private Mediafile GetNextOrPrevSongInGroup(bool prev = false)
{
//get current group (the group in which current song is playing).
Grouping <IGroupKey, Mediafile> currentGroup = TracksCollection.GetCurrentlyPlayingGroup();
//get the index of the song playing in the currentGroup (with reference to the currentGroup)
int currentSongIndex = currentGroup.GetPlayingSongIndexInGroup();
//get next song index (depending on the parameters).
int nextSongIndex = prev ? currentSongIndex - 1 : currentSongIndex + 1;
//get condition for next/prev group.
bool nextGroupCondition = nextSongIndex.Equals(prev ? -1 : currentGroup.Count);
//get next/prev group index
int nextGroupIndex = prev ? TracksCollection.IndexOf(currentGroup) - 1 : TracksCollection.IndexOf(currentGroup) + 1;
//get next/prev group.
Grouping <IGroupKey, Mediafile> nextGroup = nextGroupCondition ? TracksCollection.ElementAt(nextGroupIndex) : currentGroup;
//get nextSong index depending on if the group is new or old.
int toPlaySongIndex = nextGroup.Equals(currentGroup) ? nextSongIndex : 0;
return(nextGroup.ElementAt(toPlaySongIndex));
}
