diff --git a/includes/ApiCategoryTree.php b/includes/ApiCategoryTree.php
index 3c4042c1..197e1bc3 100644
--- a/includes/ApiCategoryTree.php
+++ b/includes/ApiCategoryTree.php
@@ -82,7 +82,7 @@ class ApiCategoryTree extends ApiBase {
 		$depth = isset( $options['depth'] ) ? (int)$options['depth'] : 1;
 
 		$ct = new CategoryTree( $options );
-		$depth = CategoryTree::capDepth( $ct->getOption( 'mode' ), $depth );
+		$depth = OptionManager::capDepth( $ct->optionManager->getOption( 'mode' ), $depth );
 		$ctConfig = $this->configFactory->makeConfig( 'categorytree' );
 		$html = $this->getHTML( $ct, $title, $depth, $ctConfig );
 
@@ -155,7 +155,7 @@ class ApiCategoryTree extends ApiBase {
 			$this->wanCache->makeKey(
 				'categorytree-html-ajax',
 				md5( $title->getDBkey() ),
-				md5( $ct->getOptionsAsCacheKey( $depth ) ),
+				md5( $ct->optionManager->getOptionsAsCacheKey( $depth ) ),
 				$this->getLanguage()->getCode(),
 				$langConv->getExtraHashOptions(),
 				$ctConfig->get( 'RenderHashAppend' )
diff --git a/includes/CategoryTree.php b/includes/CategoryTree.php
index b05aa038..6abc9ac2 100644
--- a/includes/CategoryTree.php
+++ b/includes/CategoryTree.php
@@ -24,9 +24,7 @@
 
 namespace MediaWiki\Extension\CategoryTree;
 
-use Exception;
 use ExtensionRegistry;
-use FormatJson;
 use IContextSource;
 use MediaWiki\Category\Category;
 use MediaWiki\Html\Html;
@@ -43,8 +41,8 @@ use RequestContext;
  * to display the category structure of a wiki
  */
 class CategoryTree {
-	/** @var array */
-	private $mOptions = [];
+	/** @var OptionManager */
+	public $optionManager;
 
