Handle deleting the current track gracefully

Now it should flow playback correctly to the next remaining track after
the block of deleted tracks. And if the user deletes the next queued
track, it will still be queued to flow past the deleted block. If the
user undoes their deletes and restores the tracks, playback will resume
after the originally deleted track.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Playlist/PlaylistController.h

@@ -49,6 +49,8 @@ typedef NS_ENUM(NSInteger, URLOrigin) {
 
 	PlaylistEntry *currentEntry;
 
+	PlaylistEntry *nextEntryAfterDeleted;
+
 	NSUndoManager *undoManager;
 }
 

Playlist/PlaylistController.m

@@ -362,6 +362,31 @@ static inline void dispatch_sync_reentrant(dispatch_queue_t queue, dispatch_bloc
 	if(currentEntry != nil) [self.tableView scrollRowToVisible:currentEntry.index];
 }
 
+- (void)updateNextAfterDeleted:(PlaylistEntry *)lastEntry withDeleteIndexes:(NSIndexSet *)indexes {
+	__block PlaylistEntry *pe = nil;
+	NSArray *allObjects = [self arrangedObjects];
+	[indexes enumerateRangesUsingBlock:^(NSRange range, BOOL *_Nonnull stop) {
+		if(range.location <= lastEntry.index &&
+		   range.location + range.length > lastEntry.index) {
+			NSUInteger index = range.location + range.length;
+			if(index < [allObjects count])
+				pe = [allObjects objectAtIndex:index];
+			else
+				pe = nil;
+		} else if(pe && range.location <= [pe index] &&
+		          range.location + range.length > [pe index]) {
+			NSUInteger index = range.location + range.length;
+			if(index < [allObjects count])
+				pe = [allObjects objectAtIndex:index];
+			else
+				pe = nil;
+		} else if(pe && range.location > [pe index]) {
+			*stop = YES;
+		}
+	}];
+	nextEntryAfterDeleted = pe;
+}
+
 - (void)tableView:(NSTableView *)tableView didClickTableColumn:(NSTableColumn *)tableColumn {
 	if([self shuffle] != ShuffleOff) [self resetShuffleList];
 }
@@ -577,6 +602,10 @@ static inline void dispatch_sync_reentrant(dispatch_queue_t queue, dispatch_bloc
 	[NSString stringWithFormat:@"Adding %lu entries", (unsigned long)[objects count]];
 	[[self undoManager] setActionName:actionName];
 
+	for(PlaylistEntry *pe in objects) {
+		pe.deleted = NO;
+	}
+
 	[[SQLiteStore sharedStore] playlistInsertTracks:objects
 	                                atObjectIndexes:indexes
 	                                   progressCall:^(double progress) {
@@ -607,11 +636,14 @@ static inline void dispatch_sync_reentrant(dispatch_queue_t queue, dispatch_bloc
 	NSMutableIndexSet *unarrangedIndexes = [[NSMutableIndexSet alloc] init];
 	for(PlaylistEntry *pe in objects) {
 		[unarrangedIndexes addIndex:[pe index]];
+		pe.deleted = YES;
 	}
 
 	if([indexes containsIndex:currentEntry.index]) {
-		// Safety check. The player doesn't like committing actions on a removed track
-		[playbackController stop:nil];
+		[self updateNextAfterDeleted:currentEntry withDeleteIndexes:indexes];
+	} else if(nextEntryAfterDeleted &&
+	          [indexes containsIndex:nextEntryAfterDeleted.index]) {
+		[self updateNextAfterDeleted:nextEntryAfterDeleted withDeleteIndexes:indexes];
 	}
 
 	if(currentEntry.index >= 0 && [unarrangedIndexes containsIndex:currentEntry.index]) {
@@ -828,9 +860,14 @@ static inline void dispatch_sync_reentrant(dispatch_queue_t queue, dispatch_bloc
 		return [self shuffledEntryAtIndex:(pe.shuffleIndex + 1)];
 	} else {
 		NSInteger i;
-		if(pe.index < 0) // Was a current entry, now removed.
+
+		if(pe.deleted) // Was a current entry, now removed.
 		{
-			i = -pe.index - 1;
+			if(nextEntryAfterDeleted)
+				i = nextEntryAfterDeleted.index;
+			else
+				i = 0;
+			nextEntryAfterDeleted = nil;
 		} else {
 			i = pe.index + 1;
 		}
@@ -1038,7 +1075,7 @@ static inline void dispatch_sync_reentrant(dispatch_queue_t queue, dispatch_bloc
 
 	NSMutableIndexSet *refreshSet = [[NSMutableIndexSet alloc] init];
 
-	if(currentEntry != nil) [refreshSet addIndex:currentEntry.index];
+	if(currentEntry != nil && !currentEntry.deleted) [refreshSet addIndex:currentEntry.index];
 	if(pe != nil) [refreshSet addIndex:pe.index];
 
 	// Refresh entire row to refresh tooltips

Playlist/PlaylistEntry.h

@@ -66,6 +66,8 @@
 	BOOL seekable;
 
 	BOOL metadataLoaded;
+
+	BOOL deleted;
 }
 
 + (NSSet *)keyPathsForValuesAffectingDisplay;
@@ -167,6 +169,8 @@
 
 @property BOOL metadataLoaded;
 
+@property BOOL deleted;
+
 - (void)setMetadata:(NSDictionary *)metadata;
 
 @end

Playlist/PlaylistEntry.m

@@ -66,6 +66,8 @@
 
 @synthesize metadataLoaded;
 
+@synthesize deleted;
+
 // The following read-only keys depend on the values of other properties
 
 + (NSSet *)keyPathsForValuesAffectingDisplay {
@@ -139,6 +141,7 @@
 		self.replayGainTrackGain = 0;
 		self.replayGainTrackPeak = 0;
 		self.volume = 1;
+		self.deleted = NO;
 	}
 	return self;
 }
@@ -507,6 +510,8 @@
 		pe->seekable = seekable;
 
 		pe->metadataLoaded = metadataLoaded;
+
+		pe->deleted = deleted;
 	}
 
 	return pe;