var useBSNns;

if (useBSNns)
{
	if (typeof(bsn) == "undefined")
		bsn = {}
	var _bsn = bsn;
}
else
{
	var _bsn = this;
}

// Constructor

_bsn.Crossfader = function (divs, fadetime, delay )
{	
	this.nAct = -1;
	this.aDivs = divs;
	
	for (var i=0;i<divs.length;i++)
	{
		$(divs[i]).style.opacity = 0;
		$(divs[i]).style.position = "absolute";
		$(divs[i]).style.filter = "alpha(opacity=0)";
		$(divs[i]).style.visibility = "hidden";
	}
	
	this.nDur = fadetime;
	this.nDelay = delay;

	this.stopPending = false;
	this.stopped = false;
		
	this._newfade();
}

// Public methods

_bsn.Crossfader.prototype.StopFade = function()
{
	if (this.stopped || this.stopPending)
	{
		return;
	}
	this.stopPending = true;
	//if (this.nID1)
	//	clearInterval(this.nID1);
}

_bsn.Crossfader.prototype.StartFade = function()
{
	if (this.stopPending)
	{
		this.stopPending = false; // Cancel pending stop
		return;
	}
	else if (!this.stopped)
	{
		return;
	}
	this._newfade();
}

_bsn.Crossfader.prototype.SetFade = function(newFade)
{
	newFade = parseFloat(newFade);
	if (isNaN(newFade))
	{
		return "Value provided for new fade time must be numeric";
	}
	if (newFade < 0)
	{
		return "Value provided for new fade time cannot be negative";
	}

	this.StopFade();
	this.nDur = newFade * 1000;
	this.StartFade();
	return "";
}

_bsn.Crossfader.prototype.SetDelay = function(newDelay)
{
	newDelay = parseFloat(newDelay);
	if (isNaN(newDelay))
	{
		return "Value provided for new display time must be numeric";
	}
	if (newDelay <= 0)
	{
		return "Value provided for new display time must be greater than zero";
	}

	this.StopFade();
	this.nDelay = newDelay * 1000;
	this.StartFade();
	return "";
}

// Private methods

_bsn.Crossfader.prototype._newfade = function()
{
	if (this.nID1)
		clearInterval(this.nID1);

	if (this.stopPending)
	{
		this.stopPending = false;
		this.stopped = true;
		return;
	}
	this.stopped = false;
	
	this.nOldAct = this.nAct;
	this.nAct++;
	if (!this.aDivs[this.nAct])	this.nAct = 0;
	
	if (this.nAct == this.nOldAct)
		return false;
	
	$( this.aDivs[this.nAct] ).style.visibility = "visible";
	
	this.nInt = 50;
	this.nTime = 0;
	
	var p=this;
	this.nID2 = setInterval(function() { p._fade() }, this.nInt);
}

_bsn.Crossfader.prototype._fade = function()
{
	this.nTime += this.nInt;
	
	var ieop = Math.round( this._easeInOut(this.nTime, 0, 1, this.nDur) * 100 );
	var op = ieop / 100;
	$( this.aDivs[this.nAct] ).style.opacity = op;
	$( this.aDivs[this.nAct] ).style.filter = "alpha(opacity="+ieop+")";
	
	if (this.nOldAct > -1)
	{
		$( this.aDivs[this.nOldAct] ).style.opacity = 1 - op;
		$( this.aDivs[this.nOldAct] ).style.filter = "alpha(opacity="+(100 - ieop)+")";
	}
	
	if (this.nTime == this.nDur)
	{
		clearInterval( this.nID2 );
		
		if (this.nOldAct > -1)
			$( this.aDivs[this.nOldAct] ).style.visibility = "hidden";	
		
		var p=this;
		this.nID1 = setInterval(function() { p._newfade() }, this.nDelay);
	}
}

_bsn.Crossfader.prototype._easeInOut = function(t,b,c,d)
{
	return c/2 * (1 - Math.cos(Math.PI*t/d)) + b;
}