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.io;
  
  import java.nio.ByteBuffer;
  import java.nio.channels.WritableByteChannel;
  import java.nio.charset.StandardCharsets;
  import org.apache.beam.sdk.io.DefaultFilenamePolicy.Params;
  import org.apache.beam.sdk.io.fs.ResolveOptions.StandardResolveOptions;
  import org.apache.beam.sdk.io.fs.ResourceId;
  import org.apache.beam.sdk.options.ValueProvider.StaticValueProvider;
  import org.apache.beam.sdk.util.MimeTypes;
  
  /**
   * A simple {@link FileBasedSink} that writes {@link String} values as lines with header and footer.
   */
  class SimpleSink<DestinationT> extends FileBasedSink<String, DestinationT, String> {
    public SimpleSink(
        ResourceId tempDirectory,
        DynamicDestinations<String, DestinationT, String> dynamicDestinations,
        WritableByteChannelFactory writableByteChannelFactory) {
      super(StaticValueProvider.of(tempDirectory), dynamicDestinations, writableByteChannelFactory);
    }
  
    public SimpleSink(
        ResourceId tempDirectory,
        DynamicDestinations<String, DestinationT, String> dynamicDestinations,
        Compression compression) {
      super(StaticValueProvider.of(tempDirectory), dynamicDestinations, compression);
    }
  
    public static SimpleSink<Void> makeSimpleSink(
        ResourceId tempDirectory, FilenamePolicy filenamePolicy) {
      return new SimpleSink<>(
          tempDirectory, DynamicFileDestinations.constant(filenamePolicy), Compression.UNCOMPRESSED);
    }
  
    public static SimpleSink<Void> makeSimpleSink(
        ResourceId baseDirectory,
        String prefix,
        String shardTemplate,
        String suffix,
        WritableByteChannelFactory writableByteChannelFactory) {
      DynamicDestinations<String, Void, String> dynamicDestinations =
          DynamicFileDestinations.constant(
              DefaultFilenamePolicy.fromParams(
                  new Params()
                      .withBaseFilename(
                          baseDirectory.resolve(prefix, StandardResolveOptions.RESOLVE_FILE))
                      .withShardTemplate(shardTemplate)
                      .withSuffix(suffix)));
      return new SimpleSink<>(baseDirectory, dynamicDestinations, writableByteChannelFactory);
    }
  
    public static SimpleSink<Void> makeSimpleSink(
        ResourceId baseDirectory,
        String prefix,
        String shardTemplate,
        String suffix,
        Compression compression) {
      return makeSimpleSink(
          baseDirectory,
          prefix,
          shardTemplate,
          suffix,
          FileBasedSink.CompressionType.fromCanonical(compression));
    }
  
    @Override
    public SimpleWriteOperation<DestinationT> createWriteOperation() {
      return new SimpleWriteOperation<>(this);
    }
  
    static final class SimpleWriteOperation<DestinationT>
        extends WriteOperation<DestinationT, String> {
      public SimpleWriteOperation(SimpleSink<DestinationT> sink, ResourceId tempOutputDirectory) {
        super(sink, tempOutputDirectory);
      }
  
      public SimpleWriteOperation(SimpleSink<DestinationT> sink) {
        super(sink);
      }
  
      @Override
      public SimpleWriter<DestinationT> createWriter() {
        return new SimpleWriter<>(this);
      }
    }
  
    static final class SimpleWriter<DestinationT> extends Writer<DestinationT, String> {
      static final String HEADER = "header";
      static final String FOOTER = "footer";
  
      private WritableByteChannel channel;
  
      public SimpleWriter(SimpleWriteOperation<DestinationT> writeOperation) {
        super(writeOperation, MimeTypes.TEXT);
      }
  
      private static ByteBuffer wrap(String value) {
        return ByteBuffer.wrap((value + "\n").getBytes(StandardCharsets.UTF_8));
      }
  
      @Override
      protected void prepareWrite(WritableByteChannel channel) {
        this.channel = channel;
      }
  
      @Override
      protected void writeHeader() throws Exception {
        channel.write(wrap(HEADER));
      }
  
      @Override
      protected void writeFooter() throws Exception {
        channel.write(wrap(FOOTER));
      }
  
      @Override
      public void write(String value) throws Exception {
        channel.write(wrap(value));
      }
    }
  }
  