#include <gtkmm.h>
#include <iostream>
#include <boost/filesystem/path.hpp>
#include <boost/filesystem/operations.hpp>

using namespace std::string_literals;

bool executable_exists(std::string_view dir, std::string_view executable)
{
    if (dir.size() + executable.size() + 1 >= PATH_MAX) {
        std::cerr << "Error: requested path longer than PATH_MAX" << std::endl;
        return false;
    }
    char path_buf[PATH_MAX];
    auto ptr = std::copy(dir.begin(), dir.end(), path_buf);
    *ptr = '/';
    ptr = std::copy(executable.begin(), executable.end(), ptr + 1);
    *ptr = '\0';

    return access(path_buf, F_OK | X_OK) == 0;
}

auto file_filter_for_extension(std::string_view extension)
{
    auto filter = Gtk::FileFilter::create();
    auto pattern = "*."s;
    pattern += extension;
    filter->set_name(std::string(extension));
    filter->add_pattern(pattern);

    return filter;
}

/**
 * Wrap string into a dynamically allocated c-string.
 *
 * @param str
 * @return
 */
char* wrap_string(std::string_view str) {
    if (str.empty()) {
        return nullptr;
    }

    auto wrapper = new char[str.size() + 1];
    auto ptr = std::copy(str.begin(), str.end(), wrapper);
    *ptr = '\0';

    return wrapper;
}

class Launcher : public Gtk::Window {
public:
    Launcher();
    ~Launcher() override = default;

private:
    Gtk::Grid grid;
    Gtk::FileChooserButton fmriChooser;
    Gtk::FileChooserButton modelChooser;
    Gtk::FileChooserButton weightsChooser;
    Gtk::FileChooserButton labelChooser;
    Gtk::FileChooserButton meansChooser;
    Gtk::FileChooserButton inputChooser;
    Gtk::Button startButton;

    void start();
    bool hasFile(const Gtk::FileChooserButton& fileChooser, const std::string& error);
    std::vector<std::string> getInputFiles();
    Gtk::Label* getManagedLabel(const std::string& contents);
    void findExecutable();
};

Launcher::Launcher()
        :
        Gtk::Window(),
        fmriChooser("Select FMRI executable"),
        modelChooser("Select caffe model prototxt"),
        weightsChooser("Select caffe model weights"),
        labelChooser("Select label text file"),
        meansChooser("Select means file"),
        inputChooser("Select input directory", Gtk::FileChooserAction::FILE_CHOOSER_ACTION_SELECT_FOLDER),
        startButton("Start FMRI")
{
    set_size_request(400, -1);
    add(grid);

    grid.set_row_spacing(2);
    grid.set_column_spacing(2);
    findExecutable();
    fmriChooser.set_hexpand(true);
    grid.attach(fmriChooser, 1, 0, 1, 1);
    grid.attach_next_to(*getManagedLabel("FMRI executable"), fmriChooser, Gtk::PositionType::POS_LEFT, 1, 1);
    grid.attach(modelChooser, 1, 1, 1, 1);
    modelChooser.add_filter(file_filter_for_extension("prototxt"));
    grid.attach_next_to(*getManagedLabel("Model"), modelChooser, Gtk::PositionType::POS_LEFT, 1, 1);
    grid.attach(weightsChooser, 1, 2, 1, 1);
    weightsChooser.add_filter(file_filter_for_extension("caffemodel"));
    grid.attach_next_to(*getManagedLabel("Weights"), weightsChooser, Gtk::PositionType::POS_LEFT, 1, 1);
    grid.attach(labelChooser, 1, 3, 1, 1);
    labelChooser.add_filter(file_filter_for_extension("txt"));
    grid.attach_next_to(*getManagedLabel("Labels (optional)"), labelChooser, Gtk::PositionType::POS_LEFT, 1, 1);
    grid.attach(inputChooser, 1, 4, 1, 1);
    grid.attach_next_to(*getManagedLabel("Input directory"), inputChooser, Gtk::PositionType::POS_LEFT, 1, 1);
    grid.attach(meansChooser, 1, 5, 1, 1);
    meansChooser.add_filter(file_filter_for_extension("binaryproto"));
    grid.attach_next_to(*getManagedLabel("Means (optional)"), meansChooser, Gtk::PositionType::POS_LEFT, 1, 1);

    startButton.signal_clicked().connect(sigc::mem_fun(*this, &Launcher::start));
    grid.attach_next_to(startButton, Gtk::PositionType::POS_BOTTOM, 2, 1);
    show_all_children(true);
}

void Launcher::start()
{
    if (!hasFile(fmriChooser, "Need executable") ||
            !hasFile(modelChooser, "Need model file") ||
            !hasFile(weightsChooser, "Need weights file") ||
            !hasFile(inputChooser, "Need input folder")) {
        return;
    }

    auto executable = fmriChooser.get_file()->get_path();
    auto network = modelChooser.get_file()->get_path();
    auto weights = weightsChooser.get_file()->get_path();
    auto inputs = getInputFiles();

    if (inputs.empty()) {
        Gtk::MessageDialog dialog(*this, "No inputs in folder!");
        dialog.run();
        return;
    }

    std::vector<char*> argv = {
            wrap_string(executable),
            wrap_string("-n"),
            wrap_string(network),
            wrap_string("-w"),
            wrap_string(weights),
    };

    if (labelChooser.get_file()) {
        argv.push_back(wrap_string("-l"));
        argv.push_back(wrap_string(labelChooser.get_file()->get_path()));
    }

    if (meansChooser.get_file()) {
        argv.push_back(wrap_string("-m"));
        argv.push_back(wrap_string(meansChooser.get_file()->get_path()));
    }

    std::transform(inputs.begin(), inputs.end(), std::back_inserter(argv),
            [](const auto& x) { return wrap_string(x); });

    argv.push_back(nullptr);

    execv(executable.c_str(), argv.data());
}

bool Launcher::hasFile(const Gtk::FileChooserButton& fileChooser, const std::string& error)
{
    if (!fileChooser.get_file()) {
        Gtk::MessageDialog dialog(*this, error);
        dialog.run();
        return false;
    }

    return true;
}

std::vector<std::string> Launcher::getInputFiles()
{
    using namespace boost::filesystem;

    std::vector<std::string> result;

    auto folder = path(inputChooser.get_file()->get_path());

    directory_iterator end_itr;
    for (directory_iterator itr(folder); itr!=end_itr; ++itr) {
        if (!is_regular(itr->status())) {
            continue;
        }

        result.push_back(itr->path().string());
    }

    std::sort(result.begin(), result.end());

    return result;
}

Gtk::Label* Launcher::getManagedLabel(const std::string& contents)
{
    auto label = new Gtk::Label(contents);
    Gtk::manage(label);

    return label;
}

void Launcher::findExecutable()
{
    if (executable_exists(".", "fmri")) {
        fmriChooser.set_filename("fmri");
        return;
    }

    std::string_view env_path = std::getenv("PATH");
    std::string_view::size_type offset = 0;
    while (offset != std::string_view::npos) {
        auto limit = env_path.find(":");
        auto component = env_path.substr(offset, limit);
        if (limit != std::string_view::npos) {
            offset = limit + 1;
        } else {
            offset = limit;
        }
        if (!component.empty() && executable_exists(component, "fmri")) {
            fmriChooser.set_filename(std::string(component) + "/fmri");
            return;
        }
    }
}

int main(int argc, char** argv)
{
    auto app = Gtk::Application::create(argc, argv);
    Launcher launcher;
    return app->run(launcher);
}