feat: add generated playlist service

- Add a new generated playlist service to generate m3u8 playlists for media player consumption. For now it only has a method to generate a playlist for a single video, but the ground work has been laid to support multi video/episode playlists in the future.

- Add a new endpoint to get a single-entry playlist for a file (generated on-demand, of course).

Shoko.Server/API/APIExtensions.cs

@@ -25,6 +25,7 @@
 using Shoko.Server.API.v3.Models.Shoko;
 using Shoko.Server.API.WebUI;
 using Shoko.Server.Plugin;
+using Shoko.Server.Services;
 using Shoko.Server.Utilities;
 using File = System.IO.File;
 using AniDBEmitter = Shoko.Server.API.SignalR.Aggregate.AniDBEmitter;
@@ -49,6 +50,7 @@ public static IServiceCollection AddAPI(this IServiceCollection services)
         services.AddSingleton<AVDumpEmitter>();
         services.AddSingleton<NetworkEmitter>();
         services.AddSingleton<QueueEmitter>();
+        services.AddScoped<GeneratedPlaylistService>();
         services.AddScoped<FilterFactory>();
         services.AddScoped<WebUIFactory>();
 

Shoko.Server/API/v3/Controllers/FileController.cs

@@ -57,14 +57,16 @@ public class FileController : BaseController
 
     private readonly TraktTVHelper _traktHelper;
     private readonly ISchedulerFactory _schedulerFactory;
+    private readonly GeneratedPlaylistService _playlistService;
     private readonly VideoLocalService _vlService;
     private readonly VideoLocal_PlaceService _vlPlaceService;
     private readonly VideoLocal_UserRepository _vlUsers;
     private readonly WatchedStatusService _watchedService;
 
-    public FileController(TraktTVHelper traktHelper, ISchedulerFactory schedulerFactory, ISettingsProvider settingsProvider, VideoLocal_PlaceService vlPlaceService, VideoLocal_UserRepository vlUsers, WatchedStatusService watchedService, VideoLocalService vlService) : base(settingsProvider)
+    public FileController(TraktTVHelper traktHelper, ISchedulerFactory schedulerFactory, GeneratedPlaylistService playlistService, ISettingsProvider settingsProvider, VideoLocal_PlaceService vlPlaceService, VideoLocal_UserRepository vlUsers, WatchedStatusService watchedService, VideoLocalService vlService) : base(settingsProvider)
     {
         _traktHelper = traktHelper;
+        _playlistService = playlistService;
         _vlPlaceService = vlPlaceService;
         _vlUsers = vlUsers;
         _watchedService = watchedService;
@@ -587,6 +589,24 @@ public ActionResult GetExternalSubtitle([FromRoute, Range(1, int.MaxValue)] int
         return NotFound();
     }
 
+    /// <summary>
+    /// Generate a playlist for the specified file.
+    /// </summary>
+    /// <param name="fileID">File ID</param>
+    /// <returns>The m3u8 playlist.</returns>
+    [ProducesResponseType(typeof(FileStreamResult), 200)]
+    [ProducesResponseType(404)]
+    [Produces("application/x-mpegURL")]
+    [HttpGet("{fileID}/Stream.m3u8")]
+    [HttpHead("{fileID}/Stream.m3u8")]
+    public ActionResult GetFileStreamPlaylist([FromRoute, Range(1, int.MaxValue)] int fileID)
+    {
+        if (RepoFactory.VideoLocal.GetByID(fileID) is not { } file)
+            return NotFound(FileNotFoundWithFileID);
+
+        return _playlistService.GeneratePlaylistForVideo(file);
+    }
+
     /// <summary>
     /// Get the MediaInfo model for file with VideoLocal ID
     /// </summary>

