Event.observe(window, 'load', function() {
	initViewer();
});

var v_pages, v_prev, v_next, v_cont;
var v_current = 1;

function initViewer() {
	var v = $('viewer');
	if (!v) return;
	
	v_prev = v.select('a.up')[0];
	v_next = v.select('a.down')[0];
	var num_v = v.select('li').length;
	v_cont = v.select('ul')[0];
	v_pages = (num_v > 3) ? Math.ceil(num_v / 3) : 1;
	if (v_pages > 1) {
		v_next.addClassName('down_more');
	}
}

function viewerMove(dir) {
	if (dir == 'prev') {
		if (v_current == 1) return;
		v_current--;
	} else {
		if (v_current == v_pages) return;
		v_current++;
	}
	
	new Effect.Move(v_cont, {y: (dir == 'prev' ? 3*93 : -(3*93) ), x: 0, mode: 'relative', queue: 'end'});
	
	if (v_current == 1) {
		v_prev.removeClassName('up_more');
		v_next.addClassName('down_more');
	} else if (v_current == v_pages ) {
		v_prev.addClassName('up_more');
		v_next.removeClassName('down_more');
	} else {
		v_prev.addClassName('up_more');
		v_next.addClassName('down_more');
	}
}

function changeProductImage(image, zoomImage) {
	var full_image = $('full_image');
	if (full_image) {
		$('full_image').writeAttribute('src', image);
		$('zoom_link').writeAttribute('href', zoomImage);
	}
}