 	/** @var LinkRenderer */
 	private $linkRenderer;
@@ -53,212 +51,8 @@ class CategoryTree {
 	 * @param array $options
 	 */
 	public function __construct( array $options ) {
-		global $wgCategoryTreeDefaultOptions;
+		$this->optionManager = new OptionManager( $options );
 		$this->linkRenderer = MediaWikiServices::getInstance()->getLinkRenderer();
-
-		// ensure default values and order of options.
-		// Order may become important, it may influence the cache key!
-		foreach ( $wgCategoryTreeDefaultOptions as $option => $default ) {
-			$this->mOptions[$option] = $options[$option] ?? $default;
-		}
-
-		$this->mOptions['mode'] = self::decodeMode( $this->mOptions['mode'] );
-
-		if ( $this->mOptions['mode'] === CategoryTreeMode::PARENTS ) {
-			// namespace filter makes no sense with CategoryTreeMode::PARENTS
-			$this->mOptions['namespaces'] = false;
-		}
-
-		$this->mOptions['hideprefix'] = self::decodeHidePrefix( $this->mOptions['hideprefix'] );
-		$this->mOptions['showcount'] = self::decodeBoolean( $this->mOptions['showcount'] );
-		$this->mOptions['namespaces'] = self::decodeNamespaces( $this->mOptions['namespaces'] );
-
-		if ( $this->mOptions['namespaces'] ) {
-			# automatically adjust mode to match namespace filter
-			if ( count( $this->mOptions['namespaces'] ) === 1
-				&& $this->mOptions['namespaces'][0] === NS_CATEGORY ) {
-				$this->mOptions['mode'] = CategoryTreeMode::CATEGORIES;
-			} elseif ( !in_array( NS_FILE, $this->mOptions['namespaces'] ) ) {
-				$this->mOptions['mode'] = CategoryTreeMode::PAGES;
-			} else {
-				$this->mOptions['mode'] = CategoryTreeMode::ALL;
-			}
-		}
-	}
-
-	/**
-	 * @param string $name
-	 * @return mixed
-	 */
-	public function getOption( $name ) {
-		return $this->mOptions[$name];
-	}
-
-	/**
-	 * @return bool
-	 */
-	private function isInverse() {
-		return $this->getOption( 'mode' ) === CategoryTreeMode::PARENTS;
-	}
-
-	/**
-	 * @param mixed $nn
-	 * @return array|bool
-	 */
-	private static function decodeNamespaces( $nn ) {
-		if ( $nn === false || $nn === null ) {
-			return false;
-		}
-
-		if ( !is_array( $nn ) ) {
-			$nn = preg_split( '![\s#:|]+!', $nn );
-		}
-
-		$namespaces = [];
-		$contLang = MediaWikiServices::getInstance()->getContentLanguage();
-		foreach ( $nn as $n ) {
-			if ( is_int( $n ) ) {
-				$ns = $n;
-			} else {
-				$n = trim( $n );
-				if ( $n === '' ) {
-					continue;
-				}
-
-				$lower = strtolower( $n );
-
-				if ( is_numeric( $n ) ) {
-					$ns = (int)$n;
-				} elseif ( $n === '-' || $n === '_' || $n === '*' || $lower === 'main' ) {
-					$ns = NS_MAIN;
-				} else {
-					$ns = $contLang->getNsIndex( $n );
-				}
-			}
-
-			if ( is_int( $ns ) ) {
-				$namespaces[] = $ns;
-			}
-		}
-
-		# get elements into canonical order
-		sort( $namespaces );
-		return $namespaces;
-	}
-
-	/**
-	 * @param mixed $mode
-	 * @return int|string
-	 */
-	public static function decodeMode( $mode ) {
-		global $wgCategoryTreeDefaultOptions;
-
-		if ( $mode === null ) {
-			return $wgCategoryTreeDefaultOptions['mode'];
-		}
-		if ( is_int( $mode ) ) {
-			return $mode;
-		}
-
-		$mode = trim( strtolower( $mode ) );
-
-		if ( is_numeric( $mode ) ) {
-			return (int)$mode;
-		}
-
-		if ( $mode === 'all' ) {
-			$mode = CategoryTreeMode::ALL;
-		} elseif ( $mode === 'pages' ) {
-			$mode = CategoryTreeMode::PAGES;
-		} elseif ( $mode === 'categories' || $mode === 'sub' ) {
-			$mode = CategoryTreeMode::CATEGORIES;
-		} elseif ( $mode === 'parents' || $mode === 'super' || $mode === 'inverse' ) {
-			$mode = CategoryTreeMode::PARENTS;
-		} elseif ( $mode === 'default' ) {
-			$mode = $wgCategoryTreeDefaultOptions['mode'];
-		}
-
-		return (int)$mode;
-	}
-
-	/**
-	 * Helper function to convert a string to a boolean value.
-	 * Perhaps make this a global function in MediaWiki proper
-	 * @param mixed $value
-	 * @return bool|null|string
-	 */
-	public static function decodeBoolean( $value ) {
-		if ( $value === null ) {
-			return null;
-		}
-		if ( is_bool( $value ) ) {
-			return $value;
-		}
-		if ( is_int( $value ) ) {
-			return ( $value > 0 );
-		}
-
-		$value = trim( strtolower( $value ) );
-		if ( is_numeric( $value ) ) {
-			return ( (int)$value > 0 );
-		}
-
-		if ( $value === 'yes' || $value === 'y'
-			|| $value === 'true' || $value === 't' || $value === 'on'
-		) {
-			return true;
-		} elseif ( $value === 'no' || $value === 'n'
-			|| $value === 'false' || $value === 'f' || $value === 'off'
-		) {
-			return false;
-		} elseif ( $value === 'null' || $value === 'default' || $value === 'none' || $value === 'x' ) {
-			return null;
-		} else {
-			return false;
-		}
-	}
-
-	/**
-	 * @param mixed $value
-	 * @return int|string
-	 */
-	public static function decodeHidePrefix( $value ) {
-		global $wgCategoryTreeDefaultOptions;
-
-		if ( $value === null ) {
-			return $wgCategoryTreeDefaultOptions['hideprefix'];
-		}
-		if ( is_int( $value ) ) {
-			return $value;
-		}
-		if ( $value === true ) {
-			return CategoryTreeHidePrefix::ALWAYS;
-		}
-		if ( $value === false ) {
-			return CategoryTreeHidePrefix::NEVER;
-		}
-
-		$value = trim( strtolower( $value ) );
-
-		if ( $value === 'yes' || $value === 'y'
-			|| $value === 'true' || $value === 't' || $value === 'on'
-		) {
-			return CategoryTreeHidePrefix::ALWAYS;
-		} elseif ( $value === 'no' || $value === 'n'
-			|| $value === 'false' || $value === 'f' || $value === 'off'
-		) {
-			return CategoryTreeHidePrefix::NEVER;
-		} elseif ( $value === 'always' ) {
-			return CategoryTreeHidePrefix::ALWAYS;
-		} elseif ( $value === 'never' ) {
-			return CategoryTreeHidePrefix::NEVER;
-		} elseif ( $value === 'auto' ) {
-			return CategoryTreeHidePrefix::AUTO;
-		} elseif ( $value === 'categories' || $value === 'category' || $value === 'smart' ) {
-			return CategoryTreeHidePrefix::CATEGORIES;
-		} else {
-			return $wgCategoryTreeDefaultOptions['hideprefix'];
-		}
 	}
 
