/*
 * 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.index;


import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.StreamSupport;

import org.apache.lucene.util.ArrayUtil;

Collection of FieldInfos (accessible by number or by name). @lucene.experimental /** 
 * Collection of {@link FieldInfo}s (accessible by number or by name).
 *  @lucene.experimental
 */
public class FieldInfos implements Iterable<FieldInfo> {

  
An instance without any fields. /** An instance without any fields. */
  public final static FieldInfos EMPTY = new FieldInfos(new FieldInfo[0]);

  private final boolean hasFreq;
  private final boolean hasProx;
  private final boolean hasPayloads;
  private final boolean hasOffsets;
  private final boolean hasVectors;
  private final boolean hasNorms;
  private final boolean hasDocValues;
  private final boolean hasPointValues;
  private final String softDeletesField;
  
  // used only by fieldInfo(int)
  private final FieldInfo[] byNumber;
  
  private final HashMap<String,FieldInfo> byName = new HashMap<>();
  private final Collection<FieldInfo> values; // for an unmodifiable iterator
  
  
Constructs a new FieldInfos from an array of FieldInfo objects
/**
   * Constructs a new FieldInfos from an array of FieldInfo objects
   */
  public FieldInfos(FieldInfo[] infos) {
    boolean hasVectors = false;
    boolean hasProx = false;
    boolean hasPayloads = false;
    boolean hasOffsets = false;
    boolean hasFreq = false;
    boolean hasNorms = false;
    boolean hasDocValues = false;
    boolean hasPointValues = false;
    String softDeletesField = null;

    int size = 0; // number of elements in byNumberTemp, number of used array slots
    FieldInfo[] byNumberTemp = new FieldInfo[10]; // initial array capacity of 10
    for (FieldInfo info : infos) {
      if (info.number < 0) {
        throw new IllegalArgumentException("illegal field number: " + info.number + " for field " + info.name);
      }
      size = info.number >= size ? info.number+1 : size;
      if (info.number >= byNumberTemp.length){ //grow array
        byNumberTemp = ArrayUtil.grow(byNumberTemp, info.number + 1);
      }
      FieldInfo previous = byNumberTemp[info.number];
      if (previous != null) {
        throw new IllegalArgumentException("duplicate field numbers: " + previous.name + " and " + info.name + " have: " + info.number);
      }
      byNumberTemp[info.number] = info;

      previous = byName.put(info.name, info);
      if (previous != null) {
        throw new IllegalArgumentException("duplicate field names: " + previous.number + " and " + info.number + " have: " + info.name);
      }

      hasVectors |= info.hasVectors();
      hasProx |= info.getIndexOptions().compareTo(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS) >= 0;
      hasFreq |= info.getIndexOptions() != IndexOptions.DOCS;
      hasOffsets |= info.getIndexOptions().compareTo(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS) >= 0;
      hasNorms |= info.hasNorms();
      hasDocValues |= info.getDocValuesType() != DocValuesType.NONE;
      hasPayloads |= info.hasPayloads();
      hasPointValues |= (info.getPointDimensionCount() != 0);
      if (info.isSoftDeletesField()) {
        if (softDeletesField != null && softDeletesField.equals(info.name) == false) {
          throw new IllegalArgumentException("multiple soft-deletes fields [" + info.name + ", " + softDeletesField + "]");
        }
        softDeletesField = info.name;
      }
    }
    
    this.hasVectors = hasVectors;
    this.hasProx = hasProx;
    this.hasPayloads = hasPayloads;
    this.hasOffsets = hasOffsets;
    this.hasFreq = hasFreq;
    this.hasNorms = hasNorms;
    this.hasDocValues = hasDocValues;
    this.hasPointValues = hasPointValues;
    this.softDeletesField = softDeletesField;

    List<FieldInfo> valuesTemp = new ArrayList<>();
    byNumber = new FieldInfo[size];
    for(int i=0; i<size; i++){
      byNumber[i] = byNumberTemp[i];
      if (byNumberTemp[i] != null) {
        valuesTemp.add(byNumberTemp[i]);
      }
    }
    values = Collections.unmodifiableCollection(Arrays.asList(valuesTemp.toArray(new FieldInfo[0])));
  }

  
Call this to get the (merged) FieldInfos for a
 composite reader.
 
