using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using Jellyfin.Api.Models.PlaybackDtos;
using Jellyfin.Api.Models.StreamingDtos;
using Jellyfin.Data.Enums;
using MediaBrowser.Common;
using MediaBrowser.Common.Configuration;
using MediaBrowser.Common.Extensions;
using MediaBrowser.Controller.Configuration;
using MediaBrowser.Controller.Library;
using MediaBrowser.Controller.MediaEncoding;
using MediaBrowser.Controller.Net;
using MediaBrowser.Controller.Session;
using MediaBrowser.Model.Dlna;
using MediaBrowser.Model.Entities;
using MediaBrowser.Model.IO;
using MediaBrowser.Model.MediaInfo;
using MediaBrowser.Model.Session;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;

namespace Jellyfin.Api.Helpers
{
    /// <summary>
    /// Transcoding job helpers.
    /// </summary>
    public class TranscodingJobHelper : IDisposable
    {
        /// <summary>
        /// The active transcoding jobs.
        /// </summary>
        private static readonly List<TranscodingJobDto> _activeTranscodingJobs = new List<TranscodingJobDto>();

        /// <summary>
        /// The transcoding locks.
        /// </summary>
        private static readonly Dictionary<string, SemaphoreSlim> _transcodingLocks = new Dictionary<string, SemaphoreSlim>();

        private readonly IAttachmentExtractor _attachmentExtractor;
        private readonly IApplicationPaths _appPaths;
        private readonly IAuthorizationContext _authorizationContext;
        private readonly EncodingHelper _encodingHelper;
        private readonly IFileSystem _fileSystem;
        private readonly ILogger<TranscodingJobHelper> _logger;
        private readonly IMediaEncoder _mediaEncoder;
        private readonly IMediaSourceManager _mediaSourceManager;
        private readonly IServerConfigurationManager _serverConfigurationManager;
        private readonly ISessionManager _sessionManager;
        private readonly ILoggerFactory _loggerFactory;

        /// <summary>
        /// Initializes a new instance of the <see cref="TranscodingJobHelper"/> class.
        /// </summary>
        /// <param name="attachmentExtractor">Instance of the <see cref="IAttachmentExtractor"/> interface.</param>
        /// <param name="appPaths">Instance of the <see cref="IApplicationPaths"/> interface.</param>
        /// <param name="logger">Instance of the <see cref="ILogger{TranscodingJobHelpers}"/> interface.</param>
        /// <param name="mediaSourceManager">Instance of the <see cref="IMediaSourceManager"/> interface.</param>
        /// <param name="fileSystem">Instance of the <see cref="IFileSystem"/> interface.</param>
        /// <param name="mediaEncoder">Instance of the <see cref="IMediaEncoder"/> interface.</param>
        /// <param name="serverConfigurationManager">Instance of the <see cref="IServerConfigurationManager"/> interface.</param>
        /// <param name="sessionManager">Instance of the <see cref="ISessionManager"/> interface.</param>
        /// <param name="authorizationContext">Instance of the <see cref="IAuthorizationContext"/> interface.</param>
        /// <param name="encodingHelper">Instance of <see cref="EncodingHelper"/>.</param>
        /// <param name="loggerFactory">Instance of the <see cref="ILoggerFactory"/> interface.</param>
        public TranscodingJobHelper(
            IAttachmentExtractor attachmentExtractor,
            IApplicationPaths appPaths,
            ILogger<TranscodingJobHelper> logger,
            IMediaSourceManager mediaSourceManager,
            IFileSystem fileSystem,
            IMediaEncoder mediaEncoder,
            IServerConfigurationManager serverConfigurationManager,
            ISessionManager sessionManager,
            IAuthorizationContext authorizationContext,
            EncodingHelper encodingHelper,
            ILoggerFactory loggerFactory)
        {
            _attachmentExtractor = attachmentExtractor;
            _appPaths = appPaths;
            _logger = logger;
            _mediaSourceManager = mediaSourceManager;
            _fileSystem = fileSystem;
            _mediaEncoder = mediaEncoder;
            _serverConfigurationManager = serverConfigurationManager;
            _sessionManager = sessionManager;
            _authorizationContext = authorizationContext;
            _encodingHelper = encodingHelper;
            _loggerFactory = loggerFactory;