 	/**
@@ -271,57 +65,6 @@ class CategoryTree {
 		$outputPage->addModules( 'ext.categoryTree' );
 	}
 
-	/**
-	 * @param array $options
-	 * @param string $enc
-	 * @return mixed
-	 * @throws Exception
-	 */
-	protected static function encodeOptions( array $options, $enc ) {
-		if ( $enc === 'mode' || $enc === '' ) {
-			$opt = $options['mode'];
-		} elseif ( $enc === 'json' ) {
-			$opt = FormatJson::encode( $options );
-		} else {
-			throw new Exception( 'Unknown encoding for CategoryTree options: ' . $enc );
-		}
-
-		return $opt;
-	}
-
-	/**
-	 * @param int|null $depth
-	 * @return string
-	 */
-	public function getOptionsAsCacheKey( $depth = null ) {
-		$key = '';
-
-		foreach ( $this->mOptions as $k => $v ) {
-			if ( is_array( $v ) ) {
-				$v = implode( '|', $v );
-			}
-			$key .= $k . ':' . $v . ';';
-		}
-
-		if ( $depth !== null ) {
-			$key .= ';depth=' . $depth;
-		}
-		return $key;
-	}
-
-	/**
-	 * @param int|null $depth
-	 * @return mixed
-	 */
-	public function getOptionsAsJsStructure( $depth = null ) {
-		$opt = $this->mOptions;
-		if ( $depth !== null ) {
-			$opt['depth'] = $depth;
-		}
-
-		return self::encodeOptions( $opt, 'json' );
-	}
-
 	/**
 	 * Custom tag implementation. This is called by Hooks::parserHook, which is used to
 	 * load CategoryTreeFunctions.php on demand.
@@ -363,8 +106,8 @@ class CategoryTree {
 			$attr['class'] = 'CategoryTreeTag';
 		}
 
-		$attr['data-ct-mode'] = $this->mOptions['mode'];
-		$attr['data-ct-options'] = $this->getOptionsAsJsStructure();
+		$attr['data-ct-mode'] = $this->optionManager->getOption( 'mode' );
+		$attr['data-ct-options'] = $this->optionManager->getOptionsAsJsStructure();
 
 		if ( !$allowMissing && !$title->getArticleID() ) {
 			$html = Html::rawElement( 'span', [ 'class' => 'CategoryTreeNotice' ],
@@ -400,9 +143,9 @@ class CategoryTree {
 
 		$dbr = MediaWikiServices::getInstance()->getDBLoadBalancerFactory()->getReplicaDatabase();
 
-		$inverse = $this->isInverse();
-		$mode = $this->getOption( 'mode' );
-		$namespaces = $this->getOption( 'namespaces' );
+		$inverse = $this->optionManager->isInverse();
+		$mode = $this->optionManager->getOption( 'mode' );
+		$namespaces = $this->optionManager->getOption( 'namespaces' );
 