 NOTE: the returned field numbers will likely not correspond to the actual field numbers in the underlying readers, and codec metadata (FieldInfo.getAttribute(String) will be unavailable. /** Call this to get the (merged) FieldInfos for a
   *  composite reader.
   *  <p>
   *  NOTE: the returned field numbers will likely not
   *  correspond to the actual field numbers in the underlying
   *  readers, and codec metadata ({@link FieldInfo#getAttribute(String)}
   *  will be unavailable.
   */
  public static FieldInfos getMergedFieldInfos(IndexReader reader) {
    final List<LeafReaderContext> leaves = reader.leaves();
    if (leaves.isEmpty()) {
      return FieldInfos.EMPTY;
    } else if (leaves.size() == 1) {
      return leaves.get(0).reader().getFieldInfos();
    } else {
      final String softDeletesField = leaves.stream()
          .map(l -> l.reader().getFieldInfos().getSoftDeletesField())
          .filter(Objects::nonNull)
          .findAny().orElse(null);
      final Builder builder = new Builder(new FieldNumbers(softDeletesField));
      for (final LeafReaderContext ctx : leaves) {
        builder.add(ctx.reader().getFieldInfos());
      }
      return builder.finish();
    }
  }

  
Returns a set of names of fields that have a terms index.  The order is undefined. /** Returns a set of names of fields that have a terms index.  The order is undefined. */
  public static Collection<String> getIndexedFields(IndexReader reader) {
    return reader.leaves().stream()
        .flatMap(l -> StreamSupport.stream(l.reader().getFieldInfos().spliterator(), false)
        .filter(fi -> fi.getIndexOptions() != IndexOptions.NONE))
        .map(fi -> fi.name)
        .collect(Collectors.toSet());
  }

  
Returns true if any fields have freqs /** Returns true if any fields have freqs */
  public boolean hasFreq() {
    return hasFreq;
  }
  
  
Returns true if any fields have positions /** Returns true if any fields have positions */
  public boolean hasProx() {
    return hasProx;
  }

  
Returns true if any fields have payloads /** Returns true if any fields have payloads */
  public boolean hasPayloads() {
    return hasPayloads;
  }

  
Returns true if any fields have offsets /** Returns true if any fields have offsets */
  public boolean hasOffsets() {
    return hasOffsets;
  }
  
  
Returns true if any fields have vectors /** Returns true if any fields have vectors */
  public boolean hasVectors() {
    return hasVectors;
  }
  
  
Returns true if any fields have norms /** Returns true if any fields have norms */
  public boolean hasNorms() {
    return hasNorms;
  }
  
  
Returns true if any fields have DocValues /** Returns true if any fields have DocValues */
  public boolean hasDocValues() {
    return hasDocValues;
  }

  
Returns true if any fields have PointValues /** Returns true if any fields have PointValues */
  public boolean hasPointValues() {
    return hasPointValues;
  }

  
Returns the soft-deletes field name if exists; otherwise returns null /** Returns the soft-deletes field name if exists; otherwise returns null */
  public String getSoftDeletesField() {
    return softDeletesField;
  }
  
  
Returns the number of fields /** Returns the number of fields */
  public int size() {
    return byName.size();
  }
  
  
Returns an iterator over all the fieldinfo objects present,
ordered by ascending field number
/**
   * Returns an iterator over all the fieldinfo objects present,
   * ordered by ascending field number
   */
  // TODO: what happens if in fact a different order is used?
  @Override
  public Iterator<FieldInfo> iterator() {
    return values.iterator();
  }

  
Return the fieldinfo object referenced by the field name
Returns:
the FieldInfo object or null when the given fieldName
doesn't exist./**
   * Return the fieldinfo object referenced by the field name
   * @return the FieldInfo object or null when the given fieldName
   * doesn't exist.
   */  
  public FieldInfo fieldInfo(String fieldName) {
    return byName.get(fieldName);
  }

