Allow deletion of media through preview.

When viewing a media in the media preview, you can delete it by pressing
a delete button on the action bar. It will then ask you to confirm your
choice. If you confirm, it will delete the attachment from the database
and from disk. If it was the only attachment for that message, the
message itself will also be deleted.

res/menu/media_preview.xml

@@ -13,4 +13,8 @@
           android:title="@string/media_preview__all_media_title"
           android:icon="@drawable/ic_photo_library_white_24dp"
           app:showAsAction="ifRoom"/>
+    <item android:id="@+id/delete"
+          android:title="@string/delete"
+          android:icon="@drawable/ic_delete_white_24dp"
+          app:showAsAction="ifRoom"/>
 </menu>

res/values/strings.xml

@@ -664,6 +664,8 @@
     <string name="MediaPreviewActivity_draft">Draft</string>
     <string name="MediaPreviewActivity_signal_needs_the_storage_permission_in_order_to_write_to_external_storage_but_it_has_been_permanently_denied">Signal needs the Storage permission in order to save to external storage, but it has been permanently denied. Please continue to app settings, select \"Permissions\", and enable \"Storage\".</string>
     <string name="MediaPreviewActivity_unable_to_write_to_external_storage_without_permission">Unable to save to external storage without permissions</string>
+    <string name="MediaPreviewActivity_media_delete_confirmation_title">Delete message?</string>
+    <string name="MediaPreviewActivity_media_delete_confirmation_message">This will permanently delete this message.</string>
 
 
     <!-- MessageNotifier -->

src/org/thoughtcrime/securesms/MediaPreviewActivity.java

@@ -20,6 +20,7 @@ import android.Manifest;
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.content.Context;
+import android.content.DialogInterface;
 import android.content.Intent;
 import android.database.Cursor;
 import android.net.Uri;
@@ -34,6 +35,7 @@ import android.support.v4.content.Loader;
 import android.support.v4.util.Pair;
 import android.support.v4.view.PagerAdapter;
 import android.support.v4.view.ViewPager;
+import android.support.v7.app.AlertDialog;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.Menu;
@@ -46,9 +48,13 @@ import android.view.WindowManager;
 import android.widget.FrameLayout;
 import android.widget.Toast;
 
+import org.thoughtcrime.securesms.attachments.AttachmentId;
+import org.thoughtcrime.securesms.attachments.DatabaseAttachment;
 import org.thoughtcrime.securesms.components.MediaView;
 import org.thoughtcrime.securesms.components.viewpager.ExtendedOnPageChangedListener;
 import org.thoughtcrime.securesms.database.Address;
+import org.thoughtcrime.securesms.database.AttachmentDatabase;
+import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.MediaDatabase.MediaRecord;
 import org.thoughtcrime.securesms.database.loaders.PagingMediaLoader;
 import org.thoughtcrime.securesms.mms.GlideApp;
@@ -251,6 +257,48 @@ public class MediaPreviewActivity extends PassphraseRequiredActionBarActivity im
     }
   }
 
