<?php
/* $Id: date_ical.inc,v 1.1.2.7 2007-03-07 18:07:45 karens Exp $ */

/**
 * Turn an array of events into a valid iCalendar file
 *
 * @param $events
 *   An array of associative arrays where
 *      'start'         => Unix timestamp (GMT) of start time (Required, if no allday_start)
 *      'end'           => Unix timestamp (GMT) of end time (Optional)
 *      'allday_start'  => Start date of all-day event in YYYYMMDD format (Required, if no start)
 *      'allday_end'    => End date of all-day event in YYYYMMDD format (Optional)
 *      'summary'       => Title of event (Text)
 *      'description'   => Description of event (Text)
 *      'location'      => Location of event (Text)
 *      'uid'           => ID of the event for use by calendaring program.  Recommend the url of the node
 *      'url'           => URL of event information
 *
 * @param $calname
 *   Name of the calendar.  Will use site name if none is specified.
 *
 * @return
 *   Text of a date_icalendar file
 */
function date_ical_export($events, $calname = NULL) {
  $output .= "BEGIN:VCALENDAR\nVERSION:2.0\n";
  $output .= "METHOD:PUBLISH\n";
  $output .= 'X-WR-CALNAME:'. date_ical_escape_text($calname ? $calname : variable_get('site_name', '')) ."\n";
  $output .= "PRODID:-//strange bird labs//Drupal iCal API//EN\n";
  foreach ($events as $uid => $event) {
    $output .= "BEGIN:VEVENT\n";
    $output .= "DTSTAMP;VALUE=DATE:".gmdate("Ymd\THis\Z", time())."\n";
    if ($event['allday_start'] && $event['allday_end']) {
      $output .= "DTSTART;VALUE=DATE:" . $event['allday_start'] . "\n";
      $output .= "DTEND;VALUE=DATE:" . $event['allday_end'] . "\n";
    }
    else if ($event['allday_start'] && empty($event['allday_end'])) {
      $output .= "DTSTART;VALUE=DATE:" . $event['allday_start'] . "\n";
      $output .= "DTEND;VALUE=DATE:" . date('Ymd', strtotime($event['allday_start']) + 86400) . "\n"; //If no allday end date, set to day after allday start
    }
    else if ($event['start'] && $event['end']) {
      $output .= "DTSTART;VALUE=DATE-TIME:" . gmdate("Ymd\THis\Z", $event['start']) . "\n";
      $output .= "DTEND;VALUE=DATE-TIME:" . gmdate("Ymd\THis\Z", $event['end']) . "\n";
    }
    else if ($event['start']) {
      $output .= "DTSTART;VALUE=DATE-TIME:" . gmdate("Ymd\THis\Z", $event['start']) . "\n";
    }
    $output .= "UID:" . ($event['uid'] ? $event['uid'] : $uid) . "\n";
    if ($event['url']) $output .= "URL;VALUE=URI:" . $event['url'] . "\n";
    if ($event['location']) $output .= "LOCATION:" . date_ical_escape_text($event['location']) . "\n";
    $output .= "SUMMARY:" . date_ical_escape_text($event['summary']) . "\n";
    if ($event['description']) $output .= "DESCRIPTION:" . date_ical_escape_text($event['description']) . "\n";
    $output .= "END:VEVENT\n";
  }
  $output .= "END:VCALENDAR\n";
  return $output;
}

/**
 * Escape #text elements for safe iCal use
 *
 * @param $text
 *   Text to escape
 *
 * @return
 *   Escaped text
 *
 */
function date_ical_escape_text($text) {
  //$text = strip_tags($text);
  $text = str_replace('"', '\"', $text);
  $text = str_replace("\\", "\\\\", $text);
  $text = str_replace(",", "\,", $text);
  $text = str_replace(":", "\:", $text);
  $text = str_replace(";", "\;", $text);
  $text = str_replace("\n", "\n ", $text);
  return $text;
}

