diff --git a/includes/preferences/PreferencesFactory.php b/includes/preferences/PreferencesFactory.php
index 924e3ad..b19c690 100644
--- a/includes/preferences/PreferencesFactory.php
+++ b/includes/preferences/PreferencesFactory.php
@@ -17,12 +17,46 @@
  *
  * @file
  */
+
+namespace MediaWiki\Preferences;
+
+use CentralIdLookup;
+use DateTime;
+use DateTimeZone;
+use Exception;
+use Hooks;
+use Html;
+use HTMLForm;
+use HTMLFormField;
+use IContextSource;
+use Language;
+use LanguageCode;
+use LanguageConverter;
 use MediaWiki\Auth\AuthManager;
 use MediaWiki\Auth\PasswordAuthenticationRequest;
 use MediaWiki\MediaWikiServices;
+use MWException;
+use MWNamespace;
+use MWTimestamp;
+use OOUI\ButtonWidget;
+use OOUI\HtmlSnippet;
+use OutputPage;
+use Parser;
+use ParserOptions;
+use PreferencesForm;
+use Skin;
+use SpecialPage;
+use Status;
+use Title;
+use User;
+use UserGroupMembership;
+use Xml;
 
 /**
- * We're now using the HTMLForm object with some customisation to generate the
+ * The PreferencesFactory is a MediaWiki service that provides the definitions of preferences for
+ * a given user. These definitions are in the form of HTMLForm descriptors.
+ *
+ * PreferencesForm (a subclass of HTMLForm) is used to generate the
  * Preferences form. This object handles generic submission, CSRF protection,
  * layout and other logic in a reusable manner. We subclass it as a PreferencesForm
  * to make some minor customisations.
@@ -46,26 +80,31 @@ use MediaWiki\MediaWikiServices;
  * Once fields have been retrieved and validated, submission logic is handed
  * over to the tryUISubmit static method of this class.
  */
-class Preferences {
-	/** @var array */
-	protected static $saveFilters = [
-		'timecorrection' => [ 'Preferences', 'filterTimezoneInput' ],
-		'rclimit' => [ 'Preferences', 'filterIntval' ],
-		'wllimit' => [ 'Preferences', 'filterIntval' ],
-		'searchlimit' => [ 'Preferences', 'filterIntval' ],
-	];
+class PreferencesFactory {
 
 	// Stuff that shouldn't be saved as a preference.
-	private static $saveBlacklist = [
+	protected $saveBlacklist = [
 		'realname',
 		'emailaddress',
 	];
 
 	/**
+	 * @return callable[]
+	 */
+	protected function getSaveFilters() {
+		return [
+			'timecorrection' => [ $this, 'filterTimezoneInput' ],
+			'rclimit' => [ $this, 'filterIntval' ],
+			'wllimit' => [ $this, 'filterIntval' ],
+			'searchlimit' => [ $this, 'filterIntval' ],
+		];
+	}
+
+	/**
 	 * @return array
 	 */
-	static function getSaveBlacklist() {
-		return self::$saveBlacklist;
+	public function getSaveBlacklist() {
+		return $this->saveBlacklist;
 	}
 
 	/**
@@ -74,29 +113,27 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @return array|null
 	 */
-	static function getPreferences( $user, IContextSource $context ) {
+	public function getPreferences( $user, IContextSource $context ) {
 		OutputPage::setupOOUI(
 			strtolower( $context->getSkin()->getSkinName() ),
 			$context->getLanguage()->getDir()
 		);
-
-		$defaultPreferences = [];
-
-		self::profilePreferences( $user, $context, $defaultPreferences );
-		self::skinPreferences( $user, $context, $defaultPreferences );
-		self::datetimePreferences( $user, $context, $defaultPreferences );
-		self::filesPreferences( $user, $context, $defaultPreferences );
-		self::renderingPreferences( $user, $context, $defaultPreferences );
-		self::editingPreferences( $user, $context, $defaultPreferences );
-		self::rcPreferences( $user, $context, $defaultPreferences );
-		self::watchlistPreferences( $user, $context, $defaultPreferences );
-		self::searchPreferences( $user, $context, $defaultPreferences );
-		self::miscPreferences( $user, $context, $defaultPreferences );
-
-		Hooks::run( 'GetPreferences', [ $user, &$defaultPreferences ] );
-
-		self::loadPreferenceValues( $user, $context, $defaultPreferences );
-		return $defaultPreferences;
+		$preferences = [];
+		$this->profilePreferences( $user, $context, $preferences );
+		$this->skinPreferences( $user, $context, $preferences );
+		$this->datetimePreferences( $user, $context, $preferences );
+		$this->filesPreferences( $user, $context, $preferences );
+		$this->renderingPreferences( $user, $context, $preferences );
+		$this->editingPreferences( $user, $context, $preferences );
+		$this->rcPreferences( $user, $context, $preferences );
+		$this->watchlistPreferences( $user, $context, $preferences );
+		$this->searchPreferences( $user, $context, $preferences );
+		$this->miscPreferences( $user, $context, $preferences );
+
+		Hooks::run( 'GetPreferences', [ $user, &$preferences ] );
+
+		$this->loadPreferenceValues( $user, $context, $preferences );
+		return $preferences;
 	}
 
