/*
 * 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.Map;
import java.util.Objects;

/**
 * Access to the Field Info file that describes document fields and whether or not they are indexed.
 * Each segment has a separate Field Info file. Objects of this class are thread-safe for multiple
 * readers, but only one thread can be adding documents at a time, with no other reader or writer
 * threads accessing this object.
 */
public final class FieldInfo {
  /** Field's name */
  public final String name;
  /** Internal field number */
  public final int number;

  private DocValuesType docValuesType = DocValuesType.NONE;

  // True if any document indexed term vectors
  private boolean storeTermVector;

  private boolean omitNorms; // omit norms associated with indexed fields

  private final IndexOptions indexOptions;
  private boolean storePayloads; // whether this field stores payloads together with term positions

  private final Map<String, String> attributes;

  private long dvGen;

  /**
   * If both of these are positive it means this field indexed points (see {@link
   * org.apache.lucene.codecs.PointsFormat}).
   */
  private int pointDimensionCount;

  private int pointIndexDimensionCount;
  private int pointNumBytes;

  // if it is a positive value, it means this field indexes vectors
  private final int vectorDimension;
  private final VectorEncoding vectorEncoding;
  private final VectorSimilarityFunction vectorSimilarityFunction;

  // whether this field is used as the soft-deletes field
  private final boolean softDeletesField;

  /**
   * Sole constructor.
   *
   * @lucene.experimental
   */
  public FieldInfo(
      String name,
      int number,
      boolean storeTermVector,
      boolean omitNorms,
      boolean storePayloads,
      IndexOptions indexOptions,
      DocValuesType docValues,
      long dvGen,
      Map<String, String> attributes,
      int pointDimensionCount,
      int pointIndexDimensionCount,
      int pointNumBytes,
      int vectorDimension,
      VectorEncoding vectorEncoding,
      VectorSimilarityFunction vectorSimilarityFunction,
      boolean softDeletesField) {
    this.name = Objects.requireNonNull(name);
    this.number = number;
    this.docValuesType =
        Objects.requireNonNull(
            docValues, "DocValuesType must not be null (field: \"" + name + "\")");
    this.indexOptions =
        Objects.requireNonNull(
            indexOptions, "IndexOptions must not be null (field: \"" + name + "\")");
    if (indexOptions != IndexOptions.NONE) {
      this.storeTermVector = storeTermVector;
      this.storePayloads = storePayloads;
      this.omitNorms = omitNorms;
    } else { // for non-indexed fields, leave defaults
      this.storeTermVector = false;
      this.storePayloads = false;
      this.omitNorms = false;
    }
    this.dvGen = dvGen;
    this.attributes = Objects.requireNonNull(attributes);
    this.pointDimensionCount = pointDimensionCount;
    this.pointIndexDimensionCount = pointIndexDimensionCount;
    this.pointNumBytes = pointNumBytes;
    this.vectorDimension = vectorDimension;
    this.vectorEncoding = vectorEncoding;
    this.vectorSimilarityFunction = vectorSimilarityFunction;
    this.softDeletesField = softDeletesField;
    this.checkConsistency();
  }

  /**
   * Check correctness of the FieldInfo options
   *
   * @throws IllegalArgumentException if some options are incorrect
   */
  public void checkConsistency() {
    if (indexOptions == null) {
      throw new IllegalArgumentException("IndexOptions must not be null (field: '" + name + "')");
    }
    if (indexOptions != IndexOptions.NONE) {
      // Cannot store payloads unless positions are indexed:
      if (indexOptions.compareTo(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS) < 0 && storePayloads) {
        throw new IllegalArgumentException(
            "indexed field '" + name + "' cannot have payloads without positions");
      }
    } else {
      if (storeTermVector) {
        throw new IllegalArgumentException(
            "non-indexed field '" + name + "' cannot store term vectors");
      }
      if (storePayloads) {
        throw new IllegalArgumentException(
            "non-indexed field '" + name + "' cannot store payloads");
      }
      if (omitNorms) {
        throw new IllegalArgumentException("non-indexed field '" + name + "' cannot omit norms");
      }
    }

