#include "window.hh"

namespace client {
namespace window {

// TODO

// Sliders are for numerical values of some type T.
// TODO
/*
template <typename T>
class slider_window : public basic_window {
protected:
    std::string name;
    T min;
    T cur;
    T max;
    T& var;

private:
    void handle_mousebuttondown(const SDL_Event& event) noexcept {}
    void handle_mousebuttonup(const SDL_Event& event) noexcept {}

public:
    template <typename... Args>
    slider_window(const std::string_view name, const T& min, const T& cur,
                  const T& max, T& var, Args&&... args) noexcept
        : basic_window(std::forward<Args>(args)...), name(name), min(min),
          cur(cur), max(max), var(var) {}

    // slider_window(
    virtual bool maybe_handle_event(const SDL_Event& event) noexcept
override { switch (event.type) { case SDL_MOUSEBUTTONDOWN:
            this->handle_mousebuttondown(event);
            return true;
        case SDL_MOUSEBUTTONUP:
            this->handle_mousebuttonup(event);
            return true;
        }
        return basic_window::maybe_handle_event(event);
    }
    virtual void draw() noexcept override { basic_window::draw(); }
};
*/

static void handle_event(const SDL_Event& event) noexcept; // ignore

static hud_window& get_hud_window() noexcept {
    static hud_window ret = []() {
        const auto& window = client::render::get_window_size();
        const float size = std::min(static_cast<float>(window.x) / 2.0f,
                                    static_cast<float>(window.y) / 2.0f);
        client::window::hud_window ret{size};
        return ret;
    }();
    return ret;
}

// All dynamic windows go in this list!
using layer = std::forward_list<std::unique_ptr<basic_window>>;
using layers = std::forward_list<layer>;
static layers& get_layers() noexcept {
    // We callbacks for our window manager are initialised here too.
    static layers ret = []() -> layers {
        client::input::register_event_handler(&handle_event);
        client::input::set_text_input(false);
        client::input::set_mouse_relative(true);
        return {};
    }();
    return ret;
}

void pop_window() noexcept {
    if (!get_layers().empty()) {
        get_layers().pop_front();
    }
    // Our windows might be empty here, so set our mouse mode accordingly.
    if (!client::window::is_open()) {
        client::input::set_mouse_relative(true);
    }
}

// Constants used for uniform ui sizes.
constexpr glm::vec2 lsize_extent{0.4, 0.075};
constexpr glm::vec2 ssize_extent{0.15, 0.075};

static void center_mouse_position() noexcept {
    const glm::vec2& window = client::render::get_window_size();
    client::input::set_mouse_position({window.x / 2.0f, window.y / 2.0f});
}

template <typename T, typename... Args>
void push_window(Args&&... args) noexcept {
    get_layers().front().push_front(
        std::make_unique<T>(std::forward<Args>(args)...));
}

constexpr glm::vec2 center_extent(const glm::vec2 pos,
                                  const glm::vec2 size) noexcept {
    return {pos.x, pos.y - size.y / 2.0f};
}

static void make_options_menu() noexcept {
    get_layers().push_front({});

    /*
    push_window<::slider_window<float>>(
        "Field of Vision", 0.0f,
        settings::get(std::make_pair("gameplay", "fov"), 100.0f), 145.0f,
        pop_window,
        client::draw::relative_arg{.extent =
                                       center_extent({0.3, 0.7},
    lsize_extent)}, client::draw::relative_arg{.extent = lsize_extent});
        */

    push_window<button_window>(
        "Back", pop_window,
        client::render::relative_arg{
            .extent = center_extent({0.3, 0.3}, ssize_extent)},
        client::render::relative_arg{.extent = ssize_extent});
}

static void make_main_menu() noexcept {
    get_layers().push_front({});

    push_window<button_window>(
        "Return to Game", pop_window,
        client::render::relative_arg{
            .extent = center_extent({0.3, 0.7}, lsize_extent)},
        client::render::relative_arg{.extent = lsize_extent});

    push_window<button_window>(
        "Options", make_options_menu,
        client::render::relative_arg{
            .extent = center_extent({0.55, 0.6}, ssize_extent)},
        client::render::relative_arg{.extent = ssize_extent});

    push_window<button_window>(
        "?", pop_window,
        client::render::relative_arg{
            .extent = center_extent({0.55, 0.5}, ssize_extent)},
        client::render::relative_arg{.extent = ssize_extent});

