modules/date/date_api.module

<?php
// $Id: date_api.module,v 1.71 2009/09/08 08:52:18 karens Exp $
/**
 * @file
 * This module will make the date API available to other modules.
 * Designed to provide a light but flexible assortment of functions
 * and constants, with more functionality in additional files that
 * are not loaded unless other modules specifically include them.
 */

/**
 * Set up some constants.
 *
 * Includes standard date types, format strings, strict regex strings for ISO
 * and DATETIME formats (seconds are optional).
 *
 * The loose regex will find any variety of ISO date and time, with or
 * without time, with or without dashes and colons separating the elements,
 * and with either a 'T' or a space separating date and time.
 */
define('DATE_ISO',  'date');
define('DATE_UNIX', 'datestamp');
define('DATE_DATETIME', 'datetime');
define('DATE_ARRAY', 'array');
define('DATE_OBJECT', 'object');
define('DATE_ICAL', 'ical');

define('DATE_FORMAT_ISO', "Y-m-d\TH:i:s");
define('DATE_FORMAT_UNIX', "U");
define('DATE_FORMAT_DATETIME', "Y-m-d H:i:s");
define('DATE_FORMAT_ICAL', "Ymd\THis");
define('DATE_FORMAT_ICAL_DATE', "Ymd");
define('DATE_FORMAT_DATE', 'Y-m-d');

define('DATE_REGEX_ISO', '/(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):?(\d{2})?/');
define('DATE_REGEX_DATETIME', '/(\d{4})-(\d{2})-(\d{2})\s(\d{2}):(\d{2}):?(\d{2})?/');
define('DATE_REGEX_LOOSE', '/(\d{4})-?(\d{1,2})-?(\d{1,2})([T\s]?(\d{2}):?(\d{2}):?(\d{2})?(\.\d+)?(Z|[\+\-]\d{2}:?\d{2})?)?/');
define('DATE_REGEX_ICAL_DATE', '/(\d{4})(\d{2})(\d{2})/');
define('DATE_REGEX_ICAL_DATETIME', '/(\d{4})(\d{2})(\d{2})T(\d{2})(\d{2})(\d{2})(Z)?/');

/**
 * Implementation of hook_init().
 */
function date_api_init() {
  drupal_add_css(drupal_get_path('module', 'date_api') . '/date.css', array('weight' => CSS_THEME));
}

/**
 * Implementation of hook_menu().
 */
function date_api_menu() {
  $items = array();
  $items['admin/config/regional/settings/formats'] = array(
    'title' => 'Formats',
    'description' => 'Allow users to configure date formats',
    'type' => MENU_LOCAL_TASK,
    'file' => 'date_api.admin.inc',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('date_api_date_formats_form'),
    'access arguments' => array('administer site configuration'),
    'weight' => 1,
  );
  $items['admin/config/regional/settings/formats/configure'] = array(
    'title' => 'Configure',
    'description' => 'Allow users to configure date formats',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'file' => 'date_api.admin.inc',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('date_api_date_formats_form'),
    'access arguments' => array('administer site configuration'),
    'weight' => 1,
  );
  $items['admin/config/regional/settings/formats/lookup'] = array(
    'title' => 'Date and time lookup',
    'type' => MENU_CALLBACK,
    'file' => 'date_api.admin.inc',
    'page callback' => 'date_api_date_time_lookup',
    'access arguments' => array('administer site configuration'),
  );
  $items['admin/config/regional/settings/formats/custom'] = array(
    'title' => 'Custom formats',
    'description' => 'Allow users to configure custom date formats. ',
    'type' => MENU_LOCAL_TASK,
    'file' => 'date_api.admin.inc',
    'page callback' => 'date_api_configure_custom_date_formats',
    'access arguments' => array('administer site configuration'),
    'weight' => 2,
  );
  $items['admin/config/regional/settings/formats/add'] = array(
    'title' => 'Add format',
    'description' => 'Allow users to add additional date formats. ',
    'type' => MENU_LOCAL_TASK,
    'file' => 'date_api.admin.inc',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('date_api_add_date_formats_form'),
    'access arguments' => array('administer site configuration'),
    'weight' => 3,
  );
  $items['admin/config/regional/settings/formats/delete/%'] = array(
    'title' => 'Delete date format',
    'description' => 'Allow users to delete a configured date format. ',
    'type' => MENU_CALLBACK,
    'file' => 'date_api.admin.inc',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('date_api_delete_format_form', 5),
    'access arguments' => array('administer site configuration'),
  );
  $items['admin/config/regional/settings/delete/%'] = array(
    'title' => 'Delete date format type',
    'description' => 'Allow users to delete a configured date format type. ',
    'type' => MENU_CALLBACK,
    'file' => 'date_api.admin.inc',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('date_api_delete_format_type_form', 4),
    'access arguments' => array('administer site configuration'),
  );
  return $items;
}

