playlist: Simplify playlist modified detection

Any modifications to the playlist (insert, delete, shuffle, etc)
will cause the modified flag to be set. The flag is cleared when
the playlist is saved. Code that generates playlists can manually
clear the modified flag if appropriate; there is now a proper API
for this so the tagcache and pictureflow don't need to resort to
hacks.

Change-Id: I8d3c723265a41db07a13de3f1d2abb0444528d57

apps/playlist.c

@@ -576,20 +576,18 @@ static void empty_playlist_unlocked(struct playlist_info* playlist, bool resume)
     playlist->utf8 = true;
     playlist->control_created = false;
     playlist->in_ram = false;
+    playlist->modified = false;
 
     playlist->fd = -1;
     playlist->control_fd = -1;
-    playlist->num_inserted_tracks = 0;
 
     playlist->index = 0;
     playlist->first_index = 0;
     playlist->amount = 0;
     playlist->last_insert_pos = -1;
 
-    playlist->deleted = false;
     playlist->started = false;
     playlist->pending_control_sync = false;
-    playlist->shuffle_modified = false;
 
     if (!resume && playlist == &current_playlist)
     {
@@ -810,9 +808,7 @@ static int recreate_control_unlocked(struct playlist_info* playlist)
     }
 
     playlist->seed = 0;
-    playlist->shuffle_modified = false;
-    playlist->deleted = false;
-    playlist->num_inserted_tracks = 0;
+    playlist->modified = true;
 
     for (i=0; i<playlist->amount; i++)
     {
@@ -841,8 +837,6 @@ static int recreate_control_unlocked(struct playlist_info* playlist)
 
             if (result < 0)
                 break;
-
-            playlist->num_inserted_tracks++;
         }
     }
 
@@ -1373,18 +1367,11 @@ static int remove_all_tracks_unlocked(struct playlist_info *playlist, bool write
 #endif
 
     /* Update playlist state as if by remove_track_unlocked() */
-    bool inserted = playlist->indices[0] & PLAYLIST_INSERT_TYPE_MASK;
-
     playlist->index = 0;
+    playlist->first_index = 0;
     playlist->amount = 1;
     playlist->indices[0] |= PLAYLIST_QUEUED;
-
-    if (inserted)
-        playlist->num_inserted_tracks = 1;
-    else
-        playlist->deleted = true;
-
-    playlist->first_index = 0;
+    playlist->modified = true;
 
     if (playlist->last_insert_pos == 0)
         playlist->last_insert_pos = -1;
@@ -1558,7 +1545,7 @@ static int add_track_to_playlist_unlocked(struct playlist_info* playlist,
     dc_init_filerefs(playlist, insert_position, 1);
 
     playlist->amount++;
-    playlist->num_inserted_tracks++;
+    playlist->modified = true;
 
     return insert_position;
 }
@@ -1614,13 +1601,10 @@ static int remove_track_unlocked(struct playlist_info* playlist,
 {
     int i;
     int result = 0;
-    bool inserted;
 
     if (playlist->amount <= 0)
         return -1;
 
-    inserted = playlist->indices[position] & PLAYLIST_INSERT_TYPE_MASK;
-
 #ifdef HAVE_DIRCACHE
     struct dircache_fileref *dcfrefs = NULL;
     if (playlist->dcfrefs_handle)
@@ -1638,11 +1622,7 @@ static int remove_track_unlocked(struct playlist_info* playlist,
     }
 
     playlist->amount--;
-
-    if (inserted)
-        playlist->num_inserted_tracks--;
-    else
-        playlist->deleted = true;
+    playlist->modified = true;
 
     /* update stored indices if needed */
     if (position < playlist->index)
@@ -1735,8 +1715,7 @@ static int randomise_playlist_unlocked(struct playlist_info* playlist,
     playlist->last_insert_pos = -1;
 
     playlist->seed = seed;
-    if (playlist->num_inserted_tracks > 0 || playlist->deleted)
-        playlist->shuffle_modified = true;
+    playlist->modified = true;
 
     if (write)
     {
@@ -1800,9 +1779,8 @@ static int sort_playlist_unlocked(struct playlist_info* playlist,
 
     /* indices have been moved so last insert position is no longer valid */
     playlist->last_insert_pos = -1;
+    playlist->modified = true;
 
-    if (!playlist->num_inserted_tracks && !playlist->deleted)
-        playlist->shuffle_modified = false;
     if (write && playlist->control_fd >= 0)
     {
         playlist->first_index = 0;
@@ -2905,20 +2883,25 @@ int playlist_insert_track(struct playlist_info* playlist, const char *filename,
     return result;
 }
 
-/* returns true if playlist has been modified */
+/* returns true if playlist has been modified by the user */
 bool playlist_modified(const struct playlist_info* playlist)
 {
     if (!playlist)
         playlist = &current_playlist;
 
-    if (playlist->shuffle_modified ||
-        playlist->deleted ||
-        playlist->num_inserted_tracks > 0)
-    {
-        return true;
-    }
+    return playlist->modified;
+}
 
-    return false;
+/*
+ * Set the playlist modified status. Useful for clearing the modified status
+ * after dynamically building a playlist.
+ */
+void playlist_set_modified(struct playlist_info *playlist, bool modified)
+{
+    if (!playlist)
+        playlist = &current_playlist;
+
+    playlist->modified = modified;
 }
 
 /*
@@ -3938,6 +3921,7 @@ int playlist_save(struct playlist_info* playlist, char *filename,
     if (fd >= 0)
         close(fd);
 
+    playlist->modified = false;
     cpu_boost(false);
 
     return result;
@@ -3996,9 +3980,7 @@ int playlist_set_current(struct playlist_info* playlist)
     current_playlist.amount = playlist->amount;
     current_playlist.last_insert_pos = playlist->last_insert_pos;
     current_playlist.seed = playlist->seed;
-    current_playlist.shuffle_modified = playlist->shuffle_modified;
-    current_playlist.deleted = playlist->deleted;
-    current_playlist.num_inserted_tracks = playlist->num_inserted_tracks;
+    current_playlist.modified = playlist->modified;
 
     memcpy(current_playlist.control_cache, playlist->control_cache,
         sizeof(current_playlist.control_cache));