#include <opencv2/core/core.hpp> 
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/opencv.hpp>
#include <iostream>

using namespace cv;
  
  
int main() {
  char* file = "sample-sudoku-input.jpg";
  Mat colorImg = imread(file, IMREAD_COLOR);

  if (!colorImg.data) {
    std::cout << "Could not open/find image." << std::endl;
    return -1;
  }
  
  Mat grayImg, bwImg, processedImg;
  cvtColor(colorImg, grayImg, COLOR_BGR2GRAY);
  threshold(grayImg, bwImg, 100, 255, 1);

  Mat element = getStructuringElement(MORPH_CROSS, Size(3,3), Point(1,1));
  dilate(bwImg, processedImg, element);
  erode(processedImg, processedImg, element);

  Size sizeImg = processedImg.size(); 
  int iRow, iCol, pixels;
  int horizontalLines[100];
  int iHorizontal = 0;
  int verticalLines[100];
  int iVertical = 0;
  
  // Find Horizontal Rows
  for (iRow = 0; iRow < (int) sizeImg.height; iRow++) {
    pixels = 0;
    for (iCol = 0; iCol < (int) sizeImg.width; iCol++) {
      if (processedImg.at<char>(iRow, iCol) == -1) {
        pixels++;
      }
    }  
    if (pixels > (.5 * sizeImg.width)) {
      horizontalLines[iHorizontal++] = iRow;
    }
  }
  
  // Find Vertical Rows
  for (iCol = 0; iCol < (int) sizeImg.width; iCol++) {
    pixels = 0;
    for (iRow = 0; iRow < (int) sizeImg.height; iRow++) {
      if (processedImg.at<char>(iRow, iCol) == -1) {
        pixels++;
      }
    }  
    if (pixels > (.5 * sizeImg.height)) {
      verticalLines[iVertical++] = iCol;
    }
  }
  
  Mat linesImg, numberImg;
  linesImg = Mat::zeros(sizeImg, processedImg.type());
  numberImg = Mat::zeros(sizeImg, processedImg.type());

  // Copy Horizontal Rows
  for (iRow = 0; iRow < iHorizontal; iRow++) {
    int row = horizontalLines[iRow];
    for (iCol = 0; iCol < (int) sizeImg.width; iCol++) {
      linesImg.at<char>(row, iCol) =  processedImg.at<char>(row, iCol);
    }  
  }
 
  // Copy Vertical Lines
  for (iCol = 0; iCol < iVertical; iCol++) {
    int col = verticalLines[iCol];
    for (iRow = 0; iRow < (int) sizeImg.height; iRow++) {
      linesImg.at<char>(iRow, col) = processedImg.at<char>(iRow, col);
    }
  }
  
  // Get Number Image
  numberImg = processedImg - linesImg;
  
  namedWindow("Gray", WINDOW_AUTOSIZE);
  imshow("Gray", grayImg);
  waitKey(0);
  namedWindow("BW", WINDOW_AUTOSIZE);
  imshow("BW", bwImg);
  waitKey(0);
  namedWindow("Processed", WINDOW_AUTOSIZE);
  imshow("Processed", processedImg); 
  waitKey(0);
  namedWindow("Lines", WINDOW_AUTOSIZE);
  imshow("Lines", linesImg);  
  waitKey(0);
  namedWindow("Numbers", WINDOW_AUTOSIZE);
  imshow("Numbers", numberImg); 
  waitKey(0);
  
  // Remove Noise
  erode(numberImg, numberImg, element);
  dilate(numberImg, numberImg, element);
  
  namedWindow("Processed Numbers", WINDOW_AUTOSIZE);
  imshow("Processd Numbers", numberImg); 
  
  waitKey(0);
  
  destroyWindow("Gray");
  destroyWindow("BW");
  destroyWindow("Processed");
  destroyWindow("Lines");
  destroyWindow("Numbers"); 
  destroyWindow("Processed Numbers");
}