var Game = Game || {};
var Keyboard = Keyboard || {};
var Component = Component || {};
Keyboard.Keymap = {
37: 'left',
38: 'up',

39: 'right',
40: 'down'
};
Keyboard.ControllerEvents = function () {
var self = this;
this.pressKey = null;

this.keymap = Keyboard.Keymap;

document.onkeydown = function (event) {
self.pressKey = event.which;
};

this.getKey = function () {
return this.keymap[this.pressKey];
};

};
Component.Stage = function (canvas, conf) {
this.keyEvent = new Keyboard.ControllerEvents();
this.width = canvas.width;

this.height = canvas.height;

this.length = [];
http://this.food = {};
this.score = 0;
this.direction = 'right';
this.conf = {
cw: 10,
size: 5,
fps: 1000
};
if (typeof conf == 'object') {
for (var key in conf) {
if (conf.hasOwnProperty(key)) {

this.conf[key] = conf[key];
}
}
}
};
Component.Snake = function (canvas, conf) {
this.stage = new Component.Stage(canvas, conf);

this.initSnake = function () {

for (var i = 0; i < this.stage.conf.size; i++) {

this.stage.length.push({ x: i, y: 0 });

}

};

this.initSnake();
this.initFood = function () {
http://this.stage.food = {

x: Math.round(Math.random() * (this.stage.width - http://this.stage.conf.cw) / http://this.stage.conf.cw),

y: Math.round(Math.random() * (this.stage.height - http://this.stage.conf.cw) / http://this.stage.conf.cw),

};
};
this.initFood();
this.restart = function () {
this.stage.length = [];

http://this.stage.food = {};

this.stage.score = 0;
this.stage.direction = 'right';
this.stage.keyEvent.pressKey = null;
this.initSnake();
this.initFood();
};
};
Game.Draw = function (context, snake) {
this.drawStage = function () {
var keyPress = snake.stage.keyEvent.getKey();

if (typeof (keyPress) != 'undefined') {

snake.stage.direction = keyPress;

}
context.fillStyle = "white";
context.fillRect(0, 0, snake.stage.width, snake.stage.height);
var nx = snake.stage.length[0].x;

var ny = snake.stage.length[0].y;
switch (snake.stage.direction) {

case 'right':
nx++;

break;
case 'left':
nx--;
break;
case 'up':
ny--;
break;
case 'down':
ny++;
break;
}
if (this.collision(nx, ny) == true) {
snake.restart();
return;

}
if (nx == http://snake.stage.food.x && ny == http://snake.stage.food.y) {
var tail = { x: nx, y: ny };
snake.stage.score++;

snake.initFood();
} else {
var tail = snake.stage.length.pop();
tail.x = nx;
tail.y = ny;
}
snake.stage.length.unshift(tail);
for (var i = 0; i < snake.stage.length.length; i++) {
var cell = snake.stage.length[i];
this.drawCell(cell.x, cell.y);

}
this.drawCell(http://snake.stage.food.x, http://snake.stage.food.y);
context.fillText('Score: ' + snake.stage.score, 5, (snake.stage.height - 5));
};

this.drawCell = function (x, y) {

context.fillStyle = 'orange';
context.fillRect(x * http://snake.stage.conf.cw + 1, y * http://snake.stage.conf.cw + 1, http://snake.stage.conf.cw - 2, http://snake.stage.conf.cw - 2);

};
this.collision = function (nx, ny) {
if (nx == -1 || nx == (snake.stage.width / http://snake.stage.conf.cw) || ny == -1 || ny == (snake.stage.height / http://snake.stage.conf.cw)) {
return true;

}
return false;
}
};
Game.Snake = function (elementId, conf) {
var canvas = document.getElementById(elementId);
var context = canvas.getContext("2d");
var snake = new Component.Snake(canvas, conf);
var gameDraw = new Game.Draw(context, snake);
setInterval(function () { gameDraw.drawStage(); }, snake.stage.conf.fps);

};

window.onload = function () {
var snake = new Game.Snake('stage', { fps: 100, size: 4 });
};