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package com.google.protobuf.util;

import static com.google.common.base.Preconditions.checkArgument;

import com.google.common.base.CaseFormat;
import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.primitives.Ints;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.protobuf.Descriptors.Descriptor;
import com.google.protobuf.Descriptors.FieldDescriptor;
import com.google.protobuf.FieldMask;
import com.google.protobuf.Internal;
import com.google.protobuf.Message;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

Utility helper functions to work with FieldMask. /**
 * Utility helper functions to work with {@link com.google.protobuf.FieldMask}.
 */
public class FieldMaskUtil {
  private static final String FIELD_PATH_SEPARATOR = ",";
  private static final String FIELD_PATH_SEPARATOR_REGEX = ",";
  private static final String FIELD_SEPARATOR_REGEX = "\\.";

  private FieldMaskUtil() {}

  
Converts a FieldMask to a string.
/**
   * Converts a FieldMask to a string.
   */
  public static String toString(FieldMask fieldMask) {
    // TODO(xiaofeng): Consider using com.google.common.base.Joiner here instead.
    StringBuilder result = new StringBuilder();
    boolean first = true;
    for (String value : fieldMask.getPathsList()) {
      if (value.isEmpty()) {
        // Ignore empty paths.
        continue;
      }
      if (first) {
        first = false;
      } else {
        result.append(FIELD_PATH_SEPARATOR);
      }
      result.append(value);
    }
    return result.toString();
  }

  
Parses from a string to a FieldMask.
/**
   * Parses from a string to a FieldMask.
   */
  public static FieldMask fromString(String value) {
    // TODO(xiaofeng): Consider using com.google.common.base.Splitter here instead.
    return fromStringList(null, Arrays.asList(value.split(FIELD_PATH_SEPARATOR_REGEX)));
  }

  
Parses from a string to a FieldMask and validates all field paths.
Throws:
IllegalArgumentException – if any of the field path is invalid./**
   * Parses from a string to a FieldMask and validates all field paths.
   *
   * @throws IllegalArgumentException if any of the field path is invalid.
   */
  public static FieldMask fromString(Class<? extends Message> type, String value) {
    // TODO(xiaofeng): Consider using com.google.common.base.Splitter here instead.
    return fromStringList(type, Arrays.asList(value.split(FIELD_PATH_SEPARATOR_REGEX)));
  }

  
Constructs a FieldMask for a list of field paths in a certain type.
Throws:
IllegalArgumentException – if any of the field path is not valid./**
   * Constructs a FieldMask for a list of field paths in a certain type.
   *
   * @throws IllegalArgumentException if any of the field path is not valid.
   */
  // TODO(xiaofeng): Consider renaming fromStrings()
  public static FieldMask fromStringList(Class<? extends Message> type, Iterable<String> paths) {
    FieldMask.Builder builder = FieldMask.newBuilder();
    for (String path : paths) {
      if (path.isEmpty()) {
        // Ignore empty field paths.
        continue;
      }
      if (type != null && !isValid(type, path)) {
        throw new IllegalArgumentException(path + " is not a valid path for " + type);
      }
      builder.addPaths(path);
    }
    return builder.build();
  }

  
Constructs a FieldMask from the passed field numbers.
Throws:
IllegalArgumentException – if any of the fields are invalid for the message./**
   * Constructs a FieldMask from the passed field numbers.
   *
   * @throws IllegalArgumentException if any of the fields are invalid for the message.
   */
  public static FieldMask fromFieldNumbers(Class<? extends Message> type, int... fieldNumbers) {
    return fromFieldNumbers(type, Ints.asList(fieldNumbers));
  }

  
Constructs a FieldMask from the passed field numbers.
Throws:
IllegalArgumentException – if any of the fields are invalid for the message./**
   * Constructs a FieldMask from the passed field numbers.
   *
   * @throws IllegalArgumentException if any of the fields are invalid for the message.
   */
  public static FieldMask fromFieldNumbers(
      Class<? extends Message> type, Iterable<Integer> fieldNumbers) {
    Descriptor descriptor = Internal.getDefaultInstance(type).getDescriptorForType();

