class Renderer
{
    Graphics gp;

    BackgroundRenderer backgroundRenderer;
    ZombieRenderer zombieRenderer;

    Renderer(IAssetAccess assets)
    {
        backgroundRenderer = new BackgroundRenderer(assets);
        zombieRenderer = new ZombieRenderer(assets);
    }

    void renderBackground(Background background) { backgroundRenderer.render(gp, background); }
    void renderZombie(ZombieEntity zombie) { zombieRenderer.render(gp, zombie); }
}

class BackgroundRenderer
{
    Sprite[] sprites;

    BackgroundRenderer(IAssetAccess assets) { sprites = assets.get("bg"); }

    void render(Graphics gp, Background background)
    {
        gp.drawSprite(sprites[background.index], background.x, background.y);
    }
}

class ZombieRenderer
{
    Sprite[] idleSprites;
    Sprite[] moveSprites;
    Sprite[] attackSprites;

    ZombieRenderer(IAssetAccess assets)
    {
        idleSprites = assets.get("zombie_idle");
        moveSprites = assets.get("zombie_move");
        attackSprites = assets.get("zombie_attack");
    }

    void render(Graphics gp, ZombieEntity zombie)
    {
        Sprite sprite;

        if (zombie.state == MobState.IDLE) sprite = idleSprites[zombie.idleAnim.currentFrame];
        if (zombie.state == MobState.MOVE) sprite = moveSprites[zombie.moveAnim.currentFrame];
        if (zombie.state == MobState.ATTACK) sprite = attackSprites[zombie.attackAnim.currentFrame];

        gp.drawSprite(sprite, zombie.x, zombie.y);
    }
}

class Background
{
    int index;

    void render(Renderer renderer) { renderer.drawBackground(this); }
}

class ZombieEntity
{
    Animation idleAnim;
    Animation moveAnim;
    Animation attackAnim;

    void render(Renderer renderer) { renderer.drawZombie(this); }
}