var game = new Phaser.Game(800, 600, Phaser.CANVAS, 'phaser-example', { preload: preload, create: create, update: update });

function preload() {

    game.load.image('bullet', 'assets/games/invaders/bullet.png');
    game.load.image('enemyBullet', 'assets/games/invaders/enemy-bullet.png');
    game.load.spritesheet('invader', 'assets/games/invaders/invader32x32x4.png', 32, 32);
    game.load.image('ship', 'assets/games/invaders/player.png');
    game.load.spritesheet('kaboom', 'assets/games/invaders/explode.png', 128, 128);
    game.load.image('starfield', 'assets/games/invaders/starfield.png');
    game.load.image('background', 'assets/games/starstruck/background2.png');

}

var player;
var aliens;
var bullets;
var bulletTime = 0;
var cursors;
var fireButton;
var explosions;
var starfield;

function create() {

    //  The scrolling starfield background
    starfield = game.add.tileSprite(0, 0, 800, 600, 'starfield');
    // game.add.tileSprite(0, 0, 800, 600, 'background');

    //  Our bullet group
    bullets = game.add.group();
    bullets.createMultiple(30, 'bullet');
    bullets.setAll('anchor.x', 0.5);
    bullets.setAll('anchor.y', 1);
    bullets.setAll('outOfBoundsKill', true);

    //  The hero!
    player = game.add.sprite(400, 500, 'ship');
    player.anchor.setTo(0.5, 0.5);

    //  The baddies!
    aliens = game.add.group();

    for (var y = 0; y < 4; y++)
    {
        for (var x = 0; x < 10; x++)
        {
            var alien = aliens.create(x * 48, y * 50, 'invader');
            alien.animations.add('fly', [0,1,2,3], 20, true);
            alien.play('fly');
        }
    }

    aliens.x = 100;
    aliens.y = 50;

    //  An explosion pool
    explosions = game.add.group();
    explosions.createMultiple(30, 'kaboom');
    explosions.forEach(setupInvader, this);

    //  All this does is basically start the invaders moving. Notice we're move the Group they belong to, rather than the invaders directly.
    var tween = game.add.tween(aliens).to({x: 200}, 2000, Phaser.Easing.Linear.None, true, 0, 1000, true);

    //  When the tween completes it calls descend, before looping again
    tween.onComplete.add(descend, this);

    //  And some controls to play the game with
    cursors = game.input.keyboard.createCursorKeys();
    fireButton = game.input.keyboard.addKey(Phaser.Keyboard.SPACEBAR);

}

function setupInvader (invader) {

    invader.anchor.x = 0.5;
    invader.anchor.y = 0.5;
    invader.animations.add('kaboom');

}

function descend() {

    aliens.y += 10;

}

function update() {

    //  Scroll the background
    starfield.tilePosition.y += 2;

    //  Reset the player, then check for movement keys
    player.body.velocity.setTo(0, 0);

    if (cursors.left.isDown)
    {
        player.body.velocity.x = -200;
    }
    else if (cursors.right.isDown)
    {
        player.body.velocity.x = 200;
    }

    //  Firing?
    if (fireButton.isDown)
    {
        fireBullet();
    }

    //  Run collision
    game.physics.collide(bullets, aliens, collisionHandler, null, this);

}

function fireBullet () {

    //  To avoid them being allowed to fire too fast we set a time limit
    if (game.time.now > bulletTime)
    {
        //  Grab the first bullet we can from the pool
        bullet = bullets.getFirstExists(false);

        if (bullet)
        {
            //  And fire it
            bullet.reset(player.x, player.y + 8);
            bullet.body.velocity.y = -400;
            bulletTime = game.time.now + 200;
        }
    }

}

function resetBullet (bullet) {

    //  Called if the bullet goes out of the screen
    bullet.kill();

}

function collisionHandler (bullet, alien) {

    //  When a bullet hits an alien we kill them both
    bullet.kill();
    alien.kill();

    //  Increase the score

    //  And create an explosion :)
    var explosion = explosions.getFirstDead();
    explosion.reset(alien.body.x, alien.body.y);
    explosion.play('kaboom', 30, false, true);

}