$(document).ready(function(){
	$('.carousel a.shift_left').click(shift_left);
	$('.carousel a.shift_right').click(shift_right);
	if(! has_previous()){
		disable_left();
	}
	if(! has_next()){
		disable_right();
	}
})

function disable_left(){
	$('.carousel a.shift_left').attr('disabled','disabled');
	$('.carousel a.shift_left').addClass('disabled');
	$('.carousel a.shift_left img').attr('src', '/img/ranking-end.png');
}

function disable_right(){
	$('.carousel a.shift_right').attr('disabled','disabled');
	$('.carousel a.shift_right').addClass('disabled');
	$('.carousel a.shift_right img').attr('src','/img/ranking-end.png');
}

function has_previous(){
	var left_visible=$('.carousel .carousel-element:visible:first');
	var left_notvisible=$(left_visible).prev('.carousel-element');
	if($(left_notvisible).length==0){
		return false;
	}
	else{
		return true;
	}
}

function has_next(){
	var right_visible=$('.carousel .carousel-element:visible:last');
	var right_notvisible=$(right_visible).next('.carousel-element');
	if($(right_notvisible).length==0){
		return false;
	}
	else{
		return true;
	}
}

function shift_left(){
	var left_visible=$('.carousel .carousel-element:visible:first');
	var left_notvisible=$(left_visible).prev('.carousel-element');
	var right_visible=$('.carousel .carousel-element:visible:last');
	if(left_notvisible.length>0){
		$(left_notvisible).show();
		$(right_visible).hide();
		
		if($(left_notvisible).prev('.carousel-element').length==0){
			disable_left();
		}
		
		$('.carousel a.shift_right img').attr('src', '/img/ranking-right.png');
		$('.carousel a.shift_right').removeAttr('disabled');
		$('.carousel a.shift_right').removeClass('disabled');
		
	}
}

function shift_right(){
	var left_visible=$('.carousel .carousel-element:visible:first');
	var right_visible=$('.carousel .carousel-element:visible:last');
	var right_notvisible=$(right_visible).next('.carousel-element');
	if(right_notvisible.length>0){
		$(left_visible).hide();
		$(right_notvisible).show();
		if($(right_notvisible).next('.carousel-element').length==0){
			disable_right();
		}
		$('.carousel a.shift_left img').attr('src', '/img/ranking-left.png');
		$('.carousel a.shift_left').removeAttr('disabled');
		$('.carousel a.shift_left').removeClass('disabled');
	}
	
}