using UnityEngine;
using UnityEngine.SceneManagement;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;
using OpenCVForUnity.CoreModule;
using OpenCVForUnity.ObjdetectModule;
using OpenCVForUnity.ImgprocModule;
using OpenCVForUnity.UnityUtils;
using OpenCVForUnity.UnityUtils.Helper;
using Rect = OpenCVForUnity.CoreModule.Rect;
using PositionsVector = System.Collections.Generic.List<OpenCVForUnity.CoreModule.Rect>;

namespace OpenCVForUnityExample
{
    /// <summary>
    /// Asynchronous Face Detection WebCam Example
    /// Referring to https://github.com/Itseez/opencv/blob/master/modules/objdetect/src/detection_based_tracker.cpp.
    /// </summary>
    [RequireComponent(typeof(WebCamTextureToMatHelper))]
    public class AsynchronousFaceDetectionWebCamExample : MonoBehaviour
    {
        /// <summary>
        /// The gray mat.
        /// </summary>
        Mat grayMat;

        /// <summary>
        /// The texture.
        /// </summary>
        Texture2D texture;

        /// <summary>
        /// The webcam texture to mat helper.
        /// </summary>
        WebCamTextureToMatHelper webCamTextureToMatHelper;

        /// <summary>
        /// The cascade.
        /// </summary>
        CascadeClassifier cascade;

        /// <summary>
        /// LBP_CASCADE_FILENAME
        /// </summary>
        protected static readonly string LBP_CASCADE_FILENAME = "OpenCVForUnity/objdetect/lbpcascade_frontalface.xml";

        /// <summary>
        /// The lbp cascade filepath.
        /// </summary>
        string lbp_cascade_filepath;

        /// <summary>
        /// HAAR_CASCADE_FILENAME
        /// </summary>
        protected static readonly string HAAR_CASCADE_FILENAME = "OpenCVForUnity/objdetect/haarcascade_frontalface_alt.xml";

        /// <summary>
        /// The haar_cascade_filepath.
        /// </summary>
        string haar_cascade_filepath;

        /// <summary>
        /// The rects where regions.
        /// </summary>
        Rect[] rectsWhereRegions;

        /// <summary>
        /// The detected objects in regions.
        /// </summary>
        List<Rect> detectedObjectsInRegions = new List<Rect>();

        /// <summary>
        /// The result objects.
        /// </summary>
        List<Rect> resultObjects = new List<Rect>();

        // for Thread
        CascadeClassifier cascade4Thread;
        Mat grayMat4Thread;
        MatOfRect detectionResult;
        System.Object sync = new System.Object();

        bool _isThreadRunning = false;

        bool isThreadRunning
        {
            get
            {
                lock (sync)
                    return _isThreadRunning;
            }
            set
            {
                lock (sync)
                    _isThreadRunning = value;
            }
        }

        bool _shouldStopThread = false;

        bool shouldStopThread
        {
            get
            {
                lock (sync)
                    return _shouldStopThread;
            }
            set
            {
                lock (sync)
                    _shouldStopThread = value;
            }
        }

        bool _shouldDetectInMultiThread = false;

        bool shouldDetectInMultiThread
        {
            get
            {
                lock (sync)
                    return _shouldDetectInMultiThread;
            }
            set
            {
                lock (sync)
                    _shouldDetectInMultiThread = value;
            }
        }

        bool _didUpdateTheDetectionResult = false;

        bool didUpdateTheDetectionResult
        {
            get
            {
                lock (sync)
                    return _didUpdateTheDetectionResult;
            }
            set
            {
                lock (sync)
                    _didUpdateTheDetectionResult = value;
            }
        }

        /// <summary>
        /// The FPS monitor.
        /// </summary>
        FpsMonitor fpsMonitor;

        // for tracker
        List<TrackedObject> trackedObjects = new List<TrackedObject>();
        List<float> weightsPositionsSmoothing = new List<float>();
        List<float> weightsSizesSmoothing = new List<float>();
        Parameters parameters;
        InnerParameters innerParameters;

