package org.apache.blur.manager.results;

/**
 * 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.
 */
import java.util.Comparator;
import java.util.List;

import org.apache.blur.thrift.generated.BlurException;
import org.apache.blur.thrift.generated.BlurResult;
import org.apache.blur.thrift.generated.SortFieldResult;
import org.apache.blur.utils.BlurUtil;

public class BlurResultPeekableIteratorComparator implements Comparator<PeekableIterator<BlurResult, BlurException>> {

  @Override
  public int compare(PeekableIterator<BlurResult, BlurException> o1, PeekableIterator<BlurResult, BlurException> o2) {
    BlurResult result1 = o1.peek();
    BlurResult result2 = o2.peek();

    if (result1 == null && result2 == null) {
      return 0;
    } else if (result1 == null) {
      return 1;
    } else if (result2 == null) {
      return -1;
    }

    List<SortFieldResult> sortFields1 = result1.getSortFieldResults();
    List<SortFieldResult> sortFields2 = result2.getSortFieldResults();
    if (sortFields1 != null && sortFields2 != null) {
      // Then we need to do a sort merge
      int size1 = sortFields1.size();
      int size2 = sortFields2.size();
      if (size1 != size2) {
        throw new RuntimeException("Result mismatch, sizes of sortfields must match [" + result1 + "] [" + result2
            + "]");
      }
      for (int i = 0; i < size1; i++) {
        SortFieldResult sortField1 = sortFields1.get(i);
        SortFieldResult sortField2 = sortFields2.get(i);
        int compare = BlurUtil.SORT_FIELD_COMPARATOR.compare(sortField1, sortField2);
        if (compare != 0) {
          return compare;
        }
      }
      return 0;
    }

    if (sortFields1 == null && sortFields2 == null) {
      int compare = Double.compare(result2.score, result1.score);
      if (compare == 0) {
        return result2.locationId.compareTo(result1.locationId);
      }
      return compare;
    } else {
      throw new RuntimeException("Result mismatch, one of the 2 results have null sortfields [" + result1 + "] ["
          + result2 + "]");
    }
  }

}