  
Return the fieldinfo object referenced by the fieldNumber.
Params:
fieldNumber – field's number.
Throws:
IllegalArgumentException – if fieldNumber is negative
Returns:
the FieldInfo object or null when the given fieldNumber
doesn't exist./**
   * Return the fieldinfo object referenced by the fieldNumber.
   * @param fieldNumber field's number.
   * @return the FieldInfo object or null when the given fieldNumber
   * doesn't exist.
   * @throws IllegalArgumentException if fieldNumber is negative
   */
  public FieldInfo fieldInfo(int fieldNumber) {
    if (fieldNumber < 0) {
      throw new IllegalArgumentException("Illegal field number: " + fieldNumber);
    }
    if (fieldNumber >= byNumber.length) {
      return null;
    }
    return byNumber[fieldNumber];
  }

  static final class FieldDimensions {
    public final int dimensionCount;
    public final int indexDimensionCount;
    public final int dimensionNumBytes;

    public FieldDimensions(int dimensionCount, int indexDimensionCount, int dimensionNumBytes) {
      this.dimensionCount = dimensionCount;
      this.indexDimensionCount = indexDimensionCount;
      this.dimensionNumBytes = dimensionNumBytes;
    }
  }
  
  static final class FieldNumbers {
    
    private final Map<Integer,String> numberToName;
    private final Map<String,Integer> nameToNumber;
    private final Map<String, IndexOptions> indexOptions;
    // We use this to enforce that a given field never
    // changes DV type, even across segments / IndexWriter
    // sessions:
    private final Map<String,DocValuesType> docValuesType;

    private final Map<String,FieldDimensions> dimensions;

    // TODO: we should similarly catch an attempt to turn
    // norms back on after they were already committed; today
    // we silently discard the norm but this is badly trappy
    private int lowestUnassignedFieldNumber = -1;

    // The soft-deletes field from IWC to enforce a single soft-deletes field
    private final String softDeletesFieldName;
    
    FieldNumbers(String softDeletesFieldName) {
      this.nameToNumber = new HashMap<>();
      this.numberToName = new HashMap<>();
      this.indexOptions = new HashMap<>();
      this.docValuesType = new HashMap<>();
      this.dimensions = new HashMap<>();
      this.softDeletesFieldName = softDeletesFieldName;
    }
    
    
Returns the global field number for the given field name. If the name
does not exist yet it tries to add it with the given preferred field
number assigned if possible otherwise the first unassigned field number
is used as the field number.
/**
     * Returns the global field number for the given field name. If the name
     * does not exist yet it tries to add it with the given preferred field
     * number assigned if possible otherwise the first unassigned field number
     * is used as the field number.
     */
    synchronized int addOrGet(String fieldName, int preferredFieldNumber, IndexOptions indexOptions, DocValuesType dvType, int dimensionCount, int indexDimensionCount, int dimensionNumBytes, boolean isSoftDeletesField) {
      if (indexOptions != IndexOptions.NONE) {
        IndexOptions currentOpts = this.indexOptions.get(fieldName);
        if (currentOpts == null) {
          this.indexOptions.put(fieldName, indexOptions);
        } else if (currentOpts != IndexOptions.NONE && currentOpts != indexOptions) {
          throw new IllegalArgumentException("cannot change field \"" + fieldName + "\" from index options=" + currentOpts + " to inconsistent index options=" + indexOptions);
        }
      }
      if (dvType != DocValuesType.NONE) {
        DocValuesType currentDVType = docValuesType.get(fieldName);
        if (currentDVType == null) {
          docValuesType.put(fieldName, dvType);
        } else if (currentDVType != DocValuesType.NONE && currentDVType != dvType) {
          throw new IllegalArgumentException("cannot change DocValues type from " + currentDVType + " to " + dvType + " for field \"" + fieldName + "\"");
        }
      }
      if (dimensionCount != 0) {
        FieldDimensions dims = dimensions.get(fieldName);
        if (dims != null) {
          if (dims.dimensionCount != dimensionCount) {
            throw new IllegalArgumentException("cannot change point dimension count from " + dims.dimensionCount + " to " + dimensionCount + " for field=\"" + fieldName + "\"");
          }
          if (dims.indexDimensionCount != indexDimensionCount) {
            throw new IllegalArgumentException("cannot change point index dimension count from " + dims.indexDimensionCount + " to " + indexDimensionCount + " for field=\"" + fieldName + "\"");
          }
          if (dims.dimensionNumBytes != dimensionNumBytes) {
            throw new IllegalArgumentException("cannot change point numBytes from " + dims.dimensionNumBytes + " to " + dimensionNumBytes + " for field=\"" + fieldName + "\"");
          }
        } else {
          dimensions.put(fieldName, new FieldDimensions(dimensionCount, indexDimensionCount, dimensionNumBytes));
        }
      }
      Integer fieldNumber = nameToNumber.get(fieldName);
      if (fieldNumber == null) {
        final Integer preferredBoxed = Integer.valueOf(preferredFieldNumber);
        if (preferredFieldNumber != -1 && !numberToName.containsKey(preferredBoxed)) {
          // cool - we can use this number globally
          fieldNumber = preferredBoxed;
        } else {
          // find a new FieldNumber
          while (numberToName.containsKey(++lowestUnassignedFieldNumber)) {
            // might not be up to date - lets do the work once needed
          }
          fieldNumber = lowestUnassignedFieldNumber;
        }
        assert fieldNumber >= 0;
        numberToName.put(fieldNumber, fieldName);
        nameToNumber.put(fieldName, fieldNumber);
      }