#if UNITY_WEBGL
        IEnumerator getFilePath_Coroutine;
#endif

        // Use this for initialization
        void Start()
        {
            fpsMonitor = GetComponent<FpsMonitor>();

            webCamTextureToMatHelper = gameObject.GetComponent<WebCamTextureToMatHelper>();

#if UNITY_WEBGL
            getFilePath_Coroutine = GetFilePath ();
            StartCoroutine (getFilePath_Coroutine);
#else
            lbp_cascade_filepath = Utils.getFilePath(LBP_CASCADE_FILENAME);
            haar_cascade_filepath = Utils.getFilePath(HAAR_CASCADE_FILENAME);
            Run();
#endif
        }

#if UNITY_WEBGL
        private IEnumerator GetFilePath ()
        {
            var getFilePathAsync_lbpcascade_frontalface_xml_filepath_Coroutine = Utils.getFilePathAsync (LBP_CASCADE_FILENAME, (result) => {
                lbp_cascade_filepath = result;
            });
            yield return getFilePathAsync_lbpcascade_frontalface_xml_filepath_Coroutine;
            
            var getFilePathAsync_haarcascade_frontalface_alt_xml_filepath_Coroutine = Utils.getFilePathAsync (HAAR_CASCADE_FILENAME, (result) => {
                haar_cascade_filepath = result;
            });
            yield return getFilePathAsync_haarcascade_frontalface_alt_xml_filepath_Coroutine;
            
            getFilePath_Coroutine = null;
            
            Run ();
        }
#endif

        private void Run()
        {
            weightsPositionsSmoothing.Add(1);
            weightsSizesSmoothing.Add(0.5f);
            weightsSizesSmoothing.Add(0.3f);
            weightsSizesSmoothing.Add(0.2f);

            //parameters.minObjectSize = 96;
            //parameters.maxObjectSize = int.MaxValue;
            //parameters.scaleFactor = 1.1f;
            //parameters.minNeighbors = 2;
            parameters.maxTrackLifetime = 5;

            innerParameters.numLastPositionsToTrack = 4;
            innerParameters.numStepsToWaitBeforeFirstShow = 6;
            innerParameters.numStepsToTrackWithoutDetectingIfObjectHasNotBeenShown = 3;
            innerParameters.numStepsToShowWithoutDetecting = 3;
            innerParameters.coeffTrackingWindowSize = 2.0f;
            innerParameters.coeffObjectSizeToTrack = 0.85f;
            innerParameters.coeffObjectSpeedUsingInPrediction = 0.8f;

#if UNITY_ANDROID && !UNITY_EDITOR
            // Avoids the front camera low light issue that occurs in only some Android devices (e.g. Google Pixel, Pixel2).
            webCamTextureToMatHelper.avoidAndroidFrontCameraLowLightIssue = true;
#endif
            webCamTextureToMatHelper.Initialize();
        }

        /// <summary>
        /// Raises the webcam texture to mat helper initialized event.
        /// </summary>
        public void OnWebCamTextureToMatHelperInitialized()
        {
            Debug.Log("OnWebCamTextureToMatHelperInitialized");

            Mat webCamTextureMat = webCamTextureToMatHelper.GetMat();

            texture = new Texture2D(webCamTextureMat.cols(), webCamTextureMat.rows(), TextureFormat.RGBA32, false);
            Utils.matToTexture2D(webCamTextureMat, texture);

            gameObject.GetComponent<Renderer>().material.mainTexture = texture;

            gameObject.transform.localScale = new Vector3(webCamTextureMat.cols(), webCamTextureMat.rows(), 1);