    FieldMask.Builder builder = FieldMask.newBuilder();
    for (Integer fieldNumber : fieldNumbers) {
      FieldDescriptor field = descriptor.findFieldByNumber(fieldNumber);
      checkArgument(
          field != null,
          String.format("%s is not a valid field number for %s.", fieldNumber, type));
      builder.addPaths(field.getName());
    }
    return builder.build();
  }

  
Converts a field mask to a Proto3 JSON string, that is converting from snake case to camel
case and joining all paths into one string with commas.
/**
   * Converts a field mask to a Proto3 JSON string, that is converting from snake case to camel
   * case and joining all paths into one string with commas.
   */
  public static String toJsonString(FieldMask fieldMask) {
    List<String> paths = new ArrayList<String>(fieldMask.getPathsCount());
    for (String path : fieldMask.getPathsList()) {
      if (path.isEmpty()) {
        continue;
      }
      paths.add(CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, path));
    }
    return Joiner.on(FIELD_PATH_SEPARATOR).join(paths);
  }

  
Converts a field mask from a Proto3 JSON string, that is splitting the paths along commas and
converting from camel case to snake case.
/**
   * Converts a field mask from a Proto3 JSON string, that is splitting the paths along commas and
   * converting from camel case to snake case.
   */
  public static FieldMask fromJsonString(String value) {
    Iterable<String> paths = Splitter.on(FIELD_PATH_SEPARATOR).split(value);
    FieldMask.Builder builder = FieldMask.newBuilder();
    for (String path : paths) {
      if (path.isEmpty()) {
        continue;
      }
      builder.addPaths(CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, path));
    }
    return builder.build();
  }

  
Checks whether paths in a given fields mask are valid.
/**
   * Checks whether paths in a given fields mask are valid.
   */
  public static boolean isValid(Class<? extends Message> type, FieldMask fieldMask) {
    Descriptor descriptor = Internal.getDefaultInstance(type).getDescriptorForType();

    return isValid(descriptor, fieldMask);
  }

  
Checks whether paths in a given fields mask are valid.
/**
   * Checks whether paths in a given fields mask are valid.
   */
  public static boolean isValid(Descriptor descriptor, FieldMask fieldMask) {
    for (String path : fieldMask.getPathsList()) {
      if (!isValid(descriptor, path)) {
        return false;
      }
    }
    return true;
  }

  
Checks whether a given field path is valid.
/**
   * Checks whether a given field path is valid.
   */
  public static boolean isValid(Class<? extends Message> type, String path) {
    Descriptor descriptor = Internal.getDefaultInstance(type).getDescriptorForType();

    return isValid(descriptor, path);
  }

  
Checks whether paths in a given fields mask are valid.
/**
   * Checks whether paths in a given fields mask are valid.
   */
  public static boolean isValid(Descriptor descriptor, String path) {
    String[] parts = path.split(FIELD_SEPARATOR_REGEX);
    if (parts.length == 0) {
      return false;
    }
    for (String name : parts) {
      if (descriptor == null) {
        return false;
      }
      FieldDescriptor field = descriptor.findFieldByName(name);
      if (field == null) {
        return false;
      }
      if (!field.isRepeated() && field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
        descriptor = field.getMessageType();
      } else {
        descriptor = null;
      }
    }
    return true;
  }

  
Converts a FieldMask to its canonical form. In the canonical form of a
FieldMask, all field paths are sorted alphabetically and redundant field
paths are removed.
/**
   * Converts a FieldMask to its canonical form. In the canonical form of a
   * FieldMask, all field paths are sorted alphabetically and redundant field
   * paths are removed.
   */
  public static FieldMask normalize(FieldMask mask) {
    return new FieldMaskTree(mask).toFieldMask();
  }

  
Creates a union of two or more FieldMasks.
/**
   * Creates a union of two or more FieldMasks.
   */
  public static FieldMask union(
      FieldMask firstMask, FieldMask secondMask, FieldMask... otherMasks) {
    FieldMaskTree maskTree = new FieldMaskTree(firstMask).mergeFromFieldMask(secondMask);
    for (FieldMask mask : otherMasks) {
      maskTree.mergeFromFieldMask(mask);
    }
    return maskTree.toFieldMask();
  }

  
Calculates the intersection of two FieldMasks.
/**
   * Calculates the intersection of two FieldMasks.
   */
  public static FieldMask intersection(FieldMask mask1, FieldMask mask2) {
    FieldMaskTree tree = new FieldMaskTree(mask1);
    FieldMaskTree result = new FieldMaskTree();
    for (String path : mask2.getPathsList()) {
      tree.intersectFieldPath(path, result);
    }
    return result.toFieldMask();
  }

