/**
 * 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.clustering.dirichlet;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;

import org.apache.hadoop.conf.Configuration;
import org.apache.mahout.clustering.Cluster;
import org.apache.mahout.clustering.Model;
import org.apache.mahout.common.ClassUtils;
import org.apache.mahout.common.parameters.Parameter;
import org.apache.mahout.math.Vector;
import org.apache.mahout.math.VectorWritable;

public class DirichletCluster implements Cluster {
  
  private Cluster model; // the model for this iteration
  
  private double totalCount; // total count of observations for the model
  
  public DirichletCluster(Cluster model, double totalCount) {
    this.model = model;
    this.totalCount = totalCount;
  }
  
  public DirichletCluster(Cluster model) {
    this.model = model;
    this.totalCount = 0.0;
  }
  
  public DirichletCluster() {}
  
  @Override
  public void configure(Configuration job) {
    // nothing to do
  }
  
  @Override
  public Collection<Parameter<?>> getParameters() {
    return Collections.emptyList();
  }
  
  @Override
  public void createParameters(String prefix, Configuration jobConf) {
    // nothing to do
  }
  
  public Cluster getModel() {
    return model;
  }
  
  public void setModel(Cluster model) {
    this.model = model;
    this.totalCount += model.count();
  }
  
  public double getTotalCount() {
    return totalCount;
  }
  
  @Override
  public void readFields(DataInput in) throws IOException {
    this.totalCount = in.readDouble();
    this.model = readModel(in);
  }
  
  @Override
  public void write(DataOutput out) throws IOException {
    out.writeDouble(totalCount);
    writeModel(out, model);
  }
  
  /************* Methods required by Cluster *****************/
  
  /** Writes a typed Model instance to the output stream */
  public static void writeModel(DataOutput out, Model<?> model)
      throws IOException {
    out.writeUTF(model.getClass().getName());
    model.write(out);
  }
  
  /** Reads a typed Model instance from the input stream */
  public static Cluster readModel(DataInput in) throws IOException {
    String modelClassName = in.readUTF();
    Cluster model = ClassUtils.instantiateAs(modelClassName, Cluster.class);
    model.readFields(in);
    return model;
  }
  
  @Override
  public String asFormatString(String[] bindings) {
    return "DC-" + model.getId() + " total= " + (int) totalCount + " model= "
        + model.asFormatString(bindings);
  }
  
  @Override
  public int getId() {
    return model.getId();
  }
  
  @Override
  public Vector getCenter() {
    return model.getCenter();
  }
  
  @Override
  public long getNumPoints() {
    return model.getNumPoints();
  }
  
  @Override
  public Vector getRadius() {
    return model.getRadius();
  }
  
  @Override
  public void computeParameters() {
    model.computeParameters();
  }
  
  @Override
  public long count() {
    return model.count();
  }
  
  @Override
  public void observe(VectorWritable x) {
    model.observe(x);
  }
  
  @Override
  public double pdf(VectorWritable x) {
    return model.pdf(x);
  }
  
  @Override
  public Model<VectorWritable> sampleFromPosterior() {
    return model.sampleFromPosterior();
  }
  
  @Override
  public void observe(VectorWritable x, double weight) {
    model.observe(x, weight);
    totalCount += weight;
  }
  
  @Override
  public boolean isConverged() {
    // Convergence does not apply here
    return false;
  }
  
  @Override
  public void observe(Model<VectorWritable> x) {
    model.observe(x);
    totalCount += x.count();
  }
  
}