using System;
using System.Diagnostics;
using System.IO;
using System.Threading.Tasks;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Domain.Filler;
using ErsatzTV.Core.Interfaces.FFmpeg;
using ErsatzTV.Core.Interfaces.Images;
using LanguageExt;
using Microsoft.Extensions.Logging;
using static LanguageExt.Prelude;

namespace ErsatzTV.Core.FFmpeg
{
    public class FFmpegProcessService
    {
        private readonly IFFmpegStreamSelector _ffmpegStreamSelector;
        private readonly IImageCache _imageCache;
        private readonly ILogger<FFmpegProcessService> _logger;
        private readonly FFmpegPlaybackSettingsCalculator _playbackSettingsCalculator;

        public FFmpegProcessService(
            FFmpegPlaybackSettingsCalculator ffmpegPlaybackSettingsService,
            IFFmpegStreamSelector ffmpegStreamSelector,
            IImageCache imageCache,
            ILogger<FFmpegProcessService> logger)
        {
            _playbackSettingsCalculator = ffmpegPlaybackSettingsService;
            _ffmpegStreamSelector = ffmpegStreamSelector;
            _imageCache = imageCache;
            _logger = logger;
        }

        public async Task<Process> ForPlayoutItem(
            string ffmpegPath,
            bool saveReports,
            Channel channel,
            MediaVersion videoVersion,
            MediaVersion audioVersion,
            string videoPath,
            string audioPath,
            DateTimeOffset start,
            DateTimeOffset finish,
            DateTimeOffset now,
            Option<ChannelWatermark> globalWatermark,
            VaapiDriver vaapiDriver,
            string vaapiDevice,
            bool hlsRealtime,
            FillerKind fillerKind,
            TimeSpan inPoint,
            TimeSpan outPoint)
        {
            MediaStream videoStream = await _ffmpegStreamSelector.SelectVideoStream(channel, videoVersion);
            Option<MediaStream> maybeAudioStream = await _ffmpegStreamSelector.SelectAudioStream(channel, audioVersion);

            FFmpegPlaybackSettings playbackSettings = _playbackSettingsCalculator.CalculateSettings(
                channel.StreamingMode,
                channel.FFmpegProfile,
                videoVersion,
                videoStream,
                maybeAudioStream,
                start,
                now,
                inPoint,
                outPoint);

            Option<WatermarkOptions> watermarkOptions =
                await GetWatermarkOptions(channel, globalWatermark, audioVersion);

            FFmpegProcessBuilder builder = new FFmpegProcessBuilder(ffmpegPath, saveReports, _logger)
                .WithThreads(playbackSettings.ThreadCount)
                .WithVaapiDriver(vaapiDriver, vaapiDevice)
                .WithHardwareAcceleration(
                    playbackSettings.HardwareAcceleration,
                    videoStream.PixelFormat,
                    playbackSettings.VideoCodec)
                .WithQuiet()
                .WithFormatFlags(playbackSettings.FormatFlags)
                .WithRealtimeOutput(playbackSettings.RealtimeOutput)
                .WithInputCodec(
                    playbackSettings.StreamSeek,
                    fillerKind == FillerKind.Fallback,
                    videoPath,
                    audioPath,
                    playbackSettings.VideoDecoder,
                    videoStream.Codec,
                    videoStream.PixelFormat)
                .WithWatermark(watermarkOptions, channel.FFmpegProfile.Resolution)
                .WithVideoTrackTimeScale(playbackSettings.VideoTrackTimeScale)
                .WithAlignedAudio(playbackSettings.AudioDuration)
                .WithNormalizeLoudness(playbackSettings.NormalizeLoudness);

            playbackSettings.ScaledSize.Match(
                scaledSize =>
                {
                    builder = builder.WithDeinterlace(playbackSettings.Deinterlace)
                        .WithScaling(scaledSize);

                    if (NeedToPad(channel.FFmpegProfile.Resolution, scaledSize))
                    {
                        builder = builder.WithBlackBars(channel.FFmpegProfile.Resolution);
                    }

