/**
	 * 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 id's and type.
	 *
	 * @param int[]  $object_ids  The array of indexable object id's.
	 * @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 ) {
		if ( empty( $object_ids ) ) {
			return [];
		}

		/**
		 * 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 );
	}

	/**
	 * Finds the indexables by id's.
	 *
	 * @param array $indexable_ids The indexable id's.
	 *
	 * @return Indexable[] The found indexables.
	 */
	public function find_by_ids( array $indexable_ids ) {
		if ( empty( $indexable_ids ) ) {
			return [];
		}

		$indexables = $this
			->query()
			->where_in( 'id', $indexable_ids )
			->find_many();

		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 ) {
		// If we've already set ancestors on the indexable no need to get them again.
		if ( \is_array( $indexable->ancestors ) && ! empty( $indexable->ancestors ) ) {
			return \array_map( [ $this, 'ensure_permalink' ], $indexable->ancestors );
		}

		$indexable_ids = $this->hierarchy_repository->find_ancestors( $indexable );

		// If we've set ancestors on the indexable because we had to build them to find them.
		if ( \is_array( $indexable->ancestors ) && ! empty( $indexable->ancestors ) ) {
			return \array_map( [ $this, 'ensure_permalink' ], $indexable->ancestors );
		}

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

		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 );
	}

	/**
	 * Returns all subpages with a given post_parent.
	 *
	 * @param int   $post_parent The post parent.
	 * @param array $exclude_ids The id's to exclude.
	 *
	 * @return Indexable[] array of indexables.
	 */
	public function get_subpages_by_post_parent( $post_parent, $exclude_ids = [] ) {
		$query = $this->query()
			->where( 'post_parent', $post_parent )
			->where( 'object_type', 'post' )
			->where( 'post_status', 'publish' );

		if ( ! empty( $exclude_ids ) ) {
			$query->where_not_in( 'object_id', $exclude_ids );
		}
		return $query->find_many();
	}

	/**
	 * Updates the incoming link count for an indexable without first fetching it.
	 *
	 * @param int $indexable_id The indexable id.
	 * @param int $count        The incoming link count.
	 *
	 * @return bool Whether or not the update was succeful.
	 */
	public function update_incoming_link_count( $indexable_id, $count ) {
		return (bool) $this->query()
			->set( 'incoming_link_count', $count )
			->where( 'id', $indexable_id )
			->update_many();
	}

	/**
	 * 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->permalink_helper->get_permalink_for_indexable( $indexable );

			// Only save if changed.
			if ( $indexable->permalink !== null ) {
				$indexable->save();
			}
		}
		return $indexable;
	}

	/* ********************* DEPRECATED METHODS ********************* */

	/**
	 * Returns all children of a given indexable.
	 *
	 * @deprecated 15.0
	 * @codeCoverageIgnore
	 *
	 * @param Indexable $indexable The indexable to find the children of.
	 *
	 * @return Indexable[] All children of the given indexable.
	 */
	public function get_children( Indexable $indexable ) {
		\_deprecated_function( __METHOD__, 'WPSEO 15.0' );

		$indexable_ids = $this->hierarchy_repository->find_children( $indexable );

		return $this->find_by_ids( $indexable_ids );
	}

	/**
	 * Resets the permalinks of the passed object type and subtype.
	 *
	 * @param string      $type    The type of the indexable. Can be null.
	 * @param null|string $subtype The subtype. Can be null.
	 *
	 * @return int|bool The number of permalinks changed if the query was succesful. False otherwise.
	 */
	public function reset_permalink( $type = null, $subtype = null ) {
		$query = $this->query()->set(
			[
				'permalink'      => null,
				'permalink_hash' => null,
			]
		);

		if ( $type !== null ) {
			$query->where( 'object_type', $type );
		}

		if ( $type !== null && $subtype !== null ) {
			$query->where( 'object_sub_type', $subtype );
		}

		return $query->update_many();
	}
}