import javax.microedition.lcdui.*;


class UFO extends Sprite {

	private	MyShip				myShip;
	
	private int				missileCount		= 0;
	
	private int				direction;
	
	static final int			DIRECTION_RIGHT		= 0;
	
	static final int			DIRECTION_LEFT		= 1;
	
	private static Image		ufoImg				= null;
	
	private static Image		burstImg			= null;

	
	UFO(MyShip myShip) {
		this.myShip = myShip;

		if(ufoImg == null) {
		//UFO圖像為null時就取得圖像
			try {
				ufoImg = Image.createImage("/z4.png");
				burstImg = Image.createImage("/imgenemybomb.png");
			}catch(Exception e) {}
		}

		//設定寬度與高度
		width = ufoImg.getWidth();
		height = ufoImg.getHeight();
	}

	
	void setAlive(boolean isAlive) {
		if(isAlive) {
		//由于在變成Alive狀態時會將這個UFO復活，因此要把值予以初始化
			this.isHit = false;
			missileCount = 0;
			tickCount = 0;
		}
		super.setAlive(isAlive);
	}

	
	void doMove() {
		if(this.isAlive) {		//Alive時
			if(isHit()) {		//Hit時
				tickCount++;
				//Tick計數為5的話就會從畫面消失
				if(tickCount > 4) {
					setAlive(false);
				}
			}else {				//不是Hit時
				//針對行進方向來移動UFO
				switch(direction) {
					case DIRECTION_RIGHT:
						x = x + (width / 2) + 1;
						break;

					case DIRECTION_LEFT:
						x = x - (width / 2) - 1;
						break;
				}
			}
		}
	}

	
	void doDraw(Graphics g) {
		if(isAlive) {
			//System.out.println(isHit);
			if(isHit()) {
			//Hit時就描繪爆炸圖像
				//System.out.println("BOMB!!!!");
				g.drawImage(burstImg, x, y, Graphics.TOP|Graphics.LEFT);
			}else {
				g.drawImage(ufoImg, x, y, Graphics.TOP|Graphics.LEFT);
			}
		}
	}

	
	void setDirection(int direction) {
		this.direction = direction;
	}

	
	boolean isDropBomb() {
		if(missileCount < 3) {
		//飛彈的發射數比3發還少時
			//切割出UFO的中央坐標
			int center = x + (width /2);
			if(center >= myShip.getX() && center <= myShip.getX() + myShip.getWidth()) {
			//UFO的中央坐標與自機的X坐標重疊時
				//發射飛彈
				missileCount++;
				return true;
			}
		}
		//處理到這個地方就不發射飛彈
		return false;
	}
}