using Accord.Video.FFMPEG;
using AIDiagnosisDemo.Infrastucture;
using AIDiagnosisDemo.Settings;
using System;
using System.Drawing;
using System.Threading;
using System.Windows;

namespace AIDiagnosisDemo.Service
{
    internal class FileVideoPlayer : IPlayer
    {
        private string _filepath;
        private VideoFileReader _videoFileReader;
        private Thread _playThread;
        private bool _pausing;
        private int _startTickCount;
        private int _displayCount;
        private int _fps;
        private readonly object _videoReaderLocker = new object();

        private volatile int _frameIntervalTime = 0;
        private volatile int _frameCount = 0;
        private volatile int _frameIndex = 0;

        /// <summary>
        /// 接收到图像输入的事件
        /// </summary>
        public event EventHandler<Bitmap> InputFrameReceived;

        /// <summary>
        /// FPS变更的事件
        /// </summary>
        public event EventHandler<int> FPSChanged;

        /// <summary>
        /// FileVideoPlayer构造函数
        /// </summary>
        /// <param name="filepath">文件路径</param>
        public FileVideoPlayer(string filepath)
        {
            _filepath = filepath;
        }

        /// <summary>
        /// 播放
        /// </summary>
        /// <returns>播放成功为True，播放失败为False</returns>
        public bool Play()
        {
            if (!SettingConfig.Instance.IsVideo)
            {
                if (ImagePlay())
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
            else
            {
                if (VideoPlay())
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
        }

        private bool ImagePlay()
        {
            try
            {
                if (string.IsNullOrEmpty(_filepath))
                {
                    Logger.Info("Image File Path is Empty!!!");
                    return false;
                }
                var bitmap = new Bitmap(_filepath);
                OnNewFrame(bitmap);
                bitmap.Dispose();
                return true;
            }
            catch (Exception ex)
            {
                Logger.Info($"Image Play Error: {ex} ");
                return false;
            }
        }

        private void OnNewFrame(Bitmap e)
        {
            InputFrameReceived?.Invoke(this, e);
        }

        private bool VideoPlay()
        {
            try
            {
                if (string.IsNullOrEmpty(_filepath))
                {
                    Logger.Info("Video File Path is Empty!!!");
                    return false;
                }
                _videoFileReader = new VideoFileReader();
                _videoFileReader.Open(_filepath);
                var frameRate = _videoFileReader.FrameRate.ToDouble();
                _frameIntervalTime = (int)(1000 / frameRate);
                _frameCount = (int)_videoFileReader.FrameCount;
                StartPlayThread();
                return true;
            }
            catch
            {
                return false;
            }
        }

        private void DoVideoPlay()
        {
            _startTickCount = -1;
            while (!_pausing)
            {
                Bitmap bitmap = null;
                lock (_videoReaderLocker)
                {
                    try
                    {
                        bitmap = _videoFileReader?.ReadVideoFrame(_frameIndex);
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show($"ReadVideoFrame Error:{ex}");
                    }
                }
                if (bitmap == null)
                {
                    break;
                }

                OnNewFrame(bitmap);
                var timeUsed = Environment.TickCount - _startTickCount;
                bitmap.Dispose();
                if (_startTickCount == -1)
                {
                    _displayCount = 0;
                    _startTickCount = Environment.TickCount;
                }
                else
                {
                    var currentTickCount = Environment.TickCount;
                    var fpsTimeUsed = currentTickCount - _startTickCount;
                    _displayCount++;
                    if (fpsTimeUsed > 1000)
                    {
                        var fps = (int)((double)_displayCount / fpsTimeUsed * 1000);
                        if (_fps != fps)
                        {
                            _fps = fps;
                            FPSChanged?.Invoke(this, _fps);
                        }
                        _startTickCount = currentTickCount;
                        _displayCount = 0;
                    }
                }
                var waitTime = _frameIntervalTime - timeUsed;
                Thread.Sleep(waitTime < 0 ? 1 : waitTime);

                // 如果到尾了，就从头开始
                if (_frameIndex == _frameCount - 1)
                {
                    _frameIndex = 0;
                }
                else
                {
                    _frameIndex += 1;
                }
            }
        }

        /// <summary>
        /// 暂停播放
        /// </summary>
        public void Pause()
        {
            if (SettingConfig.Instance.IsVideo)
            {
                _pausing = true;
            }
        }

        /// <summary>
        /// 继续播放
        /// </summary>
        public void Continue()
        {
            if (SettingConfig.Instance.IsVideo)
            {
                StartPlayThread();
            }
        }

        private void StartPlayThread()
        {
            _pausing = false;
            if (_playThread == null || !_playThread.IsAlive)
            {
                _playThread = new Thread(() => DoVideoPlay())
                {
                    IsBackground = true,
                    Name = "AIDiagnosisDemo_FileVideoPlay",
                };
                _playThread.Start();
            }
        }

        /// <summary>
        /// 停止播放
        /// </summary>
        public void Stop()
        {
            _pausing = true;
            lock (_videoReaderLocker)
            {
                if (_videoFileReader != null)
                {
                    _videoFileReader.Close();
                    _videoFileReader.Dispose();
                    _videoFileReader = null;
                }
            }
        }
    }
}