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.extensions.ordered;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.util.List;
  import java.util.Objects;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.coders.DefaultCoder;
  import org.apache.beam.sdk.coders.StringUtf8Coder;
  import org.apache.beam.sdk.coders.VarIntCoder;
  import org.apache.beam.sdk.coders.VarLongCoder;
  import org.apache.beam.sdk.extensions.ordered.StringBuilderState.StringBuilderStateCoder;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
  import org.checkerframework.checker.initialization.qual.Initialized;
  import org.checkerframework.checker.nullness.qual.NonNull;
  import org.checkerframework.checker.nullness.qual.UnknownKeyFor;
  
  /**
   * State used for processing test events. Uses StringBuilder to accumulate the output.
   *
   * <p>Can be configured to produce output with certain frequency.
   */
  @DefaultCoder(StringBuilderStateCoder.class)
  class StringBuilderState implements MutableState<String, String> {
  
    public static final String BAD_VALUE = "throw exception if you see me";
  
    private int emissionFrequency = 1;
    private long currentlyEmittedElementNumber;
  
    private final StringBuilder state = new StringBuilder();
  
    StringBuilderState(String initialEvent, int emissionFrequency) {
      this(initialEvent, emissionFrequency, 0L);
    }
  
    StringBuilderState(
        String initialEvent, int emissionFrequency, long currentlyEmittedElementNumber) {
      this.emissionFrequency = emissionFrequency;
      this.currentlyEmittedElementNumber = currentlyEmittedElementNumber;
      try {
        mutate(initialEvent);
      } catch (Exception e) {
        // this shouldn't happen because the input should be pre-validated.
        throw new RuntimeException(e);
      }
    }
  
    @Override
    public void mutate(String event) throws Exception {
      if (event.equals(BAD_VALUE)) {
        throw new Exception("Validation failed");
      }
      state.append(event);
    }
  
    @Override
    public String produceResult() {
      return currentlyEmittedElementNumber++ % emissionFrequency == 0 ? state.toString() : null;
    }
  
    @Override
    public String toString() {
      return state.toString();
    }
  
    @Override
    public boolean equals(Object o) {
      if (this == o) {
        return true;
      }
      if (!(o instanceof StringBuilderState)) {
        return false;
      }
      StringBuilderState that = (StringBuilderState) o;
      return emissionFrequency == that.emissionFrequency
          && currentlyEmittedElementNumber == that.currentlyEmittedElementNumber
          && state.toString().equals(that.state.toString());
    }
  
    @Override
    public int hashCode() {
      return Objects.hash(state);
    }
  
    /** Coder for the StringBuilderState. */
    static class StringBuilderStateCoder extends Coder<StringBuilderState> {
  
      private static final Coder<String> STRING_CODER = StringUtf8Coder.of();
      private static final Coder<Long> LONG_CODER = VarLongCoder.of();
      private static final Coder<Integer> INT_CODER = VarIntCoder.of();
  
      @Override
      public void encode(
          StringBuilderState value, @UnknownKeyFor @NonNull @Initialized OutputStream outStream)
          throws IOException {
        INT_CODER.encode(value.emissionFrequency, outStream);
        LONG_CODER.encode(value.currentlyEmittedElementNumber, outStream);
        STRING_CODER.encode(value.state.toString(), outStream);
      }
  
      @Override
      public StringBuilderState decode(@UnknownKeyFor @NonNull @Initialized InputStream inStream)
          throws IOException {
        int emissionFrequency = INT_CODER.decode(inStream);
        long currentlyEmittedElementNumber = LONG_CODER.decode(inStream);
        String decoded = STRING_CODER.decode(inStream);
        StringBuilderState result =
            new StringBuilderState(decoded, emissionFrequency, currentlyEmittedElementNumber);
        return result;
      }
  
      @Override
      public @UnknownKeyFor @NonNull @Initialized List<
              ? extends
                  @UnknownKeyFor @NonNull @Initialized Coder<@UnknownKeyFor @NonNull @Initialized ?>>
          getCoderArguments() {
        return ImmutableList.of();
      }
  
      @Override
      public void verifyDeterministic() {}
  
      @Override
      public boolean consistentWithEquals() {
        return true;
      }
  
      @Override
      public @UnknownKeyFor @NonNull @Initialized Object structuralValue(StringBuilderState value) {
        return super.structuralValue(value);
      }
    }
  }
  