// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
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package com.google.protobuf;

import java.io.IOException;
import java.util.AbstractMap;
import java.util.Map;

Implements the lite version of map entry messages.
This class serves as an utility class to help do serialization/parsing of map entries. It's
used in generated code and also in the full version MapEntry message.
Protobuf internal. Users shouldn't use.
/**
 * Implements the lite version of map entry messages.
 *
 * <p>This class serves as an utility class to help do serialization/parsing of map entries. It's
 * used in generated code and also in the full version MapEntry message.
 *
 * <p>Protobuf internal. Users shouldn't use.
 */
public class MapEntryLite<K, V> {

  static class Metadata<K, V> {
    public final WireFormat.FieldType keyType;
    public final K defaultKey;
    public final WireFormat.FieldType valueType;
    public final V defaultValue;

    public Metadata(
        WireFormat.FieldType keyType,
        K defaultKey,
        WireFormat.FieldType valueType,
        V defaultValue) {
      this.keyType = keyType;
      this.defaultKey = defaultKey;
      this.valueType = valueType;
      this.defaultValue = defaultValue;
    }
  }

  private static final int KEY_FIELD_NUMBER = 1;
  private static final int VALUE_FIELD_NUMBER = 2;

  private final Metadata<K, V> metadata;
  private final K key;
  private final V value;

  
Creates a default MapEntryLite message instance. /** Creates a default MapEntryLite message instance. */
  private MapEntryLite(
      WireFormat.FieldType keyType, K defaultKey, WireFormat.FieldType valueType, V defaultValue) {
    this.metadata = new Metadata<K, V>(keyType, defaultKey, valueType, defaultValue);
    this.key = defaultKey;
    this.value = defaultValue;
  }

  
Creates a new MapEntryLite message. /** Creates a new MapEntryLite message. */
  private MapEntryLite(Metadata<K, V> metadata, K key, V value) {
    this.metadata = metadata;
    this.key = key;
    this.value = value;
  }

  public K getKey() {
    return key;
  }

  public V getValue() {
    return value;
  }

  
Creates a default MapEntryLite message instance.
This method is used by generated code to create the default instance for a map entry
message. The created default instance should be used to create new map entry messages of the
same type. For each map entry message, only one default instance should be created.
/**
   * Creates a default MapEntryLite message instance.
   *
   * <p>This method is used by generated code to create the default instance for a map entry
   * message. The created default instance should be used to create new map entry messages of the
   * same type. For each map entry message, only one default instance should be created.
   */
  public static <K, V> MapEntryLite<K, V> newDefaultInstance(
      WireFormat.FieldType keyType, K defaultKey, WireFormat.FieldType valueType, V defaultValue) {
    return new MapEntryLite<K, V>(keyType, defaultKey, valueType, defaultValue);
  }

  static <K, V> void writeTo(CodedOutputStream output, Metadata<K, V> metadata, K key, V value)
      throws IOException {
    FieldSet.writeElement(output, metadata.keyType, KEY_FIELD_NUMBER, key);
    FieldSet.writeElement(output, metadata.valueType, VALUE_FIELD_NUMBER, value);
  }

  static <K, V> int computeSerializedSize(Metadata<K, V> metadata, K key, V value) {
    return FieldSet.computeElementSize(metadata.keyType, KEY_FIELD_NUMBER, key)
        + FieldSet.computeElementSize(metadata.valueType, VALUE_FIELD_NUMBER, value);
  }

  @SuppressWarnings("unchecked")
  static <T> T parseField(
      CodedInputStream input,
      ExtensionRegistryLite extensionRegistry,
      WireFormat.FieldType type,
      T value)
      throws IOException {
    switch (type) {
      case MESSAGE:
        MessageLite.Builder subBuilder = ((MessageLite) value).toBuilder();
        input.readMessage(subBuilder, extensionRegistry);
        return (T) subBuilder.buildPartial();
      case ENUM:
        return (T) (java.lang.Integer) input.readEnum();
      case GROUP:
        throw new RuntimeException("Groups are not allowed in maps.");
      default:
        return (T) FieldSet.readPrimitiveField(input, type, true);
    }
  }

