->where( 'permalink_hash', $permalink_hash )
					->where( 'permalink', $permalink )
					->find_one();
	}

	/**
	 * Retrieves all the indexable instances of a certain object type.
	 *
	 * @param string $object_type The object type.
	 *
	 * @return Indexable[] The array with all the indexable instances of a certain object type.
	 */
	public function find_all_with_type( $object_type ) {
		/**
		 * The array with all the indexable instances of a certain object type.
		 *
		 * @var Indexable[] $indexables
		 */
		$indexables = $this
			->query()
			->where( 'object_type', $object_type )
			->find_many();

		return \array_map( [ $this, 'ensure_permalink' ], $indexables );
	}

	/**
	 * Retrieves all the indexable instances of a certain object subtype.
	 *
	 * @param string $object_type     The object type.
	 * @param string $object_sub_type The object subtype.
	 *
	 * @return Indexable[] The array with all the indexable instances of a certain object subtype.
	 */
	public function find_all_with_type_and_sub_type( $object_type, $object_sub_type ) {
		/**
		 * The array with all the indexable instances of a certain object type and subtype.
		 *
		 * @var Indexable[] $indexables
		 */
		$indexables = $this
			->query()
			->where( 'object_type', $object_type )
			->where( 'object_sub_type', $object_sub_type )
			->find_many();

		return \array_map( [ $this, 'ensure_permalink' ], $indexables );
	}

	/**
	 * Retrieves the homepage indexable.
	 *
	 * @param bool $auto_create Optional. Create the indexable if it does not exist.
	 *
	 * @return bool|Indexable Instance of indexable.
	 */
	public function find_for_home_page( $auto_create = true ) {
		/**
		 * Indexable instance.
		 *
		 * @var Indexable $indexable
		 */
		$indexable = $this->query()->where( 'object_type', 'home-page' )->find_one();

		if ( $auto_create && ! $indexable ) {
			$indexable = $this->builder->build_for_home_page();
		}

		return $this->ensure_permalink( $indexable );
	}

	/**
	 * Retrieves the date archive indexable.
	 *
	 * @param bool $auto_create Optional. Create the indexable if it does not exist.
	 *
	 * @return bool|Indexable Instance of indexable.
	 */
	public function find_for_date_archive( $auto_create = true ) {
		/**
		 * Indexable instance.
		 *
		 * @var Indexable $indexable
		 */
		$indexable = $this->query()->where( 'object_type', 'date-archive' )->find_one();

		if ( $auto_create && ! $indexable ) {
			$indexable = $this->builder->build_for_date_archive();
		}

		return $this->ensure_permalink( $indexable );
	}

	/**
	 * Retrieves an indexable for a post type archive.
	 *
	 * @param string $post_type   The post type.
	 * @param bool   $auto_create Optional. Create the indexable if it does not exist.
	 *
	 * @return bool|Indexable The indexable, false if none could be found.
	 */
	public function find_for_post_type_archive( $post_type, $auto_create = true ) {
		/**
		 * Indexable instance.
		 *
		 * @var Indexable $indexable
		 */
		$indexable = $this->query()
						  ->where( 'object_type', 'post-type-archive' )
						  ->where( 'object_sub_type', $post_type )
						  ->find_one();

		if ( $auto_create && ! $indexable ) {
			$indexable = $this->builder->build_for_post_type_archive( $post_type );
		}

		return $this->ensure_permalink( $indexable );
	}

	/**
	 * Retrieves the indexable for a system page.
	 *
	 * @param string $object_sub_type The type of system page.
	 * @param bool   $auto_create     Optional. Create the indexable if it does not exist.
	 *
	 * @return bool|Indexable Instance of indexable.
	 */
	public function find_for_system_page( $object_sub_type, $auto_create = true ) {
		/**
		 * Indexable instance.
		 *
		 * @var Indexable $indexable
		 */
		$indexable = $this->query()
						  ->where( 'object_type', 'system-page' )
						  ->where( 'object_sub_type', $object_sub_type )
						  ->find_one();

		if ( $auto_create && ! $indexable ) {
			$indexable = $this->builder->build_for_system_page( $object_sub_type );
		}

