(), deletedEpisodesSize));
+        return deleteList.size();
+    }
+
+    @Override
+    public Integer getDefaultCleanupParameter(Context context) {
+        return 0;
+    }
+
+    @Override
+    public Integer getPerformCleanupParameter(Context context, List<FeedItem> items) {
+        int episodeSize = 0;
+        for (FeedItem item : items) {
+            if (item.hasMedia() && !item.getMedia().isDownloaded()) {
+                episodeSize += item.getMedia().getSize();
+            }
+        }
+        return episodeSize;
+    }
+
+    /**
+     * Returns list of FeedItems that have been downloaded, but are not one of the
+     * [numberOfNewAutomaticallyDownloadedEpisodes] most recent items.
+     */
+    private List<FeedItem> getAutoCleanupCandidates(Context context) {
+        List<FeedItem> downloaded = new ArrayList<FeedItem>(DBReader.getDownloadedItems(context));
+        List<FeedItem> recent = new ArrayList<FeedItem>(DBReader.getRecentlyPublishedEpisodes(context,
+                numberOfNewAutomaticallyDownloadedEpisodes));
+        for (FeedItem r : recent) {
+            if (r.hasMedia() && r.getMedia().isDownloaded()) {
+                for (int i = 0; i < downloaded.size(); i++) {
+                    if (downloaded.get(i).getId() == r.getId()) {
+                        downloaded.remove(i);
+                        break;
+                    }
+                }
+            }
+        }
+
+        return downloaded;
+
+    }
+}
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/APSPDownloadAlgorithm.java b/core/src/main/java/de/danoeh/antennapod/core/storage/APSPDownloadAlgorithm.java
new file mode 100644
index 000000000..feeca776e
--- /dev/null
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/APSPDownloadAlgorithm.java
@@ -0,0 +1,66 @@
+package de.danoeh.antennapod.core.storage;
+
+import android.content.Context;
+import android.util.Log;
+
+import java.util.Iterator;
+import java.util.List;
+
+import de.danoeh.antennapod.core.BuildConfig;
+import de.danoeh.antennapod.core.feed.FeedItem;
+import de.danoeh.antennapod.core.preferences.UserPreferences;
+import de.danoeh.antennapod.core.util.NetworkUtils;
+
+/**
+ * Implements the automatic download algorithm used by AntennaPodSP apps.
+ */
+public class APSPDownloadAlgorithm implements AutomaticDownloadAlgorithm {
+    private static final String TAG = "APSPDownloadAlgorithm";
+
+    private final int numberOfNewAutomaticallyDownloadedEpisodes;
+
+    public APSPDownloadAlgorithm(int numberOfNewAutomaticallyDownloadedEpisodes) {
+        this.numberOfNewAutomaticallyDownloadedEpisodes = numberOfNewAutomaticallyDownloadedEpisodes;
+    }
+
+    /**
+     * Downloads the most recent episodes automatically. The exact number of
+     * episodes that will be downloaded can be set in the AppPreferences.
+     *
+     * @param context Used for accessing the DB.
+     * @return A Runnable that will be submitted to an ExecutorService.
+     */
+    @Override
+    public Runnable autoDownloadUndownloadedItems(final Context context, final long... mediaIds) {
+        return new Runnable() {
+            @Override
+            public void run() {
+                if (BuildConfig.DEBUG)
+                    Log.d(TAG, "Performing auto-dl of undownloaded episodes");
+                if (NetworkUtils.autodownloadNetworkAvailable(context)
+                        && UserPreferences.isEnableAutodownload()) {
+                    List<FeedItem> itemsToDownload = DBReader.getRecentlyPublishedEpisodes(context,