/**
 * Given the location of a valid iCalendar file, will return an array of event information
 *
 * @param $filename
 *   Location (local or remote) of a valid iCalendar file
 *
 * @return
 *   An array of associative arrays where
 *      'start'         => Unix timestamp (GMT) of start time
 *      'end'           => Unix timestamp (GMT) of end time
 *      'allday_start'  => Start date of all-day event in YYYYMMDD format
 *      'allday_end'    => End date of all-day event in YYYYMMDD format
 *      'summary'       => Title of event
 *      'description'   => Description of event
 *      'location'      => Location of event
 *      'uid'           => ID of the event in calendaring program
 *      'url'           => URL of event information                                                                                                                    *
 */
function date_ical_import($filename) {
  $items = array();
  $ifile = @fopen($filename, "r");
  if ($ifile == FALSE) exit('Invalid input file');
  $nextline = fgets($ifile, 1024);
  if (trim($nextline) != 'BEGIN:VCALENDAR') exit('Invalid calendar file:' . $filename);
  while (!feof($ifile)) {
    $line = $nextline;
    $nextline = fgets($ifile, 1024);
    $nextline = ereg_replace("[\r\n]", "", $nextline);
    while (substr($nextline, 0, 1) == " ") {
      $line = $line . substr($nextline, 1);
      $nextline = fgets($ifile, 1024);
      $nextline = ereg_replace("[\r\n]", "", $nextline);
    }
    $line = trim($line);
    $vcal .= $line ."\n";
    switch ($line) {
    case 'BEGIN:VEVENT':
      unset($start_unixtime, $start_date, $start_time,
	    $end_unixtime, $end_date, $end_time,
	    $allday_start, $allday_end, $the_duration,
	    $uid, $summary, $description, $url, $location,
	    $start_tz, $end_tz, $start_raw, $end_raw, $start_offset, $end_offset, $vcal );
	    $vcal = $line ."\n";
      break;
    case 'END:VEVENT':
      if (empty($uid)) {
	    $uid = $uid_counter;
	    $uid_counter++;
      }
      if (empty($end_unixtime) && isset($the_duration)) {
	    $end_unixtime = $start_unixtime + $the_duration;
	    $end_time = date ('Hi', $end_unixtime);
      }

      $items[$uid] = array('start' => $start_unixtime,
			   'end' => $end_unixtime,
			   'allday_start' => $allday_start,
			   'allday_end' => $allday_end,
			   'summary' => $summary,
			   'description' => $description,
			   'location' => $location,
			   'url' => $url,
			   'uid' => $uid,
			   'start_raw' => $start_raw,
			   'start_timezone' => $start_tz,
			   'start_offset' => $start_offset,
			   'end_raw' => $end_raw,
			   'end_timezone' => $end_tz,
			   'end_offset' => $end_offset,
               'vcal' => $vcal,
			   );
      break;
    default:

      unset ($field, $data, $prop_pos, $property);
      ereg ("([^:]+):(.*)", $line, $line);
      $field = $line[1];
      $data = $line[2];

      $property = $field;
      $prop_pos = strpos($property,';');
      if ($prop_pos !== false) $property = substr($property,0,$prop_pos);
      $property = strtoupper($property);