 		$tables = [ 'page', 'categorylinks' ];
 		$fields = [ 'page_id', 'page_namespace', 'page_title',
@@ -454,8 +197,8 @@ class CategoryTree {
 		# collect categories separately from other pages
 		$categories = '';
 		$other = '';
-		$suppressTranslations = self::decodeBoolean(
-			$this->getOption( 'notranslations' )
+		$suppressTranslations = OptionManager::decodeBoolean(
+			$this->optionManager->getOption( 'notranslations' )
 		) && ExtensionRegistry::getInstance()->isLoaded( 'Translate' );
 
 		if ( $suppressTranslations ) {
@@ -544,7 +287,7 @@ class CategoryTree {
 					$special,
 					$t->getText(),
 					[ 'class' => 'CategoryTreeLabel' ],
-					[ 'target' => $t->getDBkey() ] + $this->mOptions
+					[ 'target' => $t->getDBkey() ] + $this->optionManager->getOptions()
 				)
 			);
 		}
@@ -562,7 +305,7 @@ class CategoryTree {
 		global $wgCategoryTreeUseCategoryTable;
 
 		if ( $wgCategoryTreeUseCategoryTable && $title->inNamespace( NS_CATEGORY )
-			&& !$this->isInverse()
+			&& !$this->optionManager->isInverse()
 		) {
 			$cat = Category::newFromTitle( $title );
 		} else {
@@ -581,12 +324,12 @@ class CategoryTree {
 	 * @return string
 	 */
 	public function renderNodeInfo( Title $title, Category $cat = null, $children = 0 ) {
-		$mode = $this->getOption( 'mode' );
+		$mode = $this->optionManager->getOption( 'mode' );
 
 		$isInCatNS = $title->inNamespace( NS_CATEGORY );
 		$key = $title->getDBkey();
 
-		$hideprefix = $this->getOption( 'hideprefix' );
+		$hideprefix = $this->optionManager->getOption( 'hideprefix' );
 
 		if ( $hideprefix === CategoryTreeHidePrefix::ALWAYS ) {
 			$hideprefix = true;
@@ -657,7 +400,7 @@ class CategoryTree {
 
 		$s .= $link;
 
-		if ( $count !== false && $this->getOption( 'showcount' ) ) {
+		if ( $count !== false && $this->optionManager->getOption( 'showcount' ) ) {
 			$s .= self::createCountString( RequestContext::getMain(), $cat, $count );
 		}
 
@@ -777,31 +520,4 @@ class CategoryTree {
 		}
 		return $t;
 	}
-
-	/**
-	 * Internal function to cap depth
-	 * @param string $mode
-	 * @param int $depth
-	 * @return int|mixed
-	 */
-	public static function capDepth( $mode, $depth ) {
-		global $wgCategoryTreeMaxDepth;
-
-		if ( !is_numeric( $depth ) ) {
-			return 1;
-		}
-
-		$depth = intval( $depth );
-
-		if ( is_array( $wgCategoryTreeMaxDepth ) ) {
-			$max = $wgCategoryTreeMaxDepth[$mode] ?? 1;
-		} elseif ( is_numeric( $wgCategoryTreeMaxDepth ) ) {
-			$max = $wgCategoryTreeMaxDepth;
-		} else {
-			wfDebug( 'CategoryTree::capDepth: $wgCategoryTreeMaxDepth is invalid.' );
-			$max = 1;
-		}
-
-		return min( $depth, $max );
-	}
 }
diff --git a/includes/CategoryTreePage.php b/includes/CategoryTreePage.php
index d9792d32..a3f7e698 100644
--- a/includes/CategoryTreePage.php
+++ b/includes/CategoryTreePage.php
@@ -60,7 +60,7 @@ class CategoryTreePage extends SpecialPage {
 	 */
 	private function getOption( $name ) {
 		if ( $this->tree ) {
-			return $this->tree->getOption( $name );
+			return $this->tree->optionManager->getOption( $name );
 		} else {
 			return $this->getConfig()->get( 'CategoryTreeDefaultOptions' )[$name];
 		}
@@ -197,8 +197,8 @@ class CategoryTreePage extends SpecialPage {
 		$output->addHTML( Html::rawElement( 'div',
 			[
 				'class' => 'CategoryTreeResult CategoryTreeTag',
-				'data-ct-mode' => $this->tree->getOption( 'mode' ),
-				'data-ct-options' => $this->tree->getOptionsAsJsStructure(),
+				'data-ct-mode' => $this->tree->optionManager->getOption( 'mode' ),
+				'data-ct-options' => $this->tree->optionManager->getOptionsAsJsStructure(),
 			],
 			$this->tree->renderNode( $title, 1 )
 		) );
diff --git a/includes/Hooks.php b/includes/Hooks.php
index c9b2ad11..d40621dd 100644
--- a/includes/Hooks.php
+++ b/includes/Hooks.php
@@ -198,12 +198,12 @@ class Hooks implements
 		$attr = Sanitizer::validateTagAttributes( $argv, 'div' );
 
