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: combine-per-key
  //   description: Combine per key example.
  //   multifile: false
  //   context_line: 52
  //   categories:
  //     - Quickstart
  //   complexity: MEDIUM
  //   tags:
  //     - hellobeam
  
  import org.apache.beam.learning.katas.util.Log;
  import org.apache.beam.sdk.Pipeline;
  import org.apache.beam.sdk.options.PipelineOptions;
  import org.apache.beam.sdk.options.PipelineOptionsFactory;
  import org.apache.beam.sdk.transforms.Combine;
  import org.apache.beam.sdk.transforms.Combine.BinaryCombineFn;
  import org.apache.beam.sdk.transforms.Create;
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.PCollection;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.apache.beam.sdk.transforms.DoFn;
  import org.apache.beam.sdk.transforms.ParDo;
  
  public class Task {
  
      private static final Logger LOG = LoggerFactory.getLogger(Task.class);
  
      static final String PLAYER_1 = "Player 1";
      static final String PLAYER_2 = "Player 2";
      static final String PLAYER_3 = "Player 3";
  
      public static void main(String[] args) {
          PipelineOptions options = PipelineOptionsFactory.fromArgs(args).create();
          Pipeline pipeline = Pipeline.create(options);
  
          PCollection<KV<String, Integer>> input =
                  pipeline.apply(
                          Create.of(
                                  KV.of(PLAYER_1, 15), KV.of(PLAYER_2, 10), KV.of(PLAYER_1, 100),
                                  KV.of(PLAYER_3, 25), KV.of(PLAYER_2, 75)
                          ));
  
          PCollection<KV<String, Integer>> output = applyTransform(input);
  
          output.apply(ParDo.of(new LogOutput<>()));
  
          pipeline.run();
      }
  
      static PCollection<KV<String, Integer>> applyTransform(PCollection<KV<String, Integer>> input) {
          return input.apply(Combine.perKey(new SumIntBinaryCombineFn()));
      }
  
      static class SumIntBinaryCombineFn extends BinaryCombineFn<Integer> {
  
          @Override
          public Integer apply(Integer left, Integer right) {
              return left + right;
          }
  
      }
  
      static class LogOutput<T> extends DoFn<T, T> {
          private 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());
          }
      }
  }