#include <opencv2/objdetect.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include "opencv2/opencv.hpp"
#include <iostream>
using namespace std;
using namespace cv;

// this is a note for myself
//https://www.youtube.com/watch?v=M-VHaLHC4XI

//Utility function to display the box around the detected QR Code
void display(Mat& im, Mat& bbox)
{
	int n = bbox.rows;
	for (int i = 0; i < n; i++)
	{
		line(im, Point2i(bbox.at<float>(i, 0), bbox.at<float>(i, 1)), Point2i(bbox.at<float>((i + 1) % n, 0), bbox.at<float>((i + 1) % n, 1)), Scalar(255, 0, 0), 3);
	}
	//imshow("Result", im);
}

int main(int argc, char* argv[])
{
	VideoCapture cap(0);

	cap.set(CAP_PROP_BUFFERSIZE, 3);

	if (!cap.isOpened()) {
		cout << "Error opening video stream" << endl;
		return -1;
	}

	while (1) {

		Mat frame;
		cap >> frame;

		if (frame.empty())
			break;

		QRCodeDetector qrDecoder = QRCodeDetector::QRCodeDetector();

		Mat bbox, rectifiedVideo;

		//this line here seems to cause the video lag
		std::string data = qrDecoder.detectAndDecode(frame, bbox, rectifiedVideo);

		if (data.length() > 0)
		{
			cout << "Decoded Data : " << data << endl;
		}
		else
			cout << "QR Code not detected" << endl;


		display(frame, bbox);
		frame.convertTo(frame, CV_8UC3);
		imshow("realtime", frame);

		char c = (char)waitKey(1);
		if( c == 27 )
		break;
	}
	cap.release();
	destroyAllWindows();
	return 0;
}