      if (isSoftDeletesField) {
        if (softDeletesFieldName == null) {
          throw new IllegalArgumentException("this index has [" + fieldName + "] as soft-deletes already but soft-deletes field is not configured in IWC");
        } else if (fieldName.equals(softDeletesFieldName) == false) {
          throw new IllegalArgumentException("cannot configure [" + softDeletesFieldName + "] as soft-deletes; this index uses [" + fieldName + "] as soft-deletes already");
        }
      } else if (fieldName.equals(softDeletesFieldName)) {
        throw new IllegalArgumentException("cannot configure [" + softDeletesFieldName + "] as soft-deletes; this index uses [" + fieldName + "] as non-soft-deletes already");
      }

      return fieldNumber.intValue();
    }

    synchronized void verifyConsistent(Integer number, String name, IndexOptions indexOptions) {
      if (name.equals(numberToName.get(number)) == false) {
        throw new IllegalArgumentException("field number " + number + " is already mapped to field name \"" + numberToName.get(number) + "\", not \"" + name + "\"");
      }
      if (number.equals(nameToNumber.get(name)) == false) {
        throw new IllegalArgumentException("field name \"" + name + "\" is already mapped to field number \"" + nameToNumber.get(name) + "\", not \"" + number + "\"");
      }
      IndexOptions currentIndexOptions = this.indexOptions.get(name);
      if (indexOptions != IndexOptions.NONE && currentIndexOptions != null && currentIndexOptions != IndexOptions.NONE && indexOptions != currentIndexOptions) {
        throw new IllegalArgumentException("cannot change field \"" + name + "\" from index options=" + currentIndexOptions + " to inconsistent index options=" + indexOptions);
      }
    }

    synchronized void verifyConsistent(Integer number, String name, DocValuesType dvType) {
      if (name.equals(numberToName.get(number)) == false) {
        throw new IllegalArgumentException("field number " + number + " is already mapped to field name \"" + numberToName.get(number) + "\", not \"" + name + "\"");
      }
      if (number.equals(nameToNumber.get(name)) == false) {
        throw new IllegalArgumentException("field name \"" + name + "\" is already mapped to field number \"" + nameToNumber.get(name) + "\", not \"" + number + "\"");
      }
      DocValuesType currentDVType = docValuesType.get(name);
      if (dvType != DocValuesType.NONE && currentDVType != null && currentDVType != DocValuesType.NONE && dvType != currentDVType) {
        throw new IllegalArgumentException("cannot change DocValues type from " + currentDVType + " to " + dvType + " for field \"" + name + "\"");
      }
    }

    synchronized void verifyConsistentDimensions(Integer number, String name, int dataDimensionCount, int indexDimensionCount, int dimensionNumBytes) {
      if (name.equals(numberToName.get(number)) == false) {
        throw new IllegalArgumentException("field number " + number + " is already mapped to field name \"" + numberToName.get(number) + "\", not \"" + name + "\"");
      }
      if (number.equals(nameToNumber.get(name)) == false) {
        throw new IllegalArgumentException("field name \"" + name + "\" is already mapped to field number \"" + nameToNumber.get(name) + "\", not \"" + number + "\"");
      }
      FieldDimensions dim = dimensions.get(name);
      if (dim != null) {
        if (dim.dimensionCount != dataDimensionCount) {
          throw new IllegalArgumentException("cannot change point dimension count from " + dim.dimensionCount + " to " + dataDimensionCount + " for field=\"" + name + "\"");
        }
        if (dim.indexDimensionCount != indexDimensionCount) {
          throw new IllegalArgumentException("cannot change point index dimension count from " + dim.indexDimensionCount + " to " + indexDimensionCount + " for field=\"" + name + "\"");
        }
        if (dim.dimensionNumBytes != dimensionNumBytes) {
          throw new IllegalArgumentException("cannot change point numBytes from " + dim.dimensionNumBytes + " to " + dimensionNumBytes + " for field=\"" + name + "\"");
        }
      }
    }