  
Serializes the provided key and value as though they were wrapped by a MapEntryLite to the output stream. This helper method avoids allocation of a MapEntryLite built with a key and value and is called from generated code directly. /**
   * Serializes the provided key and value as though they were wrapped by a {@link MapEntryLite} to
   * the output stream. This helper method avoids allocation of a {@link MapEntryLite} built with a
   * key and value and is called from generated code directly.
   */
  public void serializeTo(CodedOutputStream output, int fieldNumber, K key, V value)
      throws IOException {
    output.writeTag(fieldNumber, WireFormat.WIRETYPE_LENGTH_DELIMITED);
    output.writeUInt32NoTag(computeSerializedSize(metadata, key, value));
    writeTo(output, metadata, key, value);
  }

  
Computes the message size for the provided key and value as though they were wrapped by a MapEntryLite. This helper method avoids allocation of a MapEntryLite built with a key and value and is called from generated code directly. /**
   * Computes the message size for the provided key and value as though they were wrapped by a
   * {@link MapEntryLite}. This helper method avoids allocation of a {@link MapEntryLite} built with
   * a key and value and is called from generated code directly.
   */
  public int computeMessageSize(int fieldNumber, K key, V value) {
    return CodedOutputStream.computeTagSize(fieldNumber)
        + CodedOutputStream.computeLengthDelimitedFieldSize(
            computeSerializedSize(metadata, key, value));
  }

  
Parses an entry off of the input as a Entry. This helper requires an allocation so using parseInto is preferred if possible. /**
   * Parses an entry off of the input as a {@link Map.Entry}. This helper requires an allocation so
   * using {@link #parseInto} is preferred if possible.
   */
  public Map.Entry<K, V> parseEntry(ByteString bytes, ExtensionRegistryLite extensionRegistry)
      throws IOException {
    return parseEntry(bytes.newCodedInput(), metadata, extensionRegistry);
  }

  static <K, V> Map.Entry<K, V> parseEntry(
      CodedInputStream input, Metadata<K, V> metadata, ExtensionRegistryLite extensionRegistry)
      throws IOException {
    K key = metadata.defaultKey;
    V value = metadata.defaultValue;
    while (true) {
      int tag = input.readTag();
      if (tag == 0) {
        break;
      }
      if (tag == WireFormat.makeTag(KEY_FIELD_NUMBER, metadata.keyType.getWireType())) {
        key = parseField(input, extensionRegistry, metadata.keyType, key);
      } else if (tag == WireFormat.makeTag(VALUE_FIELD_NUMBER, metadata.valueType.getWireType())) {
        value = parseField(input, extensionRegistry, metadata.valueType, value);
      } else {
        if (!input.skipField(tag)) {
          break;
        }
      }
    }
    return new AbstractMap.SimpleImmutableEntry<K, V>(key, value);
  }

  
Parses an entry off of the input into the map. This helper avoids allocaton of a MapEntryLite by parsing directly into the provided MapFieldLite. /**
   * Parses an entry off of the input into the map. This helper avoids allocaton of a {@link
   * MapEntryLite} by parsing directly into the provided {@link MapFieldLite}.
   */
  public void parseInto(
      MapFieldLite<K, V> map, CodedInputStream input, ExtensionRegistryLite extensionRegistry)
      throws IOException {
    int length = input.readRawVarint32();
    final int oldLimit = input.pushLimit(length);
    K key = metadata.defaultKey;
    V value = metadata.defaultValue;

    while (true) {
      int tag = input.readTag();
      if (tag == 0) {
        break;
      }
      if (tag == WireFormat.makeTag(KEY_FIELD_NUMBER, metadata.keyType.getWireType())) {
        key = parseField(input, extensionRegistry, metadata.keyType, key);
      } else if (tag == WireFormat.makeTag(VALUE_FIELD_NUMBER, metadata.valueType.getWireType())) {
        value = parseField(input, extensionRegistry, metadata.valueType, value);
      } else {
        if (!input.skipField(tag)) {
          break;
        }
      }
    }

    input.checkLastTagWas(0);
    input.popLimit(oldLimit);
    map.put(key, value);
  }

  
For experimental runtime internal use only. /** For experimental runtime internal use only. */
  Metadata<K, V> getMetadata() {
    return metadata;
  }
}