package org.apache.lucene.codecs;

/*
 * 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.io.Closeable;
import java.io.IOException;

import org.apache.lucene.index.BinaryDocValues;
import org.apache.lucene.index.FieldInfo;
import org.apache.lucene.index.NumericDocValues;
import org.apache.lucene.index.SortedDocValues;
import org.apache.lucene.index.SortedSetDocValues;
import org.apache.lucene.util.Bits;

/** Abstract API that produces numeric, binary and
 * sorted docvalues.
 *
 * @lucene.experimental
 */
public abstract class DocValuesProducer implements Closeable {
  
  /** Sole constructor. (For invocation by subclass 
   *  constructors, typically implicit.) */
  protected DocValuesProducer() {}

  /** Returns {@link NumericDocValues} for this field.
   *  The returned instance need not be thread-safe: it will only be
   *  used by a single thread. */
  public abstract NumericDocValues getNumeric(FieldInfo field) throws IOException;

  /** Returns {@link BinaryDocValues} for this field.
   *  The returned instance need not be thread-safe: it will only be
   *  used by a single thread. */
  public abstract BinaryDocValues getBinary(FieldInfo field) throws IOException;

  /** Returns {@link SortedDocValues} for this field.
   *  The returned instance need not be thread-safe: it will only be
   *  used by a single thread. */
  public abstract SortedDocValues getSorted(FieldInfo field) throws IOException;
  
  /** Returns {@link SortedSetDocValues} for this field.
   *  The returned instance need not be thread-safe: it will only be
   *  used by a single thread. */
  public abstract SortedSetDocValues getSortedSet(FieldInfo field) throws IOException;
  
  /** Returns a {@link Bits} at the size of <code>reader.maxDoc()</code>, 
   *  with turned on bits for each docid that does have a value for this field.
   *  The returned instance need not be thread-safe: it will only be
   *  used by a single thread. */
  public abstract Bits getDocsWithField(FieldInfo field) throws IOException;
  
  /** Returns approximate RAM bytes used */
  public abstract long ramBytesUsed();
  
  /** 
   * A simple implementation of {@link DocValuesProducer#getDocsWithField} that 
   * returns {@code true} if a document has an ordinal >= 0
   * <p>
   * Codecs can choose to use this (or implement it more efficiently another way), but
   * in most cases a Bits is unnecessary anyway: users can check this as they go.
   */
  public static class SortedDocsWithField implements Bits {
    final SortedDocValues in;
    final int maxDoc;
    
    /** Creates a {@link Bits} returning true if the document has a value */
    public SortedDocsWithField(SortedDocValues in, int maxDoc) {
      this.in = in;
      this.maxDoc = maxDoc;
    }
    
    @Override
    public boolean get(int index) {
      return in.getOrd(index) >= 0;
    }

    @Override
    public int length() {
      return maxDoc;
    }
  }
  
  /** 
   * A simple implementation of {@link DocValuesProducer#getDocsWithField} that 
   * returns {@code true} if a document has any ordinals.
   * <p>
   * Codecs can choose to use this (or implement it more efficiently another way), but
   * in most cases a Bits is unnecessary anyway: users can check this as they go.
   */
  public static class SortedSetDocsWithField implements Bits {
    final SortedSetDocValues in;
    final int maxDoc;
    
    /** Creates a {@link Bits} returning true if the document has a value */
    public SortedSetDocsWithField(SortedSetDocValues in, int maxDoc) {
      this.in = in;
      this.maxDoc = maxDoc;
    }
    
    @Override
    public boolean get(int index) {
      in.setDocument(index);
      return in.nextOrd() != SortedSetDocValues.NO_MORE_ORDS;
    }

    @Override
    public int length() {
      return maxDoc;
    }
  }
}