//create modal parent div and message div
function buildDiv() {
	if (document.createElement) {
	  var modalDiv = document.createElement("div");
	  modalDiv.setAttribute ("id", "modalMessageOverlay");
	  
	  var modalContent = document.createElement("div");
	  modalContent.setAttribute ("id", "messageBox");
	  modalContent.className ="popup_block";
	  
	  //grab serviceAnnouncement div that is included in header via ssi
	  var serviceAnnouncement = document.getElementById("serviceAnnouncement");
	  modalContent.appendChild(serviceAnnouncement);
	  
	  modalDiv.appendChild(modalContent);	
	  
	  document.getElementsByTagName("body")[0].appendChild(modalDiv);
	}
};
addLoadEvent(buildDiv);

//set toggle hidden and visible
function modalWindow() {
	var el = document.getElementById("modalMessageOverlay");
	el.style.visibility = (el.style.visibility == "visible") ? "hidden" : "visible";
	var el2 = document.getElementById("serviceAnnouncement");
	el2.style.visibility = (el2.style.visibility == "visible") ? "hidden" : "visible";
	el2.style.display = (el2.style.display == "block") ? "none" : "block";
	el2.style.height = "auto";
};

//bind onclick event to anchors with specific class
function toggleModalWindow() {
	var modalTriggers = document.getElementsByTagName("a");
	for (var i=0; i< modalTriggers.length; i++) {
		if (modalTriggers[i].className == "modalTrigger") {
			modalTriggers[i].onclick = function() {
				return modalWindow();
			};		
	 	}
	}
};
addLoadEvent(toggleModalWindow);

//determine height of browser window
function getWindowHeight() {var windowHeight = 0;
	if (typeof(window.innerHeight) == 'number') {
		windowHeight = window.innerHeight;
	}
	else {
		if (document.documentElement && document.documentElement.clientHeight) {
			windowHeight = document.documentElement.clientHeight;
		}
		else {
		
			if (document.body && document.body.clientHeight) {
				windowHeight = document.body.clientHeight;
			}
		}
	}
	return windowHeight;	
};

//set the distance from top of window on message div
function setContent() {
	if (!document.getElementById('messageBox')) {
		return false;
	}
	else {
		var windowHeight = getWindowHeight();
		if (windowHeight > 0) {
			var contentElement = document.getElementById('messageBox');
			var contentHeight = contentElement.offsetHeight;
			if (windowHeight - contentHeight > 0) {
				contentElement.style.position = 'relative';
				contentElement.style.top = ((windowHeight / 2) - (contentHeight / 2)) + 'px';
			}
			else {
				contentElement.style.position = 'static';
			}
		}
	}
};

//center message div on window.onload
function initSetContent() {
	setContent();
};
addLoadEvent(initSetContent);

//keep message div centered on window resize
window.onresize = function() {
	setContent();
};