      switch ($property) {

      case 'DTSTART':
	    $zulu_time = false;
	    if (substr($data,-1) == 'Z') $zulu_time = true;
	    $data = str_replace('T', '', $data);
	    $data = str_replace('Z', '', $data);
	    $field = str_replace(';VALUE=DATE-TIME', '', $field);
	    if ((preg_match("/^DTSTART;VALUE=DATE/i", $field)) || (ereg ('^([0-9]{4})([0-9]{2})([0-9]{2})$', $data))) {
	      ereg ('([0-9]{4})([0-9]{2})([0-9]{2})', $data, $dtstart_check);
	      $allday_start = $data;
	      $start_date = $allday_start;
	      $start_unixtime = strtotime($data);
	    }
	    else {
	      if (preg_match("/^DTSTART;TZID=/i", $field)) {
	        $tz_tmp = explode('=', $field);
	        $tz_dtstart = $tz_tmp[1];
	        unset($tz_tmp);
	      }
	      elseif ($zulu_time) {
	        $tz_dtstart = 'GMT';
	      }
	      preg_match ('/([0-9]{4})([0-9]{2})([0-9]{2})([0-9]{0,2})([0-9]{0,2})/', $data, $regs);
	      $start_date = $regs[1] . $regs[2] . $regs[3];
	      $start_time = $regs[4] . $regs[5];
	      $start_unixtime = gmmktime($regs[4], $regs[5], 0, $regs[2], $regs[3], $regs[1]);
          $dlst = date('I', $start_unixtime);
	      $server_offset_tmp = _date_ical_chooseOffset($start_unixtime, 'Same as Server');
	      if (isset($tz_dtstart)) {
	        if ($tz = _date_ical_tz($tz_dtstart)) {
	          $offset_tmp = date('I', $start_unixtime) ? _date_ical_calcString($tz->offset_dst)  : _date_ical_calcString($tz->offset);
	        }
	        else {
	          $offset_tmp = '+0000';
	        }
	      } else if (isset($calendar_tz)) {
            if ($tz = _date_ical_tz($calendar_tz)) {
              $offset_tmp = date('I', $start_unixtime) ? _date_ical_calcString($tz->offset_dst)  : _date_ical_calcString($tz->offset);
	        } else {
	          $offset_tmp = '+0000';
	        }
	      } else {
	        $offset_tmp = $server_offset_tmp;
	      }
	      $start_unixtime = _date_ical_calcTime($offset_tmp, $server_offset_tmp, $start_unixtime);
	      $start_date = gmdate('Ymd', $start_unixtime);
	      $start_time = gmdate('Hi', $start_unixtime);
	      $start_offset = $offset_tmp;
	      $start_tz = $tz_dtstart;
	      $start_raw = $data;
	      unset($server_offset_tmp, $offset_tmp, $tz_dtstart);
	    }
	    break;
      case 'DTEND':
	    $zulu_time = false;
	    if (substr($data,-1) == 'Z') $zulu_time = true;
	    $data = str_replace('T', '', $data);
	    $data = str_replace('Z', '', $data);
	    $field = str_replace(';VALUE=DATE-TIME', '', $field);
        if ((preg_match("/^DTEND;VALUE=DATE/i", $field)) || (ereg ('^([0-9]{4})([0-9]{2})([0-9]{2})$', $data))) {
          $allday_end = $data;
          $end_date = $allday_end;
          $end_unixtime = strtotime($data);
        }
	    else {
	      if (preg_match("/^DTEND;TZID=/i", $field)) {
	        $tz_tmp = explode('=', $field);
	        $tz_dtend = $tz_tmp[1];
	        unset($tz_tmp);
	      }
	      elseif ($zulu_time) {
	        $tz_dtend = 'GMT';
	      }
	      preg_match ('/([0-9]{4})([0-9]{2})([0-9]{2})([0-9]{0,2})([0-9]{0,2})/', $data, $regs);
	      $end_date = $regs[1] . $regs[2] . $regs[3];
	      $end_time = $regs[4] . $regs[5];
	      $end_unixtime = gmmktime($regs[4], $regs[5], 0, $regs[2], $regs[3], $regs[1]);

