/*
 * Copyright (c) 2020, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/Optional.h>
#include <LibGUI/Application.h>
#include <LibGUI/MessageBox.h>
#include <LibGUI/MouseTracker.h>
#include <LibGUI/Painter.h>
#include <LibGUI/Widget.h>
#include <LibGfx/Bitmap.h>
#include <LibGfx/Font.h>
#include <LibGfx/StandardCursor.h>

namespace Pong {

class Game final : public GUI::Widget
    , GUI::MouseTracker {
    C_OBJECT(Game);

public:
    static const int game_width = 560;
    static const int game_height = 480;

    virtual ~Game() override;

private:
    Game();

    virtual void paint_event(GUI::PaintEvent&) override;
    virtual void keyup_event(GUI::KeyEvent&) override;
    virtual void keydown_event(GUI::KeyEvent&) override;
    virtual void timer_event(Core::TimerEvent&) override;
    virtual void track_mouse_move(Gfx::IntPoint const&) override;

    void reset();
    void reset_ball(int serve_to_player);
    void reset_paddles();
    void tick();
    void round_over(int player);
    void game_over(int player);
    void calculate_move();

    struct Ball {
        Gfx::FloatPoint position;
        Gfx::FloatPoint velocity;
        float radius { 4 };

        float x() const { return position.x(); }
        float y() const { return position.y(); }

        Gfx::FloatRect rect() const
        {
            return { x() - radius, y() - radius, radius * 2, radius * 2 };
        }
    };

    struct Paddle {
        Gfx::FloatRect rect;
        float speed { 5 };
        float width { 8 };
        float height { 28 };
        bool moving_up { false };
        bool moving_down { false };
        Gfx::Color color { Color::White };
    };

    struct Net {
        Gfx::Color color { Color::White };
        Gfx::FloatRect rect() const
        {
            return { (game_width / 2) - 1, 0, 2, game_height };
        }
    };

    constexpr static int score_margin = 5;

    Gfx::IntRect player_1_score_rect() const
    {
        int score_width = font().width(String::formatted("{}", m_player_1_score));
        return { (game_width / 2) + score_margin, score_margin, score_width, font().glyph_height() };
    }

    Gfx::IntRect player_2_score_rect() const
    {
        int score_width = font().width(String::formatted("{}", m_player_2_score));
        return { (game_width / 2) - score_width - score_margin, score_margin, score_width, font().glyph_height() };
    }

    Gfx::IntRect cursor_paddle_target_rect() const
    {
        int radius = 3;
        int center_x = m_player1_paddle.rect.center().x();
        int center_y = *m_cursor_paddle_target_y + m_player1_paddle.rect.height() / 2;
        return { center_x - radius, center_y - radius, 2 * radius, 2 * radius };
    }

    Net m_net;
    Ball m_ball;
    Paddle m_player1_paddle;
    Paddle m_player2_paddle;

    int m_score_to_win = 21;
    int m_player_1_score = 0;
    int m_player_2_score = 0;

    Optional<int> m_cursor_paddle_target_y;
    bool m_up_key_held = false;
    bool m_down_key_held = false;
};

}