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.euphoria.core.translate;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkArgument;
  
  import org.apache.beam.sdk.extensions.euphoria.core.client.operator.Join;
  import org.apache.beam.sdk.extensions.euphoria.core.client.type.TypeAwareness;
  import org.apache.beam.sdk.transforms.windowing.Window;
  import org.apache.beam.sdk.values.KV;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PCollectionList;
  
  abstract class AbstractJoinTranslator<LeftT, RightT, KeyT, OutputT>
      implements OperatorTranslator<Object, KV<KeyT, OutputT>, Join<LeftT, RightT, KeyT, OutputT>> {
  
    @Override
    public PCollection<KV<KeyT, OutputT>> translate(
        Join<LeftT, RightT, KeyT, OutputT> operator, PCollectionList<Object> inputs) {
      checkArgument(inputs.size() == 2, "Join expects exactly two inputs.");
      @SuppressWarnings("unchecked")
      final PCollection<LeftT> left = (PCollection) inputs.get(0);
      @SuppressWarnings("unchecked")
      final PCollection<RightT> right = (PCollection) inputs.get(1);
      PCollection<KV<KeyT, LeftT>> leftKeyed =
          left.apply(
              "extract-keys-left",
              new ExtractKey<>(
                  operator.getLeftKeyExtractor(), TypeAwareness.orObjects(operator.getKeyType())));
      PCollection<KV<KeyT, RightT>> rightKeyed =
          right.apply(
              "extract-keys-right",
              new ExtractKey<>(
                  operator.getRightKeyExtractor(), TypeAwareness.orObjects(operator.getKeyType())));
      // apply windowing if specified
      if (operator.getWindow().isPresent()) {
        @SuppressWarnings("unchecked")
        final Window<KV<KeyT, LeftT>> leftWindow = (Window) operator.getWindow().get();
        leftKeyed = leftKeyed.apply("window-left", leftWindow);
        @SuppressWarnings("unchecked")
        final Window<KV<KeyT, RightT>> rightWindow = (Window) operator.getWindow().get();
        rightKeyed = rightKeyed.apply("window-right", rightWindow);
      }
  
      return translate(operator, left, leftKeyed, right, rightKeyed)
          .setTypeDescriptor(
              operator
                  .getOutputType()
                  .orElseThrow(
                      () -> new IllegalStateException("Unable to infer output type descriptor.")));
    }
  
    abstract PCollection<KV<KeyT, OutputT>> translate(
        Join<LeftT, RightT, KeyT, OutputT> operator,
        PCollection<LeftT> left,
        PCollection<KV<KeyT, LeftT>> leftKeyed,
        PCollection<RightT> right,
        PCollection<KV<KeyT, RightT>> rightKeyed);
  }
  