<?php
/**
* Locale API: WP_Locale_Switcher class
*
* @package WordPress
* @subpackage i18n
* @since 4.7.0
*/

/**
* Core class used for switching locales.
*
* @since 4.7.0
*/
#[AllowDynamicProperties]
class WP_Locale_Switcher {
/**
* Locale switching stack.
*
* @since 6.2.0
* @var array
*/
private $stack = array();

/**
* Original locale.
*
* @since 4.7.0
* @var string
*/
private $original_locale;

/**
* Holds all available languages.
*
* @since 4.7.0
* @var string[] An array of language codes (file names without the .mo extension).
*/
private $available_languages;

/**
* Constructor.
*
* Stores the original locale as well as a list of all available languages.
*
* @since 4.7.0
*/
public function __construct() {
$this->original_locale = determine_locale();
$this->available_languages = array_merge( array( 'en_US' ), get_available_languages() );
}

/**
* Initializes the locale switcher.
*
* Hooks into the {@see 'locale'} and {@see 'determine_locale'} filters
* to change the locale on the fly.
*
* @since 4.7.0
*/
public function init() {
add_filter( 'locale', array( $this, 'filter_locale' ) );
add_filter( 'determine_locale', array( $this, 'filter_locale' ) );
}

/**
* Switches the translations according to the given locale.
*
* @since 4.7.0
*
* @param string $locale The locale to switch to.
* @param int|false $user_id Optional. User ID as context. Default false.
* @return bool True on success, false on failure.
*/
public function switch_to_locale( $locale, $user_id = false ) {
$current_locale = determine_locale();
if ( $current_locale === $locale ) {
return false;
}

if ( ! in_array( $locale, $this->available_languages, true ) ) {
return false;
}

$this->stack[] = array( $locale, $user_id );

$this->change_locale( $locale );

/**
* Fires when the locale is switched.
*
* @since 4.7.0
* @since 6.2.0 The `$user_id` parameter was added.
*
* @param string $locale The new locale.
* @param false|int $user_id User ID for context if available.
*/
do_action( 'switch_locale', $locale, $user_id );

return true;
}

/**
* Switches the translations according to the given user's locale.
*
* @since 6.2.0
*
* @param int $user_id User ID.
* @return bool True on success, false on failure.
*/
public function switch_to_user_locale( $user_id ) {
$locale = get_user_locale( $user_id );
return $this->switch_to_locale( $locale, $user_id );
}

/**
* Restores the translations according to the previous locale.
*
* @since 4.7.0
*
* @return string|false Locale on success, false on failure.
*/
public function restore_previous_locale() {
$previous_locale = array_pop( $this->stack );

if ( null === $previous_locale ) {
// The stack is empty, bail.
return false;
}

$entry = end( $this->stack );
$locale = is_array( $entry ) ? $entry[0] : false;

if ( ! $locale ) {
// There's nothing left in the stack: go back to the original locale.
$locale = $this->original_locale;
}

$this->change_locale( $locale );

/**
* Fires when the locale is restored to the previous one.
*
* @since 4.7.0
*
* @param string $locale The new locale.
* @param string $previous_locale The previous locale.
*/
do_action( 'restore_previous_locale', $locale, $previous_locale[0] );

return $locale;
}

/**
* Restores the translations according to the original locale.
*
* @since 4.7.0
*
* @return string|false Locale on success, false on failure.
*/
public function restore_current_locale() {
if ( empty( $this->stack ) ) {
return false;
}

$this->stack = array( array( $this->original_locale, false ) );

return $this->restore_previous_locale();
}

/**
* Whether switch_to_locale() is in effect.
*
* @since 4.7.0
*
* @return bool True if the locale has been switched, false otherwise.
*/
public function is_switched() {
return ! empty( $this->stack );
}

/**
* Returns the locale currently switched to.
*
* @since 6.2.0
*
* @return string|false Locale if the locale has been switched, false otherwise.
*/
public function get_switched_locale() {
$entry = end( $this->stack );

if ( $entry ) {
return $entry[0];
}

return false;
}

/**
* Returns the user ID related to the currently switched locale.
*
* @since 6.2.0
*
* @return int|false User ID if set and if the locale has been switched, false otherwise.
*/
public function get_switched_user_id() {
$entry = end( $this->stack );

if ( $entry ) {
return $entry[1];
}

return false;
}

/**
* Filters the locale of the WordPress installation.
*
* @since 4.7.0
*
* @param string $locale The locale of the WordPress installation.
* @return string The locale currently being switched to.
*/
public function filter_locale( $locale ) {
$switched_locale = $this->get_switched_locale();

if ( $switched_locale ) {
return $switched_locale;
}

return $locale;
}

/**
* Load translations for a given locale.
*
* When switching to a locale, translations for this locale must be loaded from scratch.
*
* @since 4.7.0
*
* @global Mo[] $l10n An array of all currently loaded text domains.
*
* @param string $locale The locale to load translations for.
*/
private function load_translations( $locale ) {
global $l10n;

$domains = $l10n ? array_keys( $l10n ) : array();

load_default_textdomain( $locale );

foreach ( $domains as $domain ) {
// The default text domain is handled by `load_default_textdomain()`.
if ( 'default' === $domain ) {
continue;
}

/*
* Unload current text domain but allow them to be reloaded
* after switching back or to another locale.
*/
unload_textdomain( $domain, true );
get_translations_for_domain( $domain );
}
}

/**
* Changes the site's locale to the given one.
*
* Loads the translations, changes the global `$wp_locale` object and updates
* all post type labels.
*
* @since 4.7.0
*
* @global WP_Locale $wp_locale WordPress date and time locale object.
*
* @param string $locale The locale to change to.
*/
private function change_locale( $locale ) {
global $wp_locale;

$this->load_translations( $locale );

$wp_locale = new WP_Locale();

WP_Translation_Controller::get_instance()->set_locale( $locale );

/**
* Fires when the locale is switched to or restored.
*
* @since 4.7.0
*
* @param string $locale The new locale.
*/
do_action( 'change_locale', $locale );
}
}