Fix actions started from the message list context menu

This patch makes sure actions started via the context menu operate on
the correct message even when the message list changes and the 'adapter
position' accessible via the menu object points to another message.
When the message the menu was opened for is deleted the context menu
will be closed.

src/com/fsck/k9/fragment/MessageListFragment.java

@@ -459,6 +459,18 @@ public class MessageListFragment extends SherlockFragment implements OnItemClick
     private BroadcastReceiver mCacheBroadcastReceiver;
     private IntentFilter mCacheIntentFilter;
 
+    /**
+     * Stores the unique ID of the message the context menu was opened for.
+     *
+     * We have to save this because the message list might change between the time the menu was
+     * opened and when the user clicks on a menu item. When this happens the 'adapter position' that
+     * is accessible via the {@code ContextMenu} object might correspond to another list item and we
+     * would end up using/modifying the wrong message.
+     *
+     * The value of this field is {@code 0} when no context menu is currently open.
+     */
+    private long mContextMenuUniqueId = 0;
+
 
     /**
      * This class is used to run operations that modify UI elements in the UI thread.
@@ -1447,8 +1459,14 @@ public class MessageListFragment extends SherlockFragment implements OnItemClick
 
     @Override
     public boolean onContextItemSelected(android.view.MenuItem item) {
-        AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
-        int adapterPosition = listViewToAdapterPosition(info.position);
+        if (mContextMenuUniqueId == 0) {
+            return false;
+        }
+
+        int adapterPosition = getPositionForUniqueId(mContextMenuUniqueId);
+        if (adapterPosition == AdapterView.INVALID_POSITION) {
+            return false;
+        }
 
         switch (item.getItemId()) {
             case R.id.reply: {
@@ -1525,6 +1543,7 @@ public class MessageListFragment extends SherlockFragment implements OnItemClick
             }
         }
 
+        mContextMenuUniqueId = 0;
         return true;
     }
 
@@ -1548,6 +1567,7 @@ public class MessageListFragment extends SherlockFragment implements OnItemClick
 
         getActivity().getMenuInflater().inflate(R.menu.message_list_item_context, menu);
 
+        mContextMenuUniqueId = cursor.getLong(mUniqueIdColumn);
         Account account = getAccountFromCursor(cursor);
 
         String subject = cursor.getString(SUBJECT_COLUMN);
@@ -3035,6 +3055,17 @@ public class MessageListFragment extends SherlockFragment implements OnItemClick
         return listViewToAdapterPosition(listViewPosition);
     }
 
+    private int getPositionForUniqueId(long uniqueId) {
+        for (int position = 0, end = mAdapter.getCount(); position < end; position++) {
+            Cursor cursor = (Cursor) mAdapter.getItem(position);
+            if (cursor.getLong(mUniqueIdColumn) == uniqueId) {
+                return position;
+            }
+        }
+
+        return AdapterView.INVALID_POSITION;
+    }
+
     private Message getMessageAtPosition(int adapterPosition) {
         if (adapterPosition == AdapterView.INVALID_POSITION) {
             return null;
@@ -3343,6 +3374,7 @@ public class MessageListFragment extends SherlockFragment implements OnItemClick
         }
 
         cleanupSelected(cursor);
+        updateContextMenu(cursor);
 
         mAdapter.swapCursor(cursor);
 
@@ -3371,6 +3403,28 @@ public class MessageListFragment extends SherlockFragment implements OnItemClick
         return loadFinished;
     }
 
+    /**
+     * Close the context menu when the message it was opened for is no longer in the message list.
+     */
+    private void updateContextMenu(Cursor cursor) {
+        if (mContextMenuUniqueId == 0) {
+            return;
+        }
+
+        for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) {
+            long uniqueId = cursor.getLong(mUniqueIdColumn);
+            if (uniqueId == mContextMenuUniqueId) {
+                return;
+            }
+        }
+
+        mContextMenuUniqueId = 0;
+        Activity activity = getActivity();
+        if (activity != null) {
+            activity.closeContextMenu();
+        }
+    }
+
     private void cleanupSelected(Cursor cursor) {
         if (mSelected.size() == 0) {
             return;