1<?php
  2/**
  3 * Locale API: WP_Locale_Switcher class
  4 *
  5 * @package WordPress
  6 * @subpackage i18n
  7 * @since 4.7.0
  8 */
  9
 10/**
 11 * Core class used for switching locales.
 12 *
 13 * @since 4.7.0
 14 */
 15#[AllowDynamicProperties]
 16class WP_Locale_Switcher {
 17	/**
 18	 * Locale switching stack.
 19	 *
 20	 * @since 6.2.0
 21	 * @var array
 22	 */
 23	private $stack = array();
 24
 25	/**
 26	 * Original locale.
 27	 *
 28	 * @since 4.7.0
 29	 * @var string
 30	 */
 31	private $original_locale;
 32
 33	/**
 34	 * Holds all available languages.
 35	 *
 36	 * @since 4.7.0
 37	 * @var string[] An array of language codes (file names without the .mo extension).
 38	 */
 39	private $available_languages;
 40
 41	/**
 42	 * Constructor.
 43	 *
 44	 * Stores the original locale as well as a list of all available languages.
 45	 *
 46	 * @since 4.7.0
 47	 */
 48	public function __construct() {
 49		$this->original_locale     = determine_locale();
 50		$this->available_languages = array_merge( array( 'en_US' ), get_available_languages() );
 51	}
 52
 53	/**
 54	 * Initializes the locale switcher.
 55	 *
 56	 * Hooks into the {@see 'locale'} and {@see 'determine_locale'} filters
 57	 * to change the locale on the fly.
 58	 *
 59	 * @since 4.7.0
 60	 */
 61	public function init() {
 62		add_filter( 'locale', array( $this, 'filter_locale' ) );
 63		add_filter( 'determine_locale', array( $this, 'filter_locale' ) );
 64	}
 65
 66	/**
 67	 * Switches the translations according to the given locale.
 68	 *
 69	 * @since 4.7.0
 70	 *
 71	 * @param string    $locale  The locale to switch to.
 72	 * @param int|false $user_id Optional. User ID as context. Default false.
 73	 * @return bool True on success, false on failure.
 74	 */
 75	public function switch_to_locale( $locale, $user_id = false ) {
 76		$current_locale = determine_locale();
 77		if ( $current_locale === $locale ) {
 78			return false;
 79		}
 80
 81		if ( ! in_array( $locale, $this->available_languages, true ) ) {
 82			return false;
 83		}
 84
 85		$this->stack[] = array( $locale, $user_id );
 86
 87		$this->change_locale( $locale );
 88
 89		/**
 90		 * Fires when the locale is switched.
 91		 *
 92		 * @since 4.7.0
 93		 * @since 6.2.0 The `$user_id` parameter was added.
 94		 *
 95		 * @param string    $locale  The new locale.
 96		 * @param false|int $user_id User ID for context if available.
 97		 */
 98		do_action( 'switch_locale', $locale, $user_id );
 99
100		return true;
101	}
102
103	/**
104	 * Switches the translations according to the given user's locale.
105	 *
106	 * @since 6.2.0
107	 *
108	 * @param int $user_id User ID.
109	 * @return bool True on success, false on failure.
110	 */
111	public function switch_to_user_locale( $user_id ) {
112		$locale = get_user_locale( $user_id );
113		return $this->switch_to_locale( $locale, $user_id );
114	}
115
116	/**
117	 * Restores the translations according to the previous locale.
118	 *
119	 * @since 4.7.0
120	 *
121	 * @return string|false Locale on success, false on failure.
122	 */
123	public function restore_previous_locale() {
124		$previous_locale = array_pop( $this->stack );
125
126		if ( null === $previous_locale ) {
127			// The stack is empty, bail.
128			return false;
129		}
130
131		$entry  = end( $this->stack );
132		$locale = is_array( $entry ) ? $entry[0] : false;
133
134		if ( ! $locale ) {
135			// There's nothing left in the stack: go back to the original locale.
136			$locale = $this->original_locale;
137		}
138
139		$this->change_locale( $locale );
140
141		/**
142		 * Fires when the locale is restored to the previous one.
143		 *
144		 * @since 4.7.0
145		 *
146		 * @param string $locale          The new locale.
