public static List <PlaylistSong> CombinationsPlaylist(List <Song> inputList, Playlist playlist, int durationSeconds)
{
//Set up the environment for the recursive combinatorial algorithm to work.
Random rand = new Random();
List <Song> resultList = new List <Song>();
//Shuffling the list of Songs each time means every Playlist will be different, even if they've
//got the samew target lengths.
List <Song> workingList = Shuffle(inputList);
List <PlaylistSong> playlistSongList = new List <PlaylistSong>();
PlaylistSong newPLS = null;
int songOrder = 1;
resultList = Combinations(workingList, durationSeconds);
//A PlaylistSong is not the same as a Song; a PlaylistSong is just a pair of foreign keys (SongID, PlaylistID)
//plus an ordinal. In order to complete the Playlist, the PlaylistSongs need to be created from the ListSong<>.
foreach (Song s in resultList)
{
newPLS = new PlaylistSong();
newPLS.PlaylistID = playlist.PlaylistID;
newPLS.SongID = s.SongID;
newPLS.SongOrder = songOrder;
CDCatalogManager.AddPlaylistSong(newPLS);
playlistSongList.Add(newPLS);
songOrder++;
}
return(playlistSongList);
}
//No longer using this code.
public static List <PlaylistSong> RandomPlayList(List <Song> sourceList, int targetSeconds, Playlist playList)
{
///Algorithm needs to:
///1) Check playlist length against target--while totalLength less than or equal to targetSeconds + 60?
///
///2) Reduce available songs to those that will fit in the time.
///3) Add a song, add song length to totalLength
///
Random rand = new Random();
List <PlaylistSong> playlistSongList = new List <PlaylistSong>();
PlaylistSong newPLS = new PlaylistSong();
bool keepGoing = true;
bool isFull = false;
bool notEnoughSongs = false;
int iterator = 0;
int index = 0;
int songOrder = 1;
int totalLength = 0;
List <Song> songList = sourceList.OrderBy(s => s.SongID).ToList();
List <Song> filteredList = songList.Where(s => s.TrackLength <= ((targetSeconds + 60) - totalLength)).ToList();
List <Song> workingList = new List <Song>();
//checking the iterator keeps this from becoming an infinite loop,
//but all testing, even with fairly small datasets, has so far found
//a solution before the iterator iterates out.
while (iterator < 1000000000 && keepGoing == true)
{
while (totalLength <= (targetSeconds + 60) && isFull == false && notEnoughSongs == false)
{
//reduce the available songs to only those which will not exceed the specified playlist length plus one minute.
filteredList = songList.Where(s => s.TrackLength <= ((targetSeconds + 60) - totalLength)).ToList();
if (filteredList.Count > 0) //If we're out of songs, we can't add any more to the playlist
{
index = rand.Next(0, filteredList.Count);
workingList.Add(songList[index]);
totalLength += songList[index].TrackLength;
songList.RemoveAt(index);
}
else
{
notEnoughSongs = true;
keepGoing = false;
}
if (totalLength >= (targetSeconds - 60))
{
isFull = true;
}
}
if (totalLength >= (targetSeconds - 60) && totalLength <= (targetSeconds + 60))
{
songOrder = 1;
Song s = new Song();
while (workingList.Count > 0)
{
newPLS = new PlaylistSong();
s = workingList[rand.Next(0, workingList.Count)];
newPLS.PlaylistID = playList.PlaylistID;
newPLS.SongID = s.SongID;
newPLS.SongOrder = songOrder;
CDCatalogManager.AddPlaylistSong(newPLS);
playlistSongList.Add(newPLS);
workingList.Remove(s);
songOrder++;
}
keepGoing = false;
}
else
{
workingList.Clear();
totalLength = 0;
isFull = false;
songList = sourceList.OrderBy(s => s.SongID).ToList();
filteredList = songList.Where(s => s.TrackLength <= ((targetSeconds + 60) - totalLength)).ToList();
iterator++;
}
}
return(playlistSongList);
}
