#include "opencv2/opencv.hpp"
#include "opencv2/videoio.hpp"
#include "opencv2/highgui.hpp"

const int FPS = 30;


bool isDiscardData = true;
int countDiscard = 0;
const int DISCARD_DURATION = 10;

int main() {
  cv::VideoCapture cap;
  cap.open(0);
  cv::CascadeClassifier faceDetector;
  if( !faceDetector.load("./haarcascade_frontalface_alt.xml"))
  {
  std::cerr << "[ERROR] Unable to load face cascade" << std::endl;
  return -1;
  };
  cv::Rect foreheadROI;
  if (!cap.isOpened()) {
    std::cerr << "[ERROR] Unable to open camera!" << std::endl;
    return -2;
  }

  while (true) {
    if(isDiscardData){
       countDiscard++;
       if(countDiscard == DISCARD_DURATION*FPS)
           isDiscardData = false;
       }
    else{
       cv::Mat frame;
       cap.read(frame);
       if (frame.empty()) {
          std::cerr << "[ERROR] blank frame grabbed" << std::endl;
          break;
       }
       std::vector<cv::Rect> faceRectangles;
       faceDetector.detectMultiScale(frame, faceRectangles, 1.1, 3, 0,cv::Size(20, 20));
       foreheadROI = faceRectangles[0];
       foreheadROI.height *= 0.3;
       cv::rectangle(frame, faceRectangles[0], cv::Scalar(0, 0, 255), 1, 1, 0);
       cv::rectangle(frame, foreheadROI, cv::Scalar(0, 255, 0), 1, 1, 0);       
       cv::imshow("Color", frame);
       if (cv::waitKey(1000.0 / FPS) >= 0)
           break;
       }
    }
    return 0;
}