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.sql.meta.provider.seqgen;
  
  import java.io.Serializable;
  import org.apache.beam.sdk.extensions.sql.impl.BeamTableStatistics;
  import org.apache.beam.sdk.extensions.sql.meta.SchemaBaseBeamTable;
  import org.apache.beam.sdk.extensions.sql.meta.Table;
  import org.apache.beam.sdk.io.GenerateSequence;
  import org.apache.beam.sdk.options.PipelineOptions;
  import org.apache.beam.sdk.schemas.Schema;
  import org.apache.beam.sdk.schemas.Schema.Field;
  import org.apache.beam.sdk.schemas.Schema.FieldType;
  import org.apache.beam.sdk.transforms.MapElements;
  import org.apache.beam.sdk.values.PBegin;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PCollection.IsBounded;
  import org.apache.beam.sdk.values.POutput;
  import org.apache.beam.sdk.values.Row;
  import org.apache.beam.sdk.values.TypeDescriptor;
  import org.joda.time.Duration;
  import org.joda.time.Instant;
  
  class GenerateSequenceTable extends SchemaBaseBeamTable implements Serializable {
    public static final Schema TABLE_SCHEMA =
        Schema.of(Field.of("sequence", FieldType.INT64), Field.of("event_time", FieldType.DATETIME));
  
    Integer elementsPerSecond = 5;
  
    GenerateSequenceTable(Table table) {
      super(TABLE_SCHEMA);
      if (table.getProperties().has("elementsPerSecond")) {
        elementsPerSecond = table.getProperties().get("elementsPerSecond").asInt();
      }
    }
  
    @Override
    public PCollection.IsBounded isBounded() {
      return IsBounded.UNBOUNDED;
    }
  
    @Override
    public PCollection<Row> buildIOReader(PBegin begin) {
      return begin
          .apply(GenerateSequence.from(0).withRate(elementsPerSecond, Duration.standardSeconds(1)))
          .apply(
              MapElements.into(TypeDescriptor.of(Row.class))
                  .via(elm -> Row.withSchema(TABLE_SCHEMA).addValues(elm, Instant.now()).build()))
          .setRowSchema(getSchema());
    }
  
    @Override
    public BeamTableStatistics getTableStatistics(PipelineOptions options) {
      return BeamTableStatistics.createUnboundedTableStatistics((double) elementsPerSecond);
    }
  
    @Override
    public POutput buildIOWriter(PCollection<Row> input) {
      throw new UnsupportedOperationException("buildIOWriter unsupported!");
    }
  }
  