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 $preselected_timezone preselected timezone (optional)
  11  *
  12  * @return an array containing the generated HTML form and Javascript code
  13  **/
  14 function generateTimeZoneForm($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     // Display config form:
  31     $timezoneForm = '';
  32     $timezoneJs = '';
  33
  34     // The list is in the form 'Europe/Paris', 'America/Argentina/Buenos_Aires'
  35     // We split the list in continents/cities.
  36     $continents = array();
  37     $cities = array();
  38
  39     // TODO: use a template to generate the HTML/Javascript form
  40
  41     foreach (timezone_identifiers_list() as $tz) {
  42         if ($tz == 'UTC') {
  43             $tz = 'UTC/UTC';
  44         }
  45         $spos = strpos($tz, '/');
  46
  47         if ($spos !== false) {
  48             $continent = substr($tz, 0, $spos);
  49             $city = substr($tz, $spos+1);
  50             $continents[$continent] = 1;
  51
  52             if (!isset($cities[$continent])) {
  53                 $cities[$continent] = '';
  54             }
  55             $cities[$continent] .= '<option value="'.$city.'"';
  56             if ($pcity == $city) {
  57                 $cities[$continent] .= ' selected="selected"';
  58             }
  59             $cities[$continent] .= '>'.$city.'</option>';
  60         }
  61     }
  62
  63     $continentsHtml = '';
  64     $continents = array_keys($continents);
  65
  66     foreach ($continents as $continent) {
  67         $continentsHtml .= '<option  value="'.$continent.'"';
  68         if ($pcontinent == $continent) {
  69             $continentsHtml .= ' selected="selected"';
  70         }
  71         $continentsHtml .= '>'.$continent.'</option>';
  72     }
  73
  74     // Timezone selection form
  75     $timezoneForm = 'Continent:';
  76     $timezoneForm .= '<select name="continent" id="continent" onChange="onChangecontinent();">';
  77     $timezoneForm .= $continentsHtml.'</select>';
  78     $timezoneForm .= '&nbsp;&nbsp;&nbsp;&nbsp;City:';
  79     $timezoneForm .= '<select name="city" id="city">'.$cities[$pcontinent].'</select><br />';
  80
  81     // Javascript handler - updates the city list when the user selects a continent
  82     $timezoneJs = '<script>';
  83     $timezoneJs .= 'function onChangecontinent() {';
  84     $timezoneJs .= 'document.getElementById("city").innerHTML =';
  85     $timezoneJs .= ' citiescontinent[document.getElementById("continent").value]; }';
  86     $timezoneJs .= 'var citiescontinent = '.json_encode($cities).';';
  87     $timezoneJs .= '</script>';
  88
  89     return array($timezoneForm, $timezoneJs);
  90 }
  91
  92 /**
  93  * Tells if a continent/city pair form a valid timezone
  94  *
  95  * Note: 'UTC/UTC' is mapped to 'UTC'
  96  *
  97  * @param string $continent the timezone continent
  98  * @param string $city      the timezone city
  99  *
 100  * @return whether continent/city is a valid timezone
 101  */
 102 function isTimeZoneValid($continent, $city)
 103 {
 104     if ($continent == 'UTC' && $city == 'UTC') {
 105         return true;
 106     }
 107
 108     return in_array(
 109         $continent.'/'.$city,
 110         timezone_identifiers_list()
 111     );
 112 }