/* Calendar output variables */
var days_to_show = 30;

/* Loads the Google data JavaScript client library */
google.load("gdata", "1");

function init() {
  // init the Google data JS client library with an error handler
  google.gdata.client.init(handleGDError);
  //loadTestCalendar();
}


function loadTestCalendar() {
  loadCalendarByAddress('developer-calendar@google.com');
}

// For converting time string (gets around google api's limitation of not being able to force a timezone.)
Date.prototype.setISO8601 = function (string) {
    var regexp = "([0-9]{4})(-([0-9]{2})(-([0-9]{2})" +
        "(T([0-9]{2}):([0-9]{2})(:([0-9]{2})(\.([0-9]+))?)?" +
        "(Z|(([-+])([0-9]{2}):([0-9]{2})))?)?)?)?";
    var d = string.match(new RegExp(regexp));

    var date = new Date(d[1], 0, 1);

    if (d[3]) { date.setMonth(d[3] - 1); }
    if (d[5]) { date.setDate(d[5]); }
    if (d[7]) { date.setHours(d[7]); }
    if (d[8]) { date.setMinutes(d[8]); }
    if (d[10]) { date.setSeconds(d[10]); }
    if (d[12]) { date.setMilliseconds(Number("0." + d[12]) * 1000); }
    
    time = (Number(date));
    this.setTime(Number(time));
}

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

function mapDay(day_num) {
	var dayMap = new Array("Sun","Mon","Tue","Wed","Thu","Fri","Sat");
	return dayMap[day_num];
}

function mapMonth(day_num) {
	var dayMonth = new Array("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec");
	return dayMonth[day_num];
}

function extractTime(date) {
	var hours = date.getHours();
	var minutes = date.getMinutes();
	var time = "";
	var ampm = "am";
	
	if (minutes < 10){
		minutes = "0" + minutes;
	}
	
	if (hours == 0){
		hours = 12;
	}
	else if(hours > 11){
		ampm = "pm";
		if (hours != 12) {
			hours -= 12;
		}
	} 
	
	if (minutes == "00") {
		time = hours + ampm;
	}
	else {
		time = hours + ":" + minutes + ampm;
	}
	return time;
}

/**
 * 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 = 'http://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, days) {

  if (days == null) {
  	days = 60;
  }	

  var service = new 
      google.gdata.calendar.CalendarService('gcal-loader');
  var query = new google.gdata.calendar.CalendarEventQuery(calendarUrl);
  
  query.setOrderBy('starttime');
  query.setSortOrder('ascending');
  query.setSingleEvents(true);

  /* set Maximum date */

  var minDate = new Date();
  var maxDate = new Date();
  maxDate.setDate(maxDate.getDate()+days);  //add days offset
  
  var gMinDate = new google.gdata.DateTime(minDate);
  var gMaxDate = new google.gdata.DateTime(maxDate);
  
  query.setMinimumStartTime(gMinDate);
  query.setMaximumStartTime(gMaxDate);

  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]);
  }	  
  
  /* set the calendarTitle div with the name of the calendar */
  if (document.getElementById('calendarTitle') != null) {
  	document.getElementById('calendarTitle').innerHTML = "<p class=\"calendar_title\">" + feedRoot.feed.title.$t + "<p>";
  }  
  
  /* 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 startDateTime = null;
    var startJSDate = null;
    var times = entry.getTimes();
    
    if (times.length > 0) {
    	
      // Parse date from the datetime string label to force timezone (google api/javascript limitation =( )
      var startDT = new Date();
      var endDT = new Date();
      
      startDT.setISO8601(entry.gd$when[0].startTime);
      endDT.setISO8601(entry.gd$when[0].endTime);
    
      startDateTime = times[0].getStartTime();
      
      startJSDate = startDT; 
      endJSDate = endDT; 
    }
    var entryLinkHref = null;
    if (entry.getHtmlLink() != null) {
      entryLinkHref = entry.getHtmlLink().getHref();
    }
    
    /* Parse out the Date String */
    var dateString = mapDay(startJSDate.getDay()) + ", ";
    dateString += mapMonth(startJSDate.getMonth()) + " " + 
    	startJSDate.getDate(); 
    
    /* Parse out the Time string */
    var timeString = "";
    if (!startDateTime.isDateOnly()) {
    	timeString += extractTime(startJSDate) +  " - " + extractTime(endJSDate);
    }
    	
    /* Parse out the Location */
    var locationString = entry.getLocations()[0].getValueString();
    
    /* Parse out the description */
    var descriptionString = entry.getContent().getText();
    //descriptionString = descriptionString.replace("\n", "<br>")
    
    // Create a 'p' element for this event
    var pEvent = document.createElement('p');
    pEvent.setAttribute('class', "event_listing");
    
    // Add Event title 
    var titleSpan = document.createElement('span');
    titleSpan.setAttribute('class', "event_title");
    /* if we have a link to the event, create an 'a' element */
    if (entryLinkHref != null) {
      entryLink = document.createElement('a');
      entryLink.setAttribute('href', entryLinkHref);
      entryLink.setAttribute('target', '_blank');
      entryLink.appendChild(document.createTextNode(dateString + ": " + title));
      titleSpan.appendChild(entryLink);
    } 
    else {
      titleSpan.appendChild(document.createTextNode(dateString + ": " + title));
    }
    pEvent.appendChild(titleSpan);
    // Add Event Time slot
    if (timeString != "") {
    	var timeSpan = document.createElement('span');
    	timeSpan.setAttribute('class', "event_time");
    	timeSpan.appendChild(document.createElement('br'));
    	timeSpan.appendChild(document.createTextNode(timeString))
    	pEvent.appendChild(timeSpan);
    }
    // Add Event Location
    if (locationString != "") {
    	var locationSpan = document.createElement('span');
    	locationSpan.setAttribute('class', "event_location");
    	locationSpan.appendChild(document.createElement('br'));
    	locationSpan.appendChild(document.createTextNode(locationString));
    	pEvent.appendChild(locationSpan);
    }
    // Add Event Description 
    if (descriptionString != "") {
    	var descriptionSpan = document.createElement('span');
    	descriptionSpan.setAttribute('class', "event_description");
    	descriptionSpan.appendChild(document.createElement('br'));
    	//descriptionSpan.innerHtml = descriptionString
    	descriptionArray = descriptionString.split("\n");
       	for (var each in descriptionArray) {
    		descriptionSpan.appendChild(document.createTextNode(descriptionArray[each]));
    		descriptionSpan.appendChild(document.createElement('br'));
    	}
    	pEvent.appendChild(descriptionSpan);
    } 

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

google.setOnLoadCallback(init);