// Studscanvas.java

import java.util.*;
import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;

public class Studscanvas extends GameCanvas {
    int ball_radius;
    double ball_x, ball_y, ball_dx, ball_dy;
    Timer the_timer;
    Graphics g;

    // Key repeat rate in milliseconds
    public static final int KEY_REPEAT_RATE = 250;

    // Key constants
    public static final int MY_UP_KEY = 0;
    public static final int MY_LEFT_KEY = 1;
    public static final int MY_DOWN_KEY = 2;
    public static final int MY_RIGHT_KEY = 3;
    public static final int MY_FIRE_KEY = 4;

    // Key states for up, left, down, right, and fire key
    private boolean[] key_is_down = {
        false, false, false, false, false
    };

    // The last time each key changed state
    private long[] last_key_time = {
        0, 0, 0, 0, 0
    };

    // Lookup table for key constants
    private int[] key_value = {
        GameCanvas.UP_PRESSED,
        GameCanvas.LEFT_PRESSED,
        GameCanvas.DOWN_PRESSED,
        GameCanvas.RIGHT_PRESSED,
        GameCanvas.FIRE_PRESSED
    };

    public Studscanvas() {
        super(false);
        int screen_width = getWidth();
        int screen_height = getHeight();

        ball_radius = 5;
        ball_x = screen_width / 2;
        ball_y = screen_height / 2;
        ball_dx = 1;
        ball_dy = -1;
    }

    public void showNotify() {
        the_timer = new Timer();
        g = getGraphics();
        TimerTask task = new TimerTask() {
                public void run() {
                    process_keys();
                    update_game_state();
                    render();
                    flushGraphics();
                }
            };
        the_timer.schedule(task, 0, 20);
    }

    public void hideNotify() {
        if (the_timer != null) {
            the_timer.cancel();
            the_timer = null;
        }
    }

    private void process_keys() {
        int keys = getKeyStates();
        long current_time = System.currentTimeMillis();

        // Loop through the keys
        for (int i = 0; i < 5; i++){

            // By default, the key is not pressed
            key_is_down[i] = false;

            // Is the user pressing this key?
            if ((keys & key_value[i]) != 0) {
                long elapsed_time = current_time - last_key_time[i];

                // Is it time to toggle the key state?
                if (elapsed_time >= KEY_REPEAT_RATE) {

                    // Save the current time
                    last_key_time[i] = current_time; 

                    // Toggle the state to "down"
                    key_is_down[i] = true;
                }
            }
        }

        if (key_is_down[MY_LEFT_KEY]) {
            System.out.println("Pressed left!");
            ball_dx -= 1;
        }
        if (key_is_down[MY_RIGHT_KEY]) {
            System.out.println("Pressed right!");
            ball_dx += 1;
        }
        if (key_is_down[MY_UP_KEY]) {
            System.out.println("Pressed up!");
            ball_dy -= 1;
        }
        if (key_is_down[MY_DOWN_KEY]) {
            System.out.println("Pressed down!");
            ball_dy += 1;
        }
        if (key_is_down[MY_FIRE_KEY]) {
            System.out.println("Pressed FIRE!");
            ball_dx = 0;
            ball_dy = 0;
        }

    }

    private void update_game_state() {
        int screen_width = getWidth();
        int screen_height = getHeight();
        ball_x += ball_dx;
        ball_y += ball_dy;
        if (ball_x + ball_radius >= screen_width) {
            ball_dx *= -1;
        }
        else if (ball_x - ball_radius <= 0) {
            ball_dx *= -1;
        }
        if (ball_y - ball_radius <= 0) {
            ball_dy *= -1;
        }
        else if (ball_y + ball_radius >= screen_height) {
            ball_dy *= -1;
        }

        // System.out.println("ball_x = " + ball_x + ", ball_y = " + ball_y +
        //                    ", ball_dx = " + ball_dx + " + ball_dy = " + ball_dy);
    }

    public void render() {
        g.setColor(0xffffff);
        g.fillRect(0, 0, getWidth(), getHeight());
        g.setColor(0x000000);
        g.drawString("dx = " + ball_dx + ", dy = " + ball_dy, 0, 0, Graphics.TOP | Graphics.LEFT);
        g.fillArc((int)(ball_x - ball_radius), (int)(ball_y - ball_radius),
                  ball_radius * 2, ball_radius * 2, 0, 360);
    }

} // class Studscanvas