    if (docValuesType == null) {
      throw new IllegalArgumentException("DocValuesType must not be null (field: '" + name + "')");
    }
    if (dvGen != -1 && docValuesType == DocValuesType.NONE) {
      throw new IllegalArgumentException(
          "field '"
              + name
              + "' cannot have a docvalues update generation without having docvalues");
    }

    if (pointDimensionCount < 0) {
      throw new IllegalArgumentException(
          "pointDimensionCount must be >= 0; got "
              + pointDimensionCount
              + " (field: '"
              + name
              + "')");
    }
    if (pointIndexDimensionCount < 0) {
      throw new IllegalArgumentException(
          "pointIndexDimensionCount must be >= 0; got "
              + pointIndexDimensionCount
              + " (field: '"
              + name
              + "')");
    }
    if (pointNumBytes < 0) {
      throw new IllegalArgumentException(
          "pointNumBytes must be >= 0; got " + pointNumBytes + " (field: '" + name + "')");
    }

    if (pointDimensionCount != 0 && pointNumBytes == 0) {
      throw new IllegalArgumentException(
          "pointNumBytes must be > 0 when pointDimensionCount="
              + pointDimensionCount
              + " (field: '"
              + name
              + "')");
    }
    if (pointIndexDimensionCount != 0 && pointDimensionCount == 0) {
      throw new IllegalArgumentException(
          "pointIndexDimensionCount must be 0 when pointDimensionCount=0"
              + " (field: '"
              + name
              + "')");
    }
    if (pointNumBytes != 0 && pointDimensionCount == 0) {
      throw new IllegalArgumentException(
          "pointDimensionCount must be > 0 when pointNumBytes="
              + pointNumBytes
              + " (field: '"
              + name
              + "')");
    }

    if (vectorSimilarityFunction == null) {
      throw new IllegalArgumentException(
          "Vector similarity function must not be null (field: '" + name + "')");
    }
    if (vectorDimension < 0) {
      throw new IllegalArgumentException(
          "vectorDimension must be >=0; got " + vectorDimension + " (field: '" + name + "')");
    }
  }

  /**
   * Verify that the provided FieldInfo has the same schema as this FieldInfo
   *
   * @param o – other FieldInfo whose schema is verified against this FieldInfo's schema
   * @throws IllegalArgumentException if the field schemas are not the same
   */
  void verifySameSchema(FieldInfo o, boolean strictlyConsistent) {
    String fieldName = this.name;
    verifySameIndexOptions(fieldName, this.indexOptions, o.getIndexOptions(), strictlyConsistent);
    if (this.indexOptions != IndexOptions.NONE) {
      verifySameOmitNorms(fieldName, this.omitNorms, o.omitNorms, strictlyConsistent);
      verifySameStoreTermVectors(
          fieldName, this.storeTermVector, o.storeTermVector, strictlyConsistent);
    }
    verifySameDocValuesType(fieldName, this.docValuesType, o.docValuesType, strictlyConsistent);
    verifySamePointsOptions(
        fieldName,
        this.pointDimensionCount,
        this.pointIndexDimensionCount,
        this.pointNumBytes,
        o.pointDimensionCount,
        o.pointIndexDimensionCount,
        o.pointNumBytes,
        strictlyConsistent);
    verifySameVectorOptions(
        fieldName,
        this.vectorDimension,
        this.vectorEncoding,
        this.vectorSimilarityFunction,
        o.vectorDimension,
        o.vectorEncoding,
        o.vectorSimilarityFunction);
  }

  /**
   * Verify that the provided index options are the same
   *
   * @throws IllegalArgumentException if they are not the same
   */
  static void verifySameIndexOptions(
      String fieldName,
      IndexOptions indexOptions1,
      IndexOptions indexOptions2,
      boolean strictlyConsistent) {
    if (strictlyConsistent == false
        && (indexOptions1 == IndexOptions.NONE || indexOptions2 == IndexOptions.NONE)) {
      return;
    }
    if (indexOptions1 != indexOptions2) {
      throw new IllegalArgumentException(
          "cannot change field \""
              + fieldName
              + "\" from index options="
              + indexOptions1
              + " to inconsistent index options="
              + indexOptions2);
    }
  }

