/* ---------------------------------------------------------------------------

    Copyright (C) 2006-2008   Valerio Proietti   mad4milk.net

    Script: Fx.Scroll.js
    Effect to smoothly scroll any element, including the window.
      Part of the Mootools 'More' library: mootools.net/more

  --------------------------------------------------------------------------- */


  Fx.Scroll = new Class({

    Extends: Fx,

    options: {
      offset: {'x': 0, 'y': 0},
      wheelStops: true
    },

    initialize: function(element, options){
      this.element = this.subject = $(element);
      this.parent(options);
      var cancel = this.cancel.bind(this, false);

      if ($type(this.element) != 'element') this.element = $(this.element.getDocument().body);

      var stopper = this.element;

      if (this.options.wheelStops){
        this.addEvent('start', function(){
          stopper.addEvent('mousewheel', cancel);
        }, true);
        this.addEvent('complete', function(){
          stopper.removeEvent('mousewheel', cancel);
        }, true);
      }
    },

    set: function(){
      var now = Array.flatten(arguments);
      this.element.scrollTo(now[0], now[1]);
    },

    compute: function(from, to, delta){
      var now = [];
      var x = 2;
      x.times(function(i){
        now.push(Fx.compute(from[i], to[i], delta));
      });
      return now;
    },

    start: function(x, y){
      if (!this.check(arguments.callee, x, y)) return this;
      var offsetSize = this.element.getSize(), scrollSize = this.element.getScrollSize();
      var scroll = this.element.getScroll(), values = {x: x, y: y};
      for (var z in values){
        var max = scrollSize[z] - offsetSize[z];
        if ($chk(values[z])) values[z] = ($type(values[z]) == 'number') ? values[z].limit(0, max) : max;
        else values[z] = scroll[z];
        values[z] += this.options.offset[z];
      }
      return this.parent([scroll.x, scroll.y], [values.x, values.y]);
    },

    toTop: function(){
      return this.start(false, 0);
    },

    toLeft: function(){
      return this.start(0, false);
    },

    toRight: function(){
      return this.start('right', false);
    },

    toBottom: function(){
      return this.start(false, 'bottom');
    },

    toElement: function(el){
      var position = $(el).getPosition(this.element);
      return this.start(position.x, position.y);
    }

  });