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.examples.twitterstreamgenerator;
  
  import java.util.ArrayList;
  import java.util.List;
  import org.apache.beam.sdk.transforms.Create;
  import org.apache.beam.sdk.transforms.PTransform;
  import org.apache.beam.sdk.transforms.ParDo;
  import org.apache.beam.sdk.values.PBegin;
  import org.apache.beam.sdk.values.PCollection;
  
  /**
   * An unbounded source for <a
   * href="https://developer.twitter.com/en/docs/tutorials/consuming-streaming-data">twitter</a>
   * stream. PTransforms for streaming live tweets from twitter. Reading from Twitter is supported by
   * read()
   *
   * <p>Standard Twitter API can be read using a list of Twitter Config
   * readStandardStream(List<TwitterConfig>)
   *
   * <p>It allow multiple Twitter configurations to demonstrate how multiple twitter streams can be
   * combined in a single pipeline.
   *
   * <pre>{@code
   * PCollection<WeatherRecord> weatherData = pipeline.apply(
   *      TwitterIO.readStandardStream(
   *          Arrays.asList(
   *                  new TwitterConfig.Builder()
   *                      .setKey("")
   *                      .setSecret("")
   *                      .setToken("")
   *                      .setTokenSecret("")
   *                      .setFilters(Arrays.asList("", ""))
   *                      .setLanguage("en")
   *                      .setTweetsCount(10L)
   *                      .setMinutesToRun(1)
   *                      .build())));
   * }</pre>
   */
  public class TwitterIO {
  
    /**
     * Initializes the stream by converting input to a Twitter connection configuration.
     *
     * @param twitterConfigs list of twitter config
     * @return PTransform of statuses
     */
    public static PTransform<PBegin, PCollection<String>> readStandardStream(
        List<TwitterConfig> twitterConfigs) {
      return new TwitterIO.Read.Builder().setTwitterConfig(twitterConfigs).build();
    }
  
    /** A {@link PTransform} to read from Twitter stream. usage and configuration. */
    private static class Read extends PTransform<PBegin, PCollection<String>> {
      private final List<TwitterConfig> twitterConfigs;
  
      private Read(Builder builder) {
        this.twitterConfigs = builder.twitterConfigs;
      }
  
      @Override
      public PCollection<String> expand(PBegin input) throws IllegalArgumentException {
        return input.apply(Create.of(this.twitterConfigs)).apply(ParDo.of(new ReadFromTwitterDoFn()));
      }
  
      private static class Builder {
        List<TwitterConfig> twitterConfigs = new ArrayList<>();
  
        TwitterIO.Read.Builder setTwitterConfig(final List<TwitterConfig> twitterConfigs) {
          this.twitterConfigs = twitterConfigs;
          return this;
        }
  
        TwitterIO.Read build() {
          return new TwitterIO.Read(this);
        }
      }
    }
  }
  