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#include <precomp.hpp>

namespace {

struct Octave
{
    Octave(const int i, const cv::Size& origObjSize, const cv::FileNode& fn)
    : index(i), scale((float)fn[SC_OCT_SCALE]), stages((int)fn[SC_OCT_STAGES]),
      size(cvRound(origObjSize.width * scale), cvRound(origObjSize.height * scale)),
      shrinkage((int)fn[SC_OCT_SHRINKAGE]) {}

    int index;
    float scale;
    int stages;
    cv::Size size;
    int shrinkage;

    static const char *const SC_OCT_SCALE;
    static const char *const SC_OCT_STAGES;
    static const char *const SC_OCT_SHRINKAGE;
};


struct Weak
{
    Weak(){}
    Weak(const cv::FileNode& fn) : threshold((float)fn[SC_STAGE_THRESHOLD]){}

    float threshold;

    static const char *const SC_STAGE_THRESHOLD;
};


struct Node
{
    Node(){}
    Node(const int offset, cv::FileNodeIterator& fIt)
    : feature((int)(*(fIt +=2)++) + offset), threshold((float)(*(fIt++))){}

    int feature;
    float threshold;
};

struct Feature
{
    Feature() {}
    Feature(const cv::FileNode& fn) : channel((int)fn[SC_F_CHANNEL])
    {
        cv::FileNode rn = fn[SC_F_RECT];
        cv::FileNodeIterator r_it = rn.begin();

        int x = *r_it++;
        int y = *r_it++;
        int w = *r_it++;
        int h = *r_it++;
        rect = cv::Rect(x, y, w, h);

        // 1 / area
        rarea = 1.f / ((rect.width - rect.x) * (rect.height - rect.y));
    }

    int channel;
    cv::Rect rect;
    float rarea;

    static const char *const SC_F_CHANNEL;
    static const char *const SC_F_RECT;

};

const char *const Octave::SC_OCT_SCALE      = "scale";
const char *const Octave::SC_OCT_STAGES     = "stageNum";
const char *const Octave::SC_OCT_SHRINKAGE  = "shrinkingFactor";
const char *const Weak::SC_STAGE_THRESHOLD  = "stageThreshold";
const char *const Feature::SC_F_CHANNEL     = "channel";
const char *const Feature::SC_F_RECT        = "rect";

struct Level
{
    const Octave* octave;

    float origScale;
    float relScale;
    int scaleshift;

    cv::Size workRect;
    cv::Size objSize;

    float scaling[2]; // 0-th for channels <= 6, 1-st otherwise
    typedef cv::SCascade::Detection Detection;

    Level(const Octave& oct, const float scale, const int shrinkage, const int w, const int h)
    :  octave(&oct), origScale(scale), relScale(scale / oct.scale),
       workRect(cv::Size(cvRound(w / (float)shrinkage),cvRound(h / (float)shrinkage))),
       objSize(cv::Size(cvRound(oct.size.width * relScale), cvRound(oct.size.height * relScale)))
    {
        scaling[0] = ((relScale >= 1.f)? 1.f : (0.89f * pow(relScale, 1.099f / log(2.f)))) / (relScale * relScale);
        scaling[1] = 1.f;
        scaleshift = static_cast<int>(relScale * (1 << 16));
    }

    void addDetection(const int x, const int y, float confidence, std::vector<Detection>& detections) const
    {
        int shrinkage = (*octave).shrinkage;
        cv::Rect rect(cvRound(x * shrinkage), cvRound(y * shrinkage), objSize.width, objSize.height);

        detections.push_back(Detection(rect, confidence));
    }

    float rescale(cv::Rect& scaledRect, const float threshold, int idx) const
    {
#define SSHIFT(a) ((a) + (1 << 15)) >> 16
        // rescale
        scaledRect.x      = SSHIFT(scaleshift * scaledRect.x);
        scaledRect.y      = SSHIFT(scaleshift * scaledRect.y);
        scaledRect.width  = SSHIFT(scaleshift * scaledRect.width);
        scaledRect.height = SSHIFT(scaleshift * scaledRect.height);
#undef SSHIFT
        float sarea = static_cast<float>((scaledRect.width - scaledRect.x) * (scaledRect.height - scaledRect.y));

