g_columnsArray = [];

$(document).ready(function(){
	collectColumnsArray();
	determineArtworksPaging();
});

collectColumnsArray = function(){
	var array = document.getElementById("artworksContainer").getElementsByTagName("div");
	
	for (var i=0; i<array.length; i++){
		if (parseInt(array[i].getAttribute("isArtworkColumn"),10) > 0){
			g_columnsArray.push(array[i]);
		}
	}
	
	$("#backwardButton").bind("click", function(e){
		for (var i=0; i<g_columnsArray.length; i++){
			if (parseInt(g_columnsArray[i].getAttribute("isVisible"),10) > 0){
				if (i==0) { 
					return;
				} else {
					break;
				}
			}
		}
		
		g_columnsArray[i].className = "artworksColumn";		
		
		i--;
		
		g_columnsArray[i].className = "firstArtworksColumn";
		g_columnsArray[i].setAttribute("isVisible",1);
		
		var indexToShut = i+4;
		
		g_columnsArray[indexToShut].className = "disabledArtworksColumn";
		g_columnsArray[indexToShut].setAttribute("isVisible",0);
		determineArtworksPaging();
	});
	
	$("#forwardButton").bind("click", function(e){		
		for (var i=g_columnsArray.length-1; i>0; i--){
			if (parseInt(g_columnsArray[i].getAttribute("isVisible"),10) > 0){
				if (i==g_columnsArray.length) {
					return;
				} else {
					break;
				}
			}
		}
		
		i++;
		
		g_columnsArray[i].className = "artworksColumn";
		g_columnsArray[i].setAttribute("isVisible",1);
		
		var indexToShut = i-4;
		g_columnsArray[indexToShut].className = "disabledArtworksColumn";
		g_columnsArray[indexToShut].setAttribute("isVisible",0);
		
		var indexToChangeClass = i-3;
		g_columnsArray[indexToChangeClass].className = "firstArtworksColumn";
		determineArtworksPaging();
	});
};

determineArtworksPaging = function(){
	if (parseInt(g_columnsArray[0].getAttribute("isVisible"),10) > 0){		
		$("#backwardButton").css("display","none");
	} else {		
		$("#backwardButton").css("display","block");
	}
	
	var lastIndex = g_columnsArray.length-1;

	if (parseInt(g_columnsArray[lastIndex].getAttribute("isVisible"),10) > 0){
		$("#forwardButton").css("display","none");
	} else {
		$("#forwardButton").css("display","block");
	}
};