MyShaarli/application/TimeZone.php

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<?php
/**
* Generates the timezone selection form and JavaScript.
*
* Note: 'UTC/UTC' is mapped to 'UTC' to form a valid option
*
* Example: preselect Europe/Paris
* list($htmlform, $js) = generateTimeZoneForm('Europe/Paris');
*
* @param string $preselectedTimezone preselected timezone (optional)
*
* @return array containing the generated HTML form and Javascript code
**/
function generateTimeZoneForm($preselectedTimezone='')
{
// Select the server timezone
if ($preselectedTimezone == '') {
$preselectedTimezone = date_default_timezone_get();
}
if ($preselectedTimezone == 'UTC') {
$pcity = $pcontinent = 'UTC';
} else {
// Try to split the provided timezone
$spos = strpos($preselectedTimezone, '/');
$pcontinent = substr($preselectedTimezone, 0, $spos);
$pcity = substr($preselectedTimezone, $spos+1);
}
// The list is in the form 'Europe/Paris', 'America/Argentina/Buenos_Aires'
// We split the list in continents/cities.
$continents = array();
$cities = array();
// TODO: use a template to generate the HTML/Javascript form
foreach (timezone_identifiers_list() as $tz) {
if ($tz == 'UTC') {
$tz = 'UTC/UTC';
}
$spos = strpos($tz, '/');
if ($spos !== false) {
$continent = substr($tz, 0, $spos);
$city = substr($tz, $spos+1);
$continents[$continent] = 1;
if (!isset($cities[$continent])) {
$cities[$continent] = '';
}
$cities[$continent] .= '<option value="'.$city.'"';
if ($pcity == $city) {
$cities[$continent] .= ' selected="selected"';
}
$cities[$continent] .= '>'.$city.'</option>';
}
}
$continentsHtml = '';
$continents = array_keys($continents);
foreach ($continents as $continent) {
$continentsHtml .= '<option value="'.$continent.'"';
if ($pcontinent == $continent) {
$continentsHtml .= ' selected="selected"';
}
$continentsHtml .= '>'.$continent.'</option>';
}
// Timezone selection form
$timezoneForm = 'Continent:';
$timezoneForm .= '<select name="continent" id="continent" onChange="onChangecontinent();">';
$timezoneForm .= $continentsHtml.'</select>';
$timezoneForm .= '&nbsp;&nbsp;&nbsp;&nbsp;City:';
$timezoneForm .= '<select name="city" id="city">'.$cities[$pcontinent].'</select><br />';
// Javascript handler - updates the city list when the user selects a continent
$timezoneJs = '<script>';
$timezoneJs .= 'function onChangecontinent() {';
$timezoneJs .= 'document.getElementById("city").innerHTML =';
$timezoneJs .= ' citiescontinent[document.getElementById("continent").value]; }';
$timezoneJs .= 'var citiescontinent = '.json_encode($cities).';';
$timezoneJs .= '</script>';
return array($timezoneForm, $timezoneJs);
}
/**
* Tells if a continent/city pair form a valid timezone
*
* Note: 'UTC/UTC' is mapped to 'UTC'
*
* @param string $continent the timezone continent
* @param string $city the timezone city
*
* @return bool whether continent/city is a valid timezone
*/
function isTimeZoneValid($continent, $city)
{
return in_array(
$continent.'/'.$city,
timezone_identifiers_list()
);
}