147		 * @param string $previous_locale The previous locale.
148		 */
149		do_action( 'restore_previous_locale', $locale, $previous_locale[0] );
150
151		return $locale;
152	}
153
154	/**
155	 * Restores the translations according to the original locale.
156	 *
157	 * @since 4.7.0
158	 *
159	 * @return string|false Locale on success, false on failure.
160	 */
161	public function restore_current_locale() {
162		if ( empty( $this->stack ) ) {
163			return false;
164		}
165
166		$this->stack = array( array( $this->original_locale, false ) );
167
168		return $this->restore_previous_locale();
169	}
170
171	/**
172	 * Whether switch_to_locale() is in effect.
173	 *
174	 * @since 4.7.0
175	 *
176	 * @return bool True if the locale has been switched, false otherwise.
177	 */
178	public function is_switched() {
179		return ! empty( $this->stack );
180	}
181
182	/**
183	 * Returns the locale currently switched to.
184	 *
185	 * @since 6.2.0
186	 *
187	 * @return string|false Locale if the locale has been switched, false otherwise.
188	 */
189	public function get_switched_locale() {
190		$entry = end( $this->stack );
191
192		if ( $entry ) {
193			return $entry[0];
194		}
195
196		return false;
197	}
198
199	/**
200	 * Returns the user ID related to the currently switched locale.
201	 *
202	 * @since 6.2.0
203	 *
204	 * @return int|false User ID if set and if the locale has been switched, false otherwise.
205	 */
206	public function get_switched_user_id() {
207		$entry = end( $this->stack );
208
209		if ( $entry ) {
210			return $entry[1];
211		}
212
213		return false;
214	}
215
216	/**
217	 * Filters the locale of the WordPress installation.
218	 *
219	 * @since 4.7.0
220	 *
221	 * @param string $locale The locale of the WordPress installation.
222	 * @return string The locale currently being switched to.
223	 */
224	public function filter_locale( $locale ) {
225		$switched_locale = $this->get_switched_locale();
226
227		if ( $switched_locale ) {
228			return $switched_locale;
229		}
230
231		return $locale;
232	}
233
234	/**
235	 * Load translations for a given locale.
236	 *
237	 * When switching to a locale, translations for this locale must be loaded from scratch.
238	 *
239	 * @since 4.7.0
240	 *
241	 * @global Mo[] $l10n An array of all currently loaded text domains.
242	 *
243	 * @param string $locale The locale to load translations for.
244	 */
245	private function load_translations( $locale ) {
246		global $l10n;
247
248		$domains = $l10n ? array_keys( $l10n ) : array();
249
250		load_default_textdomain( $locale );
251
252		foreach ( $domains as $domain ) {
253			// The default text domain is handled by `load_default_textdomain()`.
254			if ( 'default' === $domain ) {
255				continue;
256			}
257
258			/*
259			 * Unload current text domain but allow them to be reloaded
260			 * after switching back or to another locale.
261			 */
262			unload_textdomain( $domain, true );
263			get_translations_for_domain( $domain );
264		}
265	}
266
267	/**
268	 * Changes the site's locale to the given one.
269	 *
270	 * Loads the translations, changes the global `$wp_locale` object and updates
271	 * all post type labels.
272	 *
273	 * @since 4.7.0
274	 *
275	 * @global WP_Locale $wp_locale WordPress date and time locale object.
276	 * @global PHPMailer\PHPMailer\PHPMailer $phpmailer
277	 *
278	 * @param string $locale The locale to change to.
279	 */
280	private function change_locale( $locale ) {
281		global $wp_locale, $phpmailer;
282
283		$this->load_translations( $locale );
284
285		$wp_locale = new WP_Locale();
286
287		WP_Translation_Controller::get_instance()->set_locale( $locale );
288
289		if ( $phpmailer instanceof WP_PHPMailer ) {
290			$phpmailer->setLanguage();
291		}
292
293		/**
294		 * Fires when the locale is switched to or restored.
295		 *
296		 * @since 4.7.0
297		 *
298		 * @param string $locale The new locale.
299		 */
300		do_action( 'change_locale', $locale );
301	}
302}
303