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#include "precomp.hpp"

namespace {

class ICF : public cv::ChannelFeatureBuilder
{
    virtual ~ICF() {}
    virtual cv::AlgorithmInfo* info() const;
    virtual void operator()(cv::InputArray _frame, CV_OUT cv::OutputArray _integrals) const
    {
        CV_Assert(_frame.type() == CV_8UC3);

        cv::Mat frame      = _frame.getMat();
        int h = frame.rows;
        int w = frame.cols;
        _integrals.create(h / 4 * 10 + 1, w / 4 + 1, CV_32SC1);
        cv::Mat& integrals = _integrals.getMatRef();

        cv::Mat channels, gray;

        channels.create(h * 10, w, CV_8UC1);
        channels.setTo(0);

        cvtColor(frame, gray, CV_BGR2GRAY);

        cv::Mat df_dx, df_dy, mag, angle;
        cv::Sobel(gray, df_dx, CV_32F, 1, 0);
        cv::Sobel(gray, df_dy, CV_32F, 0, 1);

        cv::cartToPolar(df_dx, df_dy, mag, angle, true);
        mag *= (1.f / (8 * sqrt(2.f)));

        cv::Mat nmag;
        mag.convertTo(nmag, CV_8UC1);

        angle *=  6 / 360.f;

        for (int y = 0; y < h; ++y)
        {
            uchar* magnitude = nmag.ptr<uchar>(y);
            float* ang = angle.ptr<float>(y);

            for (int x = 0; x < w; ++x)
            {
                channels.ptr<uchar>(y + (h * (int)ang[x]))[x] = magnitude[x];
            }
        }

        cv::Mat luv, shrunk;
        cv::cvtColor(frame, luv, CV_BGR2Luv);

        std::vector<cv::Mat> splited;
        for (int i = 0; i < 3; ++i)
            splited.push_back(channels(cv::Rect(0, h * (7 + i), w, h)));
        split(luv, splited);

        float shrinkage = static_cast<float>(integrals.cols - 1) / channels.cols;

        CV_Assert(shrinkage == 0.25);

        cv::resize(channels, shrunk, cv::Size(), shrinkage, shrinkage, CV_INTER_AREA);
        cv::integral(shrunk, integrals, cv::noArray(), CV_32S);
    }
};

}

CV_INIT_ALGORITHM(ICF, "ChannelFeatureBuilder.ICF", );

cv::ChannelFeatureBuilder::~ChannelFeatureBuilder() {}

cv::Ptr<cv::ChannelFeatureBuilder> cv::ChannelFeatureBuilder::create()
{
    cv::Ptr<cv::ChannelFeatureBuilder> builder(new ICF());
    return builder;
}