MyShaarli/application/TimeZone.php

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<?php
/**
* Generates a list of available timezone continents and cities.
*
* Two distinct array based on available timezones
* and the one selected in the settings:
* - (0) continents:
* + list of available continents
* + special key 'selected' containing the value of the selected timezone's continent
* - (1) cities:
* + list of available cities associated with their continent
* + special key 'selected' containing the value of the selected timezone's city (without the continent)
*
* Example:
* [
* [
* 'America',
* 'Europe',
* 'selected' => 'Europe',
* ],
* [
* ['continent' => 'America', 'city' => 'Toronto'],
* ['continent' => 'Europe', 'city' => 'Paris'],
* 'selected' => 'Paris',
* ],
* ];
*
* Notes:
* - 'UTC/UTC' is mapped to 'UTC' to form a valid option
* - a few timezone cities includes the country/state, such as Argentina/Buenos_Aires
* - these arrays are designed to build timezone selects in template files with any HTML structure
*
* @param array $installedTimeZones List of installed timezones as string
* @param string $preselectedTimezone preselected timezone (optional)
*
* @return array[] continents and cities
**/
function generateTimeZoneData($installedTimeZones, $preselectedTimezone = '')
{
if ($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);
}
$continents = [];
$cities = [];
foreach ($installedTimeZones as $tz) {
if ($tz == 'UTC') {
$tz = 'UTC/UTC';
}
$spos = strpos($tz, '/');
// Ignore invalid timezones
if ($spos === false) {
continue;
}
$continent = substr($tz, 0, $spos);
$city = substr($tz, $spos + 1);
$cities[] = ['continent' => $continent, 'city' => $city];
$continents[$continent] = true;
}
$continents = array_keys($continents);
$continents['selected'] = $pcontinent;
$cities['selected'] = $pcity;
return [$continents, $cities];
}
/**
* 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()
);
}