/**
 * Implementation of hook_menu_alter().
 */
function date_api_menu_alter(&$callbacks) {
  // Add a new 'admin/config/regional/settings/configure' path and make it the same as
  // the 'admin/config/regional/settings' .  Also set it to be the default local task -
  // needed to make tabs work as expected.
  $callbacks['admin/config/regional/settings/configure'] = $callbacks['admin/config/regional/settings'];
  $callbacks['admin/config/regional/settings/configure']['type'] = MENU_DEFAULT_LOCAL_TASK;
}

/**
 * Helper function for getting the format string for a date type.
 */
function date_type_format($type) {
  switch ($type) {
    case DATE_ISO:
      return DATE_FORMAT_ISO;
    case DATE_UNIX:
      return DATE_FORMAT_UNIX;
    case DATE_DATETIME:
      return DATE_FORMAT_DATETIME;
    case DATE_ICAL:
      return DATE_FORMAT_ICAL;
  }
}

/**
 * An untranslated array of month names
 *
 * Needed for css, translation functions, strtotime(), and other places
 * that use the English versions of these words.
 *
 * @return
 *   an array of month names
 */
function date_month_names_untranslated() {
  static $month_names;
  if (empty($month_names)) {
    $month_names = array(1 => 'January', 2 => 'February', 3 => 'March',
      4 => 'April', 5 => 'May', 6 => 'June', 7 => 'July',
      8 => 'August', 9 => 'September', 10 => 'October',
      11 => 'November', 12 => 'December');
  }
  return $month_names;
}

/**
 * A translated array of month names
 *
 * @param $required
 *   If not required, will include a blank value at the beginning of the list.
 * @return
 *   an array of month names
 */
function date_month_names($required = FALSE) {
  $month_names = array();
  foreach (date_month_names_untranslated() as $key => $day) {
    $month_names[$key] = date_t($day, 'month_name');
  }
  $none = array('' => '');
  return !$required ? $none + $month_names : $month_names;
}

/**
 * A translated array of month name abbreviations
 *
 * @param $required
 *   If not required, will include a blank value at the beginning of the list.
 * @return
 *   an array of month abbreviations
 */
function date_month_names_abbr($required = FALSE) {
  $month_names = array();
  foreach (date_month_names_untranslated() as $key => $day) {
    $month_names[$key] = date_t($day, 'month_abbr');
  }
  $none = array('' => '');
  return !$required ? $none + $month_names : $month_names;
}

/**
 * An untranslated array of week days
 *
 * Needed for css, translation functions, strtotime(), and other places
 * that use the English versions of these words.
 *
 * @return
 *   an array of week day names
 */
function date_week_days_untranslated($refresh = TRUE) {
  static $weekdays;
  if ($refresh || empty($weekdays)) {
    $weekdays = array(0 => 'Sunday', 1 => 'Monday', 2 => 'Tuesday',
      3 => 'Wednesday', 4 => 'Thursday', 5 => 'Friday',
      6 => 'Saturday');
  }
  return $weekdays;
}

/**
 * A translated array of week days
 *
 * @param $required
 *   If not required, will include a blank value at the beginning of the array.
 * @return
 *   an array of week day names
 */
function date_week_days($required = FALSE, $refresh = TRUE) {
  $weekdays = array();
  foreach (date_week_days_untranslated() as $key => $day) {
    $weekdays[$key] = date_t($day, 'day_name');
  }
  $none = array('' => '');
  return !$required ? $none + $weekdays : $weekdays;
}

/**
 * An translated array of week day abbreviations.
 *
 * @param $required
 *   If not required, will include a blank value at the beginning of the array.
 * @return
 *   an array of week day abbreviations
 */
function date_week_days_abbr($required = FALSE, $refresh = TRUE, $length = 3) {
  $weekdays = array();
  switch ($length) {
    case 1:
      $context = 'day_abbr1';
      break;
    case 2:
      $context = 'day_abbr2';
      break;
    default:
      $context = 'day_abbr';
      break; 
  }
  foreach (date_week_days_untranslated() as $key => $day) {
    $weekdays[$key] = date_t($day, $context);
  }
  $none = array('' => '');
  return !$required ? $none + $weekdays : $weekdays;
}

/**
 * Order weekdays
 *   Correct weekdays array so first day in array matches the first day of
 *   the week. Use to create things like calendar headers.
 *
 * @param array $weekdays
 * @return array
 */
function date_week_days_ordered($weekdays) {
  if (variable_get('date_first_day', 1) > 0) {
    for ($i = 1; $i <= variable_get('date_first_day', 1); $i++) {
      $last = array_shift($weekdays);
      array_push($weekdays, $last);
    }
  }
  return $weekdays;
}

/**
 * An array of years.
 *
 * @param int $min
 *   the minimum year in the array
 * @param int $max
 *   the maximum year in the array
 * @param $required
 *   If not required, will include a blank value at the beginning of the array.
 * @return
 *   an array of years in the selected range
 */
function date_years($min = 0, $max = 0, $required = FALSE) {
  // Have to be sure $min and $max are valid values;
  if (empty($min)) $min = intval(date('Y', REQUEST_TIME) - 3);
  if (empty($max)) $max = intval(date('Y', REQUEST_TIME) + 3);
  $none = array(0 => '');
  return !$required ? $none + drupal_map_assoc(range($min, $max)) : drupal_map_assoc(range($min, $max));
}

