#include <opencv2/opencv.hpp>
#include <iostream>
#include <cstdint>
#include <cstdlib>
#include <boost/chrono.hpp>

using namespace std;

int main(int argc, char **argv) {
	if(argc<3) {
		cout<<"Usage: ./as5 input.png output.png"<<endl;
		return -1;
	}
	//cout<<argv[0]<<endl;
	//cout<<argv[1]<<endl;
	//cout<<argv[2]<<endl;
	cv::Mat image = cv::imread(argv[1],cv::IMREAD_COLOR);
	if(image.empty()) {
		cout<<"Could not load image "<<endl;
		return -2;
	}
	int rows=image.rows;
	int cols=image.cols;
	int channels=3;

	//allocate ***ptr
	uint8_t ***arr=new uint8_t **[rows];
	for(int i=0;i<rows;i++) {
		arr[i]=new uint8_t *[cols];
		for(int j=0;j<cols;j++) {
			arr[i][j]=new uint8_t [channels];
		}
	}
	for(int i=0;i<rows;i++) {
		for(int j=0;j<cols;j++) {
			cv::Vec3b pixel=image.at<cv::Vec3b>(i,j);
			for(int k=0;k<3;k++) {
				arr[i][j][k]=pixel[k];
			}
		}
	}

	for(int i=0;i<rows;i++) {
		for(int j=0;j<cols;j++) {
			uint8_t B=arr[i][j][0];
			uint8_t G=arr[i][j][1];
			uint8_t R=arr[i][j][2];
			uint8_t gray=0.299*R+0.587*G+0.114*B;
			arr[i][j][0]=gray;
			arr[i][j][1]=gray;
			arr[i][j][2]=gray;
		}
	}
	//copy back
	for(int i=0;i<rows;i++) {
		for(int j=0;j<cols;j++) {
			image.at<cv::Vec3b>(i,j)[0]=arr[i][j][0];
			image.at<cv::Vec3b>(i,j)[1]=arr[i][j][1];
			image.at<cv::Vec3b>(i,j)[2]=arr[i][j][2];
		}
	}
	cv::imwrite(argv[2],image);
	return 0;
}