Shoko.Server/Services/GeneratedPlaylistService.cs

@@ -0,0 +1,96 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Web;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using Shoko.Commons.Extensions;
+using Shoko.Plugin.Abstractions.DataModels;
+using Shoko.Plugin.Abstractions.Enums;
+using Shoko.Server.Utilities;
+
+#nullable enable
+namespace Shoko.Server.Services;
+
+public class GeneratedPlaylistService
+{
+    private readonly HttpContext _context;
+
+    public GeneratedPlaylistService(IHttpContextAccessor contentAccessor)
+    {
+        _context = contentAccessor.HttpContext!;
+    }
+
+    public FileStreamResult GeneratePlaylistForVideo(IVideo video)
+    {
+        var episode = video.CrossReferences
+            .Select(xref => xref.AnidbEpisode)
+            .WhereNotNull()
+            .OrderBy(episode => episode.Type)
+            .ThenBy(episode => episode.EpisodeNumber)
+            .FirstOrDefault();
+        return GeneratePlaylistForEpisodeList(episode is not null ? [(episode, [video])] : []);
+    }
+
+    private FileStreamResult GeneratePlaylistForEpisodeList(
+        IEnumerable<(IEpisode ep, IReadOnlyList<IVideo> videos)> episodeList,
+        string name = "Playlist"
+    )
+    {
+        var m3U8 = new StringBuilder("#EXTM3U\n");
+        var request = _context.Request;
+        var uri = new UriBuilder(
+            request.Scheme,
+            request.Host.Host,
+            request.Host.Port ?? (request.Scheme == "https" ? 443 : 80),
+            request.PathBase,
+            null
+        );
+        foreach (var (episode, videos) in episodeList)
+        {
+            var anime = episode.Series;
+            if (anime is null)
+                continue;
+
+            var index = 0;
+            foreach (var video in videos)
+                m3U8.Append(GetEpisodeEntry(new UriBuilder(uri.ToString()), anime, episode, video, ++index, videos.Count));
+        }
+
+        var bytes = Encoding.UTF8.GetBytes(m3U8.ToString());
+        var stream = new MemoryStream(bytes);
+        return new FileStreamResult(stream, "application/x-mpegURL")
+        {
+            FileDownloadName = $"{name}.m3u8",
+        };
+    }
+
+    private static string GetEpisodeEntry(UriBuilder uri, ISeries anime, IEpisode episode, IVideo video, int part, int totalParts)
+    {
+        var poster = anime.GetPreferredImageForType(ImageEntityType.Poster) ?? anime.DefaultPoster;
+        var parts = totalParts > 1 ? $" ({part}/{totalParts})" : string.Empty;
+        var episodeNumber = episode.Type is EpisodeType.Episode
+            ? episode.EpisodeNumber.ToString()
+            : $"{episode.Type.ToString()[0]}{episode.EpisodeNumber}";
+        var queryString = HttpUtility.ParseQueryString(string.Empty);
+        queryString.Add("shokoVersion", Utils.GetApplicationVersion());
+
+        // These fields are for media player plugins to consume.
+        if (poster is not null && !string.IsNullOrEmpty(poster.RemoteURL))
+            queryString.Add("posterUrl", poster.RemoteURL);
+        queryString.Add("appId", "07a58b50-5109-5aa3-abbc-782fed0df04f"); // plugin id
+        queryString.Add("animeId", anime.ID.ToString());
+        queryString.Add("animeName", anime.PreferredTitle);
+        queryString.Add("epId", episode.ID.ToString());
+        queryString.Add("episodeName", episode.PreferredTitle);
+        queryString.Add("epNo", episodeNumber);
+        queryString.Add("epCount", anime.EpisodeCounts.Episodes.ToString());
+        queryString.Add("restricted", anime.Restricted ? "true" : "false");
+
+        uri.Path = $"{(uri.Path.Length > 1 ? uri.Path + "/" : "/")}api/v3/File/{video.ID}/Stream";
+        uri.Query = queryString.ToString();
+        return $"#EXTINF:-1,{episode.PreferredTitle}{parts}\n{uri}\n";
+    }
+}