/**
 * An array of days.
 *
 * @param $required
 *   If not required, returned array will include a blank value.
 * @param integer $month (optional)
 * @param integer $year (optional)
 * @return
 *   an array of days for the selected month.
 */
function date_days($required = FALSE, $month = NULL, $year = NULL) {
  // If we have a month and year, find the right last day of the month.
  if (!empty($month) && !empty($year)) {
    $date = date_make_date($year . '-' . $month . '-01 00:00:00', 'UTC');
    $max = date_format('t', $date);
  }
  // If there is no month and year given, default to 31.
  if (empty($max)) $max = 31;
  $none = array(0 => '');
  return !$required ? $none + drupal_map_assoc(range(1, $max)) : drupal_map_assoc(range(1, $max));
}

/**
 * An array of hours.
 *
 * @param string $format
 * @param $required
 *   If not required, returned array will include a blank value.
 * @return
 *   an array of hours in the selected format.
 */
function date_hours($format = 'H', $required = FALSE) {
  $hours = array();
  if ($format == 'h' || $format == 'g') {
    $min = 1;
    $max = 12;
  }
  else  {
    $min = 0;
    $max = 23;
  }
  for ($i = $min; $i <= $max; $i++) {
    $hours[$i] = $i < 10 && ($format == 'H' || $format == 'h') ? "0$i" : $i;
  }
  $none = array('' => '');
  return !$required ? $none + $hours : $hours;
}

/**
 * An array of minutes.
 *
 * @param string $format
 * @param $required
 *   If not required, returned array will include a blank value.
 * @return
 *   an array of minutes in the selected format.
 */
function date_minutes($format = 'i', $required = FALSE, $increment = 1) {
  $minutes = array();
  // Have to be sure $increment has a value so we don't loop endlessly;
  if (empty($increment)) $increment = 1;
  for ($i = 0; $i < 60; $i += $increment) {
    $minutes[$i] = $i < 10 && $format == 'i' ? "0$i" : $i;
  }
  $none = array('' => '');
  return !$required ? $none + $minutes : $minutes;
}

/**
 * An array of seconds.
 *
 * @param string $format
 * @param $required
 *   If not required, returned array will include a blank value.
 * @return array an array of seconds in the selected format.
 */
function date_seconds($format = 's', $required = FALSE, $increment = 1) {
  $seconds = array();
  // Have to be sure $increment has a value so we don't loop endlessly;
  if (empty($increment)) $increment = 1;
  for ($i = 0; $i < 60; $i += $increment) {
    $seconds[$i] = $i < 10 && $format == 's' ? "0$i" : $i;
  }
  $none = array('' => '');
  return !$required ? $none + $seconds : $seconds;
}

/**
 * An array of am and pm options.
 * @param $required
 *   If not required, returned array will include a blank value.
 * @return array an array of am pm options.
 */
function date_ampm($required = FALSE) {
  $none = array('' => '');
  $ampm = array('am' => date_t('am', 'ampm'), 'pm' => date_t('pm', 'ampm'));
  return !$required ? $none + $ampm : $ampm;
}

/**
 * Implementation of hook_date_formats().
 *
 * @return
 *   An array of date formats with attributes 'type' (short, medium or long),
 *   'format' (the format string) and 'locales' .  The 'locales' attribute is an
 *   array of locales, which can include both 2 character language codes like
 *   'en', 'fr', but also 5 character language codes like 'en-gb' and 'en-us' .
 */
function date_api_date_formats() {
  include_once(DRUPAL_ROOT . '/' . drupal_get_path('module', 'date_api') . '/date_api_formats_list.inc');
  return _date_api_date_formats_list();
}

/**
 * Implementation of hook_date_format_types().
 */
function date_api_date_format_types() {
  return array(
    'long' => t('Long'),
    'medium' => t('Medium'),
    'short' => t('Short'),
  );
}

/**
 * Array of regex replacement strings for date format elements.
 * Used to allow input in custom formats. Based on work done for
 * the Date module by Yves Chedemois (yched).
 *
 * @return array of date() format letters and their regex equivalents.
 */
function date_format_patterns($strict = FALSE) {
  return array(
    'd' => '\d{' . ($strict ? '2' : '1,2') . '}', 
    'm' => '\d{' . ($strict ? '2' : '1,2') . '}', 
    'h' => '\d{' . ($strict ? '2' : '1,2') . '}',      
    'H' => '\d{' . ($strict ? '2' : '1,2') . '}',   
    'i' => '\d{' . ($strict ? '2' : '1,2') . '}',
    's' => '\d{' . ($strict ? '2' : '1,2') . '}',
    'j' => '\d{1,2}',    'N' => '\d',      'S' => '\w{2}',
    'w' => '\d',       'z' => '\d{1,3}',    'W' => '\d{1,2}',
    'n' => '\d{1,2}',  't' => '\d{2}',      'L' => '\d',      'o' => '\d{4}',
    'Y' => '\d{4}',    'y' => '\d{2}',      'B' => '\d{3}',   'g' => '\d{1,2}',
    'G' => '\d{1,2}',  'e' => '\w*',        'I' => '\d',      'T' => '\w*',
    'U' => '\d*',      'z' => '[+-]?\d*',   'O' => '[+-]?\d{4}',
    //Using S instead of w and 3 as well as 4 to pick up non-ASCII chars like German umlaute
    'D' => '\S{3,4}',    'l' => '\S*', 'M' => '\S{3,4}', 'F' => '\S*',
    'P' => '[+-]?\d{2}\:\d{2}',
    'c' => '(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})([+-]?\d{2}\:\d{2})',
    'r' => '(\w{3}), (\d{2})\s(\w{3})\s(\d{2,4})\s(\d{2}):(\d{2}):(\d{2})([+-]?\d{4})?',
    );
}