 	/**
@@ -107,7 +144,7 @@ class Preferences {
 	 * @param array &$defaultPreferences Array to load values for
 	 * @return array|null
 	 */
-	static function loadPreferenceValues( $user, $context, &$defaultPreferences ) {
+	public function loadPreferenceValues( $user, $context, &$defaultPreferences ) {
 		# # Remove preferences that wikis don't want to use
 		foreach ( $context->getConfig()->get( 'HiddenPrefs' ) as $pref ) {
 			if ( isset( $defaultPreferences[$pref] ) ) {
@@ -124,7 +161,7 @@ class Preferences {
 		# # Prod in defaults from the user
 		foreach ( $defaultPreferences as $name => &$info ) {
 			$prefFromUser = self::getOptionFromUser( $name, $info, $user );
-			if ( $disable && !in_array( $name, self::$saveBlacklist ) ) {
+			if ( $disable && !in_array( $name, $this->getSaveBlacklist() ) ) {
 				$info['disabled'] = 'disabled';
 			}
 			$field = HTMLForm::loadInputFromParameters( $name, $info, $dummyForm ); // For validation
@@ -157,7 +194,7 @@ class Preferences {
 	 * @param User $user
 	 * @return array|string
 	 */
-	static function getOptionFromUser( $name, $info, $user ) {
+	public function getOptionFromUser( $name, $info, $user ) {
 		$val = $user->getOption( $name );
 
 		// Handling for multiselect preferences
@@ -200,7 +237,7 @@ class Preferences {
 	 * @param array &$defaultPreferences
 	 * @return void
 	 */
-	static function profilePreferences( $user, IContextSource $context, &$defaultPreferences ) {
+	public function profilePreferences( $user, IContextSource $context, &$defaultPreferences ) {
 		global $wgContLang, $wgParser;
 
 		$authManager = AuthManager::singleton();
@@ -317,7 +354,7 @@ class Preferences {
 		if ( $canEditPrivateInfo && $authManager->allowsAuthenticationDataChange(
 			new PasswordAuthenticationRequest(), false )->isGood()
 		) {
-			$link = new OOUI\ButtonWidget( [
+			$link = new ButtonWidget( [
 				'href' => SpecialPage::getTitleFor( 'ChangePassword' )->getLinkURL( [
 					'returnto' => SpecialPage::getTitleFor( 'Preferences' )->getPrefixedText()
 				] ),
@@ -444,9 +481,9 @@ class Preferences {
 			'type' => $authManager->allowsPropertyChange( 'nickname' ) ? 'text' : 'info',
 			'maxlength' => $config->get( 'MaxSigChars' ),
 			'label-message' => 'yournick',
-			'validation-callback' => [ 'Preferences', 'validateSignature' ],
+			'validation-callback' => [ $this, 'validateSignature' ],
 			'section' => 'personal/signature',
-			'filter-callback' => [ 'Preferences', 'cleanSignature' ],
+			'filter-callback' => [ $this, 'cleanSignature' ],
 		];
 		$defaultPreferences['fancysig'] = [
 			'type' => 'toggle',
@@ -471,12 +508,12 @@ class Preferences {
 
 				$emailAddress = $user->getEmail() ? htmlspecialchars( $user->getEmail() ) : '';
 				if ( $canEditPrivateInfo && $authManager->allowsPropertyChange( 'emailaddress' ) ) {
-					$link = new OOUI\ButtonWidget( [
+					$emailAddressMsg = $user->getEmail() ? 'prefs-changeemail' : 'prefs-setemail';
+					$link = new ButtonWidget( [
 						'href' => SpecialPage::getTitleFor( 'ChangeEmail' )->getLinkURL( [
 							'returnto' => SpecialPage::getTitleFor( 'Preferences' )->getPrefixedText()
 						] ),
-						'label' =>
-							$context->msg( $user->getEmail() ? 'prefs-changeemail' : 'prefs-setemail' )->text(),
+						'label' => $context->msg( $emailAddressMsg )->text(),
 					] );
 