  /**
   * Verify that the provided docValues type are the same
   *
   * @throws IllegalArgumentException if they are not the same
   */
  static void verifySameDocValuesType(
      String fieldName,
      DocValuesType docValuesType1,
      DocValuesType docValuesType2,
      boolean strictlyConsistent) {
    if (strictlyConsistent == false
        && (docValuesType1 == DocValuesType.NONE || docValuesType2 == DocValuesType.NONE)) {
      return;
    }
    if (docValuesType1 != docValuesType2) {
      throw new IllegalArgumentException(
          "cannot change field \""
              + fieldName
              + "\" from doc values type="
              + docValuesType1
              + " to inconsistent doc values type="
              + docValuesType2);
    }
  }

  /**
   * Verify that the provided store term vectors options are the same
   *
   * @throws IllegalArgumentException if they are not the same
   */
  static void verifySameStoreTermVectors(
      String fieldName,
      boolean storeTermVector1,
      boolean storeTermVector2,
      boolean strictlyConsistent) {
    if (strictlyConsistent && storeTermVector1 != storeTermVector2) {
      throw new IllegalArgumentException(
          "cannot change field \""
              + fieldName
              + "\" from storeTermVector="
              + storeTermVector1
              + " to inconsistent storeTermVector="
              + storeTermVector2);
    }
  }

  /**
   * Verify that the provided omitNorms are the same
   *
   * @throws IllegalArgumentException if they are not the same
   */
  static void verifySameOmitNorms(
      String fieldName, boolean omitNorms1, boolean omitNorms2, boolean strictlyConsistent) {
    if (strictlyConsistent && omitNorms1 != omitNorms2) {
      throw new IllegalArgumentException(
          "cannot change field \""
              + fieldName
              + "\" from omitNorms="
              + omitNorms1
              + " to inconsistent omitNorms="
              + omitNorms2);
    }
  }

  /**
   * Verify that the provided points indexing options are the same
   *
   * @throws IllegalArgumentException if they are not the same
   */
  static void verifySamePointsOptions(
      String fieldName,
      int pointDimensionCount1,
      int indexDimensionCount1,
      int numBytes1,
      int pointDimensionCount2,
      int indexDimensionCount2,
      int numBytes2,
      boolean strictlyConsistent) {
    if (strictlyConsistent == false && (pointDimensionCount1 == 0 || pointDimensionCount2 == 0)) {
      return;
    }
    if (pointDimensionCount1 != pointDimensionCount2
        || indexDimensionCount1 != indexDimensionCount2
        || numBytes1 != numBytes2) {
      throw new IllegalArgumentException(
          "cannot change field \""
              + fieldName
              + "\" from points dimensionCount="
              + pointDimensionCount1
              + ", indexDimensionCount="
              + indexDimensionCount1
              + ", numBytes="
              + numBytes1
              + " to inconsistent dimensionCount="
              + pointDimensionCount2
              + ", indexDimensionCount="
              + indexDimensionCount2
              + ", numBytes="
              + numBytes2);
    }
  }

  /**
   * Verify that the provided vector indexing options are the same
   *
   * @throws IllegalArgumentException if they are not the same
   */
  static void verifySameVectorOptions(
      String fieldName,
      int vd1,
      VectorEncoding ve1,
      VectorSimilarityFunction vsf1,
      int vd2,
      VectorEncoding ve2,
      VectorSimilarityFunction vsf2) {
    if (vd1 != vd2 || vsf1 != vsf2 || ve1 != ve2) {
      throw new IllegalArgumentException(
          "cannot change field \""
              + fieldName
              + "\" from vector dimension="
              + vd1
              + ", vector encoding="
              + ve1
              + ", vector similarity function="
              + vsf1
              + " to inconsistent vector dimension="
              + vd2
              + ", vector encoding="
              + ve2
              + ", vector similarity function="
              + vsf2);
    }
  }