            Debug.Log("Screen.width " + Screen.width + " Screen.height " + Screen.height + " Screen.orientation " + Screen.orientation);

            if (fpsMonitor != null)
            {
                fpsMonitor.Add("width", webCamTextureMat.width().ToString());
                fpsMonitor.Add("height", webCamTextureMat.height().ToString());
                fpsMonitor.Add("orientation", Screen.orientation.ToString());
            }


            float width = webCamTextureMat.width();
            float height = webCamTextureMat.height();

            float widthScale = (float)Screen.width / width;
            float heightScale = (float)Screen.height / height;
            if (widthScale < heightScale)
            {
                Camera.main.orthographicSize = (width * (float)Screen.height / (float)Screen.width) / 2;
            }
            else
            {
                Camera.main.orthographicSize = height / 2;
            }

            grayMat = new Mat(webCamTextureMat.rows(), webCamTextureMat.cols(), CvType.CV_8UC1);

            if (string.IsNullOrEmpty(lbp_cascade_filepath))
            {
                Debug.LogError(LBP_CASCADE_FILENAME + " is not loaded. Please move from “OpenCVForUnity/StreamingAssets/OpenCVForUnity/” to “Assets/StreamingAssets/OpenCVForUnity/” folder.");
            }
            else
            {
                cascade = new CascadeClassifier(lbp_cascade_filepath);
            }

            InitThread();
        }

        /// <summary>
        /// Raises the webcam texture to mat helper disposed event.
        /// </summary>
        public void OnWebCamTextureToMatHelperDisposed()
        {
            Debug.Log("OnWebCamTextureToMatHelperDisposed");

#if !UNITY_WEBGL
            StopThread();
#else
            StopCoroutine ("ThreadWorker");
#endif

            if (grayMat4Thread != null)
                grayMat4Thread.Dispose();

            if (cascade4Thread != null)
                cascade4Thread.Dispose();

            if (grayMat != null)
                grayMat.Dispose();

            if (texture != null)
            {
                Texture2D.Destroy(texture);
                texture = null;
            }

            if (cascade != null)
                cascade.Dispose();

            trackedObjects.Clear();
        }

        /// <summary>
        /// Raises the webcam texture to mat helper error occurred event.
        /// </summary>
        /// <param name="errorCode">Error code.</param>
        public void OnWebCamTextureToMatHelperErrorOccurred(WebCamTextureToMatHelper.ErrorCode errorCode)
        {
            Debug.Log("OnWebCamTextureToMatHelperErrorOccurred " + errorCode);
        }

        // Update is called once per frame
        void Update()
        {
            if (webCamTextureToMatHelper.IsPlaying() && webCamTextureToMatHelper.DidUpdateThisFrame())
            {

                Mat rgbaMat = webCamTextureToMatHelper.GetMat();

                if (cascade == null || cascade4Thread == null)
                {
                    Imgproc.putText(rgbaMat, "model file is not loaded.", new Point(5, rgbaMat.rows() - 30), Imgproc.FONT_HERSHEY_SIMPLEX, 0.7, new Scalar(255, 255, 255, 255), 2, Imgproc.LINE_AA, false);
                    Imgproc.putText(rgbaMat, "Please read console message.", new Point(5, rgbaMat.rows() - 10), Imgproc.FONT_HERSHEY_SIMPLEX, 0.7, new Scalar(255, 255, 255, 255), 2, Imgproc.LINE_AA, false);

                    Utils.matToTexture2D(rgbaMat, texture);
                    return;
                }

                Imgproc.cvtColor(rgbaMat, grayMat, Imgproc.COLOR_RGBA2GRAY);
                Imgproc.equalizeHist(grayMat, grayMat);

                if (!shouldDetectInMultiThread)
                {
                    grayMat.copyTo(grayMat4Thread);

                    shouldDetectInMultiThread = true;
                }

                OpenCVForUnity.CoreModule.Rect[] rects;

                if (didUpdateTheDetectionResult)
                {
                    didUpdateTheDetectionResult = false;

                    //Debug.Log("DetectionBasedTracker::process: get _rectsWhereRegions were got from resultDetect");
                    rectsWhereRegions = detectionResult.toArray();

                    rects = rectsWhereRegions;
                    for (int i = 0; i < rects.Length; i++)
                    {
                        Imgproc.rectangle(rgbaMat, new Point(rects[i].x, rects[i].y), new Point(rects[i].x + rects[i].width, rects[i].y + rects[i].height), new Scalar(0, 0, 255, 255), 2);
                    }

