application/TimeZone.php

   1 <?php
   2 /**
   3  * Generates the timezone selection form and JavaScript.
   4  *
   5  * Note: 'UTC/UTC' is mapped to 'UTC' to form a valid option
   6  *
   7  * Example: preselect Europe/Paris
   8  *  list($htmlform, $js) = generateTimeZoneForm('Europe/Paris');
   9  *
  10  * @param string $preselectedTimezone preselected timezone (optional)
  11  *
  12  * @return array containing the generated HTML form and Javascript code
  13  **/
  14 function generateTimeZoneForm($preselectedTimezone='')
  15 {
  16     // Select the server timezone
  17     if ($preselectedTimezone == '') {
  18         $preselectedTimezone = date_default_timezone_get();
  19     }
  20
  21     if ($preselectedTimezone == 'UTC') {
  22         $pcity = $pcontinent = 'UTC';
  23     } else {
  24         // Try to split the provided timezone
  25         $spos = strpos($preselectedTimezone, '/');
  26         $pcontinent = substr($preselectedTimezone, 0, $spos);
  27         $pcity = substr($preselectedTimezone, $spos+1);
  28     }
  29
  30     // The list is in the form 'Europe/Paris', 'America/Argentina/Buenos_Aires'
  31     // We split the list in continents/cities.
  32     $continents = array();
  33     $cities = array();
  34
  35     // TODO: use a template to generate the HTML/Javascript form
  36
  37     foreach (timezone_identifiers_list() as $tz) {
  38         if ($tz == 'UTC') {
  39             $tz = 'UTC/UTC';
  40         }
  41         $spos = strpos($tz, '/');
  42
  43         if ($spos !== false) {
  44             $continent = substr($tz, 0, $spos);
  45             $city = substr($tz, $spos+1);
  46             $continents[$continent] = 1;
  47
  48             if (!isset($cities[$continent])) {
  49                 $cities[$continent] = '';
  50             }
  51             $cities[$continent] .= '<option value="'.$city.'"';
  52             if ($pcity == $city) {
  53                 $cities[$continent] .= ' selected="selected"';
  54             }
  55             $cities[$continent] .= '>'.$city.'</option>';
  56         }
  57     }
  58
  59     $continentsHtml = '';
  60     $continents = array_keys($continents);
  61
  62     foreach ($continents as $continent) {
  63         $continentsHtml .= '<option  value="'.$continent.'"';
  64         if ($pcontinent == $continent) {
  65             $continentsHtml .= ' selected="selected"';
  66         }
  67         $continentsHtml .= '>'.$continent.'</option>';
  68     }
  69
  70     // Timezone selection form
  71     $timezoneForm = 'Continent:';
  72     $timezoneForm .= '<select name="continent" id="continent" onChange="onChangecontinent();">';
  73     $timezoneForm .= $continentsHtml.'</select>';
  74     $timezoneForm .= '&nbsp;&nbsp;&nbsp;&nbsp;City:';
  75     $timezoneForm .= '<select name="city" id="city">'.$cities[$pcontinent].'</select><br />';
  76
  77     // Javascript handler - updates the city list when the user selects a continent
  78     $timezoneJs = '<script>';
  79     $timezoneJs .= 'function onChangecontinent() {';
  80     $timezoneJs .= 'document.getElementById("city").innerHTML =';
  81     $timezoneJs .= ' citiescontinent[document.getElementById("continent").value]; }';
  82     $timezoneJs .= 'var citiescontinent = '.json_encode($cities).';';
  83     $timezoneJs .= '</script>';
  84
  85     return array($timezoneForm, $timezoneJs);
  86 }
  87
  88 /**
  89  * Tells if a continent/city pair form a valid timezone
  90  *
  91  * Note: 'UTC/UTC' is mapped to 'UTC'
  92  *
  93  * @param string $continent the timezone continent
  94  * @param string $city      the timezone city
  95  *
  96  * @return bool whether continent/city is a valid timezone
  97  */
  98 function isTimeZoneValid($continent, $city)
  99 {
 100     return in_array(
 101         $continent.'/'.$city,
 102         timezone_identifiers_list()
 103     );
 104 }