    push_window<button_window>(
        "?", pop_window,
        client::render::relative_arg{
            .extent = center_extent({0.55, 0.4}, ssize_extent)},
        client::render::relative_arg{.extent = ssize_extent});

    push_window<button_window>(
        "Exit Game", [] { shared::should_exit = true; },
        client::render::relative_arg{
            .extent = center_extent({0.3, 0.3}, lsize_extent)},
        client::render::relative_arg{.extent = lsize_extent});

    client::input::set_mouse_relative(false);
    center_mouse_position();
}

static void make_chat_window() noexcept {
    get_layers().push_front({});

    push_window<text_input_window>(
        client::render::relative_arg{
            .extent = center_extent({0.3, 0.3}, lsize_extent)},
        client::render::relative_arg{.extent = lsize_extent});

    client::input::set_mouse_relative(false);
    center_mouse_position();
}

static void make_inventory_window() noexcept {
    get_layers().push_front({});

    const glm::vec2& window = client::render::get_window_size();

    const float size = std::min(window.x / 2.0f, window.y / 2.0f);
    const glm::vec2 pos{(window - size) / 2.0f};

    push_window<inventory_window>(
        client::render::relative_arg{.offset = pos},
        client::render::relative_arg{.offset = glm::vec2{size, size}});
    client::input::set_mouse_relative(false);
    center_mouse_position();
}

static void handle_meta_return() noexcept {
    if (!is_open()) {
        make_chat_window();
        return;
    }
}

static void handle_meta_escape() noexcept {
    if (!is_open()) {
        make_main_menu();
        return;
    }

    pop_window();
}

static void handle_meta_e() noexcept {
    if (!is_open()) {
        make_inventory_window();
        return;
    }

    // The inventory window must be open.
    if (!dynamic_cast<inventory_window*>(&*get_layers().front().front())) {
        return;
    }

    pop_window();
}

static void handle_meta_keydown(const SDL_Event& event) noexcept {
    if (event.key.repeat) { // only handle keypresses
        return;
    }

    switch (event.key.keysym.sym) {
    case SDLK_ESCAPE:
        handle_meta_escape();
        break;
    case SDLK_RETURN:
        handle_meta_return();
        break;
    case SDLK_e:
        handle_meta_e();
        break;
    case SDLK_0:
    case SDLK_1:
    case SDLK_2:
    case SDLK_3:
    case SDLK_4:
    case SDLK_5:
    case SDLK_6:
    case SDLK_7:
    case SDLK_8:
    case SDLK_9:
        get_hud_window().maybe_handle_event(event);
    default:
        break;
    }
}

static void handle_meta_mousemotion(const SDL_Event& event) noexcept {
    // We convert SDL's weird coordinates into useful ones (0,0 = bottom
    // left).
    client::input::state.mouse_pos = {
        event.motion.x,
        static_cast<int>(client::render::get_window_size().y) - event.motion.y};
}

static void handle_meta_windowevent(const SDL_Event& event) noexcept {
    if (event.window.event == SDL_WINDOWEVENT_FOCUS_LOST) {
        if (!is_open()) {
            make_main_menu();
            return;
        }
    }
}

static void handle_meta_event(const SDL_Event& event) noexcept {
    switch (event.type) {
    case SDL_KEYDOWN:
        handle_meta_keydown(event);
        break;
    case SDL_MOUSEMOTION:
        handle_meta_mousemotion(event);
        break;
    case SDL_WINDOWEVENT:
        handle_meta_windowevent(event);
        break;
    }
}

static void handle_event(const SDL_Event& event) noexcept {
    // We ALWAYS update our mouse position.
    if (event.type == SDL_MOUSEMOTION) {
        handle_meta_mousemotion(event);
    }

    // Either a window consumes our event, or no window does - so we send
    // the event to our "meta handler" which does things like closing
    // windows etc.
    if (is_open()) {
        for (const auto& window : get_layers().front()) {
            if (window->maybe_handle_event(event)) {
                return;
            }
        }
    }

    handle_meta_event(event);
}

void draw() noexcept {
    if (!is_open()) {

        if (!client::input::is_key_toggled(SDLK_F1)) {
            get_hud_window().draw();
        }

        return;
    }

    client::render::draw_colour({0.0f, 0.0f, 0.0f, 0.10f}); // very light shade
    for (const auto& window : get_layers().front()) {
        window->draw();
    }
}

bool is_open() noexcept { return !get_layers().empty(); }

} // namespace window
} // namespace client