 					$emailAddress .= $emailAddress == '' ? $link : ( '<br />' . $link );
@@ -514,7 +551,7 @@ class Preferences {
 					} else {
 						$disableEmailPrefs = true;
 						$emailauthenticated = $context->msg( 'emailnotauthenticated' )->parse() . '<br />' .
-							new OOUI\ButtonWidget( [
+							new ButtonWidget( [
 								'href' => SpecialPage::getTitleFor( 'Confirmemail' )->getLinkURL(),
 								'label' => $context->msg( 'emailconfirmlink' )->text(),
 							] );
@@ -615,7 +652,7 @@ class Preferences {
 	 * @param array &$defaultPreferences
 	 * @return void
 	 */
-	static function skinPreferences( $user, IContextSource $context, &$defaultPreferences ) {
+	public function skinPreferences( $user, IContextSource $context, &$defaultPreferences ) {
 		# # Skin #####################################
 
 		// Skin selector, if there is at least one valid skin
@@ -664,7 +701,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @param array &$defaultPreferences
 	 */
-	static function filesPreferences( $user, IContextSource $context, &$defaultPreferences ) {
+	public function filesPreferences( $user, IContextSource $context, &$defaultPreferences ) {
 		# # Files #####################################
 		$defaultPreferences['imagesize'] = [
 			'type' => 'select',
@@ -686,7 +723,7 @@ class Preferences {
 	 * @param array &$defaultPreferences
 	 * @return void
 	 */
-	static function datetimePreferences( $user, IContextSource $context, &$defaultPreferences ) {
+	public function datetimePreferences( $user, IContextSource $context, &$defaultPreferences ) {
 		# # Date and time #####################################
 		$dateOptions = self::getDateOptions( $context );
 		if ( $dateOptions ) {
@@ -763,7 +800,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @param array &$defaultPreferences
 	 */
-	static function renderingPreferences( $user, IContextSource $context, &$defaultPreferences ) {
+	public function renderingPreferences( $user, IContextSource $context, &$defaultPreferences ) {
 		# # Diffs ####################################
 		$defaultPreferences['diffonly'] = [
 			'type' => 'toggle',
@@ -825,7 +862,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @param array &$defaultPreferences
 	 */
-	static function editingPreferences( $user, IContextSource $context, &$defaultPreferences ) {
+	public function editingPreferences( $user, IContextSource $context, &$defaultPreferences ) {
 		# # Editing #####################################
 		$defaultPreferences['editsectiononrightclick'] = [
 			'type' => 'toggle',
@@ -897,7 +934,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @param array &$defaultPreferences
 	 */
-	static function rcPreferences( $user, IContextSource $context, &$defaultPreferences ) {
+	public function rcPreferences( $user, IContextSource $context, &$defaultPreferences ) {
 		$config = $context->getConfig();
 		$rcMaxAge = $config->get( 'RCMaxAge' );
 		# # RecentChanges #####################################
@@ -991,7 +1028,9 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @param array &$defaultPreferences
 	 */
-	static function watchlistPreferences( $user, IContextSource $context, &$defaultPreferences ) {
+	public function watchlistPreferences(
+		$user, IContextSource $context, &$defaultPreferences
+	) {
 		$config = $context->getConfig();
 		$watchlistdaysMax = ceil( $config->get( 'RCMaxAge' ) / ( 3600 * 24 ) );
 
@@ -1006,13 +1045,12 @@ class Preferences {
 			$linkRenderer = MediaWikiServices::getInstance()->getLinkRenderer();
 			foreach ( $editWatchlistModes as $editWatchlistMode => $mode ) {
 				// Messages: prefs-editwatchlist-edit, prefs-editwatchlist-raw, prefs-editwatchlist-clear
-				$editWatchlistLinks .=
-					new OOUI\ButtonWidget( [
-						'href' => SpecialPage::getTitleFor( $mode[0], $mode[1] )->getLinkURL(),
-						'label' => new OOUI\HtmlSnippet(
-							$context->msg( "prefs-editwatchlist-{$editWatchlistMode}" )->parse()
-						),
-					] );
+				$editWatchlistLinks .= new ButtonWidget( [
+					'href' => SpecialPage::getTitleFor( $mode[0], $mode[1] )->getLinkURL(),
+					'label' => new HtmlSnippet(
+						$context->msg( "prefs-editwatchlist-{$editWatchlistMode}" )->parse()
+					),
+				] );
 			}
 
