using Newtonsoft.Json;
using System;
using System.IO;
using System.Collections.Generic;
using System.Threading.Tasks;
using Windows.Storage;
using Windows.Storage.AccessCache;
using YoutubeExplode.Videos;
using YoutubeExplode.Videos.Streams;
using FoxTube.Utils;
using FoxTube.Models;

namespace FoxTube.Services
{
	public static class DownloadsCenter
	{
		public static List<SavedVideo> History { get; private set; }
		public static List<DownloadItem> Queue { get; } = new List<DownloadItem>();

		static DownloadsCenter() =>
			Initialize();

		private static async void Initialize()
		{
			StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync("DownloadHistory.json", CreationCollisionOption.OpenIfExists);
			try
			{
				History = JsonConvert.DeserializeObject<List<SavedVideo>>(File.ReadAllText(file.Path) ?? "") ?? new List<SavedVideo>();

				foreach (SavedVideo i in History)
					try { i.IsPathValid = await StorageApplicationPermissions.MostRecentlyUsedList.GetFileAsync(i.AccessToken) != null; }
					catch { i.IsPathValid = false; }
			}
			catch (Exception e)
			{
				History = new List<SavedVideo>();
				await file.DeleteAsync(StorageDeleteOption.PermanentDelete);
				StorageApplicationPermissions.MostRecentlyUsedList.Clear();
				Metrics.SendReport(new Exception("Failed to load downloads history", e));
			}
		}

		public static Task DownloadVideo(Video meta, IStreamInfo streamInfo) =>
			DownloadVideo(meta, streamInfo, null);

		public static async Task DownloadVideo(Video meta, IStreamInfo streamInfo, IStorageFile destination)
		{
			DownloadItem item = new DownloadItem
			{
				Title = $"[{(streamInfo as IVideoStreamInfo)?.VideoQualityLabel ?? "Audio"}] {meta.Title}",
				Author = meta.Author,
				Thumbnail = meta.Thumbnails.LowResUrl,
				Duration = meta.Duration,
				Id = meta.Id
			};
			Queue.Add(item);

			if (destination == null)
				destination = await (await GetDefaultDownloadsFolder()).CreateFileAsync($"{meta.Title.ReplaceInvalidChars('_')}.{streamInfo.Container.Name}", CreationCollisionOption.GenerateUniqueName);

			item.Path = destination.Path;

			try
			{
				await item.CommenceDownload(streamInfo, destination);

				SavedVideo savedItem = item as SavedVideo;
				savedItem.AccessToken = StorageApplicationPermissions.MostRecentlyUsedList.Add(destination);

				History.Add(savedItem);

				StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync("DownloadHistory.json", CreationCollisionOption.OpenIfExists);
				File.WriteAllText(file.Path, JsonConvert.SerializeObject(History));
			}
			catch (OperationCanceledException) { }
			catch (Exception e)
			{
				await destination.DeleteAsync(StorageDeleteOption.PermanentDelete);
				Metrics.SendReport(new Exception("Failed to download video", e), null,
					("Video ID", meta.Id),
					("Stream tag", streamInfo.Tag.ToString()));
			}
			finally
			{
				Queue.Remove(item);
			}
		}

		public static async Task RemoveItems(bool removeFiles, params SavedVideo[] items)
		{
			foreach(SavedVideo i in items)
			{
				History.Remove(i);
				try
				{
					if (removeFiles)
					{
						StorageFile file = await StorageApplicationPermissions.MostRecentlyUsedList.GetFileAsync(i.AccessToken);
						await file?.DeleteAsync();
					}
				}
				finally
				{
					StorageApplicationPermissions.MostRecentlyUsedList.Remove(i.AccessToken);
				}
			}

			StorageFile historyFile = await ApplicationData.Current.LocalFolder.CreateFileAsync("DownloadHistory.json", CreationCollisionOption.OpenIfExists);
			File.WriteAllText(historyFile.Path, JsonConvert.SerializeObject(History));
		}

		public static async Task<StorageFolder> GetDefaultDownloadsFolder()
		{
			if (string.IsNullOrWhiteSpace(Settings.DefaultDownloadsFolder))
				return await KnownFolders.VideosLibrary.CreateFolderAsync("FoxTube", CreationCollisionOption.OpenIfExists);
			else
				return await StorageApplicationPermissions.FutureAccessList.GetFolderAsync(Settings.DefaultDownloadsFolder);
		}

		public static async Task CancelAll()
		{
			Queue.ForEach(i => i.Cancel());
			while (Queue.Count > 0)
				await Task.Delay(500);
		}
	}
}