/* Loads the Google data JavaScript client library */
google.load("gdata", "2.x");

function init() {
  // init the Google data JS client library with an error handler
  google.gdata.client.init(handleGDError);
  // load the code.google.com developer calendar
 // loadDeveloperCalendar();
}

/**
 * Loads the Google Developers Event Calendar
 */
function loadDeveloperCalendar() {
  loadCalendarByAddress('developer-calendar@google.com');
}

/**
 * Adds a leading zero to a single-digit number.  Used for displaying dates.
 */
function padNumber(num) {
  if (num <= 9) {
    return "0" + num;
  }
  return num;
}

/**
 * Determines the full calendarUrl based upon the calendarAddress
 * argument and calls loadCalendar with the calendarUrl value.
 *
 * @param {string} calendarAddress is the email-style address for the calendar
 */ 
function loadCalendarByAddress(calendarAddress) {
  var calendarUrl = 'https://www.google.com/calendar/feeds/' +
                    calendarAddress + 
                    '/public/full';
  loadCalendar(calendarUrl);
}

/**
 * Uses Google data JS client library to retrieve a calendar feed from the specified
 * URL.  The feed is controlled by several query parameters and a callback 
 * function is called to process the feed results.
 *
 * @param {string} calendarUrl is the URL for a public calendar feed
 */  
function loadCalendar(calendarUrl) {
  var service = new 
      google.gdata.calendar.CalendarService('gdata-js-client-samples-simple');
  var query = new google.gdata.calendar.CalendarEventQuery(calendarUrl);
  query.setOrderBy('starttime');
  query.setSortOrder('ascending');
  query.setFutureEvents(true);
  query.setSingleEvents(true);
  query.setMaxResults(10);

  service.getEventsFeed(query, listEvents, handleGDError);
}

/**
 * Callback function for the Google data JS client library to call when an error
 * occurs during the retrieval of the feed.  Details available depend partly
 * on the web browser, but this shows a few basic examples. In the case of
 * a privileged environment using ClientLogin authentication, there may also
 * be an e.type attribute in some cases.
 *
 * @param {Error} e is an instance of an Error 
 */
function handleGDError(e) {
  document.getElementById('jsSourceFinal').setAttribute('style', 
      'display:none');
  if (e instanceof Error) {
    /* alert with the error line number, file and message */
    alert('Error at line ' + e.lineNumber +
          ' in ' + e.fileName + '\n' +
          'Message: ' + e.message);
    /* if available, output HTTP error code and status text */
    if (e.cause) {
      var status = e.cause.status;
      var statusText = e.cause.statusText;
      alert('Root cause: HTTP error ' + status + ' with status text of: ' + 
            statusText);
    }
  } else {
    alert(e.toString());
  }
}

/**
 * Callback function for the Google data JS client library to call with a feed 
 * of events retrieved.
 *
 * Creates an unordered list of events in a human-readable form.  This list of
 * events is added into a div called 'events'.  The title for the calendar is
 * placed in a div called 'calendarTitle'
 *
 * @param {json} feedRoot is the root of the feed, containing all entries 
 */ 
function listEvents(feedRoot) {
  var entries = feedRoot.feed.getEntries();
  var eventDiv = document.getElementById('events');
  if (eventDiv.childNodes.length > 0) {
    eventDiv.removeChild(eventDiv.childNodes[0]);
  }	  
  /* create a new unordered list */
  var ul = document.createElement('ul');
  /* set the calendarTitle div with the name of the calendar */
  document.getElementById('calendarTitle').innerHTML = 
    feedRoot.feed.title.$t;
  /* loop through each event in the feed */
  var len = entries.length;
  for (var i = 0; i < len; i++) {
    var entry = entries[i];
    var title = entry.getTitle().getText();
	var location = entry.getLocations()[0].getValueString();
	var content = entry.getContent().getText();
    var startDateTime = null;
    var startJSDate = null;
    var times = entry.getTimes();
    if (times.length > 0) {
      startDateTime = times[0].getStartTime();
      startJSDate = startDateTime.getDate();
    }
	
    var entryLinkHref = null;
    if (entry.getHtmlLink() != null) {
      entryLinkHref = entry.getHtmlLink().getHref();
    }
	
	var d = startJSDate.getDay();
	if (d==0) { var day = 'Sun' }
	if (d==1) { var day = 'Mon' }
	if (d==2) { var day = 'Tue' }
	if (d==3) { var day = 'Wed' }
	if (d==4) { var day = 'Thu' }
	if (d==5) { var day = 'Fri' }
	if (d==6) { var day = 'Sat' }
	
	var m = startJSDate.getMonth();
	if (m==0) { var month = 'Jan' }
	if (m==1) { var month = 'Feb' }
	if (m==2) { var month = 'Mar' }
	if (m==3) { var month = 'Apr' }
	if (m==4) { var month = 'May' }
	if (m==5) { var month = 'Jun' }
	if (m==6) { var month = 'Jul' }
	if (m==7) { var month = 'Aug' }
	if (m==8) { var month = 'Sep' }
	if (m==9) { var month = 'Oct' }
	if (m==10) { var month = 'Nov' }
	if (m==11) { var month = 'Dec' }
	
	var dateString = day + ', ' + month + ' ' + (startJSDate.getDate());
	var timeString = '';
	
    if (!startDateTime.isDateOnly()) {
		if(startJSDate.getHours()>12){
			hours = startJSDate.getHours()-1;
			var ampm = 'pm'
		} else {
			hours = startJSDate.getHours();
			var ampm = 'am'
		}
      	timeString = " " + hours + ":" + 
          padNumber(startJSDate.getMinutes()) + ampm;
    }
    var li = document.createElement('li');
	
	
	
    /* if we have a link to the event, create an 'a' element */
    if (entryLinkHref != null) {

	  whereDiv = document.createElement('div');
	  whereDiv.setAttribute('id', 'where');
	  li.appendChild(whereDiv);
	  
      entryLink = document.createElement('a');
      entryLink.setAttribute('href', entryLinkHref);
	  entryLink.setAttribute('id', 'title');
      entryLink.appendChild(document.createTextNode(title));
	  whereDiv.appendChild(entryLink);
	  
	  if(location != '') {
		  locSpan = document.createElement('span');
	  	  locSpan.setAttribute('id', 'location');
		  locSpan.appendChild(document.createElement('br'));
     	  locSpan.appendChild(document.createTextNode(location));
		  whereDiv.appendChild(locSpan);
	  }
	  
	  if(content != '') {
	  	  conSpan = document.createElement('span');
	  	  conSpan.setAttribute('id', 'content');
		  conSpan.appendChild(document.createElement('br'));
     	  conSpan.appendChild(document.createTextNode(content));
		  whereDiv.appendChild(conSpan);
	  }
	  
	  dateSpan = document.createElement('div');
	  dateSpan.setAttribute('id', 'when');
	  dateSpan.appendChild(document.createTextNode(dateString));
	  dateSpan.appendChild(document.createElement('br'));
	  dateSpan.appendChild(document.createTextNode(timeString));
	  li.appendChild(dateSpan);
	  
	  clearDiv = document.createElement('div');
	  clearDiv.setAttribute('style', 'clear:both');
	  li.appendChild(clearDiv);
	  
    } else {
      li.appendChild(document.createTextNode(title + ' - ' + dateString));
    }	    

    /* append the list item onto the unordered list */
    ul.appendChild(li);
  }
  eventDiv.appendChild(ul);
}

google.setOnLoadCallback(init);