 			$defaultPreferences['editwatchlist'] = [
@@ -1134,8 +1172,7 @@ class Preferences {
 			$defaultPreferences['watchlisttoken'] = [
 				'type' => 'api',
 			];
-
-			$tokenButton = new OOUI\ButtonWidget( [
+			$tokenButton = new ButtonWidget( [
 				'href' => SpecialPage::getTitleFor( 'ResetTokens' )->getLinkURL( [
 					'returnto' => SpecialPage::getTitleFor( 'Preferences' )->getPrefixedText()
 				] ),
@@ -1157,7 +1194,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @param array &$defaultPreferences
 	 */
-	static function searchPreferences( $user, IContextSource $context, &$defaultPreferences ) {
+	public function searchPreferences( $user, IContextSource $context, &$defaultPreferences ) {
 		foreach ( MWNamespace::getValidNamespaces() as $n ) {
 			$defaultPreferences['searchNs' . $n] = [
 				'type' => 'api',
@@ -1171,7 +1208,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @param array &$defaultPreferences
 	 */
-	static function miscPreferences( $user, IContextSource $context, &$defaultPreferences ) {
+	public function miscPreferences( $user, IContextSource $context, &$defaultPreferences ) {
 	}
 
 	/**
@@ -1179,7 +1216,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @return array Text/links to display as key; $skinkey as value
 	 */
-	static function generateSkinOptions( $user, IContextSource $context ) {
+	public function generateSkinOptions( $user, IContextSource $context ) {
 		$ret = [];
 
 		$mptitle = Title::newMainPage();
@@ -1249,7 +1286,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @return array
 	 */
-	static function getDateOptions( IContextSource $context ) {
+	public function getDateOptions( IContextSource $context ) {
 		$lang = $context->getLanguage();
 		$dateopts = $lang->getDatePreferences();
 
@@ -1283,7 +1320,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @return array
 	 */
-	static function getImageSizes( IContextSource $context ) {
+	public function getImageSizes( IContextSource $context ) {
 		$ret = [];
 		$pixels = $context->msg( 'unit-pixel' )->text();
 
@@ -1300,7 +1337,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @return array
 	 */
-	static function getThumbSizes( IContextSource $context ) {
+	public function getThumbSizes( IContextSource $context ) {
 		$ret = [];
 		$pixels = $context->msg( 'unit-pixel' )->text();
 
@@ -1318,15 +1355,15 @@ class Preferences {
 	 * @param HTMLForm $form
 	 * @return bool|string
 	 */
-	static function validateSignature( $signature, $alldata, $form ) {
+	public function validateSignature( $signature, $alldata, $form ) {
 		global $wgParser;
 		$maxSigChars = $form->getConfig()->get( 'MaxSigChars' );
 		if ( mb_strlen( $signature ) > $maxSigChars ) {
 			return Xml::element( 'span', [ 'class' => 'error' ],
 				$form->msg( 'badsiglength' )->numParams( $maxSigChars )->text() );
 		} elseif ( isset( $alldata['fancysig'] ) &&
-				$alldata['fancysig'] &&
-				$wgParser->validateSig( $signature ) === false
+				   $alldata['fancysig'] &&
+				   $wgParser->validateSig( $signature ) === false
 		) {
 			return Xml::element(
 				'span',
@@ -1344,7 +1381,7 @@ class Preferences {
 	 * @param HTMLForm $form
 	 * @return string
 	 */
-	static function cleanSignature( $signature, $alldata, $form ) {
+	public function cleanSignature( $signature, $alldata, $form ) {
 		if ( isset( $alldata['fancysig'] ) && $alldata['fancysig'] ) {
 			global $wgParser;
 			$signature = $wgParser->cleanSig( $signature );
@@ -1363,7 +1400,7 @@ class Preferences {
 	 * @param array $remove Array of items to remove
 	 * @return PreferencesForm|HTMLForm
 	 */
-	static function getFormObject(
+	public function getFormObject(
 		$user,
 		IContextSource $context,
 		$formClass = 'PreferencesForm',
@@ -1372,7 +1409,7 @@ class Preferences {
 		// We use ButtonWidgets in some of the getPreferences() functions
 		$context->getOutput()->enableOOUI();
 
