#include "window.hh"

namespace client {
namespace window {

// All window objects should derive from basic_window, and make use of multiple
// inheritance for specific behaviours.
class basic_window {
protected:
    // Colours borrowed from arc-dark(er).
    static constexpr glm::vec3 primary_clr{0.21f, 0.23f, 0.29f};   // dark
    static constexpr glm::vec3 secondary_clr{0.29f, 0.32f, 0.38f}; // less dark
    static constexpr glm::vec3 tertiary_clr{0.48, 0.50, 0.54};  // less dark ^2
    static constexpr glm::vec3 highlight_clr{0.32, 0.58, 0.88}; // light blue
    static constexpr glm::vec3 font_colour{0.88, 0.88, 0.88};   // light grey

protected:
    glm::vec2 pos;
    glm::vec2 size;

public:
    bool is_inside(const glm::vec2& v) const noexcept {
        if (v.x < this->pos.x || v.x > this->pos.x + this->size.x) {
            return false;
        }
        if (v.y < this->pos.y || v.y > this->pos.y + this->size.y) {
            return false;
        }
        return true;
    }

public:
    basic_window(const client::draw::relative_arg& p,
                 const client::draw::relative_arg& s) noexcept
        : pos(p.to_vec2()), size(s.to_vec2()) {}
    virtual ~basic_window() noexcept {}

    virtual bool maybe_handle_event(const SDL_Event&) noexcept { return false; }
    virtual void draw() noexcept {
        client::draw::draw_rectangle({.pos = {.offset = this->pos + 6.0f},
                                      .size = {.offset = this->size},
                                      .colour = {this->tertiary_clr, 0.9f}});
        client::draw::draw_rectangle({.pos = {.offset = this->pos},
                                      .size = {.offset = this->size},
                                      .colour = {this->primary_clr, 1.0f}});
    }
};

static void remove_top_layer() noexcept;
class text_input_window : public basic_window {
private:
    // text restricted to a size of 32.
    static const std::string& get_send_text() noexcept {
        auto& text = client::input::state.text_input;
        text = std::string{std::begin(text),
                           std::begin(text) +
                               static_cast<long>(std::min(
                                   std::size(text), shared::MAX_SAY_LENGTH))};
        return text;
    }
    static bool maybe_handle_keydown(const SDL_Event& event) noexcept {
        if (event.key.keysym.sym == SDLK_BACKSPACE) {
            if (!client::input::state.text_input.empty()) {
                client::input::state.text_input.pop_back();
            }
            return true;
        }

        if (event.key.keysym.sym != SDLK_RETURN || event.key.repeat) {
            return false;
        }

        if (!client::input::state.text_input.empty()) {
            client::send_say_packet(get_send_text());
        }

        remove_top_layer(); // DELETE ME
        return true;
    }
    static const glm::vec3& get_draw_colour() noexcept {
        if (client::input::state.text_input.length() >=
            shared::MAX_SAY_LENGTH) {
            return basic_window::highlight_clr;
        }
        return basic_window::primary_clr;
    }

public:
    template <typename... Args>
    text_input_window(Args&&... args) noexcept
        : basic_window(std::forward<Args>(args)...) {
        client::input::set_text_input(true);
    }
    virtual ~text_input_window() noexcept {
        client::input::set_text_input(false);
    }
    virtual bool maybe_handle_event(const SDL_Event& event) noexcept override {
        switch (event.type) {
        case SDL_KEYDOWN:
            return this->maybe_handle_keydown(event);
        }

        return basic_window::maybe_handle_event(event);
    }

    virtual void draw() noexcept override {
        basic_window::draw();

        client::draw::draw_rectangle(
            {.pos = {.offset = this->pos},
             .size = {.offset = this->size},
             .colour = {this->get_draw_colour(), 1.0f}});

        client::draw::draw_text(
            this->get_send_text(),
            {.pos = {.extent = {0.0f, 0.0f},
                     .offset = this->pos + (this->size / 2.0f)},
             .offset_height = this->size.y / 2.0f,
             .colour = {this->font_colour, 1.0f},
             .has_backing = false,
             .is_centered = true,
             .is_vcentered = true});
    };
};

class button_window : public basic_window {
protected:
    std::string name;
    std::function<void()> callback;
    bool is_pressed;

private:
    void handle_mousebuttondown(const SDL_Event& event) noexcept {
        if (event.button.button != SDL_BUTTON_LEFT) {
            return;
        }
        this->is_pressed = true;
    }
    void handle_mousebuttonup(const SDL_Event& event) noexcept {
        if (event.button.button != SDL_BUTTON_LEFT) {
            return;
        }
        if (!this->is_pressed) {
            return;
        }
        this->is_pressed = false;
        std::invoke(this->callback); // edge
    }
    const glm::vec3& get_draw_colour() noexcept {
        if (!this->is_inside(client::input::state.mouse_pos)) {
            this->is_pressed = false;
            return this->primary_clr;
        }

        if (!this->is_pressed) {
            return this->secondary_clr;
        }

        return this->highlight_clr;
    }

public:
    template <typename... Args>
    button_window(const std::string_view n, const decltype(callback)& c,
                  Args&&... args) noexcept
        : basic_window(std::forward<Args>(args)...), name(n), callback(c) {}

    virtual bool maybe_handle_event(const SDL_Event& event) noexcept override {
        if (this->is_inside(client::input::state.mouse_pos)) {
            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();

        client::draw::draw_rectangle(
            {.pos = {.offset = this->pos},
             .size = {.offset = this->size},
             .colour = {this->get_draw_colour(), 1.0f}});
        client::draw::draw_text(
            this->name, {.pos = {.extent = {0.0f, 0.0f},
                                 .offset = this->pos + (this->size / 2.0f)},
                         .offset_height = this->size.y / 2.0f,
                         .colour = {this->font_colour, 1.0f},
                         .has_backing = false,
                         .is_centered = true,
                         .is_vcentered = true});
    };
};

// 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

// All 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;
}

static void remove_top_layer() 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,
        remove_top_layer,
        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", remove_top_layer,
        client::draw::relative_arg{.extent =
                                       center_extent({0.3, 0.3}, ssize_extent)},
        client::draw::relative_arg{.extent = ssize_extent});
}

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

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

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

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

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

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

    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;
    }

    remove_top_layer();
}

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;
    }
}

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()) {
        return;
    }

    client::draw::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