Kyoo/src/Kyoo.Core/Views/SubtitleApi.cs

// Kyoo - A portable and vast media library solution.
// Copyright (c) Kyoo.
//
// See AUTHORS.md and LICENSE file in the project root for full license information.
//
// Kyoo is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// any later version.
//
// Kyoo is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Kyoo. If not, see <https://www.gnu.org/licenses/>.

using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Kyoo.Abstractions.Controllers;
using Kyoo.Abstractions.Models;
using Kyoo.Abstractions.Models.Permissions;
using Microsoft.AspNetCore.Mvc;

namespace Kyoo.Core.Api
{
	[Route("subtitle")]
	[ApiController]
	public class SubtitleApi : ControllerBase
	{
		private readonly ILibraryManager _libraryManager;
		private readonly IFileSystem _files;

		public SubtitleApi(ILibraryManager libraryManager, IFileSystem files)
		{
			_libraryManager = libraryManager;
			_files = files;
		}

		[HttpGet("{id:int}")]
		[Permission(nameof(SubtitleApi), Kind.Read)]
		public async Task<IActionResult> GetSubtitle(int id)
		{
			Track subtitle = await _libraryManager.GetOrDefault<Track>(id);
			return subtitle != null
				? _files.FileResult(subtitle.Path)
				: NotFound();
		}

		[HttpGet("{id:int}.{extension}")]
		[Permission(nameof(SubtitleApi), Kind.Read)]
		public async Task<IActionResult> GetSubtitle(int id, string extension)
		{
			Track subtitle = await _libraryManager.GetOrDefault<Track>(id);
			if (subtitle == null)
				return NotFound();
			if (subtitle.Codec == "subrip" && extension == "vtt")
				return new ConvertSubripToVtt(subtitle.Path, _files);
			return _files.FileResult(subtitle.Path);
		}

		[HttpGet("{slug}")]
		[Permission(nameof(SubtitleApi), Kind.Read)]
		public async Task<IActionResult> GetSubtitle(string slug)
		{
			string extension = null;

			if (slug.Count(x => x == '.') == 3)
			{
				int idx = slug.LastIndexOf('.');
				extension = slug[(idx + 1)..];
				slug = slug[..idx];
			}

			Track subtitle = await _libraryManager.GetOrDefault<Track>(Track.BuildSlug(slug, StreamType.Subtitle));
			if (subtitle == null)
				return NotFound();
			if (subtitle.Codec == "subrip" && extension == "vtt")
				return new ConvertSubripToVtt(subtitle.Path, _files);
			return _files.FileResult(subtitle.Path);
		}

		public class ConvertSubripToVtt : IActionResult
		{
			private readonly string _path;
			private readonly IFileSystem _files;

			public ConvertSubripToVtt(string subtitlePath, IFileSystem files)
			{
				_path = subtitlePath;
				_files = files;
			}

			public async Task ExecuteResultAsync(ActionContext context)
			{
				List<string> lines = new();

				context.HttpContext.Response.StatusCode = 200;
				context.HttpContext.Response.Headers.Add("Content-Type", "text/vtt");

				await using (StreamWriter writer = new(context.HttpContext.Response.Body))
				{
					await writer.WriteLineAsync("WEBVTT");
					await writer.WriteLineAsync(string.Empty);
					await writer.WriteLineAsync(string.Empty);

					using StreamReader reader = new(await _files.GetReader(_path));
					string line;
					while ((line = await reader.ReadLineAsync()) != null)
					{
						if (line == string.Empty)
						{
							lines.Add(string.Empty);
							IEnumerable<string> processedBlock = _ConvertBlock(lines);
							foreach (string t in processedBlock)
								await writer.WriteLineAsync(t);
							lines.Clear();
						}
						else
							lines.Add(line);
					}
				}

				await context.HttpContext.Response.Body.FlushAsync();
			}

			private static IEnumerable<string> _ConvertBlock(IList<string> lines)
			{
				if (lines.Count < 3)
					return lines;
				lines[1] = lines[1].Replace(',', '.');
				if (lines[2].Length > 5)
				{
					lines[1] += lines[2].Substring(0, 6) switch
					{
						"{\\an1}" => " line:93% position:15%",
						"{\\an2}" => " line:93%",
						"{\\an3}" => " line:93% position:85%",
						"{\\an4}" => " line:50% position:15%",
						"{\\an5}" => " line:50%",
						"{\\an6}" => " line:50% position:85%",
						"{\\an7}" => " line:7% position:15%",
						"{\\an8}" => " line:7%",
						"{\\an9}" => " line:7% position:85%",
						_ => " line:93%"
					};
				}

				if (lines[2].StartsWith("{\\an"))
					lines[2] = lines[2].Substring(6);

				return lines;
			}
		}
	}
}