    
Returns true if the fieldName exists in the map and is of the same dvType. /**
     * Returns true if the {@code fieldName} exists in the map and is of the
     * same {@code dvType}.
     */
    synchronized boolean contains(String fieldName, DocValuesType dvType) {
      // used by IndexWriter.updateNumericDocValue
      if (!nameToNumber.containsKey(fieldName)) {
        return false;
      } else {
        // only return true if the field has the same dvType as the requested one
        return dvType == docValuesType.get(fieldName);
      }
    }

    @Deprecated
    synchronized Set<String> getFieldNames() {
      return Collections.unmodifiableSet(new HashSet<>(nameToNumber.keySet()));
    }

    synchronized void clear() {
      numberToName.clear();
      nameToNumber.clear();
      indexOptions.clear();
      docValuesType.clear();
      dimensions.clear();
    }

    synchronized void setIndexOptions(int number, String name, IndexOptions indexOptions) {
      verifyConsistent(number, name, indexOptions);
      this.indexOptions.put(name, indexOptions);
    }

    synchronized void setDocValuesType(int number, String name, DocValuesType dvType) {
      verifyConsistent(number, name, dvType);
      docValuesType.put(name, dvType);
    }

    synchronized void setDimensions(int number, String name, int dimensionCount, int indexDimensionCount, int dimensionNumBytes) {
      if (dimensionCount > PointValues.MAX_DIMENSIONS) {
        throw new IllegalArgumentException("dimensionCount must be <= PointValues.MAX_DIMENSIONS (= " + PointValues.MAX_DIMENSIONS + "); got " + dimensionCount + " for field=\"" + name + "\"");
      }
      if (dimensionNumBytes > PointValues.MAX_NUM_BYTES) {
        throw new IllegalArgumentException("dimension numBytes must be <= PointValues.MAX_NUM_BYTES (= " + PointValues.MAX_NUM_BYTES + "); got " + dimensionNumBytes + " for field=\"" + name + "\"");
      }
      if (indexDimensionCount > dimensionCount) {
        throw new IllegalArgumentException("indexDimensionCount must be <= dimensionCount (= " + dimensionCount + "); got " + indexDimensionCount + " for field=\"" + name + "\"");
      }
      if (indexDimensionCount > PointValues.MAX_INDEX_DIMENSIONS) {
        throw new IllegalArgumentException("indexDimensionCount must be <= PointValues.MAX_INDEX_DIMENSIONS (= " + PointValues.MAX_INDEX_DIMENSIONS + "); got " + indexDimensionCount + " for field=\"" + name + "\"");
      }
      verifyConsistentDimensions(number, name, dimensionCount, indexDimensionCount, dimensionNumBytes);
      dimensions.put(name, new FieldDimensions(dimensionCount, indexDimensionCount, dimensionNumBytes));
    }
  }
  
  static final class Builder {
    private final HashMap<String,FieldInfo> byName = new HashMap<>();
    final FieldNumbers globalFieldNumbers;
    private boolean finished;

    
Creates a new instance with the given FieldNumbers. /**
     * Creates a new instance with the given {@link FieldNumbers}. 
     */
    Builder(FieldNumbers globalFieldNumbers) {
      assert globalFieldNumbers != null;
      this.globalFieldNumbers = globalFieldNumbers;
    }

    public void add(FieldInfos other) {
      assert assertNotFinished();
      for(FieldInfo fieldInfo : other){ 
        add(fieldInfo);
      }
    }