                }
                else
                {
                    //Debug.Log("DetectionBasedTracker::process: get _rectsWhereRegions from previous positions");
                    rectsWhereRegions = new Rect[trackedObjects.Count];

                    for (int i = 0; i < trackedObjects.Count; i++)
                    {
                        int n = trackedObjects[i].lastPositions.Count;
                        //if (n > 0) UnityEngine.Debug.LogError("n > 0 is false");

                        Rect r = trackedObjects[i].lastPositions[n - 1].clone();
                        if (r.area() == 0)
                        {
                            Debug.Log("DetectionBasedTracker::process: ERROR: ATTENTION: strange algorithm's behavior: trackedObjects[i].rect() is empty");
                            continue;
                        }

                        //correction by speed of rectangle
                        if (n > 1)
                        {
                            Point center = CenterRect(r);
                            Point center_prev = CenterRect(trackedObjects[i].lastPositions[n - 2]);
                            Point shift = new Point((center.x - center_prev.x) * innerParameters.coeffObjectSpeedUsingInPrediction,
                                              (center.y - center_prev.y) * innerParameters.coeffObjectSpeedUsingInPrediction);

                            r.x += (int)Math.Round(shift.x);
                            r.y += (int)Math.Round(shift.y);
                        }
                        rectsWhereRegions[i] = r;
                    }

                    rects = rectsWhereRegions;
                    for (int i = 0; i < rects.Length; i++)
                    {
                        Imgproc.rectangle(rgbaMat, new Point(rects[i].x, rects[i].y), new Point(rects[i].x + rects[i].width, rects[i].y + rects[i].height), new Scalar(0, 255, 0, 255), 2);
                    }
                }

                detectedObjectsInRegions.Clear();
                if (rectsWhereRegions.Length > 0)
                {

                    int len = rectsWhereRegions.Length;
                    for (int i = 0; i < len; i++)
                    {
                        DetectInRegion(grayMat, rectsWhereRegions[i], detectedObjectsInRegions);
                    }
                }

                UpdateTrackedObjects(detectedObjectsInRegions);
                GetObjects(resultObjects);

                rects = resultObjects.ToArray();
                for (int i = 0; i < rects.Length; i++)
                {
                    //Debug.Log ("detect faces " + rects [i]);
                    Imgproc.rectangle(rgbaMat, new Point(rects[i].x, rects[i].y), new Point(rects[i].x + rects[i].width, rects[i].y + rects[i].height), new Scalar(255, 0, 0, 255), 2);
                }

#if UNITY_WEBGL
                Imgproc.putText (rgbaMat, "WebGL platform does not support multi-threading.", new Point (5, rgbaMat.rows () - 10), Imgproc.FONT_HERSHEY_SIMPLEX, 0.5, new Scalar (255, 255, 255, 255), 1, Imgproc.LINE_AA, false);
#endif

                Utils.matToTexture2D(rgbaMat, texture);
            }
        }

        private void DetectInRegion(Mat img, Rect r, List<Rect> detectedObjectsInRegions)
        {
            Rect r0 = new Rect(new Point(), img.size());
            Rect r1 = new Rect(r.x, r.y, r.width, r.height);
            Rect.inflate(r1, (int)((r1.width * innerParameters.coeffTrackingWindowSize) - r1.width) / 2,
                (int)((r1.height * innerParameters.coeffTrackingWindowSize) - r1.height) / 2);
            r1 = Rect.intersect(r0, r1);

            if (r1 != null && (r1.width <= 0) || (r1.height <= 0))
            {
                Debug.Log("DetectionBasedTracker::detectInRegion: Empty intersection");
                return;
            }


            int d = Math.Min(r.width, r.height);
            d = (int)Math.Round(d * innerParameters.coeffObjectSizeToTrack);


            MatOfRect tmpobjects = new MatOfRect();

