var ARA = window.ARA || {};
  ARA.canvas = ARA.canvas || {};
  
  ARA.canvas.Starfield = function(el, params){
          this.canvas = ARA.dom.getElement(el);
          if(this.canvas && this.canvas.getContext){
                  this.ctx = this.canvas.getContext('2d');
          }else{
                  return null;
          }
          
          params = params || {};
          this.fullScreen = !!params.fullScreen;
          this.xLimit = this.canvas.offsetWidth/2;
          this.yLimit = this.canvas.offsetHeight/2;
          this.zLimit = params.depth || 255;
          this.wave = {degree:0, dir:.1, ampl:25, freq:100};
          this.animSpeed = params.animSpeed || 50;
          this.starCount = params.starCount || 100;
          this.zoomLimit = params.zoomLimit || 2;
          this.zoomFactor = params.zoomFactor || .035;
          this.starShape = params.starShape || "star";
          this.waveX = params.waveX || false;
          this.waveY = params.waveY || false;
          this.stars = [];
          this.started = false;
          this.init();
  };
  
  ARA.canvas.Starfield.prototype.toString = function(){
          return "Starfield#" + this.canvas.id;
  };
  
  ARA.canvas.Starfield.prototype.init = function(){
          this.ctx.translate(this.xLimit, this.yLimit);
          this.stars = [];
          for(var i=0; i<this.starCount; i++){
                  this.stars.push({
                          x:this.newX(),
                          y:this.newY(),
                          z:this.newZ(),
                          acc:this.newAcc(),
                          color:this.newColor()
                  });
                  this.ctx.fillStyle = "rgb(" + this.stars[i].color + "," + this.stars[i].color + "," + this.stars[i].color + ")";
          }
  };
  
  ARA.canvas.Starfield.prototype.start = function(){
          this.started = true;
          this.intervalId = window.setInterval(function(objRef){
                  return function(){
                          objRef.oneStepForward.call(objRef)
                  }
          }(this), this.animSpeed);
  };
  
  ARA.canvas.Starfield.prototype.stop = function(){
          this.started = false;
          window.clearInterval(this.intervalId);
  };
  
  ARA.canvas.Starfield.prototype.oneStepForward = function(){
          this.ctx.clearRect(-this.xLimit, -this.yLimit, this.xLimit*2, this.yLimit*2);
          for(var i=0; i<this.starCount; i++){
                  var star = this.stars[i];
                  
                  if(Math.abs(star.x) > this.xLimit){
                          this.recycleStar(star);
                  }else{
                          star.x += (star.x * star.acc) / 200;
                          if(this.waveX) star.x += this.wave.ampl * Math.sin(this.wave.degree);
                  }
  
                  if(Math.abs(star.y) > this.yLimit){
                          this.recycleStar(star);
                  }else{
                          star.y += (star.y * star.acc) / 200;
                          if(this.waveY) star.y += this.wave.ampl * Math.sin(this.wave.degree);
                  }
                  
                  star.z = (star.z < this.zoomLimit) ? star.z + this.zoomFactor : star.z;
                  star.color += (star.color < 255) ? star.acc : 0;
  
                  this.drawStar(star);
          }
          if(this.waveX || this.waveY){
                  if(this.wave.degree > 90 || this.wave.degree < 0) this.wave.dir *= -.1;
                  this.wave.degree += this.wave.dir;
          }
  }
  
  ARA.canvas.Starfield.prototype.drawStar = function(star){
          
          this.ctx.fillStyle = "rgb(" + star.color + "," + star.color + "," + star.color + ")";
          switch(this.starShape){
                  case "square":
                          this.ctx.fillRect(star.x, star.y, star.z, star.z);
                  break;
                  
                  case "circle":
                          this.ctx.beginPath();
                          this.ctx.arc(star.x, star.y, star.z, 0, Math.PI*2, true);
                          this.ctx.fill();
                  break;
                  
                  case "star":
                          var starCoords = ARA.canvas.Starfield.shapes.star;                
                          this.ctx.beginPath();
                          this.ctx.moveTo(star.x, star.y);
                          for(var i=0; i<starCoords.length; i++){
                                  var coord = starCoords[i];
                                  this.ctx.lineTo(star.x - coord.x * star.z, star.y - coord.y * star.z);
                          }
                          this.ctx.fill();
                  break;
          }
  }
  
  ARA.canvas.Starfield.prototype.recycleStar = function(star){
          star.x = this.newX();
          star.y = this.newY();
          star.z = this.newZ();
          star.acc = this.newAcc();
          star.color = this.newColor();
  }
  
  ARA.canvas.Starfield.prototype.newX = function(){
          return ARA.utils.random(-this.xLimit, this.xLimit);
  }
  
  ARA.canvas.Starfield.prototype.newY = function(){
          return ARA.utils.random(-this.yLimit, this.yLimit);
  }
  
  ARA.canvas.Starfield.prototype.newZ = function(){
          return .1;
  }
  
  ARA.canvas.Starfield.prototype.newAcc = function(){
          return ARA.utils.random(5, 25);
  }
  
  ARA.canvas.Starfield.prototype.newColor = function(){
          return 0;
  }
  
  ARA.canvas.Starfield.shapes = {};
  ARA.canvas.Starfield.shapes.star = [
          {x:0,y:0},
          {x:1.27595,y:-2.58545},
          {x:4.12915,y:-3},
          {x:2.06455,y:-5.0125},
          {x:2.55195,y:-7.85415},
          {x:0,y:-6.5125},
          {x:-2.552,y:-7.85415},
          {x:-2.0646,y:-5.0125},
          {x:-4.1292,y:-3},
          {x:-1.276,y:-2.58545}
  ];