            DeleteEncodedMediaCache();

            sessionManager.PlaybackProgress += OnPlaybackProgress;
            sessionManager.PlaybackStart += OnPlaybackProgress;
        }

        /// <summary>
        /// Get transcoding job.
        /// </summary>
        /// <param name="playSessionId">Playback session id.</param>
        /// <returns>The transcoding job.</returns>
        public TranscodingJobDto? GetTranscodingJob(string playSessionId)
        {
            lock (_activeTranscodingJobs)
            {
                return _activeTranscodingJobs.FirstOrDefault(j => string.Equals(j.PlaySessionId, playSessionId, StringComparison.OrdinalIgnoreCase));
            }
        }

        /// <summary>
        /// Get transcoding job.
        /// </summary>
        /// <param name="path">Path to the transcoding file.</param>
        /// <param name="type">The <see cref="TranscodingJobType"/>.</param>
        /// <returns>The transcoding job.</returns>
        public TranscodingJobDto? GetTranscodingJob(string path, TranscodingJobType type)
        {
            lock (_activeTranscodingJobs)
            {
                return _activeTranscodingJobs.FirstOrDefault(j => j.Type == type && string.Equals(j.Path, path, StringComparison.OrdinalIgnoreCase));
            }
        }

        /// <summary>
        /// Ping transcoding job.
        /// </summary>
        /// <param name="playSessionId">Play session id.</param>
        /// <param name="isUserPaused">Is user paused.</param>
        /// <exception cref="ArgumentNullException">Play session id is null.</exception>
        public void PingTranscodingJob(string playSessionId, bool? isUserPaused)
        {
            if (string.IsNullOrEmpty(playSessionId))
            {
                throw new ArgumentNullException(nameof(playSessionId));
            }

            _logger.LogDebug("PingTranscodingJob PlaySessionId={0} isUsedPaused: {1}", playSessionId, isUserPaused);

            List<TranscodingJobDto> jobs;

            lock (_activeTranscodingJobs)
            {
                // This is really only needed for HLS.
                // Progressive streams can stop on their own reliably.
                jobs = _activeTranscodingJobs.Where(j => string.Equals(playSessionId, j.PlaySessionId, StringComparison.OrdinalIgnoreCase)).ToList();
            }

            foreach (var job in jobs)
            {
                if (isUserPaused.HasValue)
                {
                    _logger.LogDebug("Setting job.IsUserPaused to {0}. jobId: {1}", isUserPaused, job.Id);
                    job.IsUserPaused = isUserPaused.Value;
                }

                PingTimer(job, true);
            }
        }

        private void PingTimer(TranscodingJobDto job, bool isProgressCheckIn)
        {
            if (job.HasExited)
            {
                job.StopKillTimer();
                return;
            }

            var timerDuration = 10000;

            if (job.Type != TranscodingJobType.Progressive)
            {
                timerDuration = 60000;
            }

            job.PingTimeout = timerDuration;
            job.LastPingDate = DateTime.UtcNow;

            // Don't start the timer for playback checkins with progressive streaming
            if (job.Type != TranscodingJobType.Progressive || !isProgressCheckIn)
            {
                job.StartKillTimer(OnTranscodeKillTimerStopped);
            }
            else
            {
                job.ChangeKillTimerIfStarted();
            }
        }

        /// <summary>
        /// Called when [transcode kill timer stopped].
        /// </summary>
        /// <param name="state">The state.</param>
        private async void OnTranscodeKillTimerStopped(object? state)
        {
            var job = state as TranscodingJobDto ?? throw new ArgumentException($"{nameof(state)} is not of type {nameof(TranscodingJobDto)}", nameof(state));
            if (!job.HasExited && job.Type != TranscodingJobType.Progressive)
            {
                var timeSinceLastPing = (DateTime.UtcNow - job.LastPingDate).TotalMilliseconds;

                if (timeSinceLastPing < job.PingTimeout)
                {
                    job.StartKillTimer(OnTranscodeKillTimerStopped, job.PingTimeout);
                    return;
                }
            }

