var totalSlides = 0;
var currentSlide = 1;
var contentSlides = "";
var prevSlide = 1;

$(document).ready(function(){

	$(".port-nav-back").click(showPreviousSlide);
	$(".port-nav-next").click(showNextSlide);

	contentSlides = $(".port_gallery");
	contentSlides.each(function(i){
		if (i != 0) {
			//$this.css('display','none');
			$("#gallery" + (i+1)).css("display","none");
			//alert(i);
		}
		
		totalSlides++;
	});
  
});

function showPreviousSlide()
{
	prevSlide = currentSlide;
	
	if (currentSlide == 1) {
		currentSlide = totalSlides;
	} else {
		currentSlide--;
	}
  	
  	updateContentHolder();
}

function showNextSlide()
{
	prevSlide = currentSlide;
	
	if (currentSlide == totalSlides) {
		currentSlide = 1;
	} else {
		currentSlide++;
	}

	updateContentHolder();
}

function updateContentHolder()
{
	$("#gallery" + prevSlide).fadeOut('slow');
	$("#gallery" + currentSlide).fadeIn('slow');
}