+                            numberOfNewAutomaticallyDownloadedEpisodes);
+                    Iterator<FeedItem> it = itemsToDownload.iterator();
+                    for (FeedItem item = it.next(); it.hasNext(); item = it.next()) {
+                        if (item.getMedia().isDownloaded()) {
+                            it.remove();
+                        }
+                    }
+                    if (BuildConfig.DEBUG)
+                        Log.d(TAG, "Enqueueing " + itemsToDownload.size()
+                                + " items for automatic download");
+                    if (!itemsToDownload.isEmpty()) {
+                        try {
+                            DBTasks.downloadFeedItems(false, context,
+                                    itemsToDownload.toArray(new FeedItem[itemsToDownload
+                                            .size()]));
+                        } catch (DownloadRequestException e) {
+                            e.printStackTrace();
+                        }
+                    }
+                }
+            }
+        };
+    }
+}
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/AutomaticDownloadAlgorithm.java b/core/src/main/java/de/danoeh/antennapod/core/storage/AutomaticDownloadAlgorithm.java
new file mode 100644
index 000000000..9ca9620a7
--- /dev/null
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/AutomaticDownloadAlgorithm.java
@@ -0,0 +1,20 @@
+package de.danoeh.antennapod.core.storage;
+
+import android.content.Context;
+
+public interface AutomaticDownloadAlgorithm {
+
+    /**
+     * Looks for undownloaded episodes and request a download if
+     * 1. Network is available
+     * 2. The device is charging or the user allows auto download on battery
+     * 3. There is free space in the episode cache
+     * This method is executed on an internal single thread executor.
+     *
+     * @param context  Used for accessing the DB.
+     * @param mediaIds If this list is not empty, the method will only download a candidate for automatic downloading if
+     *                 its media ID is in the mediaIds list.
+     * @return A Runnable that will be submitted to an ExecutorService.
+     */
+    public Runnable autoDownloadUndownloadedItems(Context context, long... mediaIds);
+}
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/DBTasks.java b/core/src/main/java/de/danoeh/antennapod/core/storage/DBTasks.java
index 96baeeb96..e73f9599d 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/storage/DBTasks.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/DBTasks.java
@@ -8,7 +8,6 @@ import android.util.Log;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
-import java.util.Comparator;
 import java.util.Date;
 import java.util.Iterator;
 import java.util.List;
@@ -35,8 +34,6 @@ import de.danoeh.antennapod.core.service.GpodnetSyncService;
 import de.danoeh.antennapod.core.service.download.DownloadStatus;
 import de.danoeh.antennapod.core.service.playback.PlaybackService;
 import de.danoeh.antennapod.core.util.DownloadError;
-import de.danoeh.antennapod.core.util.NetworkUtils;
-import de.danoeh.antennapod.core.util.PowerUtils;
 import de.danoeh.antennapod.core.util.QueueAccess;
 import de.danoeh.antennapod.core.util.comparator.FeedItemPubdateComparator;
 import de.danoeh.antennapod.core.util.exception.MediaFileNotFoundException;
@@ -387,8 +384,8 @@ public final class DBTasks {
         downloadFeedItems(true, context, items);
     }
 