    
Create a new field, or return existing one. /** Create a new field, or return existing one. */
    public FieldInfo getOrAdd(String name) {
      FieldInfo fi = fieldInfo(name);
      if (fi == null) {
        assert assertNotFinished();
        // This field wasn't yet added to this in-RAM
        // segment's FieldInfo, so now we get a global
        // number for this field.  If the field was seen
        // before then we'll get the same name and number,
        // else we'll allocate a new one:
        final boolean isSoftDeletesField = name.equals(globalFieldNumbers.softDeletesFieldName);
        final int fieldNumber = globalFieldNumbers.addOrGet(name, -1, IndexOptions.NONE, DocValuesType.NONE, 0, 0, 0, isSoftDeletesField);
        fi = new FieldInfo(name, fieldNumber, false, false, false, IndexOptions.NONE, DocValuesType.NONE, -1, new HashMap<>(), 0, 0, 0, isSoftDeletesField);
        assert !byName.containsKey(fi.name);
        globalFieldNumbers.verifyConsistent(Integer.valueOf(fi.number), fi.name, DocValuesType.NONE);
        byName.put(fi.name, fi);
      }

      return fi;
    }
   
    private FieldInfo addOrUpdateInternal(String name, int preferredFieldNumber,
                                          boolean storeTermVector,
                                          boolean omitNorms, boolean storePayloads, IndexOptions indexOptions,
                                          DocValuesType docValues, long dvGen,
                                          Map<String, String> attributes,
                                          int dataDimensionCount, int indexDimensionCount, int dimensionNumBytes,
                                          boolean isSoftDeletesField) {
      assert assertNotFinished();
      if (docValues == null) {
        throw new NullPointerException("DocValuesType must not be null");
      }
      if (attributes != null) {
        // original attributes is UnmodifiableMap
        attributes = new HashMap<>(attributes);
      }

      FieldInfo fi = fieldInfo(name);
      if (fi == null) {
        // This field wasn't yet added to this in-RAM
        // segment's FieldInfo, so now we get a global
        // number for this field.  If the field was seen
        // before then we'll get the same name and number,
        // else we'll allocate a new one:
        final int fieldNumber = globalFieldNumbers.addOrGet(name, preferredFieldNumber, indexOptions, docValues, dataDimensionCount, indexDimensionCount, dimensionNumBytes, isSoftDeletesField);
        fi = new FieldInfo(name, fieldNumber, storeTermVector, omitNorms, storePayloads, indexOptions, docValues, dvGen, attributes, dataDimensionCount, indexDimensionCount, dimensionNumBytes, isSoftDeletesField);
        assert !byName.containsKey(fi.name);
        globalFieldNumbers.verifyConsistent(Integer.valueOf(fi.number), fi.name, fi.getDocValuesType());
        byName.put(fi.name, fi);
      } else {
        fi.update(storeTermVector, omitNorms, storePayloads, indexOptions, attributes, dataDimensionCount, indexDimensionCount, dimensionNumBytes);

        if (docValues != DocValuesType.NONE) {
          // Only pay the synchronization cost if fi does not already have a DVType
          boolean updateGlobal = fi.getDocValuesType() == DocValuesType.NONE;
          if (updateGlobal) {
            // Must also update docValuesType map so it's
            // aware of this field's DocValuesType.  This will throw IllegalArgumentException if
            // an illegal type change was attempted.
            globalFieldNumbers.setDocValuesType(fi.number, name, docValues);
          }

          fi.setDocValuesType(docValues); // this will also perform the consistency check.
          fi.setDocValuesGen(dvGen);
        }
      }
      return fi;
    }

    public FieldInfo add(FieldInfo fi) {
      return add(fi, -1);
    }

    public FieldInfo add(FieldInfo fi, long dvGen) {
      // IMPORTANT - reuse the field number if possible for consistent field numbers across segments
      return addOrUpdateInternal(fi.name, fi.number, fi.hasVectors(),
                                 fi.omitsNorms(), fi.hasPayloads(),
                                 fi.getIndexOptions(), fi.getDocValuesType(), dvGen,
                                 fi.attributes(),
                                 fi.getPointDimensionCount(), fi.getPointIndexDimensionCount(), fi.getPointNumBytes(),
                                 fi.isSoftDeletesField());
    }
    
    public FieldInfo fieldInfo(String fieldName) {
      return byName.get(fieldName);
    }

    
Called only from assert /** Called only from assert */
    private boolean assertNotFinished() {
      if (finished) {
        throw new IllegalStateException("FieldInfos.Builder was already finished; cannot add new fields");
      }
      return true;
    }
    
    FieldInfos finish() {
      finished = true;
      return new FieldInfos(byName.values().toArray(new FieldInfo[byName.size()]));
    }
  }
}