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.grpc;
  
  import io.grpc.Metadata;
  import java.nio.charset.StandardCharsets;
  import java.util.HashSet;
  import java.util.Set;
  import java.util.stream.Collectors;
  import java.util.stream.StreamSupport;
  import org.apache.arrow.flight.CallHeaders;
  
  /**
   * A mutable adapter between the gRPC Metadata object and the Flight headers interface.
   *
   * <p>This allows us to present the headers (metadata) from gRPC without copying to/from our own
   * object.
   */
  public class MetadataAdapter implements CallHeaders {
  
    private final Metadata metadata;
  
    public MetadataAdapter(Metadata metadata) {
      this.metadata = metadata;
    }
  
    @Override
    public String get(String key) {
      return this.metadata.get(Metadata.Key.of(key, Metadata.ASCII_STRING_MARSHALLER));
    }
  
    @Override
    public byte[] getByte(String key) {
      if (key.endsWith(Metadata.BINARY_HEADER_SUFFIX)) {
        return this.metadata.get(Metadata.Key.of(key, Metadata.BINARY_BYTE_MARSHALLER));
      }
      return get(key).getBytes(StandardCharsets.UTF_8);
    }
  
    @Override
    public Iterable<String> getAll(String key) {
      return this.metadata.getAll(Metadata.Key.of(key, Metadata.ASCII_STRING_MARSHALLER));
    }
  
    @Override
    public Iterable<byte[]> getAllByte(String key) {
      if (key.endsWith(Metadata.BINARY_HEADER_SUFFIX)) {
        return this.metadata.getAll(Metadata.Key.of(key, Metadata.BINARY_BYTE_MARSHALLER));
      }
      return StreamSupport.stream(getAll(key).spliterator(), false)
          .map(String::getBytes)
          .collect(Collectors.toList());
    }
  
    @Override
    public void insert(String key, String value) {
      this.metadata.put(Metadata.Key.of(key, Metadata.ASCII_STRING_MARSHALLER), value);
    }
  
    @Override
    public void insert(String key, byte[] value) {
      this.metadata.put(Metadata.Key.of(key, Metadata.BINARY_BYTE_MARSHALLER), value);
    }
  
    @Override
    public Set<String> keys() {
      return new HashSet<>(this.metadata.keys());
    }
  
    @Override
    public boolean containsKey(String key) {
      if (key.endsWith("-bin")) {
        final Metadata.Key<?> grpcKey = Metadata.Key.of(key, Metadata.BINARY_BYTE_MARSHALLER);
        return this.metadata.containsKey(grpcKey);
      }
      final Metadata.Key<?> grpcKey = Metadata.Key.of(key, Metadata.ASCII_STRING_MARSHALLER);
      return this.metadata.containsKey(grpcKey);
    }
  
    @Override
    public String toString() {
      return this.metadata.toString();
    }
  }
  