-    private static void downloadFeedItems(boolean performAutoCleanup,
-                                          final Context context, final FeedItem... items)
+    static void downloadFeedItems(boolean performAutoCleanup,
+                                  final Context context, final FeedItem... items)
             throws DownloadRequestException {
         final DownloadRequester requester = DownloadRequester.getInstance();
 
@@ -397,8 +394,10 @@ public final class DBTasks {
 
                 @Override
                 public void run() {
-                    performAutoCleanup(context,
-                            getPerformAutoCleanupArgs(context, items.length));
+                    ClientConfig.dbTasksCallbacks.getEpisodeCacheCleanupAlgorithm()
+                            .performCleanup(context,
+                                    ClientConfig.dbTasksCallbacks.getEpisodeCacheCleanupAlgorithm()
+                                            .getPerformCleanupParameter(context, Arrays.asList(items)));
                 }
 
             }.start();
@@ -428,7 +427,7 @@ public final class DBTasks {
         }
     }
 
-    private static int getNumberOfUndownloadedEpisodes(
+    static int getNumberOfUndownloadedEpisodes(
             final List<FeedItem> queue, final List<FeedItem> unreadItems) {
         int counter = 0;
         for (FeedItem item : queue) {
@@ -460,117 +459,9 @@ public final class DBTasks {
      * @return A Future that can be used for waiting for the methods completion.
      */
     public static Future<?> autodownloadUndownloadedItems(final Context context, final long... mediaIds) {
-        return autodownloadExec.submit(new Runnable() {
-            @Override
-            public void run() {
-
-                // true if we should auto download based on network status
-                boolean networkShouldAutoDl = NetworkUtils.autodownloadNetworkAvailable(context)
-                        && UserPreferences.isEnableAutodownload();
-
-                // true if we should auto download based on power status
-                boolean powerShouldAutoDl = PowerUtils.deviceCharging(context)
-                        || UserPreferences.isEnableAutodownloadOnBattery();
-
-                // we should only auto download if both network AND power are happy
-                if (networkShouldAutoDl && powerShouldAutoDl) {
-
-                    Log.d(TAG, "Performing auto-dl of undownloaded episodes");
-
-                    final List<FeedItem> queue = DBReader.getQueue(context);
-                    final List<FeedItem> unreadItems = DBReader
-                            .getUnreadItemsList(context);
-
-                    int undownloadedEpisodes = getNumberOfUndownloadedEpisodes(queue,
-                            unreadItems);
-                    int downloadedEpisodes = DBReader
-                            .getNumberOfDownloadedEpisodes(context);
-                    int deletedEpisodes = performAutoCleanup(context,
-                            getPerformAutoCleanupArgs(context, undownloadedEpisodes));
-                    int episodeSpaceLeft = undownloadedEpisodes;
-                    boolean cacheIsUnlimited = UserPreferences.getEpisodeCacheSize() == UserPreferences
-                            .getEpisodeCacheSizeUnlimited();
-
-                    if (!cacheIsUnlimited
-                            && UserPreferences.getEpisodeCacheSize() < downloadedEpisodes
-                            + undownloadedEpisodes) {
-                        episodeSpaceLeft = UserPreferences.getEpisodeCacheSize()
-                                - (downloadedEpisodes - deletedEpisodes);
-                    }
-
-                    Arrays.sort(mediaIds);    // sort for binary search
-                    final boolean ignoreMediaIds = mediaIds.length == 0;
-                    List<FeedItem> itemsToDownload = new ArrayList<FeedItem>();
-
-                    if (episodeSpaceLeft > 0 && undownloadedEpisodes > 0) {
-                        for (int i = 0; i < queue.size(); i++) { // ignore playing item
-                            FeedItem item = queue.get(i);
-                            long mediaId = (item.hasMedia()) ? item.getMedia().getId() : -1;
-                            if ((ignoreMediaIds || Arrays.binarySearch(mediaIds, mediaId) >= 0)
-                                    && item.hasMedia()
-                                    && !item.getMedia().isDownloaded()
-                                    && !item.getMedia().isPlaying()
-                                    && item.getFeed().getPreferences().getAutoDownload()) {
-                                itemsToDownload.add(item);
-                                episodeSpaceLeft--;
-                                undownloadedEpisodes--;
-                                if (episodeSpaceLeft == 0 || undownloadedEpisodes == 0) {
-                                    break;
-                                }
-                            }
-                        }
-                    }
-
-                    if (episodeSpaceLeft > 0 && undownloadedEpisodes > 0) {
-                        for (FeedItem item : unreadItems) {
-                            long mediaId = (item.hasMedia()) ? item.getMedia().getId() : -1;
-                            if ((ignoreMediaIds || Arrays.binarySearch(mediaIds, mediaId) >= 0)
-                                    && item.hasMedia()
-                                    && !item.getMedia().isDownloaded()
-                                    && item.getFeed().getPreferences().getAutoDownload()) {
-                                itemsToDownload.add(item);
-                                episodeSpaceLeft--;
-                                undownloadedEpisodes--;
-                                if (episodeSpaceLeft == 0 || undownloadedEpisodes == 0) {
-                                    break;
-                                }
-                            }
-                        }
-                    }
-                    if (BuildConfig.DEBUG)
-                        Log.d(TAG, "Enqueueing " + itemsToDownload.size()
-                                + " items for download");
-
-                    try {
-                        downloadFeedItems(false, context,
-                                itemsToDownload.toArray(new FeedItem[itemsToDownload
-                                        .size()])
-                        );
-                    } catch (DownloadRequestException e) {
-                        e.printStackTrace();
-                    }
+        return autodownloadExec.submit(ClientConfig.dbTasksCallbacks.getAutomaticDownloadAlgorithm()
+                .autoDownloadUndownloadedItems(context, mediaIds));
 
-                }
-            }
-        });
-
-    }
-
-    private static int getPerformAutoCleanupArgs(Context context,
-                                                 final int episodeNumber) {
-        if (episodeNumber >= 0
-                && UserPreferences.getEpisodeCacheSize() != UserPreferences
-                .getEpisodeCacheSizeUnlimited()) {
-            int downloadedEpisodes = DBReader
-                    .getNumberOfDownloadedEpisodes(context);
-            if (downloadedEpisodes + episodeNumber >= UserPreferences
-                    .getEpisodeCacheSize()) {
-
-                return downloadedEpisodes + episodeNumber
-                        - UserPreferences.getEpisodeCacheSize();
-            }
-        }
-        return 0;
     }
 
