#include <vector>
#include <string>
#include <sstream>
#include <iostream>
#include <stdexcept>

#include <omp.h>

#include <opencv2/opencv.hpp>


namespace {

struct Arguments
{
    int thread_number = 0;
    std::vector<std::string> file_names;
};

Arguments parse_arguments(int argc, char **argv)
{
    const std::string THREAD_ARGUMENT = "-t";
    const std::string IMAGE_ARGUMENT  = "-i";

    Arguments args;

    std::stringstream ss;

    for (int i = 1; i < argc; ++i) {

        if (THREAD_ARGUMENT == argv[i]) {

            if (++i == argc)
                throw std::invalid_argument("thread number isn't specified");

            ss.str(argv[i]);
            ss >> args.thread_number;

            if (ss.bad() || args.thread_number < 0)
                throw std::invalid_argument("thread number is invalid");
        }
        else if (IMAGE_ARGUMENT == argv[i]) {

            if (++i == argc)
                throw std::invalid_argument("image file name isn't specified");

            args.file_names.push_back(argv[i]);
        }
        else {

            throw std::invalid_argument("unknown argument");
        }
    }

    return args;
}


}

int main(int argc, char **argv)
{
    try {

        Arguments args = parse_arguments(argc, argv);

        if (0 == args.thread_number)
            args.thread_number = omp_get_max_threads();

        for (const auto &file_name : args.file_names) {

            auto mat = cv::imread(file_name);
            if (mat.data == NULL) {

                std::cerr << "Image file " << file_name << " is absent or damaged, skipping" << std::endl;
                continue;
            }
        }
    }
    catch (const std::invalid_argument &e) {

        std::cerr << "Invalid argument: " << e.what() << std::endl;
        return -1;
    }

    return 0;
}