        // compensation areas rounding
        return (sarea == 0.0f)? threshold : (threshold * scaling[idx] * sarea);
    }
};

struct ChannelStorage
{
    std::vector<cv::Mat> hog;
    int shrinkage;
    int offset;
    int step;

    enum {HOG_BINS = 6, HOG_LUV_BINS = 10};

    ChannelStorage(const cv::Mat& colored, int shr) : shrinkage(shr)
    {
        hog.clear();
        hog.reserve(10);
        cv::SCascade::Channels ints(shr);

        // convert to grey
        cv::Mat grey;
        cv::cvtColor(colored, grey, CV_BGR2GRAY);

        ints.appendHogBins(grey, hog, 6);
        ints.appendLuvBins(colored, hog);

        step = hog[0].cols;
    }

    float get(const int channel, const cv::Rect& area) const
    {
        // CV_Assert(channel < HOG_LUV_BINS);
        const cv::Mat& m = hog[channel];
        int *ptr = ((int*)(m.data)) + offset;

        int a = ptr[area.y * step + area.x];
        int b = ptr[area.y * step + area.width];
        int c = ptr[area.height * step + area.width];
        int d = ptr[area.height * step + area.x];

        return static_cast<float>(a - b + c - d);
    }
};

}

struct cv::SCascade::Fields
{
    float minScale;
    float maxScale;
    int scales;

    int origObjWidth;
    int origObjHeight;

    int shrinkage;

    std::vector<Octave>  octaves;
    std::vector<Weak>    stages;
    std::vector<Node>    nodes;
    std::vector<float>   leaves;
    std::vector<Feature> features;

    std::vector<Level> levels;

    cv::Size frameSize;

    typedef std::vector<Octave>::iterator  octIt_t;

    void detectAt(const int dx, const int dy, const Level& level, const ChannelStorage& storage,
        std::vector<Detection>& detections) const
    {
        float detectionScore = 0.f;

        const Octave& octave = *(level.octave);
        int stBegin = octave.index * octave.stages, stEnd = stBegin + octave.stages;

        int st = stBegin;
        for(; st < stEnd; ++st)
        {
            const Weak& stage = stages[st];
            {
                int nId = st * 3;

                // work with root node
                const Node& node = nodes[nId];
                const Feature& feature = features[node.feature];
                cv::Rect scaledRect(feature.rect);

                float threshold = level.rescale(scaledRect, node.threshold,(int)(feature.channel > 6)) * feature.rarea;

                float sum = storage.get(feature.channel, scaledRect);

                int next = (sum >= threshold)? 2 : 1;

                // leaves
                const Node& leaf = nodes[nId + next];
                const Feature& fLeaf = features[leaf.feature];

                scaledRect = fLeaf.rect;
                threshold = level.rescale(scaledRect, leaf.threshold, (int)(fLeaf.channel > 6)) * fLeaf.rarea;

                sum = storage.get(fLeaf.channel, scaledRect);

                int lShift = (next - 1) * 2 + ((sum >= threshold) ? 1 : 0);
                float impact = leaves[(st * 4) + lShift];

                detectionScore += impact;
            }

            if (detectionScore <= stage.threshold) return;
        }

        if (detectionScore > 0)
            level.addDetection(dx, dy, detectionScore, detections);
    }

    octIt_t fitOctave(const float& logFactor)
    {
        float minAbsLog = FLT_MAX;
        octIt_t res =  octaves.begin();
        for (octIt_t oct = octaves.begin(); oct < octaves.end(); ++oct)
        {
            const Octave& octave =*oct;
            float logOctave = log(octave.scale);
            float logAbsScale = fabs(logFactor - logOctave);

            if(logAbsScale < minAbsLog)
            {
                res = oct;
                minAbsLog = logAbsScale;
            }
        }
        return res;
    }

    // compute levels of full pyramid
    void calcLevels(const cv::Size& curr, float mins, float maxs, int total)
    {
        if (frameSize == curr && maxs == maxScale && mins == minScale && total == scales) return;

        frameSize = curr;
        maxScale = maxs; minScale = mins; scales = total;
        CV_Assert(scales > 1);

        levels.clear();
        float logFactor = (log(maxScale) - log(minScale)) / (scales -1);

        float scale = minScale;
        for (int sc = 0; sc < scales; ++sc)
        {
            int width  = static_cast<int>(std::max(0.0f, frameSize.width  - (origObjWidth  * scale)));
            int height = static_cast<int>(std::max(0.0f, frameSize.height - (origObjHeight * scale)));

            float logScale = log(scale);
            octIt_t fit = fitOctave(logScale);