	      $server_offset_tmp = _date_ical_chooseOffset($end_unixtime, 'Same as Server');
	      if (isset($tz_dtend)) {
	        if ($tz = _date_ical_tz($tz_dtend)) {
	          $offset_tmp = date('I', $end_unixtime) ? _date_ical_calcString($tz->offset_dst)  : _date_ical_calcString($tz->offset);
	        }
	        else {
	          $offset_tmp = '+0000';
	        }
	      } else if (isset($calendar_tz)) {
            if ($tz = _date_ical_tz($calendar_tz)) {
              $offset_tmp = date('I', $end_unixtime) ? _date_ical_calcString($tz->offset_dst)  : _date_ical_calcString($tz->offset);
	        } else {
	          $offset_tmp = '+0000';
	        }
	      } else {
	        $offset_tmp = $server_offset_tmp;
	      }
	      $end_unixtime = _date_ical_calcTime($offset_tmp, $server_offset_tmp, $end_unixtime);
	      $end_date = gmdate('Ymd', $end_unixtime);
	      $end_time = gmdate('Hi', $end_unixtime);
	      $end_offset = $offset_tmp;
	      $end_tz = $tz_dtend;
	      $end_raw = $data;
	      unset($server_offset_tmp, $offset_tmp, $tz_dtend);
	    }
	    break;
      case 'DURATION':
	    if (!stristr($field, '=DURATION')) {
	      ereg ('^P([0-9]{1,2}[W])?([0-9]{1,2}[D])?([T]{0,1})?([0-9]{1,2}[H])?([0-9]{1,2}[M])?([0-9]{1,2}[S])?', $data, $duration);
	      $weeks = str_replace('W', '', $duration[1]);
	      $days = str_replace('D', '', $duration[2]);
	      $hours = str_replace('H', '', $duration[4]);
	      $minutes = str_replace('M', '', $duration[5]);
	      $seconds = str_replace('S', '', $duration[6]);
	      $the_duration = ($weeks * 60 * 60 * 24 * 7) + ($days * 60 * 60 * 24) + ($hours * 60 * 60) + ($minutes * 60) + ($seconds);
	    }
	    break;
      case 'SUMMARY':
	    $summary = $data;
	    break;
      case 'DESCRIPTION':
	    $description = $data;
	    break;
      case 'UID':
	    $uid = $data;
	    break;
      case 'X-WR-CALNAME':
	    $actual_calname = $data;
	    break;
      case 'X-WR-TIMEZONE':
	    $calendar_tz = $data;
	    break;
      case 'LOCATION':
	    $location = $data;
	    break;
      case 'URL':
	    $url = $data;
	    break;
      }
    }
  }
  return $items;
}

function _date_ical_tz($tz) {
  include_once(drupal_get_path('module', 'date_api') .'/date.inc');
  include_once(DATE_TIMEZONES);
  foreach (event_get_timezones() as $delta => $zone) {
    if ($tz == $zone['timezone']);
    return (object) $zone;
  }
}

function _date_ical_chooseOffset($time, $timezone) {
  if (!isset($timezone)) $timezone = '';
  switch ($timezone) {
  case '':
    $offset = 'none';
    break;
  case 'Same as Server':
    $offset = date('O', $time);
    break;
  default:
    if ($tz = _date_ical_tz($timezone)) {
      $offset = date('I', $time) ? _date_ical_calcString($tz->offset_dst) : _date_ical_calcString($tz->offset);
    } else {
      $offset = '+0000';
    }
  }
  return $offset;
}


/**
 * Convert time from one timezone to another.
 *
 * @param $have - a timezone string for the submitted timestamp
 * @param $want - the desired output timezone string
 * @param $time - a timestamp to be converted
 * @return converted value
 */
function _date_ical_calcTime($have, $want, $time) {
  if ($have == 'none' || $want == 'none') return $time;
  $have_secs = _date_ical_calcOffset($have);
  $want_secs = _date_ical_calcOffset($want);
  $diff = $want_secs - $have_secs;
  $time += $diff;
  return $time;
}

/**
 * Convert a timezone offset in seconds to a formatted timezone offset string
 *   i.e. +10800 becomes +0300;
 */
function _date_ical_calcString($seconds) {
  $sign = substr($seconds, 0, 1);
  $seconds = substr($seconds, 1);
  $hours = intval($seconds / 3600);
  $minutes = intval(($seconds - ($hours * 3600))/ 60);
  return $sign . sprintf("%02d", $hours) . sprintf("%02d", $minutes);
}

/**
 * Convert a formatted timezone offset string the offset value in seconds.
 *   i.e. +0300 becomes +10800.
 */
function _date_ical_calcOffset($offset_str) {
  $sign = substr($offset_str, 0, 1);
  $hours = substr($offset_str, 1, 2);
  $mins = substr($offset_str, 3, 2);
  $secs = ((int)$hours * 3600) + ((int)$mins * 60);
  if ($sign == '-') $secs = 0 - $secs;
  return $secs;
}