#include "opencv2/core/utility.hpp"
#include "opencv2/video/tracking.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"

#include <iostream>
#include <cctype>

static cv::Mat image;
static bool backprojMode = false;
static bool selectObject = false;
static int trackObject = 0;
static bool showHist = true;
static cv::Point origin;
static cv::Rect selection;
static int vmin = 10, vmax = 256, smin = 30;

static void onMouse(int event, int x, int y, int, void*)
{
    if (selectObject)
    {
        selection.x = std::min(x, origin.x);
        selection.y = std::min(y, origin.y);
        selection.width = std::abs(x - origin.x);
        selection.height = std::abs(y - origin.y);

        selection &= cv::Rect(0, 0, image.cols, image.rows);
    }

    switch(event)
    {
    case cv::EVENT_LBUTTONDOWN:
        origin = cv::Point(x, y);
        selection = cv::Rect(x, y, 0, 0);
        selectObject = true;
        break;
    case cv::EVENT_LBUTTONUP:
        selectObject = false;
        if (selection.width > 0 && selection.height > 0)
            trackObject = -1;
        break;
    default:
        break;
    }
}

static void help()
{
    std::cout << "\nThis is a demo that shows mean-shift based tracking using Transparent API\n"
            "You select a color objects such as your face and it tracks it.\n"
            "This reads from video camera (0 by default, or the camera number the user enters\n"
            "Usage: \n"
            "   ./camshiftdemo [camera number]\n";

    std::cout << "\n\nHot keys: \n"
            "\tESC - quit the program\n"
            "\tc - stop the tracking\n"
            "\tb - switch to/from backprojection view\n"
            "\th - show/hide object histogram\n"
            "\tp - pause video\n"
            "To initialize tracking, select the object with mouse\n";
}

int main(int argc, const char** argv)
{
    help();

    cv::VideoCapture cap;
    cv::Rect trackWindow;
    int hsize = 16;
    float hranges[2] = { 0, 180 };
    const float * phranges = hranges;

    const char * const keys = { "{@camera_number| 0 | camera number}" };
    cv::CommandLineParser parser(argc, argv, keys);
    int camNum = parser.get<int>(0);

    cap.open(camNum);

    if (!cap.isOpened())
    {
        help();
        std::cout << "***Could not initialize capturing...***\n";
        std::cout << "Current parameter's value: \n";
        parser.printMessage();

        return EXIT_FAILURE;
    }

    cv::namedWindow("Histogram", cv::WINDOW_NORMAL);
    cv::namedWindow("CamShift Demo", cv::WINDOW_NORMAL);
    cv::setMouseCallback("CamShift Demo", onMouse, NULL);
    cv::createTrackbar("Vmin", "CamShift Demo", &vmin, 256, NULL);
    cv::createTrackbar("Vmax", "CamShift Demo", &vmax, 256, NULL);
    cv::createTrackbar("Smin", "CamShift Demo", &smin, 256, NULL);

    cv::Mat frame, hsv, hue, mask, hist, histimg = cv::Mat::zeros(200, 320, CV_8UC3), backproj;
    bool paused = false;

    for ( ; ; )
    {
        if (!paused)
        {
            cap >> frame;
            if (frame.empty())
                break;
        }

        frame.copyTo(image);

        if (!paused)
        {
            cv::cvtColor(image, hsv, cv::COLOR_BGR2HSV);

            if (trackObject)
            {
                int _vmin = vmin, _vmax = vmax;

                cv::inRange(hsv, cv::Scalar(0, smin, std::min(_vmin, _vmax)),
                        cv::Scalar(180, 256, std::max(_vmin, _vmax)), mask);

                int ch[2] = { 0, 0 };
                hue.create(hsv.size(), hsv.depth());
                cv::mixChannels(&hsv, 1, &hue, 1, ch, 1);

                if (trackObject < 0)
                {
                    cv::Mat roi(hue, selection), maskroi(mask, selection);
                    cv::calcHist(&roi, 1, 0, maskroi, hist, 1, &hsize, &phranges);
                    cv::normalize(hist, hist, 0, 255, cv::NORM_MINMAX);

                    trackWindow = selection;
                    trackObject = 1;

                    histimg = cv::Scalar::all(0);
                    int binW = histimg.cols / hsize;
                    cv::Mat buf (1, hsize, CV_8UC3);
                    for (int i = 0; i < hsize; i++)
                        buf.at<cv::Vec3b>(i) = cv::Vec3b(cv::saturate_cast<uchar>(i*180./hsize), 255, 255);
                    cv::cvtColor(buf, buf, cv::COLOR_HSV2BGR);

                    for (int i = 0; i < hsize; i++)
                    {
                        int val = cv::saturate_cast<int>(hist.at<float>(i)*histimg.rows/255);
                        cv::rectangle(histimg, cv::Point(i*binW, histimg.rows),
                                   cv::Point((i+1)*binW, histimg.rows - val),
                                   cv::Scalar(buf.at<cv::Vec3b>(i)), -1, 8);
                    }
                }

                cv::calcBackProject(&hue, 1, 0, hist, backproj, &phranges);
                backproj &= mask;
                cv::RotatedRect trackBox = cv::CamShift(backproj, trackWindow,
                                    cv::TermCriteria(cv::TermCriteria::EPS | cv::TermCriteria::COUNT, 10, 1));
                if (trackWindow.area() <= 1)
                {
                    int cols = backproj.cols, rows = backproj.rows, r = (std::min(cols, rows) + 5)/6;
                    trackWindow = cv::Rect(trackWindow.x - r, trackWindow.y - r,
                                       trackWindow.x + r, trackWindow.y + r) &
                                  cv::Rect(0, 0, cols, rows);
                }

                if (backprojMode)
                    cv::cvtColor(backproj, image, cv::COLOR_GRAY2BGR);
                cv::ellipse(image, trackBox, cv::Scalar(0, 0, 255), 3, cv::LINE_AA);
            }
        }
        else if (trackObject < 0)
            paused = false;

        if (selectObject && selection.width > 0 && selection.height > 0)
        {
            cv::Mat roi(image, selection);
            cv::bitwise_not(roi, roi);
        }

        cv::imshow("CamShift Demo", image);
        cv::imshow("Histogram", histimg);

        char c = (char)cv::waitKey(10);
        if (c == 27)
            break;

        switch(c)
        {
        case 'b':
            backprojMode = !backprojMode;
            break;
        case 'c':
            trackObject = 0;
            histimg = cv::Scalar::all(0);
            break;
        case 'h':
            showHist = !showHist;
            if (!showHist)
                cv::destroyWindow("Histogram");
            else
                cv::namedWindow("Histogram", cv::WINDOW_AUTOSIZE);
            break;
        case 'p':
            paused = !paused;
            break;
        default:
            break;
        }
    }

    return EXIT_SUCCESS;
}