function makeHttpRequest(url, callback_function, return_xml)
{
    var http_request = false;

    if (window.XMLHttpRequest) { // Mozilla, Safari,...
        http_request = new XMLHttpRequest();
        if (http_request.overrideMimeType) {
            http_request.overrideMimeType('text/xml');
        }
    } else if (window.ActiveXObject) { // IE
        try {
            http_request = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (e) {
            try {
                http_request = new ActiveXObject("Microsoft.XMLHTTP");
            } catch (e) {}
        }
    }

    if (!http_request) {
        alert('Unfortunatelly you browser doesn\'t support this feature.');
        return false;
    }
    http_request.onreadystatechange = function() {
        if (http_request.readyState == 4) {
            if (http_request.status == 200) {
                if (return_xml) {
                    eval(callback_function + '(http_request.responseXML)');
                } else {
                    eval(callback_function + '(http_request.responseText)');
                }
            } else {
                alert('There was a problem with the request.(Code: ' + http_request.status + ')');
            }
        }
    }
    http_request.open('GET', url, true);
    http_request.send(null);
}


function makePostAjaxRequest(url, parameters, callback_function, return_xml)
{
    var http_request = false;

    if (window.XMLHttpRequest) { // Mozilla, Safari,...
        http_request = new XMLHttpRequest();
        if (http_request.overrideMimeType) {
            http_request.overrideMimeType('text/xml');
        }
    } else if (window.ActiveXObject) { // IE
        try {
            http_request = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (e) {
            try {
                http_request = new ActiveXObject("Microsoft.XMLHTTP");
            } catch (e) {}
        }
    }

    if (!http_request) {
        alert('Unfortunatelly you browser doesn\'t support this feature.');
        return false;
    }
    http_request.onreadystatechange = function() {
        if (http_request.readyState == 4) {
            if (http_request.status == 200) {
                if (return_xml) {
                    eval(callback_function + '(http_request.responseXML)');
                } else {
                    eval(callback_function + '(http_request.responseText)');
                }
            } else {
                alert('There was a problem with the request.(Code: ' + http_request.status + ')');
            }
        }
    }

	http_request.open('POST', url, true);
	http_request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	http_request.setRequestHeader("Content-length", parameters.length);
	http_request.setRequestHeader("Connection", "close");
	http_request.send(parameters);
}


function addComp(compID, userID) {
	thisCompID = compID;
	var parameters = "addAjaxComp=1&compID=" + compID + "&userID=" + userID;
	parameters = encodeURI(parameters);
	makePostAjaxRequest('php/submit.php', parameters, 'updateComps', false);
}

function updateComps(xmldoc) {
	compTextID = "compText" + thisCompID;
	participateID = "participate" + thisCompID;
	document.getElementById(compTextID).innerHTML = "Thank you for applying " + userName + ", <br/>We will notify you if you are a winner of this competition.";
	document.getElementById(compTextID).style.color = "#ED145A";
	document.getElementById(participateID).style.display = "none";
}