+  @SuppressLint("StaticFieldLeak")
+  private void deleteMedia() {
+    MediaItem mediaItem = getCurrentMediaItem();
+    if (mediaItem == null || mediaItem.attachment == null) {
+      return;
+    }
+
+    AlertDialog.Builder builder = new AlertDialog.Builder(this);
+    builder.setIconAttribute(R.attr.dialog_alert_icon);
+    builder.setTitle(R.string.MediaPreviewActivity_media_delete_confirmation_title);
+    builder.setMessage(R.string.MediaPreviewActivity_media_delete_confirmation_message);
+    builder.setCancelable(true);
+
+    builder.setPositiveButton(R.string.delete, (dialogInterface, which) -> {
+      new AsyncTask<Void, Void, Void>() {
+        @Override
+        protected Void doInBackground(Void... voids) {
+          if (mediaItem.attachment == null) {
+            return null;
+          }
+          Context      context         = MediaPreviewActivity.this.getApplicationContext();
+          AttachmentId attachmentId    = mediaItem.attachment.getAttachmentId();
+          long         mmsId           = mediaItem.attachment.getMmsId();
+          int          attachmentCount = DatabaseFactory.getAttachmentDatabase(context)
+                                                     .getAttachmentsForMessage(mmsId)
+                                                     .size();
+
+          if (attachmentCount <= 1) {
+            DatabaseFactory.getMmsDatabase(context).delete(mmsId);
+          } else {
+            DatabaseFactory.getAttachmentDatabase(context).deleteAttachment(attachmentId);
+          }
+          return null;
+        }
+      }.execute();
+
+      finish();
+    });
+    builder.setNegativeButton(android.R.string.cancel, null);
+    builder.show();
+  }
+
   @Override
   public boolean onPrepareOptionsMenu(Menu menu) {
     super.onPrepareOptionsMenu(menu);
@@ -258,7 +306,11 @@ public class MediaPreviewActivity extends PassphraseRequiredActionBarActivity im
     menu.clear();
     MenuInflater inflater = this.getMenuInflater();
     inflater.inflate(R.menu.media_preview, menu);
-    if (conversationRecipient == null) menu.findItem(R.id.media_preview__overview).setVisible(false);
+
+    if (!isMediaInDb()) {
+      menu.findItem(R.id.media_preview__overview).setVisible(false);
+      menu.findItem(R.id.delete).setVisible(false);
+    }
 
     return true;
   }
@@ -271,12 +323,17 @@ public class MediaPreviewActivity extends PassphraseRequiredActionBarActivity im
       case R.id.media_preview__overview: showOverview(); return true;
       case R.id.media_preview__forward:  forward();      return true;
       case R.id.save:                    saveToDisk();   return true;
+      case R.id.delete:                  deleteMedia();  return true;
       case android.R.id.home:            finish();       return true;
     }
 
     return false;
   }
 
+  private boolean isMediaInDb() {
+    return conversationRecipient != null;
+  }
+
   private @Nullable MediaItem getCurrentMediaItem() {
     MediaItemAdapter adapter = (MediaItemAdapter)mediaPager.getAdapter();
 
@@ -402,7 +459,7 @@ public class MediaPreviewActivity extends PassphraseRequiredActionBarActivity im
 
     @Override
     public MediaItem getMediaItemFor(int position) {
-      return new MediaItem(null, uri, mediaType, -1, true);
+      return new MediaItem(null, null, uri, mediaType, -1, true);
     }
 
     @Override
@@ -495,6 +552,7 @@ public class MediaPreviewActivity extends PassphraseRequiredActionBarActivity im
       if (mediaRecord.getAttachment().getDataUri() == null) throw new AssertionError();
 
       return new MediaItem(address != null ? Recipient.from(context, address,true) : null,
+                           mediaRecord.getAttachment(),
                            mediaRecord.getAttachment().getDataUri(),
                            mediaRecord.getContentType(),
                            mediaRecord.getDate(),
@@ -515,13 +573,21 @@ public class MediaPreviewActivity extends PassphraseRequiredActionBarActivity im
 
   private static class MediaItem {
     private final @Nullable Recipient          recipient;
+    private final @Nullable DatabaseAttachment attachment;
     private final @NonNull  Uri                uri;
     private final @NonNull  String             type;
     private final           long               date;
     private final           boolean            outgoing;
 
