interface BookOutlineStorageInterface

interface BookOutlineStorageInterface {
    
    /**
     * Gets books (the highest positioned book links).
     *
     * @return array
     *   An array of book IDs.
     */
    public function getBooks();
    
    /**
     * Checks if there are any books.
     *
     * @return bool
     *   TRUE if there are books, FALSE if not.
     */
    public function hasBooks();
    
    /**
     * Loads books.
     *
     * Each book entry consists of the following keys:
     *   - bid: The node ID of the main book.
     *   - nid: The node ID of the book entry itself.
     *   - pid: The parent node ID of the book.
     *   - has_children: A boolean to indicate whether the book has children.
     *   - weight: The weight of the book entry to order siblings.
     *   - depth: The depth in the menu hierarchy the entry is placed into.
     *
     * @param array $nids
     *   An array of node IDs.
     * @param bool $access
     *   Whether access checking should be taken into account.
     *
     * @return array
     *   Array of loaded book items.
     */
    public function loadMultiple($nids, $access = TRUE);
    
    /**
     * Gets child relative depth.
     *
     * @param array $book_link
     *   The book link.
     * @param int $max_depth
     *   The maximum supported depth of the book tree.
     *
     * @return int
     *   The depth of the searched book.
     */
    public function getChildRelativeDepth($book_link, $max_depth);
    
    /**
     * Deletes a book entry.
     *
     * @param int $nid
     *   Deletes a book entry.
     *
     * @return mixed
     *   Number of deleted book entries.
     */
    public function delete($nid);
    
    /**
     * Loads book's children using its parent ID.
     *
     * @param int $pid
     *   The book's parent ID.
     *
     * @return array
     *   Array of loaded book items.
     */
    public function loadBookChildren($pid);
    
    /**
     * Builds tree data used for the menu tree.
     *
     * @param int $bid
     *   The ID of the book that we are building the tree for.
     * @param array $parameters
     *   An associative array of build parameters. For info about individual
     *   parameters see BookManager::bookTreeBuild().
     * @param int $min_depth
     *   The minimum depth of book links in the resulting tree.
     * @param int $max_depth
     *   The maximum supported depth of the book tree.
     *
     * @return array
     *   Array of loaded book links.
     */
    public function getBookMenuTree($bid, $parameters, $min_depth, $max_depth);
    
    /**
     * Inserts a book link.
     *
     * @param array $link
     *   The link array to be inserted in the database.
     * @param array $parents
     *   The array of parent ids for the link to be inserted.
     *
     * @return mixed
     *   The last insert ID of the query, if one exists.
     */
    public function insert($link, $parents);
    
    /**
     * Updates book reference for links that were moved between books.
     *
     * @param int $nid
     *   The nid of the book entry to be updated.
     * @param array $fields
     *   The array of fields to be updated.
     *
     * @return mixed
     *   The number of rows matched by the update query.
     */
    public function update($nid, $fields);
    
    /**
     * Update the book ID of the book link that it's being moved.
     *
     * @param int $bid
     *   The ID of the book whose children we move.
     * @param array $original
     *   The original parent of the book link.
     * @param array $expressions
     *   Array of expressions to be added to the query.
     * @param int $shift
     *   The difference in depth between the old and the new position of the
     *   element being moved.
     *
     * @return mixed
     *   The number of rows matched by the update query.
     */
    public function updateMovedChildren($bid, $original, $expressions, $shift);
    
    /**
     * Count the number of original link children.
     *
     * @param array $original
     *   The book link array.
     *
     * @return int
     *   Number of children.
     */
    public function countOriginalLinkChildren($original);
    
    /**
     * Get book subtree.
     *
     * @param array $link
     *   A fully loaded book link.
     * @param int $max_depth
     *   The maximum supported depth of the book tree.
     *
     * @return array
     *   Array of unordered subtree book items.
     */
    public function getBookSubtree($link, $max_depth);

}