/**
 * Array of granularity options and their labels
 *
 * @return array
 */
function date_granularity_names() {
  return array(
    'year' => date_t('Year', 'datetime'), 
    'month' => date_t('Month', 'datetime'), 
    'day' => date_t('Day', 'datetime'),
    'hour' => date_t('Hour', 'datetime'), 
    'minute' => date_t('Minute', 'datetime'), 
    'second' => date_t('Second', 'datetime'),
    );
}

/**
 * A translated array of timezone names.
 * Cache the untranslated array, make the translated array a static variable.
 *
 * @param $required
 *   If not required, returned array will include a blank value.
 * @return
 *   an array of timezone names
 */
function date_timezone_names($required = FALSE, $refresh = FALSE) {
  static $zonenames;
  if (empty($zonenames) || $refresh) {
    $cached = cache_get('date_timezone_identifiers_list');
    $zonenames = !empty($cached) ? $cached->data : array();
    if ($refresh || empty($cached) || empty($zonenames)) {
      $data = timezone_identifiers_list();
      // Use include instead of include once in case the function gets 
      // refreshed via devel or other API and is called more than once.
      if (module_exists('date_php4')) {
        include(' ./' . drupal_get_path('module', 'date_php4') . '/date_php4_missing_data.inc');
      }
      foreach ($data as $delta => $zone) {
        // Because many time zones exist in PHP only for backward 
        // compatibility reasons and should not be used, the list is 
        // filtered by a regular expression.
        if (preg_match('!^((Africa|America|Antarctica|Arctic|Asia|Atlantic|Australia|Europe|Indian|Pacific)/|UTC$)!', $zone)) {
          $zonenames[$zone] = t($zone);
        }      
      }
      // If using PHP4, filter the list down to only the timezones
      // the PHP4 wrapper has data for.
      if (module_exists('date_php4')) {
        foreach ($missing_timezone_data as $zone) {
          unset($zonenames[$zone]);
        }
      }
    
      // If using Event, further filter the list down to only 
      // zones that exist in the event module.
      if (module_exists('event') && db_table_exists('event_timezones')) {
        $result = db_query("SELECT name FROM {event_timezones} ORDER BY name");
        $names = array();
        while ($row = db_fetch_array($result)) {
          $names[] = str_replace(' ', '_', $row['name']);
        }
        foreach ($zonenames as $name => $zone) {
          if (!in_array($name, $names)) {
            unset($zonenames[$name]);
          }
        }
      }
      if (!empty($zonenames)) {
        cache_set('date_timezone_identifiers_list', $zonenames);
      }
    }
    else {
      foreach ($zonenames as $zone) {
        $zonenames[$zone] = t('!timezone', array('!timezone' => $zone));
      }
    }
  }
  $none = array('' => '');
  return !$required ? $none + $zonenames : $zonenames;
}

/**
 * An array of timezone abbreviations that the system allows.
 * Cache an array of just the abbreviation names because the
 * whole timezone_abbreviations_list is huge so we don't want
 * to get it more than necessary.
 *
 * @return array
 */
function date_timezone_abbr($refresh = FALSE) {
  $cached = cache_get('date_timezone_abbreviations');
  $data = isset($cached->data) ? $cached->data : array();
  if (empty($data) || $refresh) {
    $data = array_keys(timezone_abbreviations_list());
    cache_set('date_timezone_abbreviations', $data);
  }
  return $data;
}

/**
 * A function to translate ambiguous short date strings.
 * 
 * Example: Pass in 'Monday', 'day_abbr' and get the translated 
 * abbreviation for Monday.
 * 
 * @param string $string
 * @param string $context
 * @param int array('langcode' => $langcode)
 * @return translated value of the string
 */
function date_t($string, $context, $langcode = NULL) {
  //static $replace = array();
  
