/*
 * 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.lucene.search;

import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.Objects;
import java.util.Set;

import org.apache.lucene.document.NumericDocValuesField;
import org.apache.lucene.document.SortedNumericDocValuesField;
import org.apache.lucene.index.DocValues;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.SortedNumericDocValues;

/**
 * Like {@link DocValuesTermsQuery}, but this query only
 * runs on a long {@link NumericDocValuesField} or a
 * {@link SortedNumericDocValuesField}, matching
 * all documents whose value in the specified field is
 * contained in the provided set of long values.
 *
 * <p>
 * <b>NOTE</b>: be very careful using this query: it is
 * typically much slower than using {@code TermsQuery},
 * but in certain specialized cases may be faster.
 *
 * @lucene.experimental
 */
public class DocValuesNumbersQuery extends Query {

  private final String field;
  private final LongHashSet numbers;

  public DocValuesNumbersQuery(String field, long[] numbers) {
    this.field = Objects.requireNonNull(field);
    this.numbers = new LongHashSet(numbers);
  }

  public DocValuesNumbersQuery(String field, Collection<Long> numbers) {
    this.field = Objects.requireNonNull(field);
    this.numbers = new LongHashSet(numbers.stream().mapToLong(Long::longValue).toArray());
  }

  public DocValuesNumbersQuery(String field, Long... numbers) {
    this(field, new HashSet<Long>(Arrays.asList(numbers)));
  }

  @Override
  public boolean equals(Object other) {
    return sameClassAs(other) &&
           equalsTo(getClass().cast(other));
  }

  private boolean equalsTo(DocValuesNumbersQuery other) {
    return field.equals(other.field) &&
           numbers.equals(other.numbers);
  }

  @Override
  public int hashCode() {
    return 31 * classHash() + Objects.hash(field, numbers);
  }

  public String getField() {
    return field;
  }

  public Set<Long> getNumbers() {
    return numbers;
  }

  @Override
  public String toString(String defaultField) {
    return new StringBuilder()
        .append(field)
        .append(": ")
        .append(numbers.toString())
        .toString();
  }

  @Override
  public Weight createWeight(IndexSearcher searcher, boolean needsScores, float boost) throws IOException {
    return new ConstantScoreWeight(this, boost) {

      @Override
      public Scorer scorer(LeafReaderContext context) throws IOException {
        final SortedNumericDocValues values = DocValues.getSortedNumeric(context.reader(), field);
        return new ConstantScoreScorer(this, score(), new TwoPhaseIterator(values) {

          @Override
          public boolean matches() throws IOException {
            int count = values.docValueCount();
            for(int i=0;i<count;i++) {
              if (numbers.contains(values.nextValue())) {
                return true;
              }
            }
            return false;
          }

          @Override
          public float matchCost() {
            return 5; // lookup in the set
          }
        });
      }
    };
  }
}