            _logger.LogInformation("Transcoding kill timer stopped for JobId {0} PlaySessionId {1}. Killing transcoding", job.Id, job.PlaySessionId);

            await KillTranscodingJob(job, true, path => true).ConfigureAwait(false);
        }

        /// <summary>
        /// Kills the single transcoding job.
        /// </summary>
        /// <param name="deviceId">The device id.</param>
        /// <param name="playSessionId">The play session identifier.</param>
        /// <param name="deleteFiles">The delete files.</param>
        /// <returns>Task.</returns>
        public Task KillTranscodingJobs(string deviceId, string? playSessionId, Func<string, bool> deleteFiles)
        {
            return KillTranscodingJobs(
                j => string.IsNullOrWhiteSpace(playSessionId)
                    ? string.Equals(deviceId, j.DeviceId, StringComparison.OrdinalIgnoreCase)
                    : string.Equals(playSessionId, j.PlaySessionId, StringComparison.OrdinalIgnoreCase),
                deleteFiles);
        }

        /// <summary>
        /// Kills the transcoding jobs.
        /// </summary>
        /// <param name="killJob">The kill job.</param>
        /// <param name="deleteFiles">The delete files.</param>
        /// <returns>Task.</returns>
        private Task KillTranscodingJobs(Func<TranscodingJobDto, bool> killJob, Func<string, bool> deleteFiles)
        {
            var jobs = new List<TranscodingJobDto>();

            lock (_activeTranscodingJobs)
            {
                // This is really only needed for HLS.
                // Progressive streams can stop on their own reliably.
                jobs.AddRange(_activeTranscodingJobs.Where(killJob));
            }

            if (jobs.Count == 0)
            {
                return Task.CompletedTask;
            }

            IEnumerable<Task> GetKillJobs()
            {
                foreach (var job in jobs)
                {
                    yield return KillTranscodingJob(job, false, deleteFiles);
                }
            }

            return Task.WhenAll(GetKillJobs());
        }

        /// <summary>
        /// Kills the transcoding job.
        /// </summary>
        /// <param name="job">The job.</param>
        /// <param name="closeLiveStream">if set to <c>true</c> [close live stream].</param>
        /// <param name="delete">The delete.</param>
        private async Task KillTranscodingJob(TranscodingJobDto job, bool closeLiveStream, Func<string, bool> delete)
        {
            job.DisposeKillTimer();

            _logger.LogDebug("KillTranscodingJob - JobId {0} PlaySessionId {1}. Killing transcoding", job.Id, job.PlaySessionId);

            lock (_activeTranscodingJobs)
            {
                _activeTranscodingJobs.Remove(job);

                if (job.CancellationTokenSource?.IsCancellationRequested == false)
                {
                    job.CancellationTokenSource.Cancel();
                }
            }

            lock (_transcodingLocks)
            {
                _transcodingLocks.Remove(job.Path!);
            }

            lock (job.ProcessLock!)
            {
                #pragma warning disable CA1849 // Can't await in lock block
                job.TranscodingThrottler?.Stop().GetAwaiter().GetResult();

                var process = job.Process;

                var hasExited = job.HasExited;

                if (!hasExited)
                {
                    try
                    {
                        _logger.LogInformation("Stopping ffmpeg process with q command for {Path}", job.Path);

                        process!.StandardInput.WriteLine("q");

                        // Need to wait because killing is asynchronous.
                        if (!process.WaitForExit(5000))
                        {
                            _logger.LogInformation("Killing FFmpeg process for {Path}", job.Path);
                            process.Kill();
                        }
                    }
                    catch (InvalidOperationException)
                    {
                    }
                }
                #pragma warning restore CA1849
            }

            if (delete(job.Path!))
            {
                await DeletePartialStreamFiles(job.Path!, job.Type, 0, 1500).ConfigureAwait(false);
            }

            if (closeLiveStream && !string.IsNullOrWhiteSpace(job.LiveStreamId))
            {
                try
                {
                    await _mediaSourceManager.CloseLiveStream(job.LiveStreamId).ConfigureAwait(false);
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "Error closing live stream for {Path}", job.Path);
                }
            }
        }

        private async Task DeletePartialStreamFiles(string path, TranscodingJobType jobType, int retryCount, int delayMs)
        {
            if (retryCount >= 10)
            {
                return;
            }