  /*
  This method will create a new instance of FieldInfo if any attribute changes (and it changes in a compatible way).
  It is intended only to be used in indices where schema validation is not strict (legacy indices). It will return null
  if no changes are done on this FieldInfo
   */
  FieldInfo handleLegacySupportedUpdates(FieldInfo otherFi) {
    IndexOptions newIndexOptions = this.indexOptions;
    boolean newStoreTermVector = this.storeTermVector;
    boolean newOmitNorms = this.omitNorms;
    boolean newStorePayloads = this.storePayloads;
    DocValuesType newDocValues = this.docValuesType;
    int newPointDimensionCount = this.pointDimensionCount;
    int newPointNumBytes = this.pointNumBytes;
    int newPointIndexDimensionCount = this.pointIndexDimensionCount;
    long newDvGen = this.dvGen;

    boolean fieldInfoChanges = false;
    // System.out.println("FI.update field=" + name + " indexed=" + indexed + " omitNorms=" +
    // omitNorms + " this.omitNorms=" + this.omitNorms);
    if (this.indexOptions != otherFi.indexOptions) {
      if (this.indexOptions == IndexOptions.NONE) {
        newIndexOptions = otherFi.indexOptions;
        fieldInfoChanges = true;
      } else if (otherFi.indexOptions != IndexOptions.NONE) {
        throw new IllegalArgumentException(
            "cannot change field \""
                + name
                + "\" from index options="
                + this.indexOptions
                + " to inconsistent index options="
                + otherFi.indexOptions);
      }
    }

    if (this.pointDimensionCount != otherFi.pointDimensionCount
        && otherFi.pointDimensionCount != 0) {
      if (this.pointDimensionCount == 0) {
        fieldInfoChanges = true;
        newPointDimensionCount = otherFi.pointDimensionCount;
      } else {
        throw new IllegalArgumentException(
            "cannot change field \""
                + name
                + "\" from points dimensionCount="
                + this.pointDimensionCount
                + " to inconsistent dimensionCount="
                + otherFi.pointDimensionCount);
      }
    }

    if (this.pointIndexDimensionCount != otherFi.pointIndexDimensionCount
        && otherFi.pointIndexDimensionCount != 0) {
      if (this.pointIndexDimensionCount == 0) {
        fieldInfoChanges = true;
        newPointIndexDimensionCount = otherFi.pointIndexDimensionCount;
      } else {
        throw new IllegalArgumentException(
            "cannot change field \""
                + name
                + "\" from points indexDimensionCount="
                + this.pointIndexDimensionCount
                + " to inconsistent indexDimensionCount="
                + otherFi.pointIndexDimensionCount);
      }
    }

    if (this.pointNumBytes != otherFi.pointNumBytes && otherFi.pointNumBytes != 0) {
      if (this.pointNumBytes == 0) {
        fieldInfoChanges = true;
        newPointNumBytes = otherFi.pointNumBytes;
      } else {
        throw new IllegalArgumentException(
            "cannot change field \""
                + name
                + "\" from points numBytes="
                + this.pointNumBytes
                + " to inconsistent numBytes="
                + otherFi.pointNumBytes);
      }
    }

    if (newIndexOptions
        != IndexOptions.NONE) { // if updated field data is not for indexing, leave the updates out
      if (this.storeTermVector != otherFi.storeTermVector && this.storeTermVector == false) {
        fieldInfoChanges = true;
        newStoreTermVector = true; // once vector, always vector
      }
      if (this.storePayloads != otherFi.storePayloads
          && this.storePayloads == false
          && newIndexOptions.compareTo(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS) >= 0) {
        fieldInfoChanges = true;
        newStorePayloads = true;
      }

