var displaybox = document.getElementById("displaybox");
var popUpMessage = document.getElementById("popUpMessage");
var popup_link = document.getElementById("popup_link");
var t;

function hidePopUp() {
    if (displaybox) {
        displaybox.style.display = "none";
        if (popUpMessage) {
            popUpMessage.style.display = "none";
            clearTimeout(t);
        }

    }
}


function showPopUp(url, text) {
    if (displaybox) {
        displaybox.style.display = "";
        displaybox.style.height = getDocHeight() + "px";

        if (popUpMessage) {
            popUpMessage.style.display = "";

            var s = getScrollOffset();
            positionPopUp(popUpMessage, s);

            if (popup_link) {
                popup_link.href = url;
                popup_link.innerHTML = text;

                t = setTimeout("location.href='" + url + "'", 15000);
            }
        }

    }

}

function getDocHeight() {
    var D = document;
    return Math.max(
                    Math.max(D.body.scrollHeight, D.documentElement.scrollHeight),
                    Math.max(D.body.offsetHeight, D.documentElement.offsetHeight),
                    Math.max(D.body.clientHeight, D.documentElement.clientHeight)
                );
}

function pageWidth() {
    return window.innerWidth != null ? window.innerWidth : document.documentElement && document.documentElement.clientWidth ? document.documentElement.clientWidth : document.body != null ? document.body.clientWidth : null;
}

function pageHeight() {
    return window.innerHeight != null ? window.innerHeight : document.documentElement && document.documentElement.clientHeight ? document.documentElement.clientHeight : document.body != null ? document.body.clientHeight : null;
}

function positionPopUp(x, scrollY) {

    //get viewport's width and height
    var vpWidth = pageWidth();
    var vpHeight = pageHeight();
    var diff = (screen.height - vpHeight) / 2;

    //get DIV's width and height
    var dialogWidth = x.offsetWidth;
    var dialogHeight = x.offsetHeight;

    //calculate position
    var dialogTop = (vpHeight / 2) - (dialogHeight / 2); // - diff;
    var dialogLeft = (vpWidth / 2) - (dialogWidth / 2);


    //Position the Dialog
    x.style.top = dialogTop + scrollY + "px";
    x.style.left = dialogLeft + "px";


}


window.onscroll = scroll;

function scroll() {
    var s = getScrollOffset();

    if (popUpMessage) {
        positionPopUp(popUpMessage, s);
    }

}

function getScrollOffset() {
    var s;
    // scrolling offset calculation 
    if (self.pageYOffset) {
        s = self.pageYOffset;
    } else if (document.documentElement && document.documentElement.scrollTop) {
        s = document.documentElement.scrollTop;
    } else if (document.body) {
        s = document.body.scrollTop;
    }

    return s;
}