function Menu( elem, params ){
  this.element = jQuery(elem);
  this.params = params || {};

  this.classActiveItem = this.params.classActiveItem || 'JS-Menu-Item-active';
  this.fadeDuration = this.params.fadeDuration || 400;
  this.durationMultiplier = this.params.durationMultiplier || 5;
  this.minHeight = this.params.minHeight || 0;

  this.__construct();
}


  Menu.prototype.__construct = function(){
    this._isBusy = false;

    this.items = this.element.find('.JS-Menu-Item').has('.JS-Menu-Subitems');
    this.buttons = this.element.find('.JS-Menu-Button');
    this.subitems = this.element.find('.JS-Menu-Subitems');
    this.active = jQuery('.JS-Menu-Active').remove().removeClass('g-hidden');
    this.submenu = jQuery('.JS-Menu-Submenu');

    this.activeHeight = this.active.css({'visibility' : 'hidden'}).appendTo('body').height();
    this.active.remove().css({'visibility' : 'visible'});

    this._init();
  };
  Menu.prototype._init = function(){
    var context = this;

    this.items.has(this.subitems).find(this.buttons).bind('click', function(){ return context.setActiveItem.apply(context, [jQuery(this)]) });
    this._openSub(this.items.filter('.JS-Menu-Item-active'), 0);
  };


  Menu.prototype.setActiveItem = function( button ){
    if( this._isBusy ){
      return false;
    }

    var item = this.items.has(button),
        current = this.items.filter('.JS-Menu-Item-active'),
        itemLen = item.length,
        currentLen = current.length;

    if( !currentLen ){
      this._openSub(item, this.durationMultiplier);
    }else if( itemLen && current[0] != item[0] ){
      this._updateSub(item);
    }else{
      this._closeSub(item, this.durationMultiplier);
    }

    return false;
  };


  Menu.prototype._closeSub = function( item, durationMultiplier ){
    this._isBusy = true;

    var context = this,
        subWrapper = this.submenu.parent(),
        subHeight = subWrapper.height() - this.minHeight;

    item.removeClass(this.classActiveItem).removeClass('JS-Menu-Item-active');

    subWrapper.animate({'height' : this.minHeight + 'px'}, subHeight * durationMultiplier, function(){
      context.cb_closeSub.apply(context, [item, durationMultiplier]);
    });

    return false;
  };
  Menu.prototype.cb_closeSub = function( item, durationMultiplier ){
    var subWrapper = this.submenu.parent();

    subWrapper.css({'height' : this.minHeight + 'px'});
    this.submenu.find(this.subitems).appendTo(item).css({'margin-left' : '0px'});
    this.active.css({'height' : '0px'});
    this.final_closeSub(item);
  };
  Menu.prototype.final_closeSub = function( item ){
    this._isBusy = false;
  };


  Menu.prototype._openSub = function( item, durationMultiplier ){
    if( !item.length ){
      return false;
    }

    this._isBusy = true;

    var context = this,
        position = 0;

    item.addClass(this.classActiveItem).addClass('JS-Menu-Item-active');

    this.submenu.append(item.find(this.subitems));
    this.active.css({'height' : '0px'}).appendTo(item).animate({'height' : this.activeHeight + 'px'}, this.activeHeight * durationMultiplier, function(){
      context.cb_openSub.apply(context, [item, durationMultiplier]);
    });

    return false;
  };
  Menu.prototype.cb_openSub = function( item, durationMultiplier ){
    var viewportLeft, viewportWidth, subitemsPosition, subitemsWidth,
        context = this,
        subWrapper = this.submenu.parent(),
        subHeight = this.submenu.height(),
        subitems = this.submenu.find(this.subitems);

    subWrapper.css({'width' : '100%', 'height' : this.minHeight + 'px'});

    viewportLeft = this.submenu.offset().left;
    viewportWidth = this.submenu.width();
    subitemsPosition = item.offset().left - viewportLeft;
    subitemsWidth = subitems.outerWidth(true);
    if( subitemsPosition + subitemsWidth > viewportWidth ){
      subitemsPosition = viewportWidth - subitemsWidth - 1;
    }
    subitemsPosition = subitemsPosition < 0 ? 0 : subitemsPosition;
    subitems.css({'margin-left' : subitemsPosition + 'px'});

    subWrapper.animate({'height' : subHeight + 'px'}, (subHeight - this.minHeight) * durationMultiplier, function(){
      context.final_openSub.apply(context, [item]);
    });
  };
  Menu.prototype.final_openSub = function( item ){
    this._isBusy = false;
  };


  Menu.prototype._updateSub = function( item ){
    this._isBusy = true;

    var context = this,
        current = this.items.filter('.JS-Menu-Item-active');

    current.removeClass(this.classActiveItem).removeClass('JS-Menu-Item-active');
    item.addClass(this.classActiveItem).addClass('JS-Menu-Item-active');

    this.submenu.find(this.subitems).css({'opacity' : '1'}).animate({'opacity' : '0'}, this.fadeDuration/2, function(){
      context.cb_updateSub.apply(context, [item, current]);
    });

    return false;
  };
  Menu.prototype.cb_updateSub = function( item, current ){
    var subitemsWidth,
        context = this,
        viewportLeft = this.submenu.offset().left,
        viewportWidth = this.submenu.width(),
        subitems = item.find(this.subitems).css({'opacity' : '0'}),
        subitemsPosition = item.offset().left - viewportLeft;

    item.append(this.active);
    this.submenu.find(this.subitems).appendTo(current).css({'opacity' : '1', 'margin-left' : '0px'});
    this.submenu.append(subitems);

    subitemsWidth = subitems.outerWidth(true);
    if( subitemsPosition + subitemsWidth > viewportWidth ){
      subitemsPosition = viewportWidth - subitemsWidth - 1;
    }
    subitemsPosition = subitemsPosition < 0 ? 0 : subitemsPosition;
    subitems.css({'margin-left' : subitemsPosition + 'px'});

    subitems.animate({'opacity' : '1'}, this.fadeDuration/2, function(){
      context.final_updateSub.apply(context, [item, current]);
    });
  };
  Menu.prototype.final_updateSub = function( item, current ){
    this._isBusy = false;
  };
/*--/menu--*/