            _logger.LogInformation("Deleting partial stream file(s) {Path}", path);

            await Task.Delay(delayMs).ConfigureAwait(false);

            try
            {
                if (jobType == TranscodingJobType.Progressive)
                {
                    DeleteProgressivePartialStreamFiles(path);
                }
                else
                {
                    DeleteHlsPartialStreamFiles(path);
                }
            }
            catch (IOException ex)
            {
                _logger.LogError(ex, "Error deleting partial stream file(s) {Path}", path);

                await DeletePartialStreamFiles(path, jobType, retryCount + 1, 500).ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error deleting partial stream file(s) {Path}", path);
            }
        }

        /// <summary>
        /// Deletes the progressive partial stream files.
        /// </summary>
        /// <param name="outputFilePath">The output file path.</param>
        private void DeleteProgressivePartialStreamFiles(string outputFilePath)
        {
            if (File.Exists(outputFilePath))
            {
                _fileSystem.DeleteFile(outputFilePath);
            }
        }

        /// <summary>
        /// Deletes the HLS partial stream files.
        /// </summary>
        /// <param name="outputFilePath">The output file path.</param>
        private void DeleteHlsPartialStreamFiles(string outputFilePath)
        {
            var directory = Path.GetDirectoryName(outputFilePath)
                            ?? throw new ArgumentException("Path can't be a root directory.", nameof(outputFilePath));

            var name = Path.GetFileNameWithoutExtension(outputFilePath);

            var filesToDelete = _fileSystem.GetFilePaths(directory)
                .Where(f => f.IndexOf(name, StringComparison.OrdinalIgnoreCase) != -1);

            List<Exception>? exs = null;
            foreach (var file in filesToDelete)
            {
                try
                {
                    _logger.LogDebug("Deleting HLS file {0}", file);
                    _fileSystem.DeleteFile(file);
                }
                catch (IOException ex)
                {
                    (exs ??= new List<Exception>(4)).Add(ex);
                    _logger.LogError(ex, "Error deleting HLS file {Path}", file);
                }
            }

            if (exs != null)
            {
                throw new AggregateException("Error deleting HLS files", exs);
            }
        }

        /// <summary>
        /// Report the transcoding progress to the session manager.
        /// </summary>
        /// <param name="job">The <see cref="TranscodingJobDto"/> of which the progress will be reported.</param>
        /// <param name="state">The <see cref="StreamState"/> of the current transcoding job.</param>
        /// <param name="transcodingPosition">The current transcoding position.</param>
        /// <param name="framerate">The framerate of the transcoding job.</param>
        /// <param name="percentComplete">The completion percentage of the transcode.</param>
        /// <param name="bytesTranscoded">The number of bytes transcoded.</param>
        /// <param name="bitRate">The bitrate of the transcoding job.</param>
        public void ReportTranscodingProgress(
            TranscodingJobDto job,
            StreamState state,
            TimeSpan? transcodingPosition,
            float? framerate,
            double? percentComplete,
            long? bytesTranscoded,
            int? bitRate)
        {
            var ticks = transcodingPosition?.Ticks;

            if (job != null)
            {
                job.Framerate = framerate;
                job.CompletionPercentage = percentComplete;
                job.TranscodingPositionTicks = ticks;
                job.BytesTranscoded = bytesTranscoded;
                job.BitRate = bitRate;
            }

            var deviceId = state.Request.DeviceId;

            if (!string.IsNullOrWhiteSpace(deviceId))
            {
                var audioCodec = state.ActualOutputAudioCodec;
                var videoCodec = state.ActualOutputVideoCodec;
                var hardwareAccelerationTypeString = _serverConfigurationManager.GetEncodingOptions().HardwareAccelerationType;
                HardwareEncodingType? hardwareAccelerationType = null;
                if (!string.IsNullOrEmpty(hardwareAccelerationTypeString)
                    && Enum.TryParse<HardwareEncodingType>(hardwareAccelerationTypeString, out var parsedHardwareAccelerationType))
                {
                    hardwareAccelerationType = parsedHardwareAccelerationType;
                }

