var photos;

function next() {
	arr = photos.split(",");
	img = document.getElementById("leftimgimg");
	for (i = 0; i < arr.length; i++) {
		if (src2file(img.src) == arr[i]) {
			img.src = (i == arr.length - 1) ? img.src.replace(src2file(img.src), arr[0]) : img.src.replace(src2file(img.src), arr[i+1]);
			btns((i == arr.length - 1) ? 0 : i+1, arr.length - 1); 
			break;
		}
	}
}

function prev() {
	arr = photos.split(",");
	img = document.getElementById("leftimgimg");
	for (i = 0; i < arr.length; i++) {
		if (src2file(img.src) == arr[i]) {
			img.src = (i == 0) ? img.src.replace(src2file(img.src), arr[arr.length - 1]) : img.src.replace(src2file(img.src), arr[i-1]);
			btns((i == 0) ? arr.length - 1 : i-1, arr.length - 1); 
			break;
		}
	}
}

function btns(i, max) {
	btn = document.getElementById("previmg"); 
	btn.style.display = (i == 0) ? "none" : "block";
	
	btn = document.getElementById("nextimg"); 
	btn.style.display = (i == max) ? "none" : "block";
}

function src2file(src) {
	return src.substring(src.lastIndexOf("/") + 1, src.length); // - src.lastIndexOf("/") + 1
}