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.
   */
  
  // beam-playground:
  //   name: CoreTransformsSolution3
  //   description: Core Transforms third motivating challenge.
  //   multifile: false
  //   context_line: 48
  //   categories:
  //     - Quickstart
  //   complexity: BASIC
  //   tags:
  //     - hellobeam
  
  import org.apache.beam.sdk.Pipeline;
  import org.apache.beam.sdk.io.TextIO;
  import org.apache.beam.sdk.options.PipelineOptions;
  import org.apache.beam.sdk.options.PipelineOptionsFactory;
  import org.apache.beam.sdk.transforms.*;
  import org.apache.beam.sdk.values.*;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.apache.beam.sdk.transforms.Flatten;
  
  import java.util.Arrays;
  import java.util.List;
  import java.util.Map;
  
  public class Task {
  
      private static final Logger LOG = LoggerFactory.getLogger(Task.class);
  
      public static void main(String[] args) {
  
          PipelineOptions options = PipelineOptionsFactory.fromArgs(args).create();
          Pipeline pipeline = Pipeline.create(options);
  
          PCollection<String> input = pipeline.apply(TextIO.read().from("gs://apache-beam-samples/shakespeare/kinglear.txt"))
                  .apply(FlatMapElements.into(TypeDescriptors.strings()).via((String line) -> Arrays.asList(line.split("[^\\p{L}]+"))))
                  .apply(Filter.by((String word) -> !word.isEmpty()));
  
          final PTransform<PCollection<String>, PCollection<Iterable<String>>> sample = Sample.fixedSizeGlobally(100);
  
          PCollection<String> limitedPCollection = input.apply(sample).apply(Flatten.iterables());
  
          PCollection<String> countWords = limitedPCollection.apply(new CountWords());
  
          TupleTag<String> wordWithUpperCase = new TupleTag<String>() {
          };
          TupleTag<String> wordWithLowerCase = new TupleTag<String>() {
          };
  
          PCollectionTuple pCollectionTuple = createPCollectionTuple(countWords, wordWithUpperCase, wordWithLowerCase);
  
          PCollection<String> upperCaseWords = pCollectionTuple.get(wordWithUpperCase);
  
          PCollectionView<List<String>> lowerCaseWordsView = createView(pCollectionTuple.get(wordWithLowerCase));
  
          checkExistUpperWordsInLowerCaseView(upperCaseWords,lowerCaseWordsView).apply(ParDo.of(new LogOutput<>()));
  
          pipeline.run();
      }
  
      static class CountWords extends PTransform<PCollection<String>, PCollection<String>> {
          @Override
          public PCollection<String> expand(PCollection<String> input) {
              PCollection<String> wordsStartWithS = input.apply(
                      ParDo.of(new WordsStartWith("i")));
  
              return wordsStartWithS.apply(Count.perElement())
                      .apply(MapElements.into(TypeDescriptors.strings()).via(KV::getKey));
          }
      }
  
      static class WordsStartWith extends DoFn<String, String> {
          String letter;
  
          WordsStartWith(String letter) {
              this.letter = letter;
          }
  
          @ProcessElement
          public void processElement(ProcessContext c) {
              if (c.element().toLowerCase().startsWith(letter)) {
                  c.output(c.element());
              }
          }
      }
  
      static PCollection<String> checkExistUpperWordsInLowerCaseView(PCollection<String> upperCaseWords, PCollectionView<List<String>> lowerCaseWordsView) {
          return upperCaseWords.apply(ParDo.of(new DoFn<String, String>() {
              @ProcessElement
              public void processElement(@Element String word, OutputReceiver<String> out, ProcessContext context) {
                  List<String> upperCaseWords = context.sideInput(lowerCaseWordsView);
                  if (upperCaseWords.contains(word.toLowerCase())) {
                      out.output(word);
                  }
              }
          }).withSideInputs(lowerCaseWordsView));
      }
  
      static PCollectionView<List<String>> createView(PCollection<String> input) {
          return input.apply(View.asList());
      }
  
      static PCollectionTuple createPCollectionTuple(PCollection<String> wordsWithStartS, TupleTag<String> wordWithUpperCase, TupleTag<String> wordWithLowerCase) {
          return wordsWithStartS.apply(ParDo.of(new DoFn<String, String>() {
              @ProcessElement
              public void processElement(@Element String word, MultiOutputReceiver out) {
                  if (word.startsWith("I")) {
                      out.get(wordWithUpperCase).output(word);
                  } else {
                      out.get(wordWithLowerCase).output(word);
                  }
              }
  
          }).withOutputTags(wordWithUpperCase, TupleTagList.of(wordWithLowerCase)));
      }
  
      static class LogOutput<T> extends DoFn<T, T> {
          private final String prefix;
  
          LogOutput() {
              this.prefix = "Processing element";
          }
  
          LogOutput(String prefix) {
              this.prefix = prefix;
          }
  
          @ProcessElement
          public void processElement(ProcessContext c) throws Exception {
              LOG.info(prefix + ": {}", c.element());
          }
      }
  }