                    builder = builder
                        .WithFilterComplex(
                            videoStream,
                            maybeAudioStream,
                            videoPath,
                            audioPath,
                            channel.FFmpegProfile.VideoCodec);
                },
                () =>
                {
                    if (playbackSettings.PadToDesiredResolution)
                    {
                        builder = builder
                            .WithDeinterlace(playbackSettings.Deinterlace)
                            .WithBlackBars(channel.FFmpegProfile.Resolution)
                            .WithFilterComplex(
                                videoStream,
                                maybeAudioStream,
                                videoPath,
                                audioPath,
                                channel.FFmpegProfile.VideoCodec);
                    }
                    else if (playbackSettings.Deinterlace)
                    {
                        builder = builder.WithDeinterlace(playbackSettings.Deinterlace)
                            .WithAlignedAudio(playbackSettings.AudioDuration)
                            .WithFilterComplex(
                                videoStream,
                                maybeAudioStream,
                                videoPath,
                                audioPath,
                                channel.FFmpegProfile.VideoCodec);
                    }
                    else
                    {
                        builder = builder
                            .WithFilterComplex(
                                videoStream,
                                maybeAudioStream,
                                videoPath,
                                audioPath,
                                channel.FFmpegProfile.VideoCodec);
                    }
                });

            builder = builder.WithPlaybackArgs(playbackSettings)
                .WithMetadata(channel, maybeAudioStream)
                .WithDuration(finish - now);

            switch (channel.StreamingMode)
            {
                // HLS needs to segment and generate playlist
                case StreamingMode.HttpLiveStreamingSegmenter:
                    return builder.WithHls(channel.Number, videoVersion)
                        .WithRealtimeOutput(hlsRealtime)
                        .Build();
                default:
                    return builder.WithFormat("mpegts")
                        .WithPipe()
                        .Build();
            }
        }

        public Process ForError(
            string ffmpegPath,
            Channel channel,
            Option<TimeSpan> duration,
            string errorMessage,
            bool hlsRealtime)
        {
            FFmpegPlaybackSettings playbackSettings =
                _playbackSettingsCalculator.CalculateErrorSettings(channel.FFmpegProfile);

            IDisplaySize desiredResolution = channel.FFmpegProfile.Resolution;

            FFmpegProcessBuilder builder = new FFmpegProcessBuilder(ffmpegPath, false, _logger)
                .WithThreads(1)
                .WithQuiet()
                .WithFormatFlags(playbackSettings.FormatFlags)
                .WithRealtimeOutput(playbackSettings.RealtimeOutput)
                .WithLoopedImage(Path.Combine(FileSystemLayout.ResourcesCacheFolder, "background.png"))
                .WithLibavfilter()
                .WithInput("anullsrc")
                .WithErrorText(desiredResolution, errorMessage)
                .WithPixfmt("yuv420p")
                .WithPlaybackArgs(playbackSettings)
                .WithMetadata(channel, None);

            duration.IfSome(d => builder = builder.WithDuration(d));

            switch (channel.StreamingMode)
            {
                // HLS needs to segment and generate playlist
                case StreamingMode.HttpLiveStreamingSegmenter:
                    return builder.WithHls(channel.Number, None)
                        .WithRealtimeOutput(hlsRealtime)
                        .Build();
                default:
                    return builder.WithFormat("mpegts")
                        .WithPipe()
                        .Build();
            }
        }

        public Process ConcatChannel(string ffmpegPath, bool saveReports, Channel channel, string scheme, string host)
        {
            FFmpegPlaybackSettings playbackSettings = _playbackSettingsCalculator.ConcatSettings;

            return new FFmpegProcessBuilder(ffmpegPath, saveReports, _logger)
                .WithThreads(1)
                .WithQuiet()
                .WithFormatFlags(playbackSettings.FormatFlags)
                .WithRealtimeOutput(playbackSettings.RealtimeOutput)
                .WithInfiniteLoop()
                .WithConcat($"http://localhost:{Settings.ListenPort}/ffmpeg/concat/{channel.Number}")
                .WithMetadata(channel, None)
                .WithFormat("mpegts")
                .WithPipe()
                .Build();
        }