-		$formDescriptor = self::getPreferences( $user, $context );
+		$formDescriptor = $this->getPreferences( $user, $context );
 		if ( count( $remove ) ) {
 			$removeKeys = array_flip( $remove );
 			$formDescriptor = array_diff_key( $formDescriptor, $removeKeys );
@@ -1397,7 +1434,7 @@ class Preferences {
 		# Used message keys: 'accesskey-preferences-save', 'tooltip-preferences-save'
 		$htmlForm->setSubmitTooltip( 'preferences-save' );
 		$htmlForm->setSubmitID( 'prefcontrol' );
-		$htmlForm->setSubmitCallback( [ 'Preferences', 'tryFormSubmit' ] );
+		$htmlForm->setSubmitCallback( [ $this, 'tryFormSubmit' ] );
 
 		return $htmlForm;
 	}
@@ -1406,7 +1443,7 @@ class Preferences {
 	 * @param IContextSource $context
 	 * @return array
 	 */
-	static function getTimezoneOptions( IContextSource $context ) {
+	public function getTimezoneOptions( IContextSource $context ) {
 		$opt = [];
 
 		$localTZoffset = $context->getConfig()->get( 'LocalTZoffset' );
@@ -1451,7 +1488,7 @@ class Preferences {
 	 * @param array $alldata
 	 * @return int
 	 */
-	static function filterIntval( $value, $alldata ) {
+	public static function filterIntval( $value, $alldata ) {
 		return intval( $value );
 	}
 
@@ -1460,7 +1497,7 @@ class Preferences {
 	 * @param array $alldata
 	 * @return string
 	 */
-	static function filterTimezoneInput( $tz, $alldata ) {
+	public static function filterTimezoneInput( $tz, $alldata ) {
 		$data = explode( '|', $tz, 3 );
 		switch ( $data[0] ) {
 			case 'ZoneInfo':
@@ -1512,7 +1549,7 @@ class Preferences {
 	 * @param PreferencesForm $form
 	 * @return bool|Status|string
 	 */
-	static function tryFormSubmit( $formData, $form ) {
+	public function tryFormSubmit( $formData, $form ) {
 		$user = $form->getModifiedUser();
 		$hiddenPrefs = $form->getConfig()->get( 'HiddenPrefs' );
 		$result = true;
@@ -1523,9 +1560,9 @@ class Preferences {
 
 		// Filter input
 		foreach ( array_keys( $formData ) as $name ) {
-			if ( isset( self::$saveFilters[$name] ) ) {
-				$formData[$name] =
-					call_user_func( self::$saveFilters[$name], $formData[$name], $formData );
+			$filters = $this->getSaveFilters();
+			if ( isset( $filters[$name] ) ) {
+				$formData[$name] = call_user_func( $filters[$name], $formData[$name], $formData );
 			}
 		}
 
@@ -1543,7 +1580,7 @@ class Preferences {
 		if ( $user->isAllowed( 'editmyoptions' ) ) {
 			$oldUserOptions = $user->getOptions();
 
-			foreach ( self::$saveBlacklist as $b ) {
+			foreach ( $this->getSaveBlacklist() as $b ) {
 				unset( $formData[$b] );
 			}
 
@@ -1569,7 +1606,7 @@ class Preferences {
 			);
 		}
 
-		MediaWiki\Auth\AuthManager::callLegacyAuthPlugin( 'updateExternalDB', [ $user ] );
+		AuthManager::callLegacyAuthPlugin( 'updateExternalDB', [ $user ] );
 		$user->saveSettings();
 
 		return $result;
@@ -1580,8 +1617,8 @@ class Preferences {
 	 * @param PreferencesForm $form
 	 * @return Status
 	 */
-	public static function tryUISubmit( $formData, $form ) {
-		$res = self::tryFormSubmit( $formData, $form );
+	public function tryUISubmit( $formData, $form ) {
+		$res = $this->tryFormSubmit( $formData, $form );
 
 		if ( $res ) {
 			$urlOptions = [];
@@ -1612,7 +1649,7 @@ class Preferences {
 	 *  preferences and the region
 	 * @since 1.26
 	 */
-	public static function getTimeZoneList( Language $language ) {
+	public function getTimeZoneList( Language $language ) {
 		$identifiers = DateTimeZone::listIdentifiers();
 		if ( $identifiers === false ) {
 			return [];