// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

package com.google.protobuf;

import java.util.List;
import java.util.Map;

/**
 * Base interface for methods common to {@link Message} and {@link Message.Builder} to provide type
 * equivalency.
 *
 * <p>This interface is intended to only be implemented by protoc created gencode. It is not
 * intended or supported to implement this interface manually.
 *
 * @author jonp@google.com (Jon Perlow)
 */
@CheckReturnValue
public interface MessageOrBuilder extends MessageLiteOrBuilder {

  // (From MessageLite, re-declared here only for return type covariance.)
  @Override
  Message getDefaultInstanceForType();

  /**
   * Returns a list of field paths (e.g. "foo.bar.baz") of required fields which are not set in this
   * message. You should call {@link MessageLiteOrBuilder#isInitialized()} first to check if there
   * are any missing fields, as that method is likely to be much faster than this one even when the
   * message is fully-initialized.
   */
  List<String> findInitializationErrors();

  /**
   * Returns a comma-delimited list of required fields which are not set in this message object. You
   * should call {@link MessageLiteOrBuilder#isInitialized()} first to check if there are any
   * missing fields, as that method is likely to be much faster than this one even when the message
   * is fully-initialized.
   */
  String getInitializationErrorString();

  /**
   * Get the message's type's descriptor. This differs from the {@code getDescriptor()} method of
   * generated message classes in that this method is an abstract method of the {@code Message}
   * interface whereas {@code getDescriptor()} is a static method of a specific class. They return
   * the same thing.
   */
  Descriptors.Descriptor getDescriptorForType();

  /**
   * Returns a collection of all the fields in this message which are set and their corresponding
   * values. A singular ("required" or "optional") field is set iff hasField() returns true for that
   * field. A "repeated" field is set iff getRepeatedFieldCount() is greater than zero. The values
   * are exactly what would be returned by calling {@link #getField(Descriptors.FieldDescriptor)}
   * for each field. The map is guaranteed to be a sorted map, so iterating over it will return
   * fields in order by field number. <br>
   * If this is for a builder, the returned map may or may not reflect future changes to the
   * builder. Either way, the returned map is itself unmodifiable.
   */
  Map<Descriptors.FieldDescriptor, Object> getAllFields();

  /**
   * Returns true if the given oneof is set.
   *
   * @throws IllegalArgumentException if {@code oneof.getContainingType() !=
   *     getDescriptorForType()}.
   */
  boolean hasOneof(Descriptors.OneofDescriptor oneof);

  /** Obtains the FieldDescriptor if the given oneof is set. Returns null if no field is set. */
  Descriptors.FieldDescriptor getOneofFieldDescriptor(Descriptors.OneofDescriptor oneof);

  /**
   * Returns true if the given field is set. This is exactly equivalent to calling the generated
   * "has" accessor method corresponding to the field. The return value of hasField() is
   * semantically meaningful only for fields where field.hasPresence() == true.
   *
   * @throws IllegalArgumentException The field is a repeated field, or {@code
   *     field.getContainingType() != getDescriptorForType()}.
   */
  boolean hasField(Descriptors.FieldDescriptor field);

  /**
   * Obtains the value of the given field, or the default value if it is not set. For primitive
   * fields, the boxed primitive value is returned. For enum fields, the EnumValueDescriptor for the
   * value is returned. For embedded message fields, the sub-message is returned. For repeated
   * fields, a java.util.List is returned.
   */
  Object getField(Descriptors.FieldDescriptor field);

  /**
   * Gets the number of elements of a repeated field. This is exactly equivalent to calling the
   * generated "Count" accessor method corresponding to the field.
   *
   * @throws IllegalArgumentException The field is not a repeated field, or {@code
   *     field.getContainingType() != getDescriptorForType()}.
   */
  int getRepeatedFieldCount(Descriptors.FieldDescriptor field);

  /**
   * Gets an element of a repeated field. For primitive fields, the boxed primitive value is
   * returned. For enum fields, the EnumValueDescriptor for the value is returned. For embedded
   * message fields, the sub-message is returned.
   *
   * @throws IllegalArgumentException The field is not a repeated field, or {@code
   *     field.getContainingType() != getDescriptorForType()}.
   */
  Object getRepeatedField(Descriptors.FieldDescriptor field, int index);

  /** Get the {@link UnknownFieldSet} for this message. */
  UnknownFieldSet getUnknownFields();
}
