// Personal selection cookie format is:
//
// cookie name = psel
// data = {work ID1}-0/1~{work ID2}-0/1~{work IDn}-0/1~
// where the 0/1 is either zero or one, 0=delete, 1=include

// name - name of the cookie
// value - value of the cookie
// [expires] - expiration date of the cookie (defaults to end of current session)
// [path] - path for which the cookie is valid (defaults to path of calling document)
// [domain] - domain for which the cookie is valid (defaults to domain of calling document)
// [secure] - Boolean value indicating if the cookie transmission requires a secure transmission
// * an argument defaults when it is assigned null as a placeholder
// * a null placeholder is not required for trailing omitted arguments
function setCookie(name, value, expires, path, domain, secure) {
  var curCookie = name + "=" + escape(value) +
      ((expires) ? "; expires=" + expires.toGMTString() : "") +
      ((path) ? "; path=" + path : "") +
      ((domain) ? "; domain=" + domain : "") +
      ((secure) ? "; secure" : "");
  document.cookie = curCookie;
}

// name - name of the desired cookie
// * return string containing value of specified cookie or null if cookie does not exist
function getCookie(name) {
  var dc = document.cookie;
  var prefix = name + "=";
  var begin = dc.indexOf("; " + prefix);
  if (begin == -1) {
    begin = dc.indexOf(prefix);
    if (begin != 0) return null;
  } else
    begin += 2;
  var end = document.cookie.indexOf(";", begin);
  if (end == -1)
    end = dc.length;
  return unescape(dc.substring(begin + prefix.length, end));
}

// name - name of the cookie
// [path] - path of the cookie (must be same as path used to create cookie)
// [domain] - domain of the cookie (must be same as domain used to create cookie)
// * path and domain default if assigned null or omitted if no explicit argument proceeds
function deleteCookie(name, path, domain) {
  if (getCookie(name)) {
    document.cookie = name + "=" +
    ((path) ? "; path=" + path : "") +
    ((domain) ? "; domain=" + domain : "") +
    "; expires=Thu, 01-Jan-70 00:00:01 GMT";
  }
}

// adds a work from the current selection
function addWorkToSelection(workID) {
	var cookieName = "psel";
	var cookieValue = GetCookie(cookieName);
	if (cookieValue != null)
	{
		var workkey = workID + "-0~";
 		var newworkkey = workID + "-1~";
  		if (cookieValue.indexOf(workkey) > -1)
  		{
  			//found key, change delete to add (-0~ to -1~)
    		cookieValue = cookieValue.replace(workkey, newworkkey);
 		}
		else if (cookieValue.indexOf(newworkkey) == -1)
		{
			//didn't find key
    		cookieValue = cookieValue + newworkkey;
		}
		else
			//key already exists for inclusion
			cookieValue = null;
   	}
	else
		cookieValue = workID + "-1~";
	
	if (cookieValue != null)
		setCookie(cookieName, cookieValue, null, null, null);
}

// removes a work from the current selection
function removeWorkFromSelection(workID) {
	var cookieName = "psel";
	var cookieValue = GetCookie(cookieName);
	if (cookieValue != null)
	{
		var workkey = workID + "-1~";
		var pos = cookieValue.indexOf(workkey);
  		if (pos > -1)
  		{
 			var regex = workkey;
 			//var newworkkey = workID + "-0~";
 			var newworkkey = "";
    		var newCookieValue = cookieValue.replace(regex, newworkkey);
    		setCookie(cookieName, newCookieValue, null, null, null);
		}
   	}
}

// adds or removes a work from the current selection
// based on whether the passed checkbox is selected or not
function modifyWorkSelection(workID, chkboxObj, checkedIsAdd)
{
	var isChecked = chkboxObj.checked;
		
	if(isChecked)
	{
		if (checkedIsAdd)
			addWorkToSelection(workID);
		else
			removeWorkFromSelection(workID);
	}
	else {
		if (checkedIsAdd)
			removeWorkFromSelection(workID);
		else
			addWorkToSelection(workID);
	}
}

//adds a list of works to the current selection
function addWorkListToSelection(workList)
{
	for (i = 0; i < workList.length; i++)
	{
		addWorkToSelection(workList[i]);
		//alert(workList[i]);
	}
	
	if (workList.length == 1)
		alert("1 work has been added to your selection");
	else
		alert(workList.length + " works have been added to your selection");
}

//determines whether a work is in the cookie (and selected)
function isWorkSelectedInSelection(workID)
{
	var cookieName = "psel";
	var cookieValue = GetCookie(cookieName);
	if (cookieValue != null)
	{
		var workkey = workID + "-1~";
		var pos = cookieValue.indexOf(workkey);
		
		return (pos > -1);
	}
	
	return false;
}