/**
 * 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.kmeans;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.clustering.WeightedVectorWritable;
import org.apache.mahout.common.distance.DistanceMeasure;
import org.apache.mahout.math.VectorWritable;

public class KMeansClusterMapper extends Mapper<WritableComparable<?>,VectorWritable,IntWritable,WeightedVectorWritable> {
  
  private final List<Cluster> clusters = new ArrayList<Cluster>();
  private KMeansClusterer clusterer;

  @Override
  protected void map(WritableComparable<?> key, VectorWritable point, Context context) throws IOException, InterruptedException {
    clusterer.outputPointWithClusterInfo(point.get(), clusters, context);
  }

  @Override
  protected void setup(Context context) throws IOException, InterruptedException {
    super.setup(context);
    Configuration conf = context.getConfiguration();
    try {
      ClassLoader ccl = Thread.currentThread().getContextClassLoader();
      DistanceMeasure measure = ccl.loadClass(conf.get(KMeansConfigKeys.DISTANCE_MEASURE_KEY))
          .asSubclass(DistanceMeasure.class).newInstance();
      measure.configure(conf);
      
      String clusterPath = conf.get(KMeansConfigKeys.CLUSTER_PATH_KEY);
      if ((clusterPath != null) && (clusterPath.length() > 0)) {
        KMeansUtil.configureWithClusterInfo(new Path(clusterPath), clusters);
        if (clusters.isEmpty()) {
          throw new IllegalStateException("No clusters found. Check your -c path.");
        }
      }  
      this.clusterer = new KMeansClusterer(measure);
    } catch (ClassNotFoundException e) {
      throw new IllegalStateException(e);
    } catch (IllegalAccessException e) {
      throw new IllegalStateException(e);
    } catch (InstantiationException e) {
      throw new IllegalStateException(e);
    }
  }
}
