var itemsPerPages = 12;

function checkScroll(){
	var containerHeight = parseInt($("#bb-res-frame").height()) + 14;
	var results = $(".s-results").length;
	var pages = Math.ceil(results / itemsPerPages);
	var maxMargin = -(containerHeight * pages);
	
	var currentMargin = parseInt($("#bb-res-contents").css("marginTop"));
	currentMargin = isNaN(currentMargin) ? 0 : currentMargin;

	if (currentMargin < 0) {
		$("#scroll_up").fadeIn(300);
	}
	else 
		$("#scroll_up").fadeOut(300);
		if (currentMargin - containerHeight <= maxMargin) 
			$("#scroll_down").fadeOut(300);
		else
			$("#scroll_down").fadeIn(300);
}

function scrollDown(containerHeight, maxmargin){
	var currentMargin = parseInt($("#bb-res-contents").css("marginTop"));
	currentMargin = isNaN(currentMargin) ? 0 : currentMargin;
	var marginToSet = parseInt(currentMargin - containerHeight);

	if(maxmargin < marginToSet){
		$("#bb-res-contents").animate({ 
	        marginTop: marginToSet
	      }, 500, checkScroll);
	}
}

function scrollUp(containerHeight){
	var currentMargin = parseInt($("#bb-res-contents").css("marginTop"));
	var marginToSet = currentMargin + containerHeight;
	if(marginToSet <= 0){
		$("#bb-res-contents").animate({ 
	        marginTop: marginToSet
	      }, 500, checkScroll);
	}
}

	
$(document).ready(function(){
	var containerHeight = parseInt($("#bb-res-frame").height()) + 14;
	var results = $(".s-results").length;
	var pages = Math.ceil(results / itemsPerPages);
	var maxMargin = - (containerHeight * pages);
	if(pages > 1){
		
		$("#scroll_down").fadeIn(300);
	}
	
	$("#scroll_down").click(function(){
		scrollDown(containerHeight, maxMargin);
	});
	
	$("#scroll_up").click(function(){
		scrollUp(containerHeight);
	});
});