<?php

require_once("sf/SforcePartnerClient.php");

$data = getCalendarData("YOUR_LOGIN","YOUR_PASSWORD");

switch ($_GET['type']){
  case 'calendar':
    echo generateCalendar($data);
    break;

  case 'freebusy':
    echo generateFreeBusy($data);
    break;

  default:
    break;
}

/**
 * We retrieve the data from SaleForce.com
 */
function getCalendarData($login,$password)
{
  $mySforceConnection = new SforcePartnerClient();
  $mySoapClient = $mySforceConnection->createConnection("sf/partner.wsdl.xml");
  $mylogin = $mySforceConnection->login($login, $password);

  $query = "SELECT DurationInMinutes,Subject, ActivityDateTime, ActivityDate,IsAllDayEvent FROM Event WHERE ActivityDate > ".date('Y-m-d',strtotime('- 24 hours'));
  $queryResult = $mySforceConnection->query($query);
  $records = $queryResult->records;
  return $records;
}

/*
 * We generate a regular ical calendar
 */
function generateCalendar($records)
{
  $ics = "BEGIN:VCALENDAR\nVERSION:2.0\nPRODID:-//hacksw/handcal//NONSGML v1.0//EN\n";

  foreach ($records as $record) {
    $sObject = new SObject($record);
  
    $eventStartTs = strtotime($sObject->fields->ActivityDateTime);
    $length = $sObject->fields->DurationInMinutes;
    $eventEndTs = $eventStartTs + $length*60;
    if ($sObject->fields->IsAllDayEvent == "true"){
      $ics .= icAllDayEventLine(strtotime($sObject->fields->ActivityDate),$sObject->fields->Subject); 
    }else{ 
      $ics .= icEventLine($eventStartTs,$eventEndTs); 
    }
  
  }
  $ics .= "END:VCALENDAR\n";

  return $ics;
}

/*
 * We generate a free busy calendar
 */
function generateFreeBusy($records)
{
  $ics = "BEGIN:VCALENDAR\nVERSION:2.0\nPRODID:-//hacksw/handcal//NONSGML v1.0//EN\n";
  $ics .= "BEGIN:VFREEBUSY\n";
  $ics .= "ORGANIZER:MAILTO:\n";
  $isc .= "DTSTART:".icFormatDateTime(mktime())."\n";
  $ics .= "DTEND:".icFormatDateTime(strtotime("+6 month",mktime()))."\n";

  foreach ($records as $record) {
    $sObject = new SObject($record);
  
    $eventStartTs = strtotime($sObject->fields->ActivityDateTime);
    $length = $sObject->fields->DurationInMinutes;
    $eventEndTs = $eventStartTs + $length*60;
  
    $ics .= icFreeBusyLine($eventStartTs,$eventEndTs); 
  
  }
  $ics .= "URL:".$PHP_SELF."\n";
  $ics .= "END:VFREEBUSY\n";
  $ics .= "END:VCALENDAR\n";

  return $ics;
}

/*
 * Format a timestamp into a ical datetime format
 */
function icFormatDateTime($timestamp)
{
  $year = gmdate('Y',$timestamp);
  $month = gmdate('m',$timestamp);
  $day = gmdate('d',$timestamp);
  $hour = gmdate('H',$timestamp);
  $minute = gmdate('i',$timestamp);
  
  return $year.$month.$day."T".$hour.$minute."00Z";
}

/*
 * Format a timestamp into a ical date format
 */
function icFormatDate($timestamp)
{
  $year = gmdate('Y',$timestamp);
  $month = gmdate('m',$timestamp);
  $day = gmdate('d',$timestamp);
  
  return $year.$month.$day;
}

/*
 * Generate a event line for a regular calendar generation.
 */
function icEventLine($startDateTs,$endDateTs)
{
  return "BEGIN:VEVENT\nDTSTART:".icFormatDateTime($startDateTs)."\nDTEND:".icFormatDateTime($endDateTs)."\nSUMMARY:Busy\nEND:VEVENT\n";
}

function icAllDayEventLine($startDateTs,$subject='Busy')
{
  // We want to display the real title of the event if the word trip is in it.
  if (preg_match('/trip/i',$subject) == 0){
    $subject = 'Busy';
  }

  return "BEGIN:VEVENT\nDTSTART:".icFormatDate($startDateTs)."\nDTEND:".icFormatDate(strtotime('+ 24 hours', $startDateTs))."\nSUMMARY:".$subject."\nEND:VEVENT\n".
  "BEGIN:VEVENT\nDTSTART:".icFormatDateTime(strtotime(gmdate('Y-m-d 11:00:00',$startDateTs)))."\nDTEND:".icFormatDateTime(strtotime(gmdate('Y-m-d 21:00:00',$startDateTs)))."\nSUMMARY:".$subject."\nEND:VEVENT\n";
}

/*
 * Generate a line for a free/busy calendar type.
 */
function icFreeBusyLine($startDate,$endDate)
{
  return 'FREEBUSY:'.icFormatDate($startDate).'/'.icFormatDate($endDate)."\n";
}

?>