#include <iostream>
#include <opencv2/opencv.hpp>
#include <cstdint>
#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];
		}
	}
	//EOF ALLOC	
	//copy image to this 3D tensor
	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];
			}
		}
	}	
	//Transformation
	
	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][0];
			uint8_t R=arr[i][j][0];
			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;
}