  if (empty($replace[$langcode])) {
    // The function to create the date string arrays is kept separate
    // so those arrays can be directly accessed by other functions.
    date_t_strings($replace, $langcode);
  }
  switch ($context) {
    case 'day_name':
    case 'day_abbr':
    case 'day_abbr1':
    case 'day_abbr2':  
      $untranslated = array_flip(date_week_days_untranslated());
      break;
    case 'month_name':
    case 'month_abbr':
      $untranslated = array_flip(date_month_names_untranslated());
      break;  
    case 'ampm':
      $untranslated = array_flip(array('am', 'pm', 'AM', 'PM'));  
      break;
    case 'datetime':
      $untranslated = array_flip(array('Year', 'Month', 'Day', 'Week', 'Hour', 'Minute', 'Second', 'All Day', 'All day'));  
      break;
    case 'datetime_plural':
      $untranslated = array_flip(array('Years', 'Months', 'Days', 'Weeks', 'Hours', 'Minutes', 'Seconds'));  
      break;
    case 'date_order':
      $untranslated = array_flip(array('Every', 'First', 'Second', 'Third', 'Fourth', 'Fifth'));  
      break;
    case 'date_order_reverse':
      $untranslated = array_flip(array('', 'Last', 'Next to last', 'Third from last', 'Fourth from last', 'Fifth from last'));  
      break;
    case 'date_nav':
      $untranslated = array_flip(array('Prev', 'Next', 'Today'));  
      break;
  }
  $pos = $untranslated[$string];
  return $replace[$langcode][$context][$pos];
}

/**
 * Construct translation arrays from pipe-delimited strings.
 * 
 * Combining these strings into a single t() gives them the context needed
 * for better translation.
 */
function date_t_strings(&$replace, $langcode) {
  $replace[$langcode]['day_name'] = explode('|', trim(t('!day-name Sunday|Monday|Tuesday|Wednesday|Thursday|Friday|Saturday', array('!day-name' => ''), array('langcode' => $langcode))));
  $replace[$langcode]['day_abbr'] = explode('|', trim(t('!day-abbreviation Sun|Mon|Tue|Wed|Thu|Fri|Sat', array('!day-abbreviation' => ''), array('langcode' => $langcode))));
  $replace[$langcode]['day_abbr1'] = explode('|', trim(t('!day-abbreviation S|M|T|W|T|F|S', array('!day-abbreviation' => ''), array('langcode' => $langcode))));
  $replace[$langcode]['day_abbr2'] = explode('|', trim(t('!day-abbreviation SU|MO|TU|WE|TH|FR|SA', array('!day-abbreviation' => ''), array('langcode' => $langcode))));
  $replace[$langcode]['ampm'] = explode('|', trim(t('!ampm-abbreviation am|pm|AM|PM', array('!ampm-abbreviation' => ''), array('langcode' => $langcode))));
  $replace[$langcode]['datetime'] = explode('|', trim(t('!datetime Year|Month|Day|Week|Hour|Minute|Second|All Day|All day', array('!datetime' => ''), array('langcode' => $langcode))));
  $replace[$langcode]['datetime_plural'] = explode('|', trim(t('!datetime_plural Years|Months|Days|Weeks|Hours|Minutes|Seconds', array('!datetime_plural' => ''), array('langcode' => $langcode))));
  $replace[$langcode]['date_order'] = explode('|', trim(t('!date_order Every|First|Second|Third|Fourth|Fifth', array('!date_order' => ''), array('langcode' => $langcode))));
  $replace[$langcode]['date_order_reverse'] = explode('|', trim(t('!date_order |Last|Next to last|Third from last|Fourth from last|Fifth from last', array('!date_order' => ''), array('langcode' => $langcode))));
  $replace[$langcode]['date_nav'] = explode('|', trim(t('!date_nav Prev|Next|Today', array('!date_nav' => ''), array('langcode' => $langcode))));
  
  // These start with a pipe so the January value will be in position 1 instead of position 0.
  $replace[$langcode]['month_name'] = explode('|', trim(t('!month-name |January|February|March|April|May|June|July|August|September|October|November|December', array('!month-name' => ''), array('langcode' => $langcode))));
  $replace[$langcode]['month_abbr'] = explode('|', trim(t('!month-abbreviation |Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec', array('!month-abbreviation' => ''), array('langcode' => $langcode))));
}