      // Awkward: only drop norms if incoming update is indexed:
      if (otherFi.indexOptions != IndexOptions.NONE
          && this.omitNorms != otherFi.omitNorms
          && this.omitNorms == false) {
        fieldInfoChanges = true;
        newOmitNorms = true; // if one require omitNorms at least once, it remains off for life
      }
    }

    if (otherFi.docValuesType != DocValuesType.NONE
        && otherFi.docValuesType != this.docValuesType) {
      if (this.docValuesType == DocValuesType.NONE) {
        fieldInfoChanges = true;
        newDocValues = otherFi.docValuesType;
        newDvGen = otherFi.dvGen;
      } else {
        throw new IllegalArgumentException(
            "cannot change DocValues type from "
                + docValuesType
                + " to "
                + otherFi.docValuesType
                + " for field \""
                + name
                + "\"");
      }
    }

    if (!fieldInfoChanges) {
      return null;
    }
    return new FieldInfo(
        this.name,
        this.number,
        newStoreTermVector,
        newOmitNorms,
        newStorePayloads,
        newIndexOptions,
        newDocValues,
        newDvGen,
        this.attributes, // attributes don't need to be handled here because they are handled for
        // the non-legacy case in FieldInfos
        newPointDimensionCount,
        newPointIndexDimensionCount,
        newPointNumBytes,
        this.vectorDimension,
        this.vectorEncoding,
        this.vectorSimilarityFunction,
        this.softDeletesField);
  }

  /**
   * Record that this field is indexed with points, with the specified number of dimensions and
   * bytes per dimension.
   */
  public void setPointDimensions(int dimensionCount, int indexDimensionCount, int numBytes) {
    if (dimensionCount <= 0) {
      throw new IllegalArgumentException(
          "point dimension count must be >= 0; got "
              + dimensionCount
              + " for field=\""
              + name
              + "\"");
    }
    if (indexDimensionCount > PointValues.MAX_INDEX_DIMENSIONS) {
      throw new IllegalArgumentException(
          "point index dimension count must be < PointValues.MAX_INDEX_DIMENSIONS (= "
              + PointValues.MAX_INDEX_DIMENSIONS
              + "); got "
              + indexDimensionCount
              + " for field=\""
              + name
              + "\"");
    }
    if (indexDimensionCount > dimensionCount) {
      throw new IllegalArgumentException(
          "point index dimension count must be <= point dimension count (= "
              + dimensionCount
              + "); got "
              + indexDimensionCount
              + " for field=\""
              + name
              + "\"");
    }
    if (numBytes <= 0) {
      throw new IllegalArgumentException(
          "point numBytes must be >= 0; got " + numBytes + " for field=\"" + name + "\"");
    }
    if (numBytes > PointValues.MAX_NUM_BYTES) {
      throw new IllegalArgumentException(
          "point numBytes must be <= PointValues.MAX_NUM_BYTES (= "
              + PointValues.MAX_NUM_BYTES
              + "); got "
              + numBytes
              + " for field=\""
              + name
              + "\"");
    }
    if (pointDimensionCount != 0 && pointDimensionCount != dimensionCount) {
      throw new IllegalArgumentException(
          "cannot change point dimension count from "
              + pointDimensionCount
              + " to "
              + dimensionCount
              + " for field=\""
              + name
              + "\"");
    }
    if (pointIndexDimensionCount != 0 && pointIndexDimensionCount != indexDimensionCount) {
      throw new IllegalArgumentException(
          "cannot change point index dimension count from "
              + pointIndexDimensionCount
              + " to "
              + indexDimensionCount
              + " for field=\""
              + name
              + "\"");
    }
    if (pointNumBytes != 0 && pointNumBytes != numBytes) {
      throw new IllegalArgumentException(
          "cannot change point numBytes from "
              + pointNumBytes
              + " to "
              + numBytes
              + " for field=\""
              + name
              + "\"");
    }

    pointDimensionCount = dimensionCount;
    pointIndexDimensionCount = indexDimensionCount;
    pointNumBytes = numBytes;

    this.checkConsistency();
  }

  /** Return point data dimension count */
  public int getPointDimensionCount() {
    return pointDimensionCount;
  }

  /** Return point data dimension count */
  public int getPointIndexDimensionCount() {
    return pointIndexDimensionCount;
  }

  /** Return number of bytes per dimension */
  public int getPointNumBytes() {
    return pointNumBytes;
  }

