/*
 * Ivory: A Hadoop toolkit for web-scale information retrieval
 *
 * Licensed 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 ivory.smrf.retrieval;

import java.io.Serializable;
import java.util.Comparator;

import com.google.common.base.Preconditions;

/**
 * @author Don Metzler
 */
public class Accumulator implements Comparable<Accumulator>, Serializable {
  private static final long serialVersionUID = -2003009119471096383L;

  public int docno = 0;
  public float score = 0.0f;

  public Accumulator(int docno, float score) {
    this.docno = docno;
    this.score = score;
  }

  public int compareTo(Accumulator a) {
    Preconditions.checkNotNull(a);

    if (score > a.score) {
      return 1;
    } else if (score < a.score) {
      return -1;
    } else if (score == a.score) {
      if (docno > a.docno) {
        return 1;
      } else if (docno < a.docno) {
        return -1;
      }
    }
    return 0;
  }

  @Override
  public String toString() {
    return "<accumulator docno=\"" + docno + "\" score=\"" + score + "\" />\n";
  }

  public static int[] accumulatorsToDocnos(Accumulator[] results) {
    Preconditions.checkNotNull(results);

    int[] ids = new int[results.length];
    for (int i = 0; i < results.length; i++) {
      ids[i] = results[i].docno;
    }
    return ids;
  }

  public static class DocnoComparator implements Comparator<Accumulator> {
    public int compare(Accumulator x, Accumulator y) {
      Preconditions.checkNotNull(x);
      Preconditions.checkNotNull(y);

      if (x.docno < y.docno) {
        return -1;
      } else if (x.docno > y.docno) {
        return 1;
      }

      return 0;
    }
  }
}