using System.Diagnostics;
using System.Globalization;
using System.Text;
using CliWrap;
using ErsatzTV.Application.Channels;
using ErsatzTV.Application.Images;
using ErsatzTV.Application.Streaming;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Errors;
using ErsatzTV.Core.FFmpeg;
using ErsatzTV.Core.Interfaces.FFmpeg;
using ErsatzTV.Core.Interfaces.Streaming;
using ErsatzTV.Core.Iptv;
using ErsatzTV.Extensions;
using ErsatzTV.FFmpeg;
using ErsatzTV.Filters;
using MediatR;
using Microsoft.AspNetCore.Mvc;

namespace ErsatzTV.Controllers;

[ApiController]
[ApiExplorerSettings(IgnoreApi = true)]
[ServiceFilter(typeof(ConditionalIptvAuthorizeFilter))]
public class IptvController : StreamingControllerBase
{
    private readonly IDirectStreamSessionTracker _directStreamSessionTracker;
    private readonly IFFmpegSegmenterService _ffmpegSegmenterService;
    private readonly ILogger<IptvController> _logger;
    private readonly IMediator _mediator;

    public IptvController(
        IMediator mediator,
        IGraphicsEngine graphicsEngine,
        ILogger<IptvController> logger,
        IFFmpegSegmenterService ffmpegSegmenterService,
        IDirectStreamSessionTracker directStreamSessionTracker)
        : base(graphicsEngine, logger)
    {
        _directStreamSessionTracker = directStreamSessionTracker;
        _mediator = mediator;
        _logger = logger;
        _ffmpegSegmenterService = ffmpegSegmenterService;
    }

    [HttpHead("iptv/channels.m3u")]
    [HttpGet("iptv/channels.m3u")]
    public Task<IActionResult> GetChannelPlaylist(
        [FromQuery]
        string mode = "mixed")
    {
        NoStoreForTokenBearingManifest();
        return _mediator.Send(
                new GetChannelPlaylist(
                    Request.Scheme,
                    Request.Host.ToString(),
                    Request.PathBase,
                    mode,
                    Request.Headers.UserAgent,
                    Request.Query["access_token"]))
            .Map<ChannelPlaylist, IActionResult>(Ok);
    }

    [HttpHead("iptv/xmltv.xml")]
    [HttpGet("iptv/xmltv.xml")]
    public Task<IActionResult> GetGuide()
    {
        NoStoreForTokenBearingManifest();
        return _mediator.Send(
                new GetChannelGuide(
                    Request.Scheme,
                    Request.Host.ToString(),
                    Request.PathBase,
                    Request.Query["access_token"]))
            .ToActionResult();
    }

    [HttpHead("iptv/hdhr/channel/{channelNumber}.ts")]
    [HttpGet("iptv/hdhr/channel/{channelNumber}.ts")]
    public Task<IActionResult> GetHDHRVideo(string channelNumber, [FromQuery] string mode = "ts")
    {
        // don't redirect to the correct channel mode for HDHR clients; always use TS
        if (mode != "ts" && mode != "ts-legacy")
        {
            mode = "ts";
        }

        return GetTransportStreamVideo(channelNumber, mode);
    }

    [HttpHead("iptv/channel/{channelNumber}.ts")]
    [HttpGet("iptv/channel/{channelNumber}.ts")]
    public async Task<IActionResult> GetTransportStreamVideo(
        string channelNumber,
        [FromQuery]
        string mode = null)
    {
        // The unspecified/mixed-mode branch below can 302 to .m3u8 with the token in the Location.
        NoStoreForTokenBearingManifest();

        Option<ChannelViewModel> maybeChannel = await _mediator.Send(new GetChannelByNumber(channelNumber));
        if (maybeChannel.IsNone || !await maybeChannel.Map(c => c.IsEnabled).IfNoneAsync(false))
        {
            return NotFound();
        }

        // if mode is "unspecified" - find the configured mode and set it or redirect
        if (string.IsNullOrWhiteSpace(mode) || mode == "mixed")
        {
            foreach (ChannelViewModel channel in maybeChannel)
            {
                switch (channel.StreamingMode)
                {
                    case StreamingMode.TransportStream:
                        mode = "ts-legacy";
                        break;
                    case StreamingMode.TransportStreamHybrid:
                        mode = "ts";
                        break;
                    default:
                        return Redirect($"~/iptv/channel/{channelNumber}.m3u8{AccessTokenQuery()}");
                }
            }
        }

        FFmpegProcessRequest request = mode switch
        {
            "ts-legacy" => new GetConcatProcessByChannelNumber(Request.Scheme, Request.Host.ToString(), channelNumber),
            _ => new GetWrappedProcessByChannelNumber(
                Request.Scheme,
                Request.Host.ToString(),
                Request.Query["access_token"],
                channelNumber)
        };

        return await _mediator.Send(request)
            .Map(result => result.Match<IActionResult>(
                processModel =>
                {
                    Command command = processModel.Process;