            Level level(*fit, scale, shrinkage, width, height);

            if (!width || !height)
                break;
            else
                levels.push_back(level);

            if (fabs(scale - maxScale) < FLT_EPSILON) break;
            scale = std::min(maxScale, expf(log(scale) + logFactor));
        }
    }

    bool fill(const FileNode &root)
    {
        // cascade properties
        static const char *const SC_STAGE_TYPE       = "stageType";
        static const char *const SC_BOOST            = "BOOST";

        static const char *const SC_FEATURE_TYPE     = "featureType";
        static const char *const SC_ICF              = "ICF";

        static const char *const SC_ORIG_W           = "width";
        static const char *const SC_ORIG_H           = "height";

        static const char *const SC_OCTAVES          = "octaves";
        static const char *const SC_STAGES           = "stages";
        static const char *const SC_FEATURES         = "features";

        static const char *const SC_WEEK             = "weakClassifiers";
        static const char *const SC_INTERNAL         = "internalNodes";
        static const char *const SC_LEAF             = "leafValues";


        // only Ada Boost supported
        std::string stageTypeStr = (string)root[SC_STAGE_TYPE];
        CV_Assert(stageTypeStr == SC_BOOST);

        // only HOG-like integral channel features cupported
        string featureTypeStr = (string)root[SC_FEATURE_TYPE];
        CV_Assert(featureTypeStr == SC_ICF);

        origObjWidth  = (int)root[SC_ORIG_W];
        origObjHeight = (int)root[SC_ORIG_H];

        // for each octave (~ one cascade in classic OpenCV xml)
        FileNode fn = root[SC_OCTAVES];
        if (fn.empty()) return false;

        // octaves.reserve(noctaves);
        FileNodeIterator it = fn.begin(), it_end = fn.end();
        int feature_offset = 0;
        int octIndex = 0;
        for (; it != it_end; ++it)
        {
            FileNode fns = *it;
            Octave octave(octIndex, cv::Size(origObjWidth, origObjHeight), fns);
            CV_Assert(octave.stages > 0);
            octaves.push_back(octave);

            FileNode ffs = fns[SC_FEATURES];
            if (ffs.empty()) return false;

            fns = fns[SC_STAGES];
            if (fn.empty()) return false;

            // for each stage (~ decision tree with H = 2)
            FileNodeIterator st = fns.begin(), st_end = fns.end();
            for (; st != st_end; ++st )
            {
                fns = *st;
                stages.push_back(Weak(fns));

                fns = fns[SC_WEEK];
                FileNodeIterator ftr = fns.begin(), ft_end = fns.end();
                for (; ftr != ft_end; ++ftr)
                {
                    fns = (*ftr)[SC_INTERNAL];
                    FileNodeIterator inIt = fns.begin(), inIt_end = fns.end();
                    for (; inIt != inIt_end;)
                        nodes.push_back(Node(feature_offset, inIt));

                    fns = (*ftr)[SC_LEAF];
                    inIt = fns.begin(), inIt_end = fns.end();
                    for (; inIt != inIt_end; ++inIt)
                        leaves.push_back((float)(*inIt));
                }
            }

            st = ffs.begin(), st_end = ffs.end();
            for (; st != st_end; ++st )
                features.push_back(Feature(*st));

            feature_offset += octave.stages * 3;
            ++octIndex;
        }

        shrinkage = octaves[0].shrinkage;
        return true;
    }
};

cv::SCascade::SCascade(const double mins, const double maxs, const int nsc, const int rej)
: fields(0), minScale(mins), maxScale(maxs), scales(nsc), rejCriteria(rej) {}

cv::SCascade::~SCascade() { delete fields;}

void cv::SCascade::read(const FileNode& fn)
{
    Algorithm::read(fn);
}

bool cv::SCascade::load(const FileNode& fn)
{
    if (fields) delete fields;

    fields = new Fields;
    return fields->fill(fn);
}

namespace {
typedef cv::SCascade::Detection Detection;
typedef std::vector<Detection>  dvector;


struct ConfidenceGt
{
    bool operator()(const Detection& a, const Detection& b) const
    {
        return a.confidence > b.confidence;
    }
};

static float overlap(const cv::Rect &a, const cv::Rect &b)
{
    int w = std::min(a.x + a.width,  b.x + b.width)  - std::max(a.x, b.x);
    int h = std::min(a.y + a.height, b.y + b.height) - std::max(a.y, b.y);

