namespace SpotiGrabber;
using SpotifyAPI.Web;
using System.Diagnostics;
using YoutubeExplode;
using YoutubeExplode.Videos.Streams;

class Program
{
	static SpotifyClient SpotiClient = null!;
	static YoutubeClient YtClient = new();

	static YouTubeTrackMatcher TrackMatcher = new(YtClient);

	public static string? ExtractSpotifyId(string url) 
	{ 
		var match = System.Text.RegularExpressions.Regex.Match(url, @"(?:open\.spotify\.com/|spotify:)(?:intl-[a-z]{2}/)?(?:track|playlist|album)[/:]([a-zA-Z0-9]+)", 
			System.Text.RegularExpressions.RegexOptions.IgnoreCase); 
		return match.Success ? match.Groups[1].Value : null; 
	}

	static void Main(string[] args)
	{
		MainAsync(args).GetAwaiter().GetResult();
	}

	static async Task MainAsync(string[] args)
	{
		string token = File.ReadAllText("token.txt");
		SpotiClient = new(token);

		if (args.Length == 0)
		{
			Console.WriteLine("Please provide spotify link!");
			return;
		}

		string spotiString = args[0];
		string id = ExtractSpotifyId(spotiString)!;

		if (spotiString.Contains("track"))
			await ExportSingleTrack(id);
		else if (spotiString.Contains("playlist"))
			await ExportPlaylist(id);
		else
			Console.WriteLine("Link not supported!");
	}

	static async Task ExportSingleTrack(string id)
	{
		var track = await SpotiClient.Tracks.Get(id);
		await InternalExportTrack(track, $"{track.Artists.First().Name} - {track.Name}");
	}

	static async Task ExportPlaylist(string id)
	{
		var playlist = await SpotiClient.Playlists.Get(id);
		var trackPage = playlist.Items!;

		Directory.CreateDirectory($"./{playlist.Name}");

		using var semaphore = new SemaphoreSlim(5);
		var tasks = new List<Task>();
		int index = 0;

		await foreach (var playlistTrack in SpotiClient.Paginate(trackPage))
		{
			if (playlistTrack.Item is not FullTrack track)
				continue;

			int currentIndex = index++;

			await semaphore.WaitAsync();

			tasks.Add(Task.Run(async () =>
			{
				try
				{
					await InternalExportTrack(track,$"./{playlist.Name}/[{currentIndex}] {track.Artists.First().Name} - {track.Name}");
				}
				finally
				{
					semaphore.Release();
				}
			}));
		}

		await Task.WhenAll(tasks);
	}

	static async Task InternalExportTrack(FullTrack track, string outputName)
	{
		var result = (await TrackMatcher.SearchAsync(track, 3)).First();
		var manifests = await YtClient.Videos.Streams.GetManifestAsync(result.Video.Id);
		var streamInfo = manifests.GetAudioOnlyStreams().GetWithHighestBitrate();
		await Process.Start("ffmpeg.exe", $"-hide_banner -i \"{streamInfo.Url}\" -n \"{outputName}.mp3\"").WaitForExitAsync();
	}
}