using OpenCvSharp;
using System.Threading;

namespace AIParkingApplication
{
    public delegate void CameraEvent(Mat videoFrame);

    public class Camera
    {
        private string streamUrl;
        private volatile bool isFrameRequested;
        private Thread readStreamThread;
        private VideoCapture videoCapture;
        public volatile Mat CurrentFrame;

        public event CameraEvent OnVideoFrameReceived;
        public event CameraEvent OnOpenVideoStreamFailed;

        public Camera(string streamUrl)
        {
            this.streamUrl = streamUrl;
            isFrameRequested = false;
            videoCapture = new VideoCapture();
            readStreamThread = new Thread(new ThreadStart(ReadVideoStream));
            readStreamThread.IsBackground = true;
        }

        ~Camera()
        {
            Stop();
            videoCapture?.Dispose();
        }

        public void Start()
        {
            if (!readStreamThread.IsAlive)
            {
                readStreamThread = new Thread(new ThreadStart(ReadVideoStream));
                readStreamThread.IsBackground = true;
                readStreamThread.Start();
            }
        }

        public void RequestCaptureOneFrame()
        {
            isFrameRequested = true;
        }

        public void ReadVideoStream()
        {
            if (!videoCapture.Open(streamUrl))
            {
                OnOpenVideoStreamFailed?.Invoke(Cv2.ImRead(AppConstant.CAMERA_FAILED_IMAGE_PATH));
                return;
            }

            Mat videoFrame = new Mat();
            while (true)
            {
                //Thread.Sleep(5);
                Thread.Sleep(50);     //Stream Thread Sleep
                //Thread.Sleep(40);     //Video Thread Sleep

                if (videoCapture.Read(videoFrame) && videoFrame.Width > 0 && videoFrame.Height > 0)
                {
                    OnVideoFrameReceived?.Invoke(videoFrame);
                    if (isFrameRequested)
                    {
                        CurrentFrame = videoFrame;
                        isFrameRequested = false;
                    }
                }
                else
                {
                    OnOpenVideoStreamFailed?.Invoke(Cv2.ImRead(AppConstant.CAMERA_FAILED_IMAGE_PATH));
                }
            }
        }

        public void Stop()
        {
            if (readStreamThread.IsAlive)
            {
                readStreamThread.Abort();
            }
        }
    }
}