		return $this->ensure_permalink( $indexable );
	}

	/**
	 * Retrieves an indexable by its ID and type.
	 *
	 * @param int    $object_id   The indexable object ID.
	 * @param string $object_type The indexable object type.
	 * @param bool   $auto_create Optional. Create the indexable if it does not exist.
	 *
	 * @return bool|Indexable Instance of indexable.
	 */
	public function find_by_id_and_type( $object_id, $object_type, $auto_create = true ) {
		$indexable = $this->query()
						  ->where( 'object_id', $object_id )
						  ->where( 'object_type', $object_type )
						  ->find_one();

		if ( $auto_create && ! $indexable ) {
			$indexable = $this->builder->build_for_id_and_type( $object_id, $object_type );
		}

		return $this->ensure_permalink( $indexable );
	}

	/**
	 * Retrieves multiple indexables at once by their IDs and type.
	 *
	 * @param int[]  $object_ids  The array of indexable object IDs.
	 * @param string $object_type The indexable object type.
	 * @param bool   $auto_create Optional. Create the indexable if it does not exist.
	 *
	 * @return Indexable[] An array of indexables.
	 */
	public function find_by_multiple_ids_and_type( $object_ids, $object_type, $auto_create = true ) {
		/**
		 * Represents an array of indexable objects.
		 *
		 * @var Indexable[] $indexables
		 */
		$indexables = $this->query()
						   ->where_in( 'object_id', $object_ids )
						   ->where( 'object_type', $object_type )
						   ->find_many();

		if ( $auto_create ) {
			$indexables_available = [];
			foreach ( $indexables as $indexable ) {
				$indexables_available[] = $indexable->object_id;
			}

			$indexables_to_create = \array_diff( $object_ids, $indexables_available );

			foreach ( $indexables_to_create as $indexable_to_create ) {
				$indexables[] = $this->builder->build_for_id_and_type( $indexable_to_create, $object_type );
			}
		}

		return \array_map( [ $this, 'ensure_permalink' ], $indexables );
	}

	/**
	 * Returns all ancestors of a given indexable.
	 *
	 * @param Indexable $indexable The indexable to find the ancestors of.
	 *
	 * @return Indexable[] All ancestors of the given indexable.
	 */
	public function get_ancestors( Indexable $indexable ) {
		$ancestors = $this->hierarchy_repository->find_ancestors( $indexable );

		if ( empty( $ancestors ) ) {
			return [];
		}

		$indexable_ids = [];
		foreach ( $ancestors as $ancestor ) {
			$indexable_ids[] = $ancestor->ancestor_id;
		}

		if ( $indexable_ids[0] === 0 && \count( $indexable_ids ) === 1 ) {
			return [];
		}

		$indexables = $this->query()
						   ->where_in( 'id', $indexable_ids )
						   ->order_by_expr( 'FIELD(id,' . \implode( ',', $indexable_ids ) . ')' )
						   ->find_many();

		return \array_map( [ $this, 'ensure_permalink' ], $indexables );
	}

	/**
	 * Ensures that the given indexable has a permalink.
	 *
	 * @param Indexable $indexable The indexable.
	 *
	 * @return bool|Indexable The indexable.
	 */
	protected function ensure_permalink( $indexable ) {
		if ( $indexable && $indexable->permalink === null ) {
			$indexable->permalink = $this->get_permalink_for_indexable( $indexable );
			$indexable->save();
		}
		return $indexable;
	}

	/**
	 * Retrieves the permalink for an indexable.
	 *
	 * @param Indexable $indexable The indexable.
	 *
	 * @return string|null The permalink.
	 */
	protected function get_permalink_for_indexable( $indexable ) {
		switch ( true ) {
			case $indexable->object_type === 'post':
			case $indexable->object_type === 'home-page':
				return get_permalink( $indexable->object_id );
			case $indexable->object_type === 'term':
				$term = get_term( $indexable->object_id );

				return get_term_link( $term, $term->taxonomy );
			case $indexable->object_type === 'system-page' && $indexable->object_sub_type === 'search-page':
				return get_search_link();
			case $indexable->object_type === 'post-type-archive':
				return get_post_type_archive_link( $indexable->object_sub_type );
			case $indexable->object_type === 'user':
				return get_author_posts_url( $indexable->object_id );
		}

		return null;
	}
}