-    private MediaItem(@Nullable Recipient recipient, @NonNull Uri uri, @NonNull String type, long date, boolean outgoing) {
+    private MediaItem(@Nullable Recipient recipient,
+                      @Nullable DatabaseAttachment attachment,
+                      @NonNull Uri uri,
+                      @NonNull String type,
+                      long date,
+                      boolean outgoing)
+    {
       this.recipient  = recipient;
+      this.attachment = attachment;
       this.uri        = uri;
       this.type       = type;
       this.date       = date;
@@ -533,5 +599,4 @@ public class MediaPreviewActivity extends PassphraseRequiredActionBarActivity im
     MediaItem getMediaItemFor(int position);
     void pause(int position);
   }
-
 }

src/org/thoughtcrime/securesms/database/AttachmentDatabase.java

@@ -234,16 +234,7 @@ public class AttachmentDatabase extends Database {
                               new String[] {mmsId+""}, null, null, null);
 
       while (cursor != null && cursor.moveToNext()) {
-        String data = cursor.getString(0);
+        deleteAttachmentOnDisk(cursor.getString(0), cursor.getString(1));
-        String thumbnail = cursor.getString(1);
-
-        if (!TextUtils.isEmpty(data)) {
-          new File(data).delete();
-        }
-
-        if (!TextUtils.isEmpty(thumbnail)) {
-          new File(thumbnail).delete();
-        }
       }
     } finally {
       if (cursor != null)
@@ -251,8 +242,34 @@ public class AttachmentDatabase extends Database {
     }
 
     database.delete(TABLE_NAME, MMS_ID + " = ?", new String[] {mmsId + ""});
+    notifyAttachmentListeners();
+  }
+
+  public void deleteAttachment(@NonNull AttachmentId id) {
+    SQLiteDatabase database = databaseHelper.getWritableDatabase();
+
+    try (Cursor cursor = database.query(TABLE_NAME,
+                                        new String[]{DATA, THUMBNAIL},
+                                        PART_ID_WHERE,
+                                        id.toStrings(),
+                                        null,
+                                        null,
+                                        null))
+    {
+      if (cursor == null || !cursor.moveToNext()) {
+        Log.w(TAG, "Tried to delete an attachment, but it didn't exist.");
+        return;
+      }
+      String data      = cursor.getString(0);
+      String thumbnail = cursor.getString(1);
+
+      database.delete(TABLE_NAME, PART_ID_WHERE, id.toStrings());
+      deleteAttachmentOnDisk(data, thumbnail);
+      notifyAttachmentListeners();
+    }
   }
 
+
   @SuppressWarnings("ResultOfMethodCallIgnored")
   void deleteAllAttachments() {
     SQLiteDatabase database = databaseHelper.getWritableDatabase();
@@ -264,6 +281,19 @@ public class AttachmentDatabase extends Database {
     for (File attachment : attachments) {
       attachment.delete();
     }
+
+    notifyAttachmentListeners();
+  }
+
+  @SuppressWarnings("ResultOfMethodCallIgnored")
+  private void deleteAttachmentOnDisk(@Nullable String data, @Nullable String thumbnail) {
+    if (!TextUtils.isEmpty(data)) {
+      new File(data).delete();
+    }
+
+    if (!TextUtils.isEmpty(thumbnail)) {
+      new File(thumbnail).delete();
+    }
   }
 
   public void insertAttachmentsForPlaceholder(long mmsId, @NonNull AttachmentId attachmentId, @NonNull InputStream inputStream)

src/org/thoughtcrime/securesms/database/Database.java

@@ -17,8 +17,10 @@
 package org.thoughtcrime.securesms.database;
 
 import android.content.Context;
+import android.database.ContentObserver;
 import android.database.Cursor;
 import android.net.Uri;
+import android.support.annotation.NonNull;
 
 import org.thoughtcrime.securesms.database.helpers.SQLCipherOpenHelper;
 
@@ -29,6 +31,7 @@ public abstract class Database {
   protected static final String ID_WHERE              = "_id = ?";
   private   static final String CONVERSATION_URI      = "content://textsecure/thread/";
   private   static final String CONVERSATION_LIST_URI = "content://textsecure/conversation-list";
+  private   static final String ATTACHMENT_URI        = "content://textsecure/attachment/";
 
   protected       SQLCipherOpenHelper databaseHelper;
   protected final Context             context;
@@ -59,6 +62,16 @@ public abstract class Database {
     cursor.setNotificationUri(context.getContentResolver(), Uri.parse(CONVERSATION_LIST_URI));
   }
 
