var ajaxreq = false, ajaxCallback;

var imgKadraId = 'swap_kadra_img';
var imgStudId = 'swap_stud_img';

var timerID = null;
var timerTick = 5;

var phpScript = 'gal_swap.php';

function startTimer() {
	timerID = setTimeout('getImgSrc()', timerTick * 1000);
}

function ajaxRequest(filename, params) {
	try {
		ajaxreq = new XMLHttpRequest();
	}
	catch (error) {
		try {
			ajaxreq = new ActiveXObject("Microsoft.XMLHTTP");
		}
		catch (error) {
			return false;
		}
	}
	
	ajaxreq.open('POST', filename);
	ajaxreq.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded')
	ajaxreq.onreadystatechange = ajaxResponse;
	ajaxreq.send(params);
}

function ajaxResponse() {
	if (ajaxreq.readyState != 4)
		return;
	if (ajaxreq.status == 200) {
		if (ajaxCallback)
			ajaxCallback();
	}
	else {
		alert("Błąd żądania[" + ajaxreq.status + "]: " + ajaxreq.statusText);
	}
	return true;
}

function trim(str) {
	return str.replace(/^\s+|\s+$/g, '');
}

function swapImages() {
	var r = trim(ajaxreq.responseText);
	if (r != '') {
		var tmp = r.split('#');
		
		if (tmp[0] != 'err') {
			document.images[imgStudId].src = tmp[0];
		}
		if (tmp[1] != 'err') {
			document.images[imgKadraId].src = tmp[1];
		}
	}
	
	startTimer();
}

function getImgSrc() {
	var params = 'src_stud=' + document.images[imgStudId].src;
	params += '&src_kadra=' + document.images[imgKadraId].src;
	var path = phpScript;
	
	ajaxCallback = swapImages;
	ajaxRequest(path, params);
}