  
Options to customize merging behavior.
/**
   * Options to customize merging behavior.
   */
  public static final class MergeOptions {
    private boolean replaceMessageFields = false;
    private boolean replaceRepeatedFields = false;
    // TODO(b/28277137): change the default behavior to always replace primitive fields after
    // fixing all failing TAP tests.
    private boolean replacePrimitiveFields = false;

    
Whether to replace message fields (i.e., discard existing content in
destination message fields).
/**
     * Whether to replace message fields (i.e., discard existing content in
     * destination message fields).
     */
    public boolean replaceMessageFields() {
      return replaceMessageFields;
    }

    
Whether to replace repeated fields (i.e., discard existing content in
destination repeated fields).
/**
     * Whether to replace repeated fields (i.e., discard existing content in
     * destination repeated fields).
     */
    public boolean replaceRepeatedFields() {
      return replaceRepeatedFields;
    }

    
Whether to replace primitive (non-repeated and non-message) fields in
destination message fields with the source primitive fields (i.e., clear
destination field if source field is not set).
/**
     * Whether to replace primitive (non-repeated and non-message) fields in
     * destination message fields with the source primitive fields (i.e., clear
     * destination field if source field is not set).
     */
    public boolean replacePrimitiveFields() {
      return replacePrimitiveFields;
    }

    
Specify whether to replace message fields. Defaults to false.
If true, discard existing content in destination message fields when merging.
If false, merge the source message field into the destination message field.
/**
     * Specify whether to replace message fields. Defaults to false.
     *
     * <p>If true, discard existing content in destination message fields when merging.
     *
     * <p>If false, merge the source message field into the destination message field.
     */
    @CanIgnoreReturnValue
    public MergeOptions setReplaceMessageFields(boolean value) {
      replaceMessageFields = value;
      return this;
    }

    
Specify whether to replace repeated fields. Defaults to false.
If true, discard existing content in destination repeated fields) when merging.
If false, append elements from source repeated field to the destination repeated field.
/**
     * Specify whether to replace repeated fields. Defaults to false.
     *
     * <p>If true, discard existing content in destination repeated fields) when merging.
     *
     * <p>If false, append elements from source repeated field to the destination repeated field.
     */
    @CanIgnoreReturnValue
    public MergeOptions setReplaceRepeatedFields(boolean value) {
      replaceRepeatedFields = value;
      return this;
    }

    
Specify whether to replace primitive (non-repeated and non-message) fields in destination
message fields with the source primitive fields. Defaults to false.
If true, set the value of the destination primitive field to the source primitive field if
the source field is set, but clear the destination field otherwise.
If false, always set the value of the destination primitive field to the source primitive
field, and if the source field is unset, the default value of the source field is copied to
the destination.
/**
     * Specify whether to replace primitive (non-repeated and non-message) fields in destination
     * message fields with the source primitive fields. Defaults to false.
     *
     * <p>If true, set the value of the destination primitive field to the source primitive field if
     * the source field is set, but clear the destination field otherwise.
     *
     * <p>If false, always set the value of the destination primitive field to the source primitive
     * field, and if the source field is unset, the default value of the source field is copied to
     * the destination.
     */
    @CanIgnoreReturnValue
    public MergeOptions setReplacePrimitiveFields(boolean value) {
      replacePrimitiveFields = value;
      return this;
    }
  }

  
Merges fields specified by a FieldMask from one message to another with the specified merge
options. The destination will remain unchanged if an empty FieldMask is provided.
/**
   * Merges fields specified by a FieldMask from one message to another with the specified merge
   * options. The destination will remain unchanged if an empty FieldMask is provided.
   */
  public static void merge(
      FieldMask mask, Message source, Message.Builder destination, MergeOptions options) {
    new FieldMaskTree(mask).merge(source, destination, options);
  }

  
Merges fields specified by a FieldMask from one message to another.
/**
   * Merges fields specified by a FieldMask from one message to another.
   */
  public static void merge(FieldMask mask, Message source, Message.Builder destination) {
    merge(mask, source, destination, new MergeOptions());
  }
}