 		$hideroot = isset( $argv['hideroot'] )
-			? CategoryTree::decodeBoolean( $argv['hideroot'] ) : null;
+			? OptionManager::decodeBoolean( $argv['hideroot'] ) : null;
 		$onlyroot = isset( $argv['onlyroot'] )
-			? CategoryTree::decodeBoolean( $argv['onlyroot'] ) : null;
+			? OptionManager::decodeBoolean( $argv['onlyroot'] ) : null;
 		$depthArg = isset( $argv['depth'] ) ? (int)$argv['depth'] : null;
 
-		$depth = CategoryTree::capDepth( $ct->getOption( 'mode' ), $depthArg );
+		$depth = OptionManager::capDepth( $ct->optionManager->getOption( 'mode' ), $depthArg );
 		if ( $onlyroot ) {
 			$depth = 0;
 		}
@@ -243,10 +243,10 @@ class Hooks implements
 	 */
 	public static function getDataForJs( RL\Context $context, Config $config ) {
 		// Look, this is pretty bad but CategoryTree is just whacky, it needs to be rewritten
-		$ct = new CategoryTree( $config->get( 'CategoryTreeCategoryPageOptions' ) );
+		$optionManager = new OptionManager( $config->get( 'CategoryTreeCategoryPageOptions' ) );
 
 		return [
-			'defaultCtOptions' => $ct->getOptionsAsJsStructure(),
+			'defaultCtOptions' => $optionManager->getOptionsAsJsStructure(),
 		];
 	}
 
