YoutubeDownloader/YoutubeDownloader.Core/Downloading/VideoDownloader.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Threading;
using System.Threading.Tasks;
using Gress;
using YoutubeDownloader.Core.Utils;
using YoutubeExplode;
using YoutubeExplode.Converter;
using YoutubeExplode.Videos;
using YoutubeExplode.Videos.ClosedCaptions;

namespace YoutubeDownloader.Core.Downloading;

public class VideoDownloader(IReadOnlyList<Cookie>? initialCookies = null)
{
    private readonly YoutubeClient _youtube = new(Http.Client, initialCookies ?? []);

    public async Task<IReadOnlyList<VideoDownloadOption>> GetDownloadOptionsAsync(
        VideoId videoId,
        bool includeLanguageSpecificAudioStreams = true,
        CancellationToken cancellationToken = default
    )
    {
        var manifest = await _youtube.Videos.Streams.GetManifestAsync(videoId, cancellationToken);
        return VideoDownloadOption.ResolveAll(manifest, includeLanguageSpecificAudioStreams);
    }

    public async Task<VideoDownloadOption> GetBestDownloadOptionAsync(
        VideoId videoId,
        VideoDownloadPreference preference,
        bool includeLanguageSpecificAudioStreams = true,
        CancellationToken cancellationToken = default
    )
    {
        var options = await GetDownloadOptionsAsync(
            videoId,
            includeLanguageSpecificAudioStreams,
            cancellationToken
        );

        return preference.TryGetBestOption(options)
            ?? throw new InvalidOperationException("No suitable download option found.");
    }

    public async Task DownloadVideoAsync(
        string filePath,
        IVideo video,
        VideoDownloadOption downloadOption,
        bool includeSubtitles = true,
        IProgress<Percentage>? progress = null,
        CancellationToken cancellationToken = default
    )
    {
        // Include subtitles in the output container
        var trackInfos = new List<ClosedCaptionTrackInfo>();
        if (includeSubtitles && !downloadOption.Container.IsAudioOnly)
        {
            var manifest = await _youtube.Videos.ClosedCaptions.GetManifestAsync(
                video.Id,
                cancellationToken
            );

            trackInfos.AddRange(manifest.Tracks);
        }

        var dirPath = Path.GetDirectoryName(filePath);
        if (!string.IsNullOrWhiteSpace(dirPath))
            Directory.CreateDirectory(dirPath);

        await _youtube.Videos.DownloadAsync(
            downloadOption.StreamInfos,
            trackInfos,
            new ConversionRequestBuilder(filePath)
                .SetFFmpegPath(FFmpeg.TryGetCliFilePath() ?? "ffmpeg")
                .SetContainer(downloadOption.Container)
                .SetPreset(ConversionPreset.Medium)
                .Build(),
            progress?.ToDoubleBased(),
            cancellationToken
        );
    }
}