                    _logger.LogInformation("Starting ts stream for channel {ChannelNumber}", channelNumber);
                    _logger.LogDebug("ffmpeg arguments {FFmpegArguments}", command.Arguments);
                    var process = new FFmpegProcess
                    {
                        StartInfo = new ProcessStartInfo
                        {
                            FileName = command.TargetFilePath,
                            Arguments = command.Arguments,
                            RedirectStandardOutput = true,
                            RedirectStandardError = false,
                            UseShellExecute = false,
                            CreateNoWindow = true
                        }
                    };
                    HttpContext.Response.RegisterForDispose(process);

                    foreach ((string key, string value) in command.EnvironmentVariables)
                    {
                        process.StartInfo.Environment[key] = value;
                    }

                    process.Start();
                    return mode == "ts-legacy"
                        ? new TrackedFileStreamResult(
                            process.StandardOutput.BaseStream,
                            "video/mp2t",
                            _directStreamSessionTracker,
                            channelNumber,
                            StreamingMode.TransportStream)
                        : new FileStreamResult(process.StandardOutput.BaseStream, "video/mp2t");
                },
                error => BadRequest(error.Value)));
    }

    [HttpHead("iptv/session/{channelNumber}/hls.m3u8")]
    [HttpGet("iptv/session/{channelNumber}/hls.m3u8")]
    public async Task<IActionResult> GetLivePlaylist(string channelNumber, CancellationToken cancellationToken)
    {
        // _logger.LogDebug("Checking for session worker for channel {Channel}", channelNumber);

        if (_ffmpegSegmenterService.TryGetWorker(channelNumber, out IHlsSessionWorker worker) && worker is not null)
        {
            // _logger.LogDebug("Trimming playlist for channel {Channel}", channelNumber);

            DateTimeOffset now = DateTimeOffset.Now.AddSeconds(-30);
            Option<TrimPlaylistResult> maybePlaylist = await worker.TrimPlaylist(now, cancellationToken);
            foreach (TrimPlaylistResult result in maybePlaylist)
            {
                return Content(result.Playlist, "application/vnd.apple.mpegurl");
            }

            // TODO: better error here?
            _logger.LogWarning("Trim playlist failure; will return not found for channel {Channel}", channelNumber);
            return NotFound();
        }

        _logger.LogWarning(
            "Unable to locate session worker for channel {Channel}; will redirect to start session",
            channelNumber);
        return RedirectToAction(nameof(GetHttpLiveStreamingVideo), new { channelNumber });
    }

    [HttpHead("iptv/channel/{channelNumber}.m3u8")]
    [HttpGet("iptv/channel/{channelNumber}.m3u8")]
    public async Task<IActionResult> GetHttpLiveStreamingVideo(
        string channelNumber,
        [FromQuery]
        string mode = "mixed")
    {
        // The multi-variant/media playlists and the redirect Location below all carry the access_token.
        NoStoreForTokenBearingManifest();

        Option<ChannelViewModel> maybeChannel = await _mediator.Send(new GetChannelByNumber(channelNumber));
        if (maybeChannel.IsNone || !await maybeChannel.Map(c => c.IsEnabled).IfNoneAsync(false))
        {
            return NotFound();
        }

        // if mode is "unspecified" - find the configured mode and set it or redirect
        if (string.IsNullOrWhiteSpace(mode) || mode == "mixed")
        {
            foreach (ChannelViewModel channel in maybeChannel)
            {
                switch (channel.StreamingMode)
                {
                    case StreamingMode.HttpLiveStreamingDirect:
                        mode = "hls-direct";
                        break;
                    case StreamingMode.HttpLiveStreamingSegmenter:
                        mode = "segmenter";
                        break;
                    default:
                        return Redirect($"~/iptv/channel/{channelNumber}.ts{AccessTokenQuery()}");
                }
            }
        }

        switch (mode)
        {
            case "segmenter":
            case "segmenter-v2":
            case "segmenter-fmp4":
                _logger.LogDebug(
                    "Maybe starting ffmpeg session for channel {Channel}, mode {Mode}",
                    channelNumber,
                    mode);
                var request = new StartFFmpegSession(channelNumber, mode, Request.Scheme, Request.Host.ToString());
                Either<BaseError, Unit> result = await _mediator.Send(request);
                string multiVariantPlaylist = await GetMultiVariantPlaylist(channelNumber);
                return result.Match<IActionResult>(
                    _ =>
                    {
                        _logger.LogDebug(
                            "Session started; returning multi-variant playlist for channel {Channel}",
                            channelNumber);

                        return Content(multiVariantPlaylist, "application/vnd.apple.mpegurl");
                        // return Redirect($"~/iptv/session/{channelNumber}/hls.m3u8");
                    },
                    error =>
                    {
                        switch (error)
                        {
                            case ChannelSessionAlreadyActive:
                                _logger.LogDebug(
                                    "Session is already active; returning multi-variant playlist for channel {Channel}",
                                    channelNumber);