diff --git a/includes/OptionManager.php b/includes/OptionManager.php
new file mode 100644
index 00000000..a177ab0e
--- /dev/null
+++ b/includes/OptionManager.php
@@ -0,0 +1,333 @@
+<?php
+/**
+ * © 2006-2007 Daniel Kinzler
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Extensions
+ * @author Daniel Kinzler, brightbyte.de
+ */
+
+namespace MediaWiki\Extension\CategoryTree;
+
+use Exception;
+use FormatJson;
+use MediaWiki\MediaWikiServices;
+
+/**
+ * Core functions to handle the options
+ */
+class OptionManager {
+	/** @var array */
+	private $mOptions = [];
+
+	/**
+	 * @param array $options
+	 */
+	public function __construct( array $options ) {
+		global $wgCategoryTreeDefaultOptions;
+
+		// ensure default values and order of options.
+		// Order may become important, it may influence the cache key!
+		foreach ( $wgCategoryTreeDefaultOptions as $option => $default ) {
+			$this->mOptions[$option] = $options[$option] ?? $default;
+		}
+
+		$this->mOptions['mode'] = self::decodeMode( $this->mOptions['mode'] );
+
+		if ( $this->mOptions['mode'] === CategoryTreeMode::PARENTS ) {
+			// namespace filter makes no sense with CategoryTreeMode::PARENTS
+			$this->mOptions['namespaces'] = false;
+		}
+
+		$this->mOptions['hideprefix'] = self::decodeHidePrefix( $this->mOptions['hideprefix'] );
+		$this->mOptions['showcount'] = self::decodeBoolean( $this->mOptions['showcount'] );
+		$this->mOptions['namespaces'] = self::decodeNamespaces( $this->mOptions['namespaces'] );
+
+		if ( $this->mOptions['namespaces'] ) {
+			# automatically adjust mode to match namespace filter
+			if ( count( $this->mOptions['namespaces'] ) === 1
+				&& $this->mOptions['namespaces'][0] === NS_CATEGORY ) {
+				$this->mOptions['mode'] = CategoryTreeMode::CATEGORIES;
+			} elseif ( !in_array( NS_FILE, $this->mOptions['namespaces'] ) ) {
+				$this->mOptions['mode'] = CategoryTreeMode::PAGES;
+			} else {
+				$this->mOptions['mode'] = CategoryTreeMode::ALL;
+			}
+		}
+	}
+
+	/**
+	 * @return array
+	 */
+	public function getOptions() {
+		return $this->mOptions;
+	}
+
+	/**
+	 * @param string $name
+	 * @return mixed
+	 */
+	public function getOption( $name ) {
+		return $this->mOptions[$name];
+	}
+
+	/**
+	 * @return bool
+	 */
+	public function isInverse() {
+		return $this->getOption( 'mode' ) === CategoryTreeMode::PARENTS;
+	}
+
+	/**
+	 * @param mixed $nn
+	 * @return array|bool
+	 */
+	private static function decodeNamespaces( $nn ) {
+		if ( $nn === false || $nn === null ) {
+			return false;
+		}
+
+		if ( !is_array( $nn ) ) {
+			$nn = preg_split( '![\s#:|]+!', $nn );
+		}
+
+		$namespaces = [];
+		$contLang = MediaWikiServices::getInstance()->getContentLanguage();
+		foreach ( $nn as $n ) {
+			if ( is_int( $n ) ) {
+				$ns = $n;
+			} else {
+				$n = trim( $n );
+				if ( $n === '' ) {
+					continue;
+				}
+
+				$lower = strtolower( $n );
+
+				if ( is_numeric( $n ) ) {
+					$ns = (int)$n;
+				} elseif ( $n === '-' || $n === '_' || $n === '*' || $lower === 'main' ) {
+					$ns = NS_MAIN;
+				} else {
+					$ns = $contLang->getNsIndex( $n );
+				}
+			}
+
+			if ( is_int( $ns ) ) {
+				$namespaces[] = $ns;
+			}
+		}
+
+		# get elements into canonical order
+		sort( $namespaces );
+		return $namespaces;
+	}
+
+	/**
+	 * @param mixed $mode
+	 * @return int|string
+	 */
+	private static function decodeMode( $mode ) {
+		global $wgCategoryTreeDefaultOptions;
+
+		if ( $mode === null ) {
+			return $wgCategoryTreeDefaultOptions['mode'];
+		}
+		if ( is_int( $mode ) ) {
+			return $mode;
+		}
+
+		$mode = trim( strtolower( $mode ) );
+
+		if ( is_numeric( $mode ) ) {
+			return (int)$mode;
+		}
+
+		if ( $mode === 'all' ) {
+			$mode = CategoryTreeMode::ALL;
+		} elseif ( $mode === 'pages' ) {
+			$mode = CategoryTreeMode::PAGES;
+		} elseif ( $mode === 'categories' || $mode === 'sub' ) {
+			$mode = CategoryTreeMode::CATEGORIES;
+		} elseif ( $mode === 'parents' || $mode === 'super' || $mode === 'inverse' ) {
+			$mode = CategoryTreeMode::PARENTS;