                _sessionManager.ReportTranscodingInfo(deviceId, new TranscodingInfo
                {
                    Bitrate = bitRate ?? state.TotalOutputBitrate,
                    AudioCodec = audioCodec,
                    VideoCodec = videoCodec,
                    Container = state.OutputContainer,
                    Framerate = framerate,
                    CompletionPercentage = percentComplete,
                    Width = state.OutputWidth,
                    Height = state.OutputHeight,
                    AudioChannels = state.OutputAudioChannels,
                    IsAudioDirect = EncodingHelper.IsCopyCodec(state.OutputAudioCodec),
                    IsVideoDirect = EncodingHelper.IsCopyCodec(state.OutputVideoCodec),
                    HardwareAccelerationType = hardwareAccelerationType,
                    TranscodeReason = state.TranscodeReason
                });
            }
        }

        /// <summary>
        /// Starts FFmpeg.
        /// </summary>
        /// <param name="state">The state.</param>
        /// <param name="outputPath">The output path.</param>
        /// <param name="commandLineArguments">The command line arguments for FFmpeg.</param>
        /// <param name="request">The <see cref="HttpRequest"/>.</param>
        /// <param name="transcodingJobType">The <see cref="TranscodingJobType"/>.</param>
        /// <param name="cancellationTokenSource">The cancellation token source.</param>
        /// <param name="workingDirectory">The working directory.</param>
        /// <returns>Task.</returns>
        public async Task<TranscodingJobDto> StartFfMpeg(
            StreamState state,
            string outputPath,
            string commandLineArguments,
            HttpRequest request,
            TranscodingJobType transcodingJobType,
            CancellationTokenSource cancellationTokenSource,
            string? workingDirectory = null)
        {
            var directory = Path.GetDirectoryName(outputPath) ?? throw new ArgumentException($"Provided path ({outputPath}) is not valid.", nameof(outputPath));
            Directory.CreateDirectory(directory);

            await AcquireResources(state, cancellationTokenSource).ConfigureAwait(false);

            if (state.VideoRequest != null && !EncodingHelper.IsCopyCodec(state.OutputVideoCodec))
            {
                var auth = await _authorizationContext.GetAuthorizationInfo(request).ConfigureAwait(false);
                if (auth.User != null && !auth.User.HasPermission(PermissionKind.EnableVideoPlaybackTranscoding))
                {
                    this.OnTranscodeFailedToStart(outputPath, transcodingJobType, state);

                    throw new ArgumentException("User does not have access to video transcoding.");
                }
            }

            if (string.IsNullOrEmpty(_mediaEncoder.EncoderPath))
            {
                throw new ArgumentException("FFmpeg path not set.");
            }

            // If subtitles get burned in fonts may need to be extracted from the media file
            if (state.SubtitleStream != null && state.SubtitleDeliveryMethod == SubtitleDeliveryMethod.Encode)
            {
                var attachmentPath = Path.Combine(_appPaths.CachePath, "attachments", state.MediaSource.Id);
                await _attachmentExtractor.ExtractAllAttachments(state.MediaPath, state.MediaSource, attachmentPath, cancellationTokenSource.Token).ConfigureAwait(false);

                if (state.SubtitleStream.IsExternal)
                {
                    string subtitlePath = state.SubtitleStream.Path;
                    string subtitlePathArgument = string.Format(CultureInfo.InvariantCulture, "file:\"{0}\"", subtitlePath.Replace("\"", "\\\"", StringComparison.Ordinal));
                    string subtitleId = subtitlePath.GetMD5().ToString("N", CultureInfo.InvariantCulture);

                    await _attachmentExtractor.ExtractAllAttachmentsExternal(subtitlePathArgument, subtitleId, attachmentPath, cancellationTokenSource.Token).ConfigureAwait(false);
                }
            }

            var process = new Process
            {
                StartInfo = new ProcessStartInfo
                {
                    WindowStyle = ProcessWindowStyle.Hidden,
                    CreateNoWindow = true,
                    UseShellExecute = false,

