#include "elna/tester.hpp"

#include <iostream>
#include <algorithm>
#include <boost/process/env.hpp>

namespace elna
{
    std::uint32_t test_results::total() const noexcept
    {
        return m_total;
    }

    std::uint32_t test_results::passed() const noexcept
    {
        return m_passed;
    }

    std::uint32_t test_results::failed() const noexcept
    {
        return m_total - m_passed;
    }

    int test_results::exit_code() const noexcept
    {
        return m_total == m_passed ? EXIT_SUCCESS : EXIT_FAILURE;
    }

    void test_results::add_exit_code(const test_status status) noexcept
    {
        ++m_total;
        if (status == test_status::successful)
        {
            ++m_passed;
        }
    }

    static std::filesystem::path in_build_directory()
    {
        return "build/riscv";
    }

    static std::string in_build_directory(const std::filesystem::path& path)
    {
        return in_build_directory() / path;
    }

    boost::process::v2::process_stdio get_output_streams(const std::uint8_t stream_number,
            boost::asio::readable_pipe& read_pipe)
    {
        if (stream_number == 1)
        {
            return boost::process::v2::process_stdio{ nullptr, read_pipe };
        }
        if (stream_number == 2)
        {
            return boost::process::v2::process_stdio{ nullptr, {}, read_pipe };
        }
        return boost::process::v2::process_stdio{ nullptr, read_pipe, read_pipe };
    }

    test_result run_for_output(boost::asio::io_context& context, const std::uint8_t stream_number,
            const std::filesystem::path& binary, std::initializer_list<boost::string_view> arguments)
    {
        boost::asio::readable_pipe read_pipe{ context };
        test_result result{};
        std::string output;
        boost::asio::dynamic_string_buffer buffer = boost::asio::dynamic_buffer(output);
        boost::system::error_code ec;

        boost::process::v2::process_stdio process_stdio;
        boost::process::v2::process elna_child(context,
                binary, arguments,
                get_output_streams(stream_number, read_pipe));
        do
        {
            std::size_t transferred = read_pipe.read_some(buffer.prepare(512), ec);

            if (transferred == 0)
            {
                break;
            }
            buffer.commit(transferred);
            result.output.append(boost::asio::buffer_cast<const char *>(buffer.data()), buffer.size());
            buffer.consume(transferred);
        }
        while (ec == boost::system::errc::success);
        result.code = elna_child.wait();

        return result;
    }

    std::string find_object(const std::vector<std::filesystem::path>& environment, const std::string& object)
    {
        auto variable = std::find(environment.cbegin(), environment.cend(), object);

        for (const auto& variable : environment)
        {
            auto full_path = variable / object;

            if (std::filesystem::exists(full_path))
            {
                return full_path.native();
            }
        }
        return object;
    }

    test_result build_test(boost::asio::io_context& context, const std::filesystem::directory_entry& test_entry)
    {
        const std::filesystem::path test_filename = test_entry.path().filename();

        std::filesystem::path test_binary = in_build_directory(test_filename);
        std::filesystem::path test_object = test_binary;
        test_binary.replace_extension();
        test_object.replace_extension(".o");

        std::filesystem::remove(test_binary);
        std::filesystem::remove(test_object);

        test_result result = run_for_output(context, 2, "./build/bin/elna",
                { "-o", test_object.string(), test_entry.path().string() });

        if (result.code != 0)
        {
            result.status = test_status::compile_failed;
            return result;
        }
        std::vector<std::filesystem::path> environment;
        std::vector<std::string> linker_arguments = { "-o", test_binary.string() };

        for (const auto segment : boost::this_process::environment()["LIBRARY_PATH"].to_vector())
        {
            linker_arguments.push_back("-L" + segment);
            environment.push_back(std::filesystem::path(segment));
        }
        linker_arguments.push_back(find_object(environment, "crt0.o"));
        linker_arguments.push_back(find_object(environment, "crtbegin.o"));
        linker_arguments.push_back(test_object.string());
        linker_arguments.insert(linker_arguments.cend(),
                { "--start-group", "-lgcc", "-lc", "-lgloss", "--end-group" });
        linker_arguments.push_back(find_object(environment, "crtend.o"));

        boost::process::v2::execute(boost::process::v2::process(context,
                    boost::process::search_path("ld"),
                    linker_arguments
        ));
        return test_result{};
    }

    static test_result check_expectation(const std::filesystem::directory_entry& test_entry, const test_result& run)
    {
        std::filesystem::path test_filename = test_entry.path().filename();
        test_filename.replace_extension(".txt");

        const std::filesystem::path expectation_path =
            test_entry.path().parent_path() / "expectations" / test_filename;
        const std::filesystem::path failures_path =
            test_entry.path().parent_path() / "failures" / test_filename;

        std::string expected_result_path;
        if (std::filesystem::exists(expectation_path))
        {
            expected_result_path = expectation_path.string();
        }
        else if (std::filesystem::exists(failures_path))
        {
            expected_result_path = failures_path.string();
        }
        else
        {
            return test_result{ test_status::expectation_not_found, run.code, run.output };
        }
        boost::process::opstream pipe_stream;
        boost::process::child diff(
                boost::process::search_path("diff"), "-Nur", "--color",
                expected_result_path, "-",
                boost::process::std_in < pipe_stream
        );

        pipe_stream << run.output;
        pipe_stream.flush();
        pipe_stream.pipe().close();
        diff.wait();

        if (diff.exit_code() == 0)
        {
            return test_result{ test_status::successful, run.code, run.output };
        }
        return test_result{ test_status::expectation_failed, run.code, run.output };
    }

    test_result run_test(boost::asio::io_context& context, const std::filesystem::directory_entry& test_entry)
    {
        const std::filesystem::path test_filename = test_entry.path().filename();

        std::filesystem::path test_binary = in_build_directory(test_filename);
        test_binary.replace_extension();

        return run_for_output(context, 1,
                boost::process::search_path("qemu-riscv32"),
                { test_binary.string() });
    }

    static test_results run_in_path(const std::filesystem::path test_directory)
    {
        test_results results;
        boost::asio::io_context context;

        for (const auto& test_entry : std::filesystem::directory_iterator(test_directory))
        {
            if (test_entry.path().extension() != ".eln" || !test_entry.is_regular_file())
            {
                continue;
            }
            test_result result;

            std::cout << "Running " << test_entry << std::endl;
            try
            {
                result = build_test(context, test_entry);
                if (result.status == test_status::successful)
                {
                    result = run_test(context, test_entry);
                }
                result = check_expectation(test_entry, result);
            }
            catch (const boost::process::process_error& exception)
            {
                result.status = test_status::build_failed;
                result.output = exception.what();
                std::cout << result.output << std::endl;
            }
            print_result(test_entry, result);
            results.add_exit_code(result.status);
        }
        return results;
    }

    void print_result(const std::filesystem::directory_entry& test_entry, const test_result& result)
    {
        if (result.status != test_status::successful)
        {
            std::cout << test_entry << " failed." << std::endl;
        }
    }
};

int main()
{
    std::filesystem::create_directory(elna::in_build_directory());

    std::cout << "Run all tests and check the results" << std::endl;
    std::filesystem::path test_directory{ "tests" };
    const auto results = elna::run_in_path(test_directory);

    std::cout << std::endl;
    std::cout << results.total() << " tests run, "
        << results.passed() << " passed, "
        << results.failed() << " failed." << std::endl;

    return results.exit_code();
}