/*
 * 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.query;

import elki.database.ids.DBID;

/**
 * Encapsulates the attributes for a object that can be stored in a heap. The
 * object to be stored represents a node in a M-Tree and some additional
 * information. Additionally to the regular expansion candidate, this object
 * holds the id of the routing object of the underlying M-Tree node and its
 * covering radius.
 * 
 * @author Elke Achtert
 * @since 0.5.5
 */
public class MTreeSearchCandidate implements Comparable<MTreeSearchCandidate> {
  /**
   * Distance value
   */
  public double mindist;

  /**
   * Page id
   */
  public int nodeID;

  /**
   * The id of the routing object.
   */
  public DBID routingObjectID;

  /**
   * The distance from the query object to the routing object
   */
  public double routingDistance;

  /**
   * Creates a new heap node with the specified parameters.
   * 
   * @param mindist the minimum distance of the node
   * @param nodeID the id of the node
   * @param routingObjectID the id of the routing object of the node
   * @param routingDistance the distance from the query object to the query
   *        object
   */
  public MTreeSearchCandidate(final double mindist, final int nodeID, final DBID routingObjectID, double routingDistance) {
    super();
    this.mindist = mindist;
    this.nodeID = nodeID;
    this.routingObjectID = routingObjectID;
    this.routingDistance = routingDistance;
  }

  @Override
  public boolean equals(Object obj) {
    return (obj instanceof MTreeSearchCandidate) //
        && this.nodeID == ((MTreeSearchCandidate) obj).nodeID;
  }

  @Override
  public int hashCode() {
    return nodeID;
  }

  @Override
  public int compareTo(MTreeSearchCandidate o) {
    return Double.compare(this.mindist, o.mindist);
  }
}
