import greenfoot.*;

public class Player extends Actor
{
    private int speed = 6;
    private int jumpStrength = 20;
    private int gravity = 1;

    private int verticalSpeed = 0;
    private boolean onGround = false;

    public void act()
    {
        moveLeftAndRight();
        jump();
        fall();
    }

    // Bewegung nach links und rechts
    private void moveLeftAndRight()
    {
        if (Greenfoot.isKeyDown("a"))
        {
            setLocation(getX() - speed, getY());
        }

        if (Greenfoot.isKeyDown("d"))
        {
            setLocation(getX() + speed, getY());
        }
    }

    // Springen
    private void jump()
    {
        if (Greenfoot.isKeyDown("space") && onGround)
        {
            verticalSpeed = -jumpStrength;
            onGround = false;
        }
    }

    // Schwerkraft
    private void fall()
    {
        int oldY = getY();

        verticalSpeed += gravity;

        int newY = getY() + verticalSpeed;

        setLocation(getX(), newY);

        Actor ground = getOneIntersectingObject(Ground.class);

        if (ground != null && verticalSpeed >= 0)
        {
            int groundTop = ground.getY() 
                          - ground.getImage().getHeight() / 2;

            int characterBottom = getY() 
                                + getImage().getHeight() / 2;

            // Nur landen, wenn der Spieler vorher über dem Boden war
            int oldCharacterBottom = oldY 
                                   + getImage().getHeight() / 2;

            if (oldCharacterBottom <= groundTop && 
                characterBottom >= groundTop)
            {
                setLocation(
                    getX(),
                    groundTop - getImage().getHeight() / 2
                );

                verticalSpeed = 0;
                onGround = true;
            }
        }
        else
        {
            onGround = false;
        }
    }
}