/*
 * 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.nexmark.queries;

import static org.apache.beam.vendor.guava.v20_0.com.google.common.base.Preconditions.checkState;

import java.util.Map;
import org.apache.beam.sdk.nexmark.NexmarkConfiguration;
import org.apache.beam.sdk.nexmark.model.Bid;
import org.apache.beam.sdk.nexmark.model.Event;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.transforms.View;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PCollectionView;

/**
 * Query that joins a stream to a bounded side input, modeling basic stream enrichment.
 *
 * <pre>
 * SELECT bid.*, sideInput.*
 * FROM bid, sideInput
 * WHERE bid.id = sideInput.id
 * </pre>
 */
public class BoundedSideInputJoin extends NexmarkQueryTransform<Bid> {
  private final NexmarkConfiguration configuration;

  public BoundedSideInputJoin(NexmarkConfiguration configuration) {
    super("BoundedSideInputJoin");
    this.configuration = configuration;
  }

  @Override
  public boolean needsSideInput() {
    return true;
  }

  @Override
  public PCollection<Bid> expand(PCollection<Event> events) {

    checkState(getSideInput() != null, "Configuration error: side input is null");

    final PCollectionView<Map<Long, String>> sideInputMap = getSideInput().apply(View.asMap());

    return events
        // Only want the bid events; easier to fake some side input data
        .apply(NexmarkQueryUtil.JUST_BIDS)

        // Map the conversion function over all bids.
        .apply(
            name + ".JoinToFiles",
            ParDo.of(
                    new DoFn<Bid, Bid>() {
                      @ProcessElement
                      public void processElement(ProcessContext c) {
                        Bid bid = c.element();
                        c.output(
                            new Bid(
                                bid.auction,
                                bid.bidder,
                                bid.price,
                                bid.dateTime,
                                c.sideInput(sideInputMap)
                                    .get(bid.bidder % configuration.sideInputRowCount)));
                      }
                    })
                .withSideInputs(sideInputMap));
  }
}