snake

var Board = function() {
    var SIZE = {
        WIDTH: 30,
        HEIGHT: 30
    }

    var score = 0
    var snake
    var apples = []

    var canvas = document.querySelector('.container')

    if(canvas.getContext) {
        var ctx = canvas.getContext('2d')
    } else {
        console.error('Canvas not supported')
    }

    function addSnake(snakeObj) {
        snake = snakeObj
    }

    function addApple(apple) {
        apples.push(apple)
        apple.notify('game-start', {board: null})
    }

    function render() {
        //render snake
        var positions = snake.getPositions()
        positions.forEach(function(pos) {
            ctx.fillRect(pos.x*15, pos.y*15, 15, 15)
        })

        //render apples
        apples.forEach(function(apple) {
            var pos = apple.getPosition()
            ctx.fillRect(pos.x*15, pos.y*15, 15, 15)
        })
    }

    function clear() {
        ctx.clearRect(0, 0, 600, 600)
    }

    function getAvailablePositions() {}

    return {
        addSnake: addSnake,
        addApple: addApple,
        render: render,
        clear: clear,
        getAvailablePositions: getAvailablePositions
    }
}

var Snake = function() {
    var DIRECTIONS = {
        RIGHT: 'right',
        LEFT: 'left',
        DOWN: 'down',
        UP: 'up'
    }

    var direction = DIRECTIONS.RIGHT

    var snake = [
        {x: 0, y: 0},
        {x: 1, y: 0},
        {x: 2, y: 0},
        {x: 3, y: 0}
    ]

    function getPositions() {
        return snake
    }

    function advance() {
        if(direction == DIRECTIONS.RIGHT) {
            snake = snake.map(function(pos) {
                return {
                    x: pos.x + 1,
                    y: pos.y
                }
            })
        }
    }

    return {
        getPositions: getPositions,
        advance: advance
    }
}

var Apple = function() {
    var EVENTS = {
        GAME_START: 'game-start'
    }

    var apple

    function getPosition() {
        return apple
    }

    function notify(event, data) {
        if(event === EVENTS.GAME_START) {
            //TODO: use data.board to exclude random aquired squares
            var randomPosition = Math.floor(Math.random() * 30)

            apple = {
                x: randomPosition,
                y: randomPosition
            }
        }
    }

    return {
        getPosition: getPosition,
        notify: notify
    }
}

var Game = (function() {
    function run() {
        var board = new Board()
        var snake = new Snake()
        var apple = new Apple()
        board.addSnake(snake)
        board.addApple(apple)

        var gameloop = setInterval(function() {
            board.clear()
            board.render()
            snake.advance()
        }, 60)
    }

    return {
        run: run
    }
})()

Game.run()