// Set a browser cookie with name and value
function setCookie(name, value) {
	document.cookie = name + "=" + value + "" + "; path=/";
}

// Return the value of the browser cookie name, or null if none
function getCookie(name) {
	var cookies = document.cookie.split(';');
	var name = name + "=";
	for(var i = 0; i < cookies.length; i++) {
		var cookie = cookies[i];
				while (cookie.charAt(0)==' ') {
			cookie = cookie.substring(1, cookie.length);
		}
		if (cookie.indexOf(name) == 0) {
			return cookie.substring(name.length, cookie.length);
		}
	}
	return null;
}

// Delete the browser cookie name
function removeCookie(name) {
	document.cookie = name + "=''; expires=Fri, 13 Jul 2001 00:00:00 UTC; path=/";
}

// Set the display for elementId to displayState
function setStyleDisplay(elementId, displayState) {
  var element = document.getElementById(elementId);
  if (element) {
    element.style.display = displayState;
  }
}

// Show the control panel based on the user's preferences
function adjustControlPanelVisibility() {
  if (getCookie("controlPanel")) {
	  setStyleDisplay("controlPanelOff", getCookie("controlPanelOff"));
	  setStyleDisplay("controlPanel", getCookie("controlPanel"));
  }
  else {
	  setStyleDisplay("controlPanelOff", "inline");
  }
}	

// Toggle the control panel
function toggleControlPanel() {

  // Toggle the control panel visibility
  document.getElementById("controlPanelOff").style.display = document.getElementById("controlPanelOff").style.display == "none" ? "inline" : "none";
  toggleVisibility("controlPanel");

  // Remember what's showing 
  setCookie("controlPanelOff", document.getElementById("controlPanelOff").style.display);
  setCookie("controlPanel",    document.getElementById("controlPanel").style.display);
}

// Return the div id corresponding to the toggle arrow for expanding menu menuId
function toggleMenuArrow(menuId) {
    return menuId + "_toggle";
}

// Toggle expanding menu named menuId
function toggleMenu(menuId) {

    // Toggle the control panel visibility
    toggleVisibility(menuId);

    // Note the new display state
    state = document.getElementById(menuId).style.display;

    // Remember what's showing 
    setCookie(menuId, state);
    
    // Adjust the arrow
    document.getElementById(toggleMenuArrow(menuId)).className = (state == "block") ? "menuOpen" : "menuClosed";
}

// Adjust the visibility for the expanding menu based on the user's selection, defaulting to open
function adjustMenuVisibility(menuId) {
    state = getCookie(menuId) ? getCookie(menuId) : "none";
    if (document.getElementById(menuId)) {
        document.getElementById(menuId).style.display = state;
    }
    if (document.getElementById(toggleMenuArrow(menuId))) {
        document.getElementById(toggleMenuArrow(menuId)).className = (state == "block") ? "menuOpen" : "menuClosed";
    }
}