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.arrow.flight;
  
  import com.fasterxml.jackson.databind.util.ByteBufferBackedInputStream;
  import com.google.common.collect.ImmutableList;
  import com.google.protobuf.ByteString;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.Channels;
  import java.util.Objects;
  import org.apache.arrow.flight.impl.Flight;
  import org.apache.arrow.vector.ipc.ReadChannel;
  import org.apache.arrow.vector.ipc.WriteChannel;
  import org.apache.arrow.vector.ipc.message.IpcOption;
  import org.apache.arrow.vector.ipc.message.MessageSerializer;
  import org.apache.arrow.vector.types.pojo.Schema;
  import org.apache.arrow.vector.validate.MetadataV4UnionChecker;
  
  /**
   * Opaque result returned after executing a getSchema request.
   *
   * <p>POJO wrapper around the Flight protocol buffer message sharing the same name.
   */
  public class SchemaResult {
  
    private final Schema schema;
    private final IpcOption option;
  
    public SchemaResult(Schema schema) {
      this(schema, IpcOption.DEFAULT);
    }
  
    /** Create a schema result with specific IPC options for serialization. */
    public SchemaResult(Schema schema, IpcOption option) {
      Objects.requireNonNull(schema);
      MetadataV4UnionChecker.checkForUnion(schema.getFields().iterator(), option.metadataVersion);
      this.schema = schema;
      this.option = option;
    }
  
    public Schema getSchema() {
      return schema;
    }
  
    /** Converts to the protocol buffer representation. */
    Flight.SchemaResult toProtocol() {
      // Encode schema in a Message payload
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      try {
        MessageSerializer.serialize(new WriteChannel(Channels.newChannel(baos)), schema, option);
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
      return Flight.SchemaResult.newBuilder()
          .setSchema(ByteString.copyFrom(baos.toByteArray()))
          .build();
    }
  
    /** Converts from the protocol buffer representation. */
    static SchemaResult fromProtocol(Flight.SchemaResult pbSchemaResult) {
      try {
        final ByteBuffer schemaBuf = pbSchemaResult.getSchema().asReadOnlyByteBuffer();
        Schema schema =
            pbSchemaResult.getSchema().size() > 0
                ? MessageSerializer.deserializeSchema(
                    new ReadChannel(Channels.newChannel(new ByteBufferBackedInputStream(schemaBuf))))
                : new Schema(ImmutableList.of());
        return new SchemaResult(schema);
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  }
  