     /**
@@ -582,63 +473,8 @@ public final class DBTasks {
      * @param context Used for accessing the DB.
      */
     public static void performAutoCleanup(final Context context) {
-        performAutoCleanup(context, getPerformAutoCleanupArgs(context, 0));
-    }
-
-    private static int performAutoCleanup(final Context context,
-                                          final int episodeNumber) {
-        List<FeedItem> candidates = new ArrayList<FeedItem>();
-        List<FeedItem> downloadedItems = DBReader.getDownloadedItems(context);
-        QueueAccess queue = QueueAccess.IDListAccess(DBReader.getQueueIDList(context));
-        List<FeedItem> delete;
-        for (FeedItem item : downloadedItems) {
-            if (item.hasMedia() && item.getMedia().isDownloaded()
-                    && !queue.contains(item.getId()) && item.isRead()) {
-                candidates.add(item);
-            }
-
-        }
-
-        Collections.sort(candidates, new Comparator<FeedItem>() {
-            @Override
-            public int compare(FeedItem lhs, FeedItem rhs) {
-                Date l = lhs.getMedia().getPlaybackCompletionDate();
-                Date r = rhs.getMedia().getPlaybackCompletionDate();
-
-                if (l == null) {
-                    l = new Date(0);
-                }
-                if (r == null) {
-                    r = new Date(0);
-                }
-                return l.compareTo(r);
-            }
-        });
-
-        if (candidates.size() > episodeNumber) {
-            delete = candidates.subList(0, episodeNumber);
-        } else {
-            delete = candidates;
-        }
-
-        for (FeedItem item : delete) {
-            try {
-                DBWriter.deleteFeedMediaOfItem(context, item.getMedia().getId()).get();
-            } catch (InterruptedException e) {
-                e.printStackTrace();
-            } catch (ExecutionException e) {
-                e.printStackTrace();
-            }
-        }
-
-        int counter = delete.size();
-
-        if (BuildConfig.DEBUG)
-            Log.d(TAG, String.format(
-                    "Auto-delete deleted %d episodes (%d requested)", counter,
-                    episodeNumber));
-
-        return counter;
+        ClientConfig.dbTasksCallbacks.getEpisodeCacheCleanupAlgorithm().performCleanup(context,
+                ClientConfig.dbTasksCallbacks.getEpisodeCacheCleanupAlgorithm().getDefaultCleanupParameter(context));
     }
 
     /**
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/EpisodeCleanupAlgorithm.java b/core/src/main/java/de/danoeh/antennapod/core/storage/EpisodeCleanupAlgorithm.java
new file mode 100644
index 000000000..6a8b4a441
--- /dev/null
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/EpisodeCleanupAlgorithm.java
@@ -0,0 +1,36 @@
+package de.danoeh.antennapod.core.storage;
+
+import android.content.Context;
+
+import java.util.List;
+
+import de.danoeh.antennapod.core.feed.FeedItem;
+
+public interface EpisodeCleanupAlgorithm<T> {
+
+    /**
+     * Deletes downloaded episodes that are no longer needed. What episodes are deleted and how many
+     * of them depends on the implementation.
+     *
+     * @param context   Can be used for accessing the database
+     * @param parameter An additional parameter. This parameter is either returned by getDefaultCleanupParameter
+     *                  or getPerformCleanupParameter.
+     * @return The number of episodes that were deleted.
+     */
+    public int performCleanup(Context context, T parameter);
+
+    /**
+     * Returns a parameter for performCleanup. The implementation of this interface should decide how much
+     * space to free to satisfy the episode cache conditions. If the conditions are already satisfied, this
+     * method should not have any effects.
+     */
+    public T getDefaultCleanupParameter(Context context);
+
+    /**
+     * Returns a parameter for performCleanup.
+     *
+     * @param items A list of FeedItems that are about to be downloaded. The implementation of this interface
+     *              should decide how much space to free to satisfy the episode cache conditions.
+     */
+    public T getPerformCleanupParameter(Context context, List<FeedItem> items);
+}