/**
 * Reworked from Drupal's format_date function to handle pre-1970 and
 * post-2038 dates and accept a date object instead of a timestamp as input.
 *
 * Translates formatted date results, unlike PHP function date_format().
 *
 * @param $oject
 *   A date object, could be created by date_make_date().
 * @param $type
 *   The format to use. Can be "small", "medium" or "large" for the preconfigured
 *   date formats. If "custom" is specified, then $format is required as well.
 * @param $format
 *   A PHP date format string as required by date(). A backslash should be used
 *   before a character to avoid interpreting the character as part of a date
 *   format.
 * @return
 *   A translated date string in the requested format.
 */
function date_format_date($date, $type = 'medium', $format = '', $langcode = NULL) {
  if (empty($date)) {
    return '';
  }
  switch ($type) {
    case 'small':
    case 'short':
      $format = variable_get('date_format_short', 'm/d/Y - H:i');
      break;
    case 'large':
    case 'long':
      $format = variable_get('date_format_long', 'l, F j, Y - H:i');
      break;
    case 'custom':
      $format = $format;
      break;
    case 'medium':
    default:
      $format = variable_get('date_format_medium', 'D, m/d/Y - H:i');
  }
  $max = strlen($format);
  $datestring = '';
  for ($i = 0; $i < $max; $i++) {
    $c = $format[$i];
    switch ($c) {
      // Use date_t() for ambiguous short strings that need translation.
      // We send long day and month names to date_t(), along with context.
      case 'l':
        $datestring .= date_t(date_format($date, 'l'), 'day_name', $langcode);
        break;
      case 'D':
        $datestring .= date_t(date_format($date, 'l'), 'day_abbr', $langcode);
        break;
      case 'F':
        $datestring .= date_t(date_format($date, 'F'), 'month_name', $langcode);
        break;  
      case 'M':
        $datestring .= date_t(date_format($date, 'F'), 'month_abbr', $langcode);
        break;  
      case 'A':
      case 'a':
        $datestring .= date_t(date_format($date, $c), 'ampm', $langcode);
        break;  
      // The timezone name translations can use t().  
      case 'e':
      case 'T':
        $datestring .= t(date_format($date, $c));
        break;
      // Remaining date parts need no translation.
      case 'O':
        $datestring .= sprintf('%s%02d%02d', (date_offset_get($date) < 0 ? '-' : '+'), abs(date_offset_get($date) / 3600), abs(date_offset_get($date) % 3600) / 60);
        break;
      case 'P':
        $datestring .= sprintf('%s%02d:%02d', (date_offset_get($date) < 0 ? '-' : '+'), abs(date_offset_get($date) / 3600), abs(date_offset_get($date) % 3600) / 60);
        break;
      case 'Z':
        $datestring .= date_offset_get($date);
        break;              
      case '\\':
        $datestring .= $format[++$i];
        break;
      default:
        if (strpos('BdcgGhHiIjLmnsStTUwWYyz', $c) !== FALSE) {
          $datestring .= date_format($date, $c);
        }
        elseif ($c == 'r') {
          $datestring .= format_date($date, 'custom', 'D, d M Y H:i:s O', $langcode);
        }
        else {
          $datestring .= $c;
        }
    }
  }
  return $datestring;
}

/**
 * An override for interval formatting that adds past and future context
 *
 * @param DateTime $date
 * @param integer $granularity
 * @return formatted string
 */
function date_format_interval($date, $granularity = 2) {
  // If no date is sent, then return nothing
  if (empty($date)) {
    return NULL;
  }

  $interval = REQUEST_TIME - date_format($date, 'U');
  if($interval > 0 ) {
    return t('!time ago', array('!time' => format_interval($interval, $granularity)));
  } 
  else {
    return format_interval(abs($interval), $granularity);
  }
}

/**
 * A date object for the current time.
 *
 * @param $timezone
 *   Optional method to force time to a specific timezone,
 *   defaults to user timezone, if set, otherwise site timezone.
 * @return object date
 */
function date_now($timezone = NULL) {
  return date_make_date('now', $timezone);
}

/**
 *  Convert a date of any type or an array of date parts into a valid date
 *  object.

 *  @param $date
 *    A date in any format or the string 'now' .
 *  @param $timezone
 *    Optional, the name of the timezone this date is in, defaults
 *    to the user timezone, if set, otherwise the site timezone.
 *    Accepts either a timezone name or a timezone object as input.
 *  @param $type
 *    The type of date provided, could be
 *    DATE_ARRAY, DATE_UNIX, DATE_DATETIME, DATE_ISO, or DATE_OBJECT.
 *  @param $granularity
 *    The granularity of the date value provided. Set this for partial
 *    dates so they pass validation and don't get reset to 'now' .
 */
function date_make_date($date, $timezone = NULL, $type = DATE_DATETIME, $granularity = array('year', 'month', 'day', 'hour', 'minute')) {
  // No value or one that can't be used.
  if (empty($date) || is_array($date)) {
    return NULL;
  }

  // Make sure some value is set for the date and timezone even if the
  // site timezone is not yet set up to avoid fatal installation
  // errors.
  if (empty($timezone) || !date_timezone_is_valid($timezone)) {
    $timezone = date_default_timezone();
  }
    
  // Special handling for partial dates that don't need precision.
  $max_granularity = array_pop($granularity);
  if (in_array($max_granularity, array('year', 'month')) || $type == DATE_ISO || $type == DATE_ARRAY) {
    if ($type == DATE_UNIX) {
      $date = date_convert($date, $type, DATE_DATETIME);
    }
    $date = date_fuzzy_datetime($date);
    $type = DATE_DATETIME;
  }
  

  if (!date_is_valid($date, $type, $granularity)) {
    $date = 'now';
  }
  if (!empty($timezone) && !empty($date)) {
    if ($date == 'now') {
      return date_create('now', timezone_open($timezone));
    }
    elseif ($datetime = date_convert($date, $type, DATE_DATETIME, $timezone)) {
      return date_create($datetime, timezone_open($timezone));
    }
  }
  return NULL;
}

function date_timezone_is_valid($timezone) {
  static $timezone_names;
  if (empty($timezone_names)) {
    $timezone_names = array_keys(date_timezone_names(TRUE));
  }
  if (!in_array($timezone, $timezone_names)) {
    return FALSE;
  }
  return TRUE;
}