                    // Must consume both stdout and stderr or deadlocks may occur
                    // RedirectStandardOutput = true,
                    RedirectStandardError = true,
                    RedirectStandardInput = true,
                    FileName = _mediaEncoder.EncoderPath,
                    Arguments = commandLineArguments,
                    WorkingDirectory = string.IsNullOrWhiteSpace(workingDirectory) ? string.Empty : workingDirectory,
                    ErrorDialog = false
                },
                EnableRaisingEvents = true
            };

            var transcodingJob = this.OnTranscodeBeginning(
                outputPath,
                state.Request.PlaySessionId,
                state.MediaSource.LiveStreamId,
                Guid.NewGuid().ToString("N", CultureInfo.InvariantCulture),
                transcodingJobType,
                process,
                state.Request.DeviceId,
                state,
                cancellationTokenSource);

            _logger.LogInformation("{Filename} {Arguments}", process.StartInfo.FileName, process.StartInfo.Arguments);

            var logFilePrefix = "FFmpeg.Transcode-";
            if (state.VideoRequest != null
                && EncodingHelper.IsCopyCodec(state.OutputVideoCodec))
            {
                logFilePrefix = EncodingHelper.IsCopyCodec(state.OutputAudioCodec)
                    ? "FFmpeg.Remux-"
                    : "FFmpeg.DirectStream-";
            }

            var logFilePath = Path.Combine(
                _serverConfigurationManager.ApplicationPaths.LogDirectoryPath,
                $"{logFilePrefix}{DateTime.Now:yyyy-MM-dd_HH-mm-ss}_{state.Request.MediaSourceId}_{Guid.NewGuid().ToString()[..8]}.log");

            // FFmpeg writes debug/error info to stderr. This is useful when debugging so let's put it in the log directory.
            Stream logStream = new FileStream(logFilePath, FileMode.Create, FileAccess.Write, FileShare.Read, IODefaults.FileStreamBufferSize, FileOptions.Asynchronous);

            var commandLineLogMessage = process.StartInfo.FileName + " " + process.StartInfo.Arguments;
            var commandLineLogMessageBytes = Encoding.UTF8.GetBytes(request.Path + Environment.NewLine + Environment.NewLine + JsonSerializer.Serialize(state.MediaSource) + Environment.NewLine + Environment.NewLine + commandLineLogMessage + Environment.NewLine + Environment.NewLine);
            await logStream.WriteAsync(commandLineLogMessageBytes, cancellationTokenSource.Token).ConfigureAwait(false);

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

            try
            {
                process.Start();
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error starting FFmpeg");

                this.OnTranscodeFailedToStart(outputPath, transcodingJobType, state);

                throw;
            }

            _logger.LogDebug("Launched FFmpeg process");
            state.TranscodingJob = transcodingJob;

            // Important - don't await the log task or we won't be able to kill FFmpeg when the user stops playback
            _ = new JobLogger(_logger).StartStreamingLog(state, process.StandardError.BaseStream, logStream);

            // Wait for the file to exist before proceeding
            var ffmpegTargetFile = state.WaitForPath ?? outputPath;
            _logger.LogDebug("Waiting for the creation of {0}", ffmpegTargetFile);
            while (!File.Exists(ffmpegTargetFile) && !transcodingJob.HasExited)
            {
                await Task.Delay(100, cancellationTokenSource.Token).ConfigureAwait(false);
            }

            _logger.LogDebug("File {0} created or transcoding has finished", ffmpegTargetFile);

            if (state.IsInputVideo && transcodingJob.Type == TranscodingJobType.Progressive && !transcodingJob.HasExited)
            {
                await Task.Delay(1000, cancellationTokenSource.Token).ConfigureAwait(false);

                if (state.ReadInputAtNativeFramerate && !transcodingJob.HasExited)
                {
                    await Task.Delay(1500, cancellationTokenSource.Token).ConfigureAwait(false);
                }
            }

            if (!transcodingJob.HasExited)
            {
                StartThrottler(state, transcodingJob);
            }
            else if (transcodingJob.ExitCode != 0)
            {
                throw new FfmpegException(string.Format(CultureInfo.InvariantCulture, "FFmpeg exited with code {0}", transcodingJob.ExitCode));
            }