            Mat img1 = new Mat(img, r1);//subimage for rectangle -- without data copying

            cascade.detectMultiScale(img1, tmpobjects, 1.1, 2, 0 | Objdetect.CASCADE_DO_CANNY_PRUNING | Objdetect.CASCADE_SCALE_IMAGE | Objdetect.CASCADE_FIND_BIGGEST_OBJECT, new Size(d, d), new Size());


            Rect[] tmpobjectsArray = tmpobjects.toArray();
            int len = tmpobjectsArray.Length;
            for (int i = 0; i < len; i++)
            {
                Rect tmp = tmpobjectsArray[i];
                Rect curres = new Rect(new Point(tmp.x + r1.x, tmp.y + r1.y), tmp.size());
                detectedObjectsInRegions.Add(curres);
            }
        }

        public Point CenterRect(Rect r)
        {
            return new Point(r.x + (r.width / 2), r.y + (r.height / 2));
        }

        private void InitThread()
        {
            StopThread();

            grayMat4Thread = new Mat();

            if (string.IsNullOrEmpty(haar_cascade_filepath))
            {
                Debug.LogError(HAAR_CASCADE_FILENAME + " is not loaded. Please move from “OpenCVForUnity/StreamingAssets/OpenCVForUnity/” to “Assets/StreamingAssets/OpenCVForUnity/” folder.");
            }
            else
            {
                cascade4Thread = new CascadeClassifier(haar_cascade_filepath);
            }

            shouldDetectInMultiThread = false;

#if !UNITY_WEBGL
            StartThread(ThreadWorker);
#else
            StartCoroutine ("ThreadWorker");
#endif
        }

        private void StartThread(Action action)
        {
            shouldStopThread = false;

#if UNITY_METRO && NETFX_CORE
            System.Threading.Tasks.Task.Run(() => action());
#elif UNITY_METRO
            action.BeginInvoke(ar => action.EndInvoke(ar), null);
#else
            ThreadPool.QueueUserWorkItem(_ => action());
#endif

            Debug.Log("Thread Start");
        }

        private void StopThread()
        {
            if (!isThreadRunning)
                return;

            shouldStopThread = true;

            while (isThreadRunning)
            {
                //Wait threading stop
            }
            Debug.Log("Thread Stop");
        }

#if !UNITY_WEBGL
        private void ThreadWorker()
        {
            isThreadRunning = true;

            while (!shouldStopThread)
            {
                if (!shouldDetectInMultiThread)
                    continue;

                Detect();

                shouldDetectInMultiThread = false;
                didUpdateTheDetectionResult = true;
            }

            isThreadRunning = false;
        }


#else
        private IEnumerator ThreadWorker ()
        {
            while (true) {
                while (!shouldDetectInMultiThread) {
                    yield return null;
                }

                Detect ();

                shouldDetectInMultiThread = false;
                didUpdateTheDetectionResult = true;
            }
        }
#endif


        private void Detect()
        {
            MatOfRect objects = new MatOfRect();
            if (cascade4Thread != null)
                cascade4Thread.detectMultiScale(grayMat4Thread, objects, 1.1, 2, Objdetect.CASCADE_SCALE_IMAGE, // TODO: objdetect.CV_HAAR_SCALE_IMAGE
                    new Size(grayMat4Thread.height() * 0.2, grayMat4Thread.height() * 0.2), new Size());

            //Thread.Sleep(200);

            detectionResult = objects;
        }


        /// <summary>
        /// Raises the destroy event.
        /// </summary>
        void OnDestroy()
        {
            webCamTextureToMatHelper.Dispose();

#if UNITY_WEBGL
            if (getFilePath_Coroutine != null) {
                StopCoroutine (getFilePath_Coroutine);
                ((IDisposable)getFilePath_Coroutine).Dispose ();
            }
#endif
        }

        /// <summary>
        /// Raises the back button click event.
        /// </summary>
        public void OnBackButtonClick()
        {
            SceneManager.LoadScene("OpenCVForUnityExample");
        }

        /// <summary>
        /// Raises the play button click event.
        /// </summary>
        public void OnPlayButtonClick()
        {
            webCamTextureToMatHelper.Play();
        }