/**
 * Return a timezone name to use as a default.
 *
 * @return a timezone name
 *   Identify the default timezone for a user, if available, otherwise the site.
 *   Must return a value even if no timezone info has been set up.
 */
function date_default_timezone($check_user = TRUE) {
  global $user;
  if ($check_user && variable_get('configurable_timezones', 1) && !empty($user->timezone)) {
    return $user->timezone;
  }
  else {
    $default = variable_get('date_default_timezone', '');
    return empty($default) ? 'UTC' : $default;
  }
}

/**
 * A timezone object for the default timezone.
 *
 * @return a timezone name
 *   Identify the default timezone for a user, if available, otherwise the site.
 */
function date_default_timezone_object($check_user = TRUE) {
  $timezone = date_default_timezone($check_user);
  return timezone_open(date_default_timezone($check_user));
}

/**
 * Identify the number of days in a month for a date.
 */
function date_days_in_month($year, $month) {
  // Pick a day in the middle of the month to avoid timezone shifts.
  $datetime = date_pad($year, 4) . '-' . date_pad($month) . '-15 00:00:00';
  $date = date_make_date($datetime);
  return date_format($date, 't');
}

/**
 * Identify the number of days in a year for a date.
 *
 * @param mixed $date
 * @param string $type
 * @return integer
 */
function date_days_in_year($date = NULL, $type = DATE_OBJECT) {
  if (empty($date)) {
    $date = date_now();
    $type = DATE_OBJECT;
  }
  $date = date_convert($date, $type, DATE_OBJECT);
  if (is_object($date)) {
    if (date_format($date, 'L')) {
      return 366;
    }
    else {
      return 365;
    }
  }
  return NULL;
}

/**
 * Identify the number of ISO weeks in a year for a date.
 *
 * December 28 is always in the last ISO week of the year.
 *
 * @param mixed $date
 * @param string $type
 * @return integer
 */
function date_iso_weeks_in_year($date = NULL, $type = DATE_OBJECT) {
  if (empty($date)) {
    $date = date_now();
    $type = DATE_OBJECT;
  }
  $date = date_convert($date, $type, DATE_OBJECT);
  if (is_object($date)) {
    date_date_set($date, date_format($date, 'Y'), 12, 28);
    return date_format($date, 'W');
  }
  return NULL;
}

/**
 * Returns day of week for a given date (0 = Sunday).
 *
 * @param mixed  $date
 *   a date, default is current local day
 * @param string  $type
 *   The type of date, DATE_ISO, DATE_DATETIME, or DATE_UNIX
 * @return
 *    the number of the day in the week
 */
function date_day_of_week($date = NULL, $type = DATE_OBJECT) {
  if (empty($date)) {
    $date = date_now();
    $type = DATE_OBJECT;
  }
  $date = date_convert($date, $type, DATE_OBJECT);
  if (is_object($date)) {
    return date_format($date, 'w');
  }
  return NULL;
}

/**
 * Returns translated name of the day of week for a given date.
 *
 * @param mixed  $date
 *   a date, default is current local day
 * @param string  $type
 *   The type of date, DATE_ISO, DATE_DATETIME, or DATE_UNIX
 * @param string $abbr
 *   Whether to return the abbreviated name for that day
 * @return
 *    the name of the day in the week for that date
 */
function date_day_of_week_name($date = NULL, $abbr = TRUE, $type = DATE_DATETIME) {
  $dow = date_day_of_week($date, $type);
  $days = $abbr ? date_week_days_abbr() : date_week_days();
  return $days[$dow];
}

/**
 * Compute difference between two days using a given measure.
 *
 * @param mixed $date1
 *   the starting date
 * @param mixed $date2
 *   the ending date
 * @param string $measure
 *   'years', 'months', 'weeks', 'days', 'hours', 'minutes', 'seconds'
 * @param string $type
 *   the type of dates provided:
 *   DATE_OBJECT, DATE_DATETIME, DATE_ISO, DATE_UNIX, DATE_ARRAY
 */
function date_difference($date1_in, $date2_in, $measure = 'seconds', $type = DATE_OBJECT) {
  // Create cloned objects or original dates will be impacted by
  // the date_modify() operations done in this code.
  $date1 = clone(date_convert($date1_in, $type, DATE_OBJECT));
  $date2 = clone(date_convert($date2_in, $type, DATE_OBJECT));
  if (is_object($date1) && is_object($date2)) {
    $diff = date_format($date2, 'U') - date_format($date1, 'U');
    if ($diff == 0 ) {
      return 0;
    }
    elseif ($diff < 0) {
      // Make sure $date1 is the smaller date.
      $temp = $date2;
      $date2 = $date1;
      $date1 = $temp;
      $diff = date_format($date2, 'U') - date_format($date1, 'U');
    }
    $year_diff = intval(date_format($date2, 'Y') - date_format($date1, 'Y'));
    switch ($measure) {

