using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using MediaBrowser.Model.IO;
using MediaBrowser.Common.IO;
using MediaBrowser.Common.Net;
using MediaBrowser.Controller;
using MediaBrowser.Controller.IO;
using MediaBrowser.Controller.MediaEncoding;
using MediaBrowser.Model.Diagnostics;
using MediaBrowser.Model.Dto;
using MediaBrowser.Model.Entities;
using MediaBrowser.Model.LiveTv;
using MediaBrowser.Model.Logging;
using MediaBrowser.Model.Serialization;

namespace Emby.Server.Implementations.LiveTv.EmbyTV
{
    public class EncodedRecorder : IRecorder
    {
        private readonly ILogger _logger;
        private readonly IFileSystem _fileSystem;
        private readonly IHttpClient _httpClient;
        private readonly IMediaEncoder _mediaEncoder;
        private readonly IServerApplicationPaths _appPaths;
        private readonly LiveTvOptions _liveTvOptions;
        private bool _hasExited;
        private string _targetPath;
        private IProcess _process;
        private readonly IProcessFactory _processFactory;
        private readonly IJsonSerializer _json;
        private readonly TaskCompletionSource<bool> _taskCompletionSource = new TaskCompletionSource<bool>();

        public EncodedRecorder(ILogger logger, IFileSystem fileSystem, IMediaEncoder mediaEncoder, IServerApplicationPaths appPaths, IJsonSerializer json, LiveTvOptions liveTvOptions, IHttpClient httpClient, IProcessFactory processFactory)
        {
            _logger = logger;
            _fileSystem = fileSystem;
            _mediaEncoder = mediaEncoder;
            _appPaths = appPaths;
            _json = json;
            _liveTvOptions = liveTvOptions;
            _httpClient = httpClient;
            _processFactory = processFactory;
        }

        private string OutputFormat
        {
            get
            {
                var format = _liveTvOptions.RecordingEncodingFormat;

                if (string.Equals(format, "mkv", StringComparison.OrdinalIgnoreCase))
                {
                    return "mkv";
                }

                return "mp4";
            }
        }

        public string GetOutputPath(MediaSourceInfo mediaSource, string targetFile)
        {
            return Path.ChangeExtension(targetFile, "." + OutputFormat);
        }

        public async Task Record(MediaSourceInfo mediaSource, string targetFile, TimeSpan duration, Action onStarted, CancellationToken cancellationToken)
        {
            var durationToken = new CancellationTokenSource(duration);
            cancellationToken = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, durationToken.Token).Token;

            await RecordFromFile(mediaSource, mediaSource.Path, targetFile, duration, onStarted, cancellationToken).ConfigureAwait(false);

            _logger.Info("Recording completed to file {0}", targetFile);
        }

        private Task RecordFromFile(MediaSourceInfo mediaSource, string inputFile, string targetFile, TimeSpan duration, Action onStarted, CancellationToken cancellationToken)
        {
            _targetPath = targetFile;
            _fileSystem.CreateDirectory(Path.GetDirectoryName(targetFile));

            var logFilePath = Path.Combine(_appPaths.LogDirectoryPath, "record-transcode-" + Guid.NewGuid().ToString("N") + ".txt");
            _fileSystem.CreateDirectory(Path.GetDirectoryName(logFilePath));

            var process = _processFactory.Create(new ProcessOptions
            {
                CreateNoWindow = true,
                UseShellExecute = true,

                // Must consume both stdout and stderr or deadlocks may occur
                //RedirectStandardOutput = true,
                RedirectStandardError = false,
                RedirectStandardInput = false,

                FileName = _mediaEncoder.EncoderPath,
                Arguments = GetCommandLineArgs(mediaSource, inputFile, targetFile, duration),

                IsHidden = true,
                ErrorDialog = false,
                EnableRaisingEvents = true,
                WorkingDirectory = Path.GetDirectoryName(logFilePath)
            });

            _process = process;

            var commandLineLogMessage = process.StartInfo.FileName + " " + process.StartInfo.Arguments;
            _logger.Info(commandLineLogMessage);

            _mediaEncoder.SetLogFilename(Path.GetFileName(logFilePath));

            //var commandLineLogMessageBytes = Encoding.UTF8.GetBytes(_json.SerializeToString(mediaSource) + Environment.NewLine + Environment.NewLine + commandLineLogMessage + Environment.NewLine + Environment.NewLine);

            process.Exited += (sender, args) => OnFfMpegProcessExited(process, inputFile);

            process.Start();

            cancellationToken.Register(Stop);

            // MUST read both stdout and stderr asynchronously or a deadlock may occurr
            //process.BeginOutputReadLine();

            onStarted();

