/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.mahout.classifier.df.node;

import org.apache.mahout.classifier.df.data.Instance;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

/**
 * Represents a node that splits using a numerical attribute
 */
public class NumericalNode extends Node {
  /** numerical attribute to split for */
  private int attr;
  
  /** split value */
  private double split;
  
  /** child node when attribute's value < split value */
  private Node loChild;
  
  /** child node when attribute's value >= split value */
  private Node hiChild;
  
  public NumericalNode() { } 
  
  public NumericalNode(int attr, double split, Node loChild, Node hiChild) {
    this.attr = attr;
    this.split = split;
    this.loChild = loChild;
    this.hiChild = hiChild;
  }
  
  @Override
  public double classify(Instance instance) {
    if (instance.get(attr) < split) {
      return loChild.classify(instance);
    } else {
      return hiChild.classify(instance);
    }
  }
  
  @Override
  public long maxDepth() {
    return 1 + Math.max(loChild.maxDepth(), hiChild.maxDepth());
  }
  
  @Override
  public long nbNodes() {
    return 1 + loChild.nbNodes() + hiChild.nbNodes();
  }
  
  @Override
  protected Type getType() {
    return Type.NUMERICAL;
  }
  
  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (!(obj instanceof NumericalNode)) {
      return false;
    }
    
    NumericalNode node = (NumericalNode) obj;
    
    return attr == node.attr && split == node.split && loChild.equals(node.loChild) && hiChild.equals(node.hiChild);
  }
  
  @Override
  public int hashCode() {
    return attr + (int) Double.doubleToLongBits(split) + loChild.hashCode() + hiChild.hashCode();
  }
  
  @Override
  protected String getString() {
    return loChild.toString() + ',' + hiChild.toString();
  }
  
  @Override
  public void readFields(DataInput in) throws IOException {
    attr = in.readInt();
    split = in.readDouble();
    loChild = Node.read(in);
    hiChild = Node.read(in);
  }
  
  @Override
  protected void writeNode(DataOutput out) throws IOException {
    out.writeInt(attr);
    out.writeDouble(split);
    loChild.write(out);
    hiChild.write(out);
  }
}