                                return Content(multiVariantPlaylist, "application/vnd.apple.mpegurl");
                            // return RedirectPreserveMethod($"iptv/session/{channelNumber}/hls.m3u8");
                            default:
                                _logger.LogWarning(
                                    "Failed to start segmenter for channel {ChannelNumber}: {Error}",
                                    channelNumber,
                                    error.ToString());
                                return NotFound();
                        }
                    });
            default:
                return await _mediator.Send(
                        new GetHlsPlaylistByChannelNumber(
                            Request.Scheme,
                            Request.Host.ToString(),
                            channelNumber,
                            mode))
                    .Map(r => r.Match<IActionResult>(
                        playlist => Content(playlist, "application/vnd.apple.mpegurl"),
                        error => BadRequest(error.Value)));
        }
    }

    [HttpHead("iptv/logos/{fileName}")]
    [HttpGet("iptv/logos/{fileName}")]
    [HttpHead("iptv/logos/{fileName}.jpg")]
    [HttpGet("iptv/logos/{fileName}.jpg")]
    public async Task<IActionResult> GetImage(string fileName)
    {
        Either<BaseError, CachedImagePathViewModel> cachedImagePath =
            await _mediator.Send(new GetCachedImagePath(fileName, ArtworkKind.Logo));
        return cachedImagePath.Match<IActionResult>(
            Left: _ => new NotFoundResult(),
            Right: r => new PhysicalFileResult(r.FileName, r.MimeType));
    }

    [HttpGet("iptv/hls-direct/{channelNumber}")]
    [HttpGet("iptv/hls-direct/{channelNumber}.ts")]
    [HttpGet("iptv/hls-direct/{channelNumber}.mkv")]
    [HttpGet("iptv/hls-direct/{channelNumber}.mp4")]
    public async Task<IActionResult> GetStream(string channelNumber) =>
        await GetHlsDirectStream(channelNumber);

    private async Task<string> GetMultiVariantPlaylist(string channelNumber)
    {
        var variantPlaylist =
            $"{Request.Scheme}://{Request.Host}{Request.PathBase}/iptv/session/{channelNumber}/hls.m3u8{AccessTokenQuery()}";

        Option<ChannelStreamingSpecsViewModel> maybeStreamingSpecs =
            await _mediator.Send(new GetChannelStreamingSpecs(channelNumber));
        string resolution = string.Empty;
        var bitrate = "10000000";
        foreach (ChannelStreamingSpecsViewModel streamingSpecs in maybeStreamingSpecs)
        {
            string videoCodec = streamingSpecs.VideoFormat switch
            {
                FFmpegProfileVideoFormat.Av1 => "av01.0.01M.08",
                FFmpegProfileVideoFormat.Hevc => "hvc1.1.6.L93.B0",
                FFmpegProfileVideoFormat.H264 => "avc1.4D4028",
                _ => string.Empty
            };

            string audioCodec = streamingSpecs.AudioFormat switch
            {
                FFmpegProfileAudioFormat.Ac3 => "ac-3",
                FFmpegProfileAudioFormat.Aac or FFmpegProfileAudioFormat.AacLatm => "mp4a.40.2",
                _ => string.Empty
            };

            List<string> codecStrings = [];
            if (!string.IsNullOrWhiteSpace(videoCodec))
            {
                codecStrings.Add(videoCodec);
            }

            if (!string.IsNullOrWhiteSpace(audioCodec))
            {
                codecStrings.Add(audioCodec);
            }

            string codecs = codecStrings.Count > 0 ? $",CODECS=\"{string.Join(",", codecStrings)}\"" : string.Empty;
            resolution = $",RESOLUTION={streamingSpecs.Width}x{streamingSpecs.Height}{codecs}";
            bitrate = streamingSpecs.Bitrate.ToString(CultureInfo.InvariantCulture);
        }

        return $@"#EXTM3U
#EXT-X-VERSION:3
#EXT-X-STREAM-INF:BANDWIDTH={bitrate}{resolution}
{variantPlaylist}";
    }

    private async Task<IActionResult> GetHlsDirectStream(string channelNumber)
    {
        var request = new GetPlayoutItemProcessByChannelNumber(
            channelNumber,
            StreamingMode.HttpLiveStreamingDirect,
            DateTimeOffset.Now,
            false,
            true,
            DateTimeOffset.Now,
            TimeSpan.Zero,
            Option<FrameRate>.None,
            IsTroubleshooting: false,
            Option<int>.None);

        Either<BaseError, PlayoutItemProcessModel> result = await _mediator.Send(request);

        return GetProcessResponse(
            result,
            channelNumber,
            StreamingMode.HttpLiveStreamingDirect,
            _directStreamSessionTracker);
    }

    // Percent-encode the token so a value containing '"' or '&' cannot break the M3U/HLS URL it is placed
    // into (#421). ASP.NET decodes Request.Query, so re-encoding round-trips to the original token; for a
    // normal base64url JWT this is a no-op.
    private string AccessTokenQuery() => string.IsNullOrWhiteSpace(Request.Query["access_token"])
        ? string.Empty
        : $"?access_token={Uri.EscapeDataString(Request.Query["access_token"].ToString())}";

    // Dynamic /iptv manifests embed the caller's access_token in their body/URLs; mark them no-store so a
    // browser or intermediary cache can't retain the token-bearing response and replay it (#559).
    private void NoStoreForTokenBearingManifest() =>
        Response.Headers.CacheControl = "private, no-store";
}