        /// <summary>
        /// Raises the pause button click event.
        /// </summary>
        public void OnPauseButtonClick()
        {
            webCamTextureToMatHelper.Pause();
        }

        /// <summary>
        /// Raises the stop button click event.
        /// </summary>
        public void OnStopButtonClick()
        {
            webCamTextureToMatHelper.Stop();
        }

        /// <summary>
        /// Raises the change camera button click event.
        /// </summary>
        public void OnChangeCameraButtonClick()
        {
            webCamTextureToMatHelper.requestedIsFrontFacing = !webCamTextureToMatHelper.requestedIsFrontFacing;
        }

        //
        // tracker
        //
        private void GetObjects(List<Rect> result)
        {
            result.Clear();

            for (int i = 0; i < trackedObjects.Count; i++)
            {
                Rect r = CalcTrackedObjectPositionToShow(i);
                if (r.area() == 0)
                {
                    continue;
                }
                result.Add(r);
                //LOGD("DetectionBasedTracker::process: found a object with SIZE %d x %d, rect={%d, %d, %d x %d}", r.width, r.height, r.x, r.y, r.width, r.height);
            }
        }

        private enum TrackedState : int
        {
            NEW_RECTANGLE = -1,
            INTERSECTED_RECTANGLE = -2
        }

        private void UpdateTrackedObjects(List<Rect> detectedObjects)
        {
            int N1 = (int)trackedObjects.Count;
            int N2 = (int)detectedObjects.Count;

            for (int i = 0; i < N1; i++)
            {
                trackedObjects[i].numDetectedFrames++;
            }

            int[] correspondence = new int[N2];
            for (int i = 0; i < N2; i++)
            {
                correspondence[i] = (int)TrackedState.NEW_RECTANGLE;
            }


            for (int i = 0; i < N1; i++)
            {
                TrackedObject curObject = trackedObjects[i];

                int bestIndex = -1;
                int bestArea = -1;

                int numpositions = (int)curObject.lastPositions.Count;

                //if (numpositions > 0) UnityEngine.Debug.LogError("numpositions > 0 is false");

                Rect prevRect = curObject.lastPositions[numpositions - 1];

                for (int j = 0; j < N2; j++)
                {
                    if (correspondence[j] >= 0)
                    {
                        //Debug.Log("DetectionBasedTracker::updateTrackedObjects: j=" + i + " is rejected, because it has correspondence=" + correspondence[j]);
                        continue;
                    }
                    if (correspondence[j] != (int)TrackedState.NEW_RECTANGLE)
                    {
                        //Debug.Log("DetectionBasedTracker::updateTrackedObjects: j=" + j + " is rejected, because it is intersected with another rectangle");
                        continue;
                    }

                    Rect r = Rect.intersect(prevRect, detectedObjects[j]);
                    if (r != null && (r.width > 0) && (r.height > 0))
                    {
                        //LOGD("DetectionBasedTracker::updateTrackedObjects: There is intersection between prevRect and detectedRect, r={%d, %d, %d x %d}",
                        //        r.x, r.y, r.width, r.height);
                        correspondence[j] = (int)TrackedState.INTERSECTED_RECTANGLE;

                        if (r.area() > bestArea)
                        {
                            //LOGD("DetectionBasedTracker::updateTrackedObjects: The area of intersection is %d, it is better than bestArea=%d", r.area(), bestArea);
                            bestIndex = j;
                            bestArea = (int)r.area();
                        }
                    }
                }

                if (bestIndex >= 0)
                {
                    //LOGD("DetectionBasedTracker::updateTrackedObjects: The best correspondence for i=%d is j=%d", i, bestIndex);
                    correspondence[bestIndex] = i;

                    for (int j = 0; j < N2; j++)
                    {
                        if (correspondence[j] >= 0)
                            continue;

