import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;


public class GamePanel {
    JFrame window;
    Player player;

    Color boardColor = new Color(100,200,255);
    Color playerColor = new Color(100,100,100);

    boolean upPressed = false;
    boolean downPressed = false;

    final int timerDelay = 20;

    public static void main(String[] args){
        GamePanel gameP = new GamePanel();
    }

    public GamePanel(){
        player = new Player();

        window = new JFrame("Simple Game");
        window.setSize(800, 400);
        window.setLocation(300, 150);
        window.setLayout(new BorderLayout());
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        GameField game = new GameField();
        game.setBackground(boardColor);
        window.add(game, BorderLayout.CENTER);
        window.setVisible(true);
    }

    private class Player{
        final int sizeX = 10;
        final int sizeY = 30;
        final int gunSizeX = sizeX/2;
        final int gunSizeY = sizeY/4;
        final int playerMoveSpeed = 10;
        int playerPositionX = 5;
        int playerPositionY = 200;
        int gunPositionX = 5 + sizeX;
        int gunPositionY = playerPositionY - 2;
        int bulletSpawnPositionX = gunPositionX + 10;

        public void update(){
            gunPositionX = 5 + sizeX;
            gunPositionY = playerPositionY - 2;
            bulletSpawnPositionX = gunPositionX + 10;

            if (upPressed){
                playerPositionY -= playerMoveSpeed;
            }
            else if (downPressed)
                playerPositionY += playerMoveSpeed;
            if (playerPositionY < (0 - (sizeY/2)))
                playerPositionY = (0 - (sizeY/2));
            else if (playerPositionY > window.getHeight() + (sizeY/2))
                playerPositionY = window.getHeight() + (sizeY/2);
        }

        public void draw(Graphics g){
            g.setColor(playerColor);
            g.fillRoundRect(playerPositionX, playerPositionY - (sizeY/2), sizeX, sizeY, 20, 20);
            g.fillRect(gunPositionX, gunPositionY, gunSizeX, gunSizeY);
        }
    }

    private class GameField extends JPanel{
        ActionListener timerAction;
        Timer animationTimer;

        public GameField(){

            addFocusListener(new FocusListener(){
                public void focusGained(FocusEvent e){
                    animationTimer.start();
                }
                public void focusLost(FocusEvent e) {
                    animationTimer.stop();
                }
            });

            addKeyListener(new KeyListener(){
                public void keyPressed(KeyEvent e) {
                    if (e.getKeyCode() == KeyEvent.VK_UP)
                        upPressed = true;
                    if (e.getKeyCode() == KeyEvent.VK_DOWN)
                        downPressed = true;
                }
                public void keyReleased(KeyEvent e) {
                    if (e.getKeyCode() == KeyEvent.VK_UP)
                        upPressed = false;
                    if (e.getKeyCode() == KeyEvent.VK_DOWN)
                        downPressed = false;
                }
                public void keyTyped(KeyEvent e) {}
            });

            timerAction = new ActionListener(){
                public void actionPerformed(ActionEvent e) {
                    player.update();
                    repaint();
                }
            };

            animationTimer = new Timer(timerDelay, timerAction);

            addMouseListener(new MouseAdapter(){
                public void mouseClicked(MouseEvent e){
                    requestFocus();
                }
            });
        }

        public void paintComponent(Graphics g){
            super.paintComponent(g);
            player.draw(g);
        }
    }
}