/* scroll spy plugin / class */
var ScrollSpy = new Class({
    /* implements */
    Implements: [Options,Events],
    /* options */
    options: {
        min: 0,
        mode: 'vertical',
        max: 0,
        container: window,
        onEnter: $empty,
        onLeave: $empty,
        onTick: $empty
    },
    /* initialization */
    initialize: function(options) {
        /* set options */
        this.setOptions(options);
        this.container = $(this.options.container);
        this.enters = this.leaves = 0;
        this.max = this.options.max;
        /* fix max */
        if(this.max == 0)
        {
            var ss = this.container.getScrollSize();
            this.max = this.options.mode == 'vertical' ? ss.y : ss.x;
        }
        /* make it happen */
        this.addListener();
    },
    /* a method that does whatever you want */
    addListener: function() {
        /* state trackers */
        this.inside = false;
        this.container.addEvent('scroll',function() {
            /* if it has reached the level */
            var position = this.container.getScroll();
            var xy = this.options.mode == 'vertical' ? position.y : position.x;
            /* if we reach the minimum and are still below the max... */
            if(xy >= this.options.min && xy <= this.max) {
                    /* trigger Enter event if necessary */
                    if(!this.inside) {
                        /* record as inside */
                        this.inside = true;
                        this.enters++;
                        /* fire enter event */
                        this.fireEvent('enter',[position,this.enters]);
                    }
                    /* trigger the "tick", always */
                    this.fireEvent('tick',[position,this.inside,this.enters,this.leaves]);
            }
            else {
                /* trigger leave */
                if(this.inside)
                {
                    this.inside = false;
                    this.leaves++;
                    this.fireEvent('leave',[position,this.leaves]);
                }
            }
        }.bind(this));
    }
});
window.addEvent('domready',function() {
	/* smooth */
	new SmoothScroll({duration:500});
	
	/* link management */
	$('gototop').set('opacity','0').setStyle('display','block');
	
	/* scrollspy instance */
	var ss = new ScrollSpy({
		min: 200,
		onEnter: function(position,state,enters) {
			$('gototop').fade('in');
		},
		onLeave: function(position,state,leaves) {
			$('gototop').fade('out');
		},
		container: window
	});
});