    return (w < 0 || h < 0)? 0.f : (float)(w * h);
}

void DollarNMS(dvector& objects)
{
    static const float DollarThreshold = 0.65f;
    std::sort(objects.begin(), objects.end(), ConfidenceGt());

    for (dvector::iterator dIt = objects.begin(); dIt != objects.end(); ++dIt)
    {
        const Detection &a = *dIt;
        for (dvector::iterator next = dIt + 1; next != objects.end(); )
        {
            const Detection &b = *next;

            const float ovl =  overlap(a.bb, b.bb) / std::min(a.bb.area(), b.bb.area());

            if (ovl > DollarThreshold)
                next = objects.erase(next);
            else
                ++next;
        }
    }
}

static void suppress(int type, std::vector<Detection>& objects)
{
    CV_Assert(type == cv::SCascade::DOLLAR);
    DollarNMS(objects);
}

}

void cv::SCascade::detectNoRoi(const cv::Mat& image, std::vector<Detection>& objects) const
{
    Fields& fld = *fields;
    // create integrals
    ChannelStorage storage(image, fld.shrinkage);

    typedef std::vector<Level>::const_iterator lIt;
    for (lIt it = fld.levels.begin(); it != fld.levels.end(); ++it)
    {
        const Level& level = *it;

        for (int dy = 0; dy < level.workRect.height; ++dy)
        {
            for (int dx = 0; dx < level.workRect.width; ++dx)
            {
                storage.offset = dy * storage.step + dx;
                fld.detectAt(dx, dy, level, storage, objects);
            }
        }
    }

    if (rejCriteria != NO_REJECT) suppress(rejCriteria, objects);
}

void cv::SCascade::detect(cv::InputArray _image, cv::InputArray _rois, std::vector<Detection>& objects) const
{
    // only color images are supperted
    cv::Mat image = _image.getMat();
    CV_Assert(image.type() == CV_8UC3);

    Fields& fld = *fields;
    fld.calcLevels(image.size(),(float) minScale, (float)maxScale, scales);

    objects.clear();

    if (_rois.kind() == cv::_InputArray::NONE)
        return detectNoRoi(image, objects);

    int shr = fld.shrinkage;

    cv::Mat roi = _rois.getMat();
    cv::Mat mask(image.rows / shr, image.cols / shr, CV_8UC1);

    mask.setTo(cv::Scalar::all(0));
    cv::Rect* r = roi.ptr<cv::Rect>(0);
    for (int i = 0; i < (int)roi.cols; ++i)
        cv::Mat(mask, cv::Rect(r[i].x / shr, r[i].y / shr, r[i].width / shr , r[i].height / shr)).setTo(cv::Scalar::all(1));

    // create integrals
    ChannelStorage storage(image, shr);

    typedef std::vector<Level>::const_iterator lIt;
    for (lIt it = fld.levels.begin(); it != fld.levels.end(); ++it)
    {
         const Level& level = *it;

         for (int dy = 0; dy < level.workRect.height; ++dy)
         {
             uchar* m  = mask.ptr<uchar>(dy);
             for (int dx = 0; dx < level.workRect.width; ++dx)
             {
                 if (m[dx])
                 {
                     storage.offset = dy * storage.step + dx;
                     fld.detectAt(dx, dy, level, storage, objects);
                 }
             }
         }
    }

    if (rejCriteria != NO_REJECT) suppress(rejCriteria, objects);
}

void cv::SCascade::detect(InputArray _image, InputArray _rois,  OutputArray _rects, OutputArray _confs) const
{
    std::vector<Detection> objects;
    detect( _image, _rois, objects);

    _rects.create(1, objects.size(), CV_32SC4);
    cv::Mat_<cv::Rect> rects = (cv::Mat_<cv::Rect>)_rects.getMat();
    cv::Rect* rectPtr = rects.ptr<cv::Rect>(0);

    _confs.create(1, objects.size(), CV_32F);
    cv::Mat confs = _confs.getMat();
    float* confPtr = rects.ptr<float>(0);

    typedef std::vector<Detection>::const_iterator IDet;

    int i = 0;
    for (IDet it = objects.begin(); it != objects.end(); ++it, ++i)
    {
        rectPtr[i] = (*it).bb;
        confPtr[i] = (*it).confidence;
    }
}