            _logger.Info("ffmpeg recording process started for {0}", _targetPath);
            _mediaEncoder.ClearLogFilename();

            return _taskCompletionSource.Task;
        }

        private string GetCommandLineArgs(MediaSourceInfo mediaSource, string inputTempFile, string targetFile, TimeSpan duration)
        {
            string videoArgs;
            if (EncodeVideo(mediaSource))
            {
                var maxBitrate = 25000000;
                videoArgs = string.Format(
                        "-codec:v:0 libx264 -force_key_frames \"expr:gte(t,n_forced*5)\" {0} -pix_fmt yuv420p -preset superfast -crf 23 -b:v {1} -maxrate {1} -bufsize ({1}*2) -vsync -1 -profile:v high -level 41",
                        GetOutputSizeParam(),
                        maxBitrate.ToString(CultureInfo.InvariantCulture));
            }
            else
            {
                videoArgs = "-codec:v:0 copy";
            }

            var durationParam = " -t " + _mediaEncoder.GetTimeParameter(duration.Ticks);
            var inputModifiers = "-fflags +genpts -async 1 -vsync -1";
            var commandLineArgs = "-i \"{0}\"{4} -sn {2} -map_metadata -1 -threads 0 {3} -loglevel info -y \"{1}\"";

            long startTimeTicks = 0;
            //if (mediaSource.DateLiveStreamOpened.HasValue)
            //{
            //    var elapsed = DateTime.UtcNow - mediaSource.DateLiveStreamOpened.Value;
            //    elapsed -= TimeSpan.FromSeconds(10);
            //    if (elapsed.TotalSeconds >= 0)
            //    {
            //        startTimeTicks = elapsed.Ticks + startTimeTicks;
            //    }
            //}

            if (mediaSource.ReadAtNativeFramerate)
            {
                inputModifiers += " -re";
            }

            if (startTimeTicks > 0)
            {
                inputModifiers = "-ss " + _mediaEncoder.GetTimeParameter(startTimeTicks) + " " + inputModifiers;
            }

            var analyzeDurationSeconds = 5;
            var analyzeDuration = " -analyzeduration " +
                  (analyzeDurationSeconds * 1000000).ToString(CultureInfo.InvariantCulture);
            inputModifiers += analyzeDuration;

            commandLineArgs = string.Format(commandLineArgs, inputTempFile, targetFile, videoArgs, GetAudioArgs(mediaSource), durationParam);

            return inputModifiers + " " + commandLineArgs;
        }

        private string GetAudioArgs(MediaSourceInfo mediaSource)
        {
            var mediaStreams = mediaSource.MediaStreams ?? new List<MediaStream>();
            var inputAudioCodec = mediaStreams.Where(i => i.Type == MediaStreamType.Audio).Select(i => i.Codec).FirstOrDefault() ?? string.Empty;

            // do not copy aac because many players have difficulty with aac_latm
            if (_liveTvOptions.EnableOriginalAudioWithEncodedRecordings && !string.Equals(inputAudioCodec, "aac", StringComparison.OrdinalIgnoreCase))
            {
                return "-codec:a:0 copy";
            }

            var audioChannels = 2;
            var audioStream = mediaStreams.FirstOrDefault(i => i.Type == MediaStreamType.Audio);
            if (audioStream != null)
            {
                audioChannels = audioStream.Channels ?? audioChannels;
            }
            return "-codec:a:0 aac -strict experimental -ab 320000";
        }

        private bool EncodeVideo(MediaSourceInfo mediaSource)
        {
            if (string.Equals(_liveTvOptions.RecordedVideoCodec, "copy", StringComparison.OrdinalIgnoreCase))
            {
                return false;
            }

            var mediaStreams = mediaSource.MediaStreams ?? new List<MediaStream>();
            return !mediaStreams.Any(i => i.Type == MediaStreamType.Video && string.Equals(i.Codec, "h264", StringComparison.OrdinalIgnoreCase) && !i.IsInterlaced);
        }

        protected string GetOutputSizeParam()
        {
            var filters = new List<string>();

            filters.Add("yadif=0:-1:0");

            var output = string.Empty;

            if (filters.Count > 0)
            {
                output += string.Format(" -vf \"{0}\"", string.Join(",", filters.ToArray()));
            }

            return output;
        }

        private bool _isCancelled;
        private void Stop()
        {
            if (!_hasExited)
            {
                try
                {
                    _isCancelled = true;

                    _logger.Info("Killing ffmpeg recording process for {0}", _targetPath);

                    _process.Kill();
                    //_process.StandardInput.WriteLine("q");
                }
                catch (Exception ex)
                {
                    _logger.ErrorException("Error killing transcoding job for {0}", ex, _targetPath);
                }
            }
        }

        /// <summary>
        /// Processes the exited.
        /// </summary>
        private void OnFfMpegProcessExited(IProcess process, string inputFile)
        {
            _hasExited = true;

            try
            {
                var exitCode = _isCancelled ? 0 : process.ExitCode;

                _logger.Info("FFMpeg recording exited with code {0} for {1}", exitCode, _targetPath);

                if (exitCode == 0)
                {
                    _taskCompletionSource.TrySetResult(true);
                }
                else
                {
                    _taskCompletionSource.TrySetException(new Exception(string.Format("Recording for {0} failed. Exit code {1}", _targetPath, exitCode)));
                }
            }
            catch
            {
                _logger.Error("FFMpeg recording exited with an error for {0}.", _targetPath);
                _taskCompletionSource.TrySetException(new Exception(string.Format("Recording for {0} failed", _targetPath)));
            }
        }
    }
}