content: /*
   * Copyright (C) 2012 Facebook, Inc.
   *
   * Licensed 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 io.airlift.drift.codec.internal;
  
  import com.google.errorprone.annotations.Immutable;
  import io.airlift.drift.codec.ThriftCodec;
  import io.airlift.drift.codec.metadata.ThriftEnumMetadata;
  import io.airlift.drift.codec.metadata.ThriftType;
  import io.airlift.drift.protocol.TProtocolReader;
  import io.airlift.drift.protocol.TProtocolWriter;
  
  import static java.lang.String.format;
  import static java.util.Objects.requireNonNull;
  
  /**
   * EnumThriftCodec is a codec for Java enum types.  An enum is encoded as an I32 in Thrift, and this
   * class handles converting this vale to a Java enum constant.
   */
  @Immutable
  public class EnumThriftCodec<T extends Enum<T>>
          implements ThriftCodec<T>
  {
      private final ThriftType type;
      private final ThriftEnumMetadata<T> enumMetadata;
  
      public EnumThriftCodec(ThriftType type)
      {
          this.type = type;
          enumMetadata = (ThriftEnumMetadata<T>) type.getEnumMetadata();
      }
  
      @Override
      public ThriftType getType()
      {
          return type;
      }
  
      @Override
      public T read(TProtocolReader protocol)
              throws Exception
      {
          int enumValue = protocol.readI32();
          T enumConstant = enumMetadata.getByEnumValue().get(enumValue);
          if (enumConstant != null) {
              return enumConstant;
          }
          return enumMetadata.getUnknownEnumConstant()
                  .orElseThrow(() -> new UnknownEnumValueException(format("Enum %s does not have a constant for value: %s", enumMetadata.getEnumClass().getName(), enumValue)));
      }
  
      @Override
      public void write(T enumConstant, TProtocolWriter protocol)
              throws Exception
      {
          requireNonNull(enumConstant, "enumConstant is null");
          protocol.writeI32(enumMetadata.getByEnumConstant().get(enumConstant));
      }
  }
  