      // The easy cases first.
      case 'seconds':
        return $diff;
      case 'minutes':
        return $diff / 60;
      case 'hours':
        return $diff / 3600;
      case 'years':
        return $year_diff;

      case 'months':
        $format = 'n';
        $item1 = date_format($date1, $format);
        $item2 = date_format($date2, $format);
        if ($year_diff == 0) {
          return intval($item2 - $item1);
        }
        else {
          $item_diff = 12 - $item1;
          $item_diff += intval(($year_diff - 1) * 12);
          return $item_diff + $item2;
       }
       break;

      case 'days':
        $format = 'z';
        $item1 = date_format($date1, $format);
        $item2 = date_format($date2, $format);
        if ($year_diff == 0) {
          return intval($item2 - $item1);
        }
        else {
          $item_diff = date_days_in_year($date1) - $item1;
          for ($i = 1; $i < $year_diff; $i++) {
            date_modify($date1, '+1 year');
            $item_diff += date_days_in_year($date1);
          }
          return $item_diff + $item2;
       }
       break;

      case 'weeks':
        $week_diff = date_format($date2, 'W') - date_format($date1, 'W');
        $year_diff = date_format($date2, 'o') - date_format($date1, 'o');
        for ($i = 1; $i <= $year_diff; $i++) {
          date_modify($date1, '+1 year');
          $week_diff += date_iso_weeks_in_year($date1);
        }
        return $week_diff;
    }
  }
  return NULL;
}

/**
 * Start and end dates for a calendar week, adjusted to use the
 * chosen first day of week for this site.
 */
function date_week_range($week, $year) {
  $min_date = date_make_date($year . '-01-01 00:00:00', date_default_timezone());
  date_timezone_set($min_date, date_default_timezone());

  // move to the right week
  date_modify($min_date, '+' . strval(7 * ($week - 1)) . ' days');

  // move backwards to the first day of the week
  $first_day = variable_get('date_first_day', 0);
  $day_wday = date_format($min_date, 'w');
  date_modify($min_date, '-' . strval((7 + $day_wday - $first_day) % 7) . ' days');

  // move forwards to the last day of the week
  $max_date = clone($min_date);
  date_modify($max_date, '+7 days');

  if (date_format($min_date, 'Y') != $year) {
    $min_date = date_make_date($year . '-01-01 00:00:00', date_default_timezone());
  }
  return array($min_date, $max_date);
}

/**
 * The number of calendar weeks in a year.
 * 
 * PHP week functions return the ISO week, not the calendar week.
 *
 * @param int $year
 * @return int number of calendar weeks in selected year.
 */
function date_weeks_in_year($year) {
  $date = date_make_date(($year + 1) . '-01-01 12:00:00', 'UTC');
  date_modify($date, '-1 day');
  return date_week(date_format($date, 'Y-m-d'));
}

/**
 * The calendar week number for a date.
 * 
 * PHP week functions return the ISO week, not the calendar week.
 *
 * @param string $date, in the format Y-m-d
 * @return int calendar week number.
 */
function date_week($date) {
  $date = substr($date, 0, 10);
  $parts = explode('-', $date);

  $date = date_make_date($date . ' 12:00:00', 'UTC');
  $year_date = date_make_date($parts[0] . '-01-01 12:00:00', 'UTC');

  $week = intval(date_format($date, 'W'));
  $year_week = intval(date_format($year_date, 'W'));
  $date_year = intval(date_format($date, 'o'));

  // remove the leap week if it's present
  if ($date_year > intval($parts[0])) {
    $last_date = clone($date);
    date_modify($last_date, '-7 days');
    $week = date_format($last_date, 'W') + 1;
  } 
  elseif ($date_year < intval($parts[0])) {
    $week = 0;
  }
  if ($year_week != 1) $week++;

  // convert to ISO-8601 day number, to match weeks calculated above
  $iso_first_day = 1 + (variable_get('date_first_day', 0) + 6) % 7;

  // if it's before the starting day, it's the previous week
  if (intval(date_format($date, 'N')) < $iso_first_day) $week--;

  // if the year starts before, it's an extra week at the beginning
  if (intval(date_format($year_date, 'N')) < $iso_first_day) $week++;

  return $week;
}

/**
 * Date conversion helper function.
 *
 * A variety of ways to convert dates from one type to another.
 * No timezone conversion is done in this operation, except
 * when handling timestamps because create_date() assumes
 * timestamps hold the UTC value for the time.
 *
 * @param mixed $date
 *   the date to convert
 * @param string $from_type
 *   the type of date to convert from
 * @param string $to_type
 *   the type of date to convert to
 * @param string $tz
 *   the timezone of the supplied value, only needed when using timestamps
 *   for dates not set to UTC.
 */
function date_convert($date, $from_type, $to_type, $tz = 'UTC') {
  if (empty($date) && !$date === 0) return NULL;
  if (empty($from_type) || empty($to_type) || $from_type == $to_type) return $date;
  switch ($from_type) {
    case DATE_ARRAY:
      if (!is_array($date)) return NULL;