#include <iostream>
#include <filesystem>
#include <algorithm>
#include <opencv2/highgui.hpp>

static constexpr char OUTPUT_DIR[] = "./out";

static bool extensionMatches(const std::filesystem::path& path)
{
	std::string extension = path.extension();
	if(extension == ".png")
		return true;
	if(extension == ".PNG")
		return true;
	if(extension == ".jpg")
		return true;
	if(extension == ".JPG")
		return true;
	if(extension == ".jpeg")
		return true;
	return false;
}

int main(int argc, char** argv)
{
	if(argc < 2)
	{
		std::cout<<"a directory must be specified\n";
		return 1;
	}

	std::cout<<"Using folder "<<argv[1]<<'\n';

	std::vector<std::filesystem::path> images;
	const std::filesystem::path directoryPath{argv[1]};
	for(const std::filesystem::directory_entry& dirent : std::filesystem::directory_iterator{directoryPath})
	{
		std::string fileName = dirent.path().filename();
		if(dirent.is_regular_file() && extensionMatches(dirent.path()))
		{
			std::cout<<"Found: "<<dirent.path().filename()<<'\n';
			images.push_back(dirent.path());
		}
	}

	if(images.empty())
	{
		std::cout<<"No images found\n";
		return 1;
	}

	std::random_shuffle(images.begin(), images.end());

	for(const std::filesystem::path& path : images)
		std::cout<<"Found: "<<path.filename()<<'\n';

	std::filesystem::path outDirPath(OUTPUT_DIR);
	if(!std::filesystem::is_directory(outDirPath) && !std::filesystem::create_directory(outDirPath))
	{
		std::cout<<"Could not create or read "<<OUTPUT_DIR<<'\n';
		return 1;
	}

	cv::namedWindow("Viewer", cv::WINDOW_NORMAL);
	cv::setWindowTitle("Viewer", "Choose");

	std::vector<std::vector<std::filesystem::path>> rounds;

	while(images.size() > 1)
	{
		std::cout<<"New round "<<images.size()<<" images remaining\n";
		rounds.push_back(std::vector<std::filesystem::path>());
		std::vector<size_t> removeIndexies;
		for(size_t i = 0; i < images.size()-1; i+=2)
		{
			cv::Mat imageA = cv::imread(images[i]);
			cv::Mat imageB = cv::imread(images[i+1]);

			if(!imageA.data || !imageB.data)
			{
				std::cout<<"Images: "<<images[i]<<' '<<images[i+1]<<" failed to read";
				return 1;
			}
			cv::Size2i outSize(imageA.cols+imageB.cols, std::max(imageA.rows, imageB.rows));
			cv::Mat image = cv::Mat::zeros(outSize, imageA.type());

			cv::Rect roiA(cv::Point(0, 0), imageA.size());
			cv::Rect roiB(cv::Point(imageA.cols, 0), imageB.size());
			imageA.copyTo(image(roiA));
			imageB.copyTo(image(roiB));

			cv::imshow("Viewer", image);
			while(true)
			{
				int keycode = cv::waitKey(0);
				if(keycode == 49)
				{
					removeIndexies.push_back(i+1);
					break;
				}
				else if(keycode == 50)
				{
					removeIndexies.push_back(i);
					break;
				}
				else if(keycode == 51)
				{
					removeIndexies.push_back(i);
					removeIndexies.push_back(i+1);
					break;
				}
				else if(keycode == 52)
				{
					break;
				}
			}
		}
		for(ssize_t i = removeIndexies.size()-1; i >= 0; --i)
		{
			rounds.back().push_back(images[removeIndexies[i]]);
			images.erase(images.begin()+removeIndexies[i]);
		}
	}


	for(size_t round = 0; round < rounds.size(); ++round)
	{
		std::string roundDirName = std::string("round_") + std::to_string(round);
		if(!std::filesystem::is_directory(outDirPath/roundDirName) && !std::filesystem::create_directory(outDirPath/roundDirName))
		{
			std::cout<<"Could not create or read "<<outDirPath/roundDirName<<'\n';
			return 1;
		}
		for(const std::filesystem::path& path : rounds[round])
		{
			std::cout<<"Saveing "<<path<<std::endl; //flush
			std::error_code ec;
			std::filesystem::create_hard_link(path, outDirPath/roundDirName/(path.filename()), ec);
			if(ec.value() != 0)
			{
				std::cout<<"Could not create hard link for "<<outDirPath/roundDirName/path.filename()<<'\n';
			}
		}
	}

	std::error_code ec;
	std::filesystem::path winnerPath(outDirPath/(std::string("winner_") + std::string(images[0].filename())));
	std::filesystem::create_hard_link(images[0], winnerPath, ec);
	if(ec.value() != 0)
	{
		std::cout<<"Could not create hard link for "<<winnerPath<<'\n';
	}

	return 0;
}