+		} elseif ( $mode === 'default' ) {
+			$mode = $wgCategoryTreeDefaultOptions['mode'];
+		}
+
+		return (int)$mode;
+	}
+
+	/**
+	 * Helper function to convert a string to a boolean value.
+	 * Perhaps make this a global function in MediaWiki proper
+	 * @param mixed $value
+	 * @return bool|null|string
+	 */
+	public static function decodeBoolean( $value ) {
+		if ( $value === null ) {
+			return null;
+		}
+		if ( is_bool( $value ) ) {
+			return $value;
+		}
+		if ( is_int( $value ) ) {
+			return ( $value > 0 );
+		}
+
+		$value = trim( strtolower( $value ) );
+		if ( is_numeric( $value ) ) {
+			return ( (int)$value > 0 );
+		}
+
+		if ( $value === 'yes' || $value === 'y'
+			|| $value === 'true' || $value === 't' || $value === 'on'
+		) {
+			return true;
+		} elseif ( $value === 'no' || $value === 'n'
+			|| $value === 'false' || $value === 'f' || $value === 'off'
+		) {
+			return false;
+		} elseif ( $value === 'null' || $value === 'default' || $value === 'none' || $value === 'x' ) {
+			return null;
+		} else {
+			return false;
+		}
+	}
+
+	/**
+	 * @param mixed $value
+	 * @return int|string
+	 */
+	private static function decodeHidePrefix( $value ) {
+		global $wgCategoryTreeDefaultOptions;
+
+		if ( $value === null ) {
+			return $wgCategoryTreeDefaultOptions['hideprefix'];
+		}
+		if ( is_int( $value ) ) {
+			return $value;
+		}
+		if ( $value === true ) {
+			return CategoryTreeHidePrefix::ALWAYS;
+		}
+		if ( $value === false ) {
+			return CategoryTreeHidePrefix::NEVER;
+		}
+
+		$value = trim( strtolower( $value ) );
+
+		if ( $value === 'yes' || $value === 'y'
+			|| $value === 'true' || $value === 't' || $value === 'on'
+		) {
+			return CategoryTreeHidePrefix::ALWAYS;
+		} elseif ( $value === 'no' || $value === 'n'
+			|| $value === 'false' || $value === 'f' || $value === 'off'
+		) {
+			return CategoryTreeHidePrefix::NEVER;
+		} elseif ( $value === 'always' ) {
+			return CategoryTreeHidePrefix::ALWAYS;
+		} elseif ( $value === 'never' ) {
+			return CategoryTreeHidePrefix::NEVER;
+		} elseif ( $value === 'auto' ) {
+			return CategoryTreeHidePrefix::AUTO;
+		} elseif ( $value === 'categories' || $value === 'category' || $value === 'smart' ) {
+			return CategoryTreeHidePrefix::CATEGORIES;
+		} else {
+			return $wgCategoryTreeDefaultOptions['hideprefix'];
+		}
+	}
+
+	/**
+	 * @param array $options
+	 * @param string $enc
+	 * @return mixed
+	 * @throws Exception
+	 */
+	private static function encodeOptions( array $options, $enc ) {
+		if ( $enc === 'mode' || $enc === '' ) {
+			$opt = $options['mode'];
+		} elseif ( $enc === 'json' ) {
+			$opt = FormatJson::encode( $options );
+		} else {
+			throw new Exception( 'Unknown encoding for CategoryTree options: ' . $enc );
+		}
+
+		return $opt;
+	}
+
+	/**
+	 * @param int|null $depth
+	 * @return string
+	 */
+	public function getOptionsAsCacheKey( $depth = null ) {
+		$key = '';
+
+		foreach ( $this->mOptions as $k => $v ) {
+			if ( is_array( $v ) ) {
+				$v = implode( '|', $v );
+			}
+			$key .= $k . ':' . $v . ';';
+		}
+
+		if ( $depth !== null ) {
+			$key .= ';depth=' . $depth;
+		}
+		return $key;
+	}
+
+	/**
+	 * @param int|null $depth
+	 * @return mixed
+	 */
+	public function getOptionsAsJsStructure( $depth = null ) {
+		$opt = $this->mOptions;
+		if ( $depth !== null ) {
+			$opt['depth'] = $depth;
+		}
+
+		return self::encodeOptions( $opt, 'json' );
+	}
+
+	/**
+	 * Internal function to cap depth
+	 * @param string $mode
+	 * @param int $depth
+	 * @return int|mixed
+	 */
+	public static function capDepth( $mode, $depth ) {
+		global $wgCategoryTreeMaxDepth;
+
+		if ( !is_numeric( $depth ) ) {
+			return 1;
+		}
+
+		$depth = intval( $depth );
+
+		if ( is_array( $wgCategoryTreeMaxDepth ) ) {
+			$max = $wgCategoryTreeMaxDepth[$mode] ?? 1;
+		} elseif ( is_numeric( $wgCategoryTreeMaxDepth ) ) {
+			$max = $wgCategoryTreeMaxDepth;
+		} else {
+			wfDebug( __METHOD__ . ': $wgCategoryTreeMaxDepth is invalid.' );
+			$max = 1;
+		}
+
+		return min( $depth, $max );
+	}
+}