            _logger.LogDebug("StartFfMpeg() finished successfully");

            return transcodingJob;
        }

        private void StartThrottler(StreamState state, TranscodingJobDto transcodingJob)
        {
            if (EnableThrottling(state))
            {
                transcodingJob.TranscodingThrottler = state.TranscodingThrottler = new TranscodingThrottler(transcodingJob, new Logger<TranscodingThrottler>(new LoggerFactory()), _serverConfigurationManager, _fileSystem);
                state.TranscodingThrottler.Start();
            }
        }

        private bool EnableThrottling(StreamState state)
        {
            var encodingOptions = _serverConfigurationManager.GetEncodingOptions();

            // enable throttling when NOT using hardware acceleration
            if (string.IsNullOrEmpty(encodingOptions.HardwareAccelerationType))
            {
                return state.InputProtocol == MediaProtocol.File &&
                       state.RunTimeTicks.HasValue &&
                       state.RunTimeTicks.Value >= TimeSpan.FromMinutes(5).Ticks &&
                       state.IsInputVideo &&
                       state.VideoType == VideoType.VideoFile &&
                       !EncodingHelper.IsCopyCodec(state.OutputVideoCodec);
            }

            return false;
        }

        /// <summary>
        /// Called when [transcode beginning].
        /// </summary>
        /// <param name="path">The path.</param>
        /// <param name="playSessionId">The play session identifier.</param>
        /// <param name="liveStreamId">The live stream identifier.</param>
        /// <param name="transcodingJobId">The transcoding job identifier.</param>
        /// <param name="type">The type.</param>
        /// <param name="process">The process.</param>
        /// <param name="deviceId">The device id.</param>
        /// <param name="state">The state.</param>
        /// <param name="cancellationTokenSource">The cancellation token source.</param>
        /// <returns>TranscodingJob.</returns>
        public TranscodingJobDto OnTranscodeBeginning(
            string path,
            string? playSessionId,
            string? liveStreamId,
            string transcodingJobId,
            TranscodingJobType type,
            Process process,
            string? deviceId,
            StreamState state,
            CancellationTokenSource cancellationTokenSource)
        {
            lock (_activeTranscodingJobs)
            {
                var job = new TranscodingJobDto(_loggerFactory.CreateLogger<TranscodingJobDto>())
                {
                    Type = type,
                    Path = path,
                    Process = process,
                    ActiveRequestCount = 1,
                    DeviceId = deviceId,
                    CancellationTokenSource = cancellationTokenSource,
                    Id = transcodingJobId,
                    PlaySessionId = playSessionId,
                    LiveStreamId = liveStreamId,
                    MediaSource = state.MediaSource
                };

                _activeTranscodingJobs.Add(job);

                ReportTranscodingProgress(job, state, null, null, null, null, null);

                return job;
            }
        }

        /// <summary>
        /// Called when [transcode end].
        /// </summary>
        /// <param name="job">The transcode job.</param>
        public void OnTranscodeEndRequest(TranscodingJobDto job)
        {
            job.ActiveRequestCount--;
            _logger.LogDebug("OnTranscodeEndRequest job.ActiveRequestCount={ActiveRequestCount}", job.ActiveRequestCount);
            if (job.ActiveRequestCount <= 0)
            {
                PingTimer(job, false);
            }
        }

        /// <summary>
        /// <summary>
        /// The progressive
        /// </summary>
        /// Called when [transcode failed to start].
        /// </summary>
        /// <param name="path">The path.</param>
        /// <param name="type">The type.</param>
        /// <param name="state">The state.</param>
        public void OnTranscodeFailedToStart(string path, TranscodingJobType type, StreamState state)
        {
            lock (_activeTranscodingJobs)
            {
                var job = _activeTranscodingJobs.FirstOrDefault(j => j.Type == type && string.Equals(j.Path, path, StringComparison.OrdinalIgnoreCase));

                if (job != null)
                {
                    _activeTranscodingJobs.Remove(job);
                }
            }

            lock (_transcodingLocks)
            {
                _transcodingLocks.Remove(path);
            }

            if (!string.IsNullOrWhiteSpace(state.Request.DeviceId))
            {
                _sessionManager.ClearTranscodingInfo(state.Request.DeviceId);
            }
        }

        /// <summary>
        /// Processes the exited.
        /// </summary>
        /// <param name="process">The process.</param>
        /// <param name="job">The job.</param>
        /// <param name="state">The state.</param>
        private void OnFfMpegProcessExited(Process process, TranscodingJobDto job, StreamState state)
        {
            job.HasExited = true;
            job.ExitCode = process.ExitCode;