        private bool NeedToPad(IDisplaySize target, IDisplaySize displaySize) =>
            displaySize.Width != target.Width || displaySize.Height != target.Height;

        private async Task<WatermarkOptions> GetWatermarkOptions(
            Channel channel,
            Option<ChannelWatermark> globalWatermark,
            MediaVersion audioVersion)
        {
            if (channel.StreamingMode != StreamingMode.HttpLiveStreamingDirect && channel.FFmpegProfile.Transcode &&
                channel.FFmpegProfile.NormalizeVideo)
            {
                // check for channel watermark
                if (channel.Watermark != null)
                {
                    switch (channel.Watermark.ImageSource)
                    {
                        case ChannelWatermarkImageSource.Custom:
                            string customPath = _imageCache.GetPathForImage(
                                channel.Watermark.Image,
                                ArtworkKind.Watermark,
                                Option<int>.None);
                            return new WatermarkOptions(
                                channel.Watermark,
                                customPath,
                                None,
                                await _imageCache.IsAnimated(customPath));
                        case ChannelWatermarkImageSource.ChannelLogo:
                            Option<string> maybeChannelPath = channel.Artwork
                                .Filter(a => a.ArtworkKind == ArtworkKind.Logo)
                                .HeadOrNone()
                                .Map(a => _imageCache.GetPathForImage(a.Path, ArtworkKind.Logo, Option<int>.None));
                            return new WatermarkOptions(
                                channel.Watermark,
                                maybeChannelPath,
                                None,
                                await maybeChannelPath.Match(
                                    p => _imageCache.IsAnimated(p),
                                    () => Task.FromResult(false)));
                        case ChannelWatermarkImageSource.CoverArt:
                            Option<MediaStream> maybeAttachedPicStream =
                                Optional(audioVersion.Streams.Find(s => s.AttachedPic));

                            // only return a watermark if there is an attachment
                            // to allow falling back on a global watermark
                            foreach (MediaStream attachedPicStream in maybeAttachedPicStream)
                            {
                                return new WatermarkOptions(
                                    channel.Watermark,
                                    audioVersion.MediaFiles.Head().Path,
                                    attachedPicStream.Index,
                                    false);
                            }

                            break;
                        default:
                            throw new NotSupportedException("Unsupported watermark image source");
                    }
                }

                // check for global watermark
                foreach (ChannelWatermark watermark in globalWatermark)
                {
                    switch (watermark.ImageSource)
                    {
                        case ChannelWatermarkImageSource.Custom:
                            string customPath = _imageCache.GetPathForImage(
                                watermark.Image,
                                ArtworkKind.Watermark,
                                Option<int>.None);
                            return new WatermarkOptions(
                                watermark,
                                customPath,
                                None,
                                await _imageCache.IsAnimated(customPath));
                        case ChannelWatermarkImageSource.ChannelLogo:
                            Option<string> maybeChannelPath = channel.Artwork
                                .Filter(a => a.ArtworkKind == ArtworkKind.Logo)
                                .HeadOrNone()
                                .Map(a => _imageCache.GetPathForImage(a.Path, ArtworkKind.Logo, Option<int>.None));
                            return new WatermarkOptions(
                                watermark,
                                maybeChannelPath,
                                None,
                                await maybeChannelPath.Match(
                                    p => _imageCache.IsAnimated(p),
                                    () => Task.FromResult(false)));
                        case ChannelWatermarkImageSource.CoverArt:
                            Option<MediaStream> maybeAttachedPicStream =
                                Optional(audioVersion.Streams.Find(s => s.AttachedPic));
                            
                            // only return a watermark if there is an attachment
                            foreach (MediaStream attachedPicStream in maybeAttachedPicStream)
                            {
                                return new WatermarkOptions(
                                    channel.Watermark,
                                    audioVersion.MediaFiles.Head().Path,
                                    attachedPicStream.Index,
                                    false);
                            }

                            break;
                        default:
                            throw new NotSupportedException("Unsupported watermark image source");
                    }
                }
            }

            return new WatermarkOptions(None, None, None, false);
        }
    }
}