+  protected void registerAttachmentListeners(@NonNull ContentObserver observer) {
+    context.getContentResolver().registerContentObserver(Uri.parse(ATTACHMENT_URI),
+                                                         true,
+                                                         observer);
+  }
+
+  protected void notifyAttachmentListeners() {
+    context.getContentResolver().notifyChange(Uri.parse(ATTACHMENT_URI), null);
+  }
+
   public void reset(SQLCipherOpenHelper databaseHelper) {
     this.databaseHelper = databaseHelper;
   }

src/org/thoughtcrime/securesms/database/MediaDatabase.java

@@ -1,6 +1,8 @@
 package org.thoughtcrime.securesms.database;
 
 import android.content.Context;
+import android.database.ContentObservable;
+import android.database.ContentObserver;
 import android.database.Cursor;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
@@ -55,6 +57,14 @@ public class MediaDatabase extends Database {
     return cursor;
   }
 
+  public void subscribeToMediaChanges(@NonNull ContentObserver observer) {
+    registerAttachmentListeners(observer);
+  }
+
+  public void unsubscribeToMediaChanges(@NonNull ContentObserver observer) {
+    context.getContentResolver().unregisterContentObserver(observer);
+  }
+
   public Cursor getDocumentMediaForThread(long threadId) {
     SQLiteDatabase database = databaseHelper.getReadableDatabase();
     Cursor cursor = database.rawQuery(DOCUMENT_MEDIA_QUERY, new String[]{threadId+""});
@@ -98,7 +108,7 @@ public class MediaDatabase extends Database {
       return new MediaRecord(attachment, address, date, outgoing);
     }
 
-    public Attachment getAttachment() {
+    public DatabaseAttachment getAttachment() {
       return attachment;
     }
 

src/org/thoughtcrime/securesms/database/loaders/BucketedThreadMediaLoader.java

@@ -2,6 +2,7 @@ package org.thoughtcrime.securesms.database.loaders;
 
 
 import android.content.Context;
+import android.database.ContentObserver;
 import android.database.Cursor;
 import android.support.annotation.NonNull;
 import android.support.v4.content.AsyncTaskLoader;
@@ -10,6 +11,7 @@ import com.annimon.stream.Stream;
 
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.database.Address;
+import org.thoughtcrime.securesms.database.Database;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.MediaDatabase;
 import org.thoughtcrime.securesms.recipients.Recipient;
@@ -31,10 +33,12 @@ public class BucketedThreadMediaLoader extends AsyncTaskLoader<BucketedThreadMed
   private static final String TAG = BucketedThreadMediaLoader.class.getSimpleName();
 
   private final Address         address;
+  private final ContentObserver observer;
 
   public BucketedThreadMediaLoader(@NonNull Context context, @NonNull Address address) {
     super(context);
     this.address  = address;
+    this.observer = new ForceLoadContentObserver();
 
     onContentChanged();
   }
@@ -51,11 +55,17 @@ public class BucketedThreadMediaLoader extends AsyncTaskLoader<BucketedThreadMed
     cancelLoad();
   }
 
+  @Override
+  protected void onAbandon() {
+    DatabaseFactory.getMediaDatabase(getContext()).unsubscribeToMediaChanges(observer);
+  }
+
   @Override
   public BucketedThreadMedia loadInBackground() {
     BucketedThreadMedia result   = new BucketedThreadMedia(getContext());
     long                threadId = DatabaseFactory.getThreadDatabase(getContext()).getThreadIdFor(Recipient.from(getContext(), address, true));
 
+    DatabaseFactory.getMediaDatabase(getContext()).subscribeToMediaChanges(observer);
     try (Cursor cursor = DatabaseFactory.getMediaDatabase(getContext()).getGalleryMediaForThread(threadId)) {
       while (cursor != null && cursor.moveToNext()) {
         result.add(MediaDatabase.MediaRecord.from(getContext(), cursor));