/*
 * 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 org.apache.beam.sdk.nexmark.NexmarkConfiguration;
import org.apache.beam.sdk.nexmark.model.AuctionPrice;
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.Filter;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.values.PCollection;

/**
 * Query 2, 'Filtering. Find bids with specific auction ids and show their bid price. In CQL syntax:
 *
 * <pre>
 * SELECT Rstream(auction, price)
 * FROM Bid [NOW]
 * WHERE auction = 1007 OR auction = 1020 OR auction = 2001 OR auction = 2019 OR auction = 2087;
 * </pre>
 *
 * <p>As written that query will only yield a few hundred results over event streams of arbitrary
 * size. To make it more interesting we instead choose bids for every {@code auctionSkip}'th
 * auction.
 */
public class Query2 extends NexmarkQueryTransform<AuctionPrice> {
  private final int auctionSkip;

  public Query2(NexmarkConfiguration configuration) {
    super("Query2");
    this.auctionSkip = configuration.auctionSkip;
  }

  @Override
  public PCollection<AuctionPrice> expand(PCollection<Event> events) {
    return events
        // Only want the bid events.
        .apply(NexmarkQueryUtil.JUST_BIDS)

        // Select just the bids for the auctions we care about.
        .apply(Filter.by(bid -> bid.auction % this.auctionSkip == 0))

        // Project just auction id and price.
        .apply(
            name + ".Project",
            ParDo.of(
                new DoFn<Bid, AuctionPrice>() {
                  @ProcessElement
                  public void processElement(ProcessContext c) {
                    Bid bid = c.element();
                    c.output(new AuctionPrice(bid.auction, bid.price));
                  }
                }));
  }
}