                        Rect r = Rect.intersect(detectedObjects[j], detectedObjects[bestIndex]);
                        if (r != null && (r.width > 0) && (r.height > 0))
                        {
                            //LOGD("DetectionBasedTracker::updateTrackedObjects: Found intersection between "
                            //    "rectangles j=%d and bestIndex=%d, rectangle j=%d is marked as intersected", j, bestIndex, j);
                            correspondence[j] = (int)TrackedState.INTERSECTED_RECTANGLE;
                        }
                    }
                }
                else
                {
                    //LOGD("DetectionBasedTracker::updateTrackedObjects: There is no correspondence for i=%d ", i);
                    curObject.numFramesNotDetected++;
                }
            }

            //LOGD("DetectionBasedTracker::updateTrackedObjects: start second cycle");
            for (int j = 0; j < N2; j++)
            {
                int i = correspondence[j];
                if (i >= 0)
                {//add position
                    //Debug.Log("DetectionBasedTracker::updateTrackedObjects: add position");
                    trackedObjects[i].lastPositions.Add(detectedObjects[j]);
                    while ((int)trackedObjects[i].lastPositions.Count > (int)innerParameters.numLastPositionsToTrack)
                    {
                        trackedObjects[i].lastPositions.Remove(trackedObjects[i].lastPositions[0]);
                    }
                    trackedObjects[i].numFramesNotDetected = 0;
                }
                else if (i == (int)TrackedState.NEW_RECTANGLE)
                { //new object
                    //Debug.Log("DetectionBasedTracker::updateTrackedObjects: new object");
                    trackedObjects.Add(new TrackedObject(detectedObjects[j]));
                }
                else
                {
                    //Debug.Log ("DetectionBasedTracker::updateTrackedObjects: was auxiliary intersection");
                }
            }

            int t = 0;
            TrackedObject it;
            while (t < trackedObjects.Count)
            {
                it = trackedObjects[t];

                if ((it.numFramesNotDetected > parameters.maxTrackLifetime)
                    ||
                    ((it.numDetectedFrames <= innerParameters.numStepsToWaitBeforeFirstShow)
                    &&
                    (it.numFramesNotDetected > innerParameters.numStepsToTrackWithoutDetectingIfObjectHasNotBeenShown)))
                {
                    //int numpos = (int)it.lastPositions.Count;
                    //if (numpos > 0) UnityEngine.Debug.LogError("numpos > 0 is false");
                    //Rect r = it.lastPositions [numpos - 1];
                    //Debug.Log("DetectionBasedTracker::updateTrackedObjects: deleted object " + r.x + " " + r.y + " " + r.width + " " + r.height);

                    trackedObjects.Remove(it);

                }
                else
                {
                    t++;
                }
            }
        }

        private Rect CalcTrackedObjectPositionToShow(int i)
        {
            if ((i < 0) || (i >= trackedObjects.Count))
            {
                Debug.Log("DetectionBasedTracker::calcTrackedObjectPositionToShow: ERROR: wrong i=" + i);
                return new Rect();
            }
            if (trackedObjects[i].numDetectedFrames <= innerParameters.numStepsToWaitBeforeFirstShow)
            {
                //Debug.Log("DetectionBasedTracker::calcTrackedObjectPositionToShow: " + "trackedObjects[" + i + "].numDetectedFrames=" + trackedObjects[i].numDetectedFrames + " <= numStepsToWaitBeforeFirstShow=" + innerParameters.numStepsToWaitBeforeFirstShow + " --- return empty Rect()");
                return new Rect();
            }
            if (trackedObjects[i].numFramesNotDetected > innerParameters.numStepsToShowWithoutDetecting)
            {
                return new Rect();
            }

            List<Rect> lastPositions = trackedObjects[i].lastPositions;

            int N = lastPositions.Count;
            if (N <= 0)
            {
                Debug.Log("DetectionBasedTracker::calcTrackedObjectPositionToShow: ERROR: no positions for i=" + i);
                return new Rect();
            }

            int Nsize = Math.Min(N, (int)weightsSizesSmoothing.Count);
            int Ncenter = Math.Min(N, (int)weightsPositionsSmoothing.Count);

