content: /*
   * 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.beam.sdk.extensions.protobuf;
  
  import static org.apache.beam.sdk.schemas.transforms.Cast.castRow;
  import static org.apache.beam.sdk.util.Preconditions.checkArgumentNotNull;
  
  import com.google.auto.service.AutoService;
  import com.google.protobuf.Message;
  import java.util.Map;
  import javax.annotation.Nonnull;
  import org.apache.beam.sdk.annotations.Internal;
  import org.apache.beam.sdk.schemas.Schema;
  import org.apache.beam.sdk.schemas.io.payloads.PayloadSerializer;
  import org.apache.beam.sdk.schemas.io.payloads.PayloadSerializerProvider;
  import org.apache.beam.sdk.transforms.SimpleFunction;
  import org.apache.beam.sdk.values.Row;
  import org.apache.beam.sdk.values.TypeDescriptor;
  
  @Internal
  @AutoService(PayloadSerializerProvider.class)
  public class ProtoPayloadSerializerProvider implements PayloadSerializerProvider {
    @Override
    public String identifier() {
      return "proto";
    }
  
    private static Class<? extends Message> getClass(Map<String, Object> tableParams) {
      String protoClassName = checkArgumentNotNull(tableParams.get("protoClass")).toString();
      try {
        Class<?> protoClass = Class.forName(protoClassName);
        return protoClass.asSubclass(Message.class);
      } catch (ClassNotFoundException e) {
        throw new IllegalArgumentException("Incorrect proto class provided: " + protoClassName, e);
      }
    }
  
    private static <T extends Message> void inferAndVerifySchema(
        Class<T> protoClass, Schema requiredSchema) {
      @Nonnull
      Schema inferredSchema =
          checkArgumentNotNull(new ProtoMessageSchema().schemaFor(TypeDescriptor.of(protoClass)));
      if (!inferredSchema.assignableTo(requiredSchema)) {
        throw new IllegalArgumentException(
            String.format(
                "Given message schema: '%s'%n"
                    + "does not match schema inferred from protobuf class.%n"
                    + "Protobuf class: '%s'%n"
                    + "Inferred schema: '%s'",
                requiredSchema, protoClass.getName(), inferredSchema));
      }
    }
  
    @Override
    public PayloadSerializer getSerializer(Schema schema, Map<String, Object> tableParams) {
      Class<? extends Message> protoClass = getClass(tableParams);
      inferAndVerifySchema(protoClass, schema);
      SimpleFunction<byte[], Row> toRowFn = ProtoMessageSchema.getProtoBytesToRowFn(protoClass);
      return PayloadSerializer.of(
          ProtoMessageSchema.getRowToProtoBytesFn(protoClass),
          bytes -> {
            Row rawRow = toRowFn.apply(bytes);
            return castRow(rawRow, rawRow.getSchema(), schema);
          });
    }
  }
  