            ReportTranscodingProgress(job, state, null, null, null, null, null);

            _logger.LogDebug("Disposing stream resources");
            state.Dispose();

            if (process.ExitCode == 0)
            {
                _logger.LogInformation("FFmpeg exited with code 0");
            }
            else
            {
                _logger.LogError("FFmpeg exited with code {0}", process.ExitCode);
            }

            job.Dispose();
        }

        private async Task AcquireResources(StreamState state, CancellationTokenSource cancellationTokenSource)
        {
            if (state.MediaSource.RequiresOpening && string.IsNullOrWhiteSpace(state.Request.LiveStreamId))
            {
                var liveStreamResponse = await _mediaSourceManager.OpenLiveStream(
                        new LiveStreamRequest { OpenToken = state.MediaSource.OpenToken },
                        cancellationTokenSource.Token)
                    .ConfigureAwait(false);
                var encodingOptions = _serverConfigurationManager.GetEncodingOptions();

                _encodingHelper.AttachMediaSourceInfo(state, encodingOptions, liveStreamResponse.MediaSource, state.RequestedUrl);

                if (state.VideoRequest != null)
                {
                    _encodingHelper.TryStreamCopy(state);
                }
            }

            if (state.MediaSource.BufferMs.HasValue)
            {
                await Task.Delay(state.MediaSource.BufferMs.Value, cancellationTokenSource.Token).ConfigureAwait(false);
            }
        }

        /// <summary>
        /// Called when [transcode begin request].
        /// </summary>
        /// <param name="path">The path.</param>
        /// <param name="type">The type.</param>
        /// <returns>The <see cref="TranscodingJobDto"/>.</returns>
        public TranscodingJobDto? OnTranscodeBeginRequest(string path, TranscodingJobType type)
        {
            lock (_activeTranscodingJobs)
            {
                var job = _activeTranscodingJobs.FirstOrDefault(j => j.Type == type && string.Equals(j.Path, path, StringComparison.OrdinalIgnoreCase));

                if (job == null)
                {
                    return null;
                }

                OnTranscodeBeginRequest(job);

                return job;
            }
        }

        private void OnTranscodeBeginRequest(TranscodingJobDto job)
        {
            job.ActiveRequestCount++;

            if (string.IsNullOrWhiteSpace(job.PlaySessionId) || job.Type == TranscodingJobType.Progressive)
            {
                job.StopKillTimer();
            }
        }

        /// <summary>
        /// Gets the transcoding lock.
        /// </summary>
        /// <param name="outputPath">The output path of the transcoded file.</param>
        /// <returns>A <see cref="SemaphoreSlim"/>.</returns>
        public SemaphoreSlim GetTranscodingLock(string outputPath)
        {
            lock (_transcodingLocks)
            {
                if (!_transcodingLocks.TryGetValue(outputPath, out SemaphoreSlim? result))
                {
                    result = new SemaphoreSlim(1, 1);
                    _transcodingLocks[outputPath] = result;
                }

                return result;
            }
        }

        private void OnPlaybackProgress(object? sender, PlaybackProgressEventArgs e)
        {
            if (!string.IsNullOrWhiteSpace(e.PlaySessionId))
            {
                PingTranscodingJob(e.PlaySessionId, e.IsPaused);
            }
        }

        /// <summary>
        /// Deletes the encoded media cache.
        /// </summary>
        private void DeleteEncodedMediaCache()
        {
            var path = _serverConfigurationManager.GetTranscodePath();
            if (!Directory.Exists(path))
            {
                return;
            }

            foreach (var file in _fileSystem.GetFilePaths(path, true))
            {
                _fileSystem.DeleteFile(file);
            }
        }

        /// <summary>
        /// Dispose transcoding job helper.
        /// </summary>
        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        /// <summary>
        /// Dispose throttler.
        /// </summary>
        /// <param name="disposing">Disposing.</param>
        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                _loggerFactory.Dispose();
                _sessionManager.PlaybackProgress -= OnPlaybackProgress;
                _sessionManager.PlaybackStart -= OnPlaybackProgress;
            }
        }
    }
}