  /** Returns the number of dimensions of the vector value */
  public int getVectorDimension() {
    return vectorDimension;
  }

  /** Returns the number of dimensions of the vector value */
  public VectorEncoding getVectorEncoding() {
    return vectorEncoding;
  }

  /** Returns {@link VectorSimilarityFunction} for the field */
  public VectorSimilarityFunction getVectorSimilarityFunction() {
    return vectorSimilarityFunction;
  }

  /** Record that this field is indexed with docvalues, with the specified type */
  public void setDocValuesType(DocValuesType type) {
    if (type == null) {
      throw new NullPointerException("DocValuesType must not be null (field: \"" + name + "\")");
    }
    if (docValuesType != DocValuesType.NONE
        && type != DocValuesType.NONE
        && docValuesType != type) {
      throw new IllegalArgumentException(
          "cannot change DocValues type from "
              + docValuesType
              + " to "
              + type
              + " for field \""
              + name
              + "\"");
    }
    docValuesType = type;
    this.checkConsistency();
  }

  /** Returns IndexOptions for the field, or IndexOptions.NONE if the field is not indexed */
  public IndexOptions getIndexOptions() {
    return indexOptions;
  }

  /**
   * Returns name of this field
   *
   * @return name
   */
  public String getName() {
    return name;
  }

  /**
   * Returns the field number
   *
   * @return field number
   */
  public int getFieldNumber() {
    return number;
  }

  /**
   * Returns {@link DocValuesType} of the docValues; this is {@code DocValuesType.NONE} if the field
   * has no docvalues.
   */
  public DocValuesType getDocValuesType() {
    return docValuesType;
  }

  /** Sets the docValues generation of this field. */
  void setDocValuesGen(long dvGen) {
    this.dvGen = dvGen;
    this.checkConsistency();
  }

  /** Returns the docValues generation of this field, or -1 if no docValues updates exist for it. */
  public long getDocValuesGen() {
    return dvGen;
  }

  void setStoreTermVectors() {
    storeTermVector = true;
    this.checkConsistency();
  }

  void setStorePayloads() {
    if (indexOptions.compareTo(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS) >= 0) {
      storePayloads = true;
    }
    this.checkConsistency();
  }

  /** Returns true if norms are explicitly omitted for this field */
  public boolean omitsNorms() {
    return omitNorms;
  }

  /** Omit norms for this field. */
  public void setOmitsNorms() {
    if (indexOptions == IndexOptions.NONE) {
      throw new IllegalStateException("cannot omit norms: this field is not indexed");
    }
    omitNorms = true;
    this.checkConsistency();
  }

  /** Returns true if this field actually has any norms. */
  public boolean hasNorms() {
    return indexOptions != IndexOptions.NONE && omitNorms == false;
  }

  /** Returns true if any payloads exist for this field. */
  public boolean hasPayloads() {
    return storePayloads;
  }

  /** Returns true if any term vectors exist for this field. */
  public boolean hasVectors() {
    return storeTermVector;
  }

  /** Returns whether any (numeric) vector values exist for this field */
  public boolean hasVectorValues() {
    return vectorDimension > 0;
  }

  /** Get a codec attribute value, or null if it does not exist */
  public String getAttribute(String key) {
    return attributes.get(key);
  }

  /**
   * Puts a codec attribute value.
   *
   * <p>This is a key-value mapping for the field that the codec can use to store additional
   * metadata, and will be available to the codec when reading the segment via {@link
   * #getAttribute(String)}
   *
   * <p>If a value already exists for the key in the field, it will be replaced with the new value.
   * If the value of the attributes for a same field is changed between the documents, the behaviour
   * after merge is undefined.
   */
  public String putAttribute(String key, String value) {
    return attributes.put(key, value);
  }

  /** Returns internal codec attributes map. */
  public Map<String, String> attributes() {
    return attributes;
  }

  /**
   * Returns true if this field is configured and used as the soft-deletes field. See {@link
   * IndexWriterConfig#softDeletesField}
   */
  public boolean isSoftDeletesField() {
    return softDeletesField;
  }
}