            Point center = new Point();
            double w = 0, h = 0;
            if (Nsize > 0)
            {
                double sum = 0;
                for (int j = 0; j < Nsize; j++)
                {
                    int k = N - j - 1;
                    w += lastPositions[k].width * weightsSizesSmoothing[j];
                    h += lastPositions[k].height * weightsSizesSmoothing[j];
                    sum += weightsSizesSmoothing[j];
                }
                w /= sum;
                h /= sum;
            }
            else
            {
                w = lastPositions[N - 1].width;
                h = lastPositions[N - 1].height;
            }

            if (Ncenter > 0)
            {
                double sum = 0;
                for (int j = 0; j < Ncenter; j++)
                {
                    int k = N - j - 1;
                    Point tl = lastPositions[k].tl();
                    Point br = lastPositions[k].br();
                    Point c1;
                    //c1=tl;
                    //c1=c1* 0.5f;//
                    c1 = new Point(tl.x * 0.5f, tl.y * 0.5f);
                    Point c2;
                    //c2=br;
                    //c2=c2*0.5f;
                    c2 = new Point(br.x * 0.5f, br.y * 0.5f);
                    //c1=c1+c2;
                    c1 = new Point(c1.x + c2.x, c1.y + c2.y);

                    //center=center+  (c1  * weightsPositionsSmoothing[j]);
                    center = new Point(center.x + (c1.x * weightsPositionsSmoothing[j]), center.y + (c1.y * weightsPositionsSmoothing[j]));
                    sum += weightsPositionsSmoothing[j];
                }
                //center *= (float)(1 / sum);
                center = new Point(center.x * (1 / sum), center.y * (1 / sum));
            }
            else
            {
                int k = N - 1;
                Point tl = lastPositions[k].tl();
                Point br = lastPositions[k].br();
                Point c1;
                //c1=tl;
                //c1=c1* 0.5f;
                c1 = new Point(tl.x * 0.5f, tl.y * 0.5f);
                Point c2;
                //c2=br;
                //c2=c2*0.5f;
                c2 = new Point(br.x * 0.5f, br.y * 0.5f);

                //center=c1+c2;
                center = new Point(c1.x + c2.x, c1.y + c2.y);
            }
            //Point2f tl=center-(Point2f(w,h)*0.5);
            Point tl2 = new Point(center.x - (w * 0.5f), center.y - (h * 0.5f));
            //Rect res(cvRound(tl.x), cvRound(tl.y), cvRound(w), cvRound(h));
            Rect res = new Rect((int)Math.Round(tl2.x), (int)Math.Round(tl2.y), (int)Math.Round(w), (int)Math.Round(h));
            //LOGD("DetectionBasedTracker::calcTrackedObjectPositionToShow: Result for i=%d: {%d, %d, %d x %d}", i, res.x, res.y, res.width, res.height);

            return res;
        }

        private struct Parameters
        {
            //public int minObjectSize;
            //public int maxObjectSize;
            //public float scaleFactor;
            //public int minNeighbors;

            public int maxTrackLifetime;
            //public int minDetectionPeriod; //the minimal time between run of the big object detector (on the whole frame) in ms (1000 mean 1 sec), default=0
        };

        private struct InnerParameters
        {
            public int numLastPositionsToTrack;
            public int numStepsToWaitBeforeFirstShow;
            public int numStepsToTrackWithoutDetectingIfObjectHasNotBeenShown;
            public int numStepsToShowWithoutDetecting;
            public float coeffTrackingWindowSize;
            public float coeffObjectSizeToTrack;
            public float coeffObjectSpeedUsingInPrediction;
        };

        private class TrackedObject
        {
            public PositionsVector lastPositions;
            public int numDetectedFrames;
            public int numFramesNotDetected;
            public int id;
            static private int _id = 0;

            public TrackedObject(OpenCVForUnity.CoreModule.Rect rect)
            {
                lastPositions = new PositionsVector();

                numDetectedFrames = 1;
                numFramesNotDetected = 0;

                lastPositions.Add(rect.clone());

                _id = GetNextId();
                id = _id;
            }

            static int GetNextId()
            {
                _id++;
                return _id;
            }
        }
    }
}