/*
 * 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.tajo.master;

import com.google.common.base.Objects;
import org.apache.tajo.storage.fragment.FileFragment;

/**
 * FragmentPair consists of two fragments, a left fragment and a right fragment.
 * According to queries, it can have the different values.
 * For join queries, it is assumed to have both fragments.
 * Also, the left fragment is assumed to be a fragment of the larger table.
 * For other queries, it is assumed to have only a left fragment.
 */
public class FragmentPair {
  private FileFragment leftFragment;
  private FileFragment rightFragment;

  public FragmentPair(FileFragment left) {
    this.leftFragment = left;
  }

  public FragmentPair(FileFragment left, FileFragment right) {
    this.leftFragment = left;
    this.rightFragment = right;
  }

  public FileFragment getLeftFragment() {
    return leftFragment;
  }

  public FileFragment getRightFragment() {
    return rightFragment;
  }

  @Override
  public boolean equals(Object o) {
    if (o instanceof FragmentPair) {
      FragmentPair other = (FragmentPair) o;
      boolean eq = this.leftFragment.equals(other.leftFragment);
      if (this.rightFragment != null && other.rightFragment != null) {
        eq &= this.rightFragment.equals(other.rightFragment);
      } else if (this.rightFragment == null && other.rightFragment == null) {
        eq &= true;
      } else {
        return false;
      }
      return eq;
    }
    return false;
  }

  @Override
  public int hashCode() {
    return Objects.hashCode(leftFragment, rightFragment);
  }
}