#include <opencv2/imgproc/types_c.h>
#include <iostream>
#include "SG_labelling.h"

using namespace std;
//using namespace cv;

/// <summary>
/// 两步法标注
/// </summary>
/// <param name="bwImg"> 目标点为“1”， 空白点为“0”</param>
/// <param name="labImg"> 标注结果。每个点为rgnID, ID从2开始 </param>
/// <param name="labelRgns"></param>
void SG_TwoPassLabel(const cv::Mat& bwImg, cv::Mat& labImg, std::vector<SSG_Region>& labelRgns)
{
    assert(bwImg.type() == CV_8UC1);
    bwImg.convertTo(labImg, CV_32SC1);
    int rows = bwImg.rows - 1;
    int cols = bwImg.cols - 1;

    //二值图像像素值为0或1，为了不冲突，label从2开始
    int label = 2;
    std::vector<int> labelSet;
    labelSet.push_back(0);
    labelSet.push_back(1);

    //第一次扫描
    int* data_prev = (int*)labImg.data;
    int* data_cur = (int*)(labImg.data + labImg.step);
    int left, up;//指针指向的像素点的左方点和上方点
    int neighborLabels[2];
    for (int i = 1; i < rows; i++)// 忽略第一行和第一列,其实可以将labImg的宽高加1，然后在初始化为0就可以了
    {
        data_cur++;
        data_prev++;
        for (int j = 1; j < cols; j++, data_cur++, data_prev++)
        {
            if (*data_cur != 1)//当前点不为1，扫描下一个点
                continue;
            left = *(data_cur - 1);
            up = *data_prev;

            int count = 0;
            for (int curLabel : {left, up})
            {
                if (curLabel > 1)
                    neighborLabels[count++] = curLabel;
            }
            if (!count)//赋予一个新的label
            {
                labelSet.push_back(label);
                *data_cur = label;
                label++;
                continue;
            }
            //将当前点标记设为左点和上点label的最小值
            int smallestLabel = neighborLabels[0];
            if (count == 2 && neighborLabels[1] < smallestLabel)
                smallestLabel = neighborLabels[1];
            *data_cur = smallestLabel;
            //设置等价表，这里可能有点难理解
            //左点有可能比上点小，也有可能比上点大，两种情况都要考虑,例如
            //0 0 1 0 1 0       x x 2 x 3 x
            //1 1 1 1 1 1  ->   4 4 2 2 2 2
            //要将labelSet中3的位置设置为2
            for (int k = 0; k < count; k++)
            {
                int neiLabel = neighborLabels[k];
                int oldSmallestLabel = labelSet[neiLabel];
                if (oldSmallestLabel > smallestLabel)
                {
                    labelSet[oldSmallestLabel] = smallestLabel;
                }
                else if (oldSmallestLabel < smallestLabel)
                    labelSet[smallestLabel] = oldSmallestLabel;
            }
        }
        data_cur++;
        data_prev++;
    }
    //上面一步中,有的labelSet的位置还未设为最小值，例如
    //0 0 1 0 1      x x 2 x 3
    //0 1 1 1 1  ->  x 4 2 2 2
    //1 1 1 0 1      5 4 2 x 2
    //上面这波操作中，把labelSet[4]设为2，但labelSet[5]仍为4
    //这里可以将labelSet[5]设为2
    for (size_t i = 2; i < labelSet.size(); i++)
    {
        int curLabel = labelSet[i];
        int prelabel = labelSet[curLabel];
        while (prelabel != curLabel)
        {
            curLabel = prelabel;
            prelabel = labelSet[prelabel];
        }
        labelSet[i] = curLabel;
    }
    //第二次扫描，用labelSet进行更新，最后一列
    std::vector<SSG_Region*> labelInfo;
    labelInfo.resize(labelSet.size(), nullptr);

    data_cur = (int*)labImg.data;
    for (int i = 0; i < labImg.rows; i++)
    {
        for (int j = 0; j < labImg.cols; j++)
        {
            *data_cur = labelSet[*data_cur];
            if (*data_cur > 1) //有效label
            {
                //统计Region信息
                SSG_Region* info_cur = (SSG_Region*)labelInfo[*data_cur];
                if (nullptr == info_cur)
                {
                    SSG_Region new_rgn = { {j,j,i,i}, 1, *data_cur };
                    labelRgns.push_back(new_rgn); //push_back()后，vector中内存单元可能会被改动
                    for (int m = 0; m < labelRgns.size(); m++)  
                    {
                        info_cur = &labelRgns[m];
                        labelInfo[info_cur->labelID] = info_cur;
                    }
                }
                else
                {
                    assert(*data_cur == info_cur->labelID);
                    if (info_cur->roi.left > j)
                        info_cur->roi.left = j;
                    if (info_cur->roi.right < j)
                        info_cur->roi.right = j;
                    if (info_cur->roi.top > i)
                        info_cur->roi.top = i;
                    if (info_cur->roi.bottom < i)
                        info_cur->roi.bottom = i;
                    info_cur->ptCounter++;
                }
            }
            data_cur++;
        }
    }

    return;
}