Rico.ArrayExtensions = new Array();

Rico.Effect = {};
Rico.Effect.FadeTo = Class.create();
Rico.Effect.FadeTo.prototype = {

   initialize: function( element, opacity, duration, steps, options) {
      this.element  = $(element);
      this.opacity  = opacity;
      this.duration = duration;
      this.steps    = steps;
      this.options  = arguments[4] || {};
      this.fadeTo();
   },

   fadeTo: function() {
      if (this.isFinished()) {
         if(this.options.complete) this.options.complete(this);
         return;
      }

      if (this.timer)
         clearTimeout(this.timer);

      var stepDuration = Math.round(this.duration/this.steps) ;
      var currentOpacity = this.getElementOpacity();
      var delta = this.steps > 0 ? (this.opacity - currentOpacity)/this.steps : 0;

      this.changeOpacityBy(delta);
      this.duration -= stepDuration;
      this.steps--;

      this.timer = setTimeout(this.fadeTo.bind(this), stepDuration);
   },

   changeOpacityBy: function(v) {
      var currentOpacity = this.getElementOpacity();
      var newOpacity = Math.max(0, Math.min(currentOpacity+v, 1));
      this.element.ricoOpacity = newOpacity;

      this.element.style.filter = "alpha(opacity:"+Math.round(newOpacity*100)+")";
      this.element.style.opacity = newOpacity; /*//*/;
   },

   isFinished: function() {
      return this.steps <= 0;
   },

   getElementOpacity: function() {
      if ( this.element.ricoOpacity == undefined ) {
         var opacity = RicoUtil.getElementsComputedStyle(this.element, 'opacity');
         this.element.ricoOpacity = opacity != undefined ? opacity : 1.0;
      }
      return parseFloat(this.element.ricoOpacity);
   }
}

var RicoUtil = {
   getElementsComputedStyle: function ( htmlElement, cssProperty, mozillaEquivalentCSS) {
      if ( arguments.length == 2 )
         mozillaEquivalentCSS = cssProperty;

      var el = $(htmlElement);
      if ( el.currentStyle )
         return el.currentStyle[cssProperty];
      else
         return document.defaultView.getComputedStyle(el, null).getPropertyValue(mozillaEquivalentCSS);
   }
};