/*
 * This file is part of ELKI:
 * Environment for Developing KDD-Applications Supported by Index-Structures
 *
 * Copyright (C) 2022
 * ELKI Development Team
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package elki.index.tree.metrical.mtreevariants;

import java.io.Externalizable;

import elki.database.ids.DBID;

/**
 * Defines the requirements for an entry in an M-Tree node.
 * 
 * @author Elke Achtert
 * @since 0.1
 */
public interface MTreeEntry extends Externalizable {
  /**
   * Returns the id of the underlying database object of this entry, if this
   * entry is a leaf entry, the id of the routing object, otherwise.
   * 
   * @return the id of the underlying database object of this entry, if this
   *         entry is a leaf entry, the id of the routing object, otherwise
   */
  DBID getRoutingObjectID();

  /**
   * Sets the id of the underlying database object of this entry, if this entry
   * is a leaf entry, the id of the routing object, otherwise.
   * 
   * @param objectID the id to be set
   * @return TODO
   */
  boolean setRoutingObjectID(DBID objectID);

  /**
   * Returns the distance from the routing object of this entry to the routing
   * object of its parent.
   * 
   * @return the distance from the object to its parent object
   */
  double getParentDistance();

  /**
   * Sets the distance from the routing object to routing object of its parent.
   * 
   * @param parentDistance the distance to be set
   * @return TODO
   */
  boolean setParentDistance(double parentDistance);

  /**
   * Returns the covering radius if this entry is a directory entry, null
   * otherwise.
   * 
   * @return the covering radius of this entry
   */
  double getCoveringRadius();

  /**
   * Sets the covering radius of this entry if this entry is a directory entry,
   * throws an UnsupportedOperationException otherwise.
   * 
   * @param coveringRadius the covering radius to be set
   * @return TODO
   */
  boolean setCoveringRadius(double coveringRadius);
}
