/*
 * 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.queries.payloads;

import org.apache.lucene.queries.spans.Spans;
import org.apache.lucene.search.Explanation;

/**
 * An abstract class that defines a way for PayloadScoreQuery instances to transform the cumulative
 * effects of payload scores for a document.
 *
 * @see org.apache.lucene.queries.payloads.PayloadScoreQuery for more information
 * @lucene.experimental This class and its derivations are experimental and subject to change
 */
public abstract class PayloadFunction {

  /**
   * Calculate the score up to this point for this doc and field
   *
   * @param docId The current doc
   * @param field The field
   * @param start The start position of the matching Span
   * @param end The end position of the matching Span
   * @param numPayloadsSeen The number of payloads seen so far
   * @param currentScore The current score so far
   * @param currentPayloadScore The score for the current payload
   * @return The new current Score
   * @see Spans
   */
  public abstract float currentScore(
      int docId,
      String field,
      int start,
      int end,
      int numPayloadsSeen,
      float currentScore,
      float currentPayloadScore);

  /**
   * Calculate the final score for all the payloads seen so far for this doc/field
   *
   * @param docId The current doc
   * @param field The current field
   * @param numPayloadsSeen The total number of payloads seen on this document
   * @param payloadScore The raw score for those payloads
   * @return The final score for the payloads
   */
  public abstract float docScore(int docId, String field, int numPayloadsSeen, float payloadScore);

  public Explanation explain(int docId, String field, int numPayloadsSeen, float payloadScore) {
    return Explanation.match(
        docScore(docId, field, numPayloadsSeen, payloadScore),
        getClass().getSimpleName() + ".docScore()");
  }

  @Override
  public abstract int hashCode();

  @Override
  public abstract boolean equals(Object o);
}
