/*
 * 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.runners.dataflow.worker;

import static com.google.api.client.util.Base64.decodeBase64;
import static org.apache.beam.runners.dataflow.util.Structs.getBoolean;
import static org.apache.beam.runners.dataflow.util.Structs.getString;
import static org.apache.beam.vendor.guava.v20_0.com.google.common.base.Preconditions.checkArgument;

import com.google.auto.service.AutoService;
import java.util.Map;
import javax.annotation.Nullable;
import org.apache.beam.runners.dataflow.DataflowRunner;
import org.apache.beam.runners.dataflow.options.DataflowPipelineDebugOptions;
import org.apache.beam.runners.dataflow.util.CloudObject;
import org.apache.beam.runners.dataflow.util.PropertyNames;
import org.apache.beam.runners.dataflow.worker.util.WorkerPropertyNames;
import org.apache.beam.runners.dataflow.worker.util.common.worker.NativeReader;
import org.apache.beam.runners.dataflow.worker.util.common.worker.ShuffleReadCounterFactory;
import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.util.WindowedValue;
import org.apache.beam.sdk.values.KV;
import org.apache.beam.vendor.guava.v20_0.com.google.common.collect.ImmutableMap;

/** Creates a GroupingShuffleReader from a CloudObject spec. */
public class GroupingShuffleReaderFactory implements ReaderFactory {

  /** A {@link ReaderFactory.Registrar} for grouping shuffle sources. */
  @AutoService(ReaderFactory.Registrar.class)
  public static class Registrar implements ReaderFactory.Registrar {

    @Override
    public Map<String, ReaderFactory> factories() {
      return ImmutableMap.of("GroupingShuffleSource", new GroupingShuffleReaderFactory());
    }
  }

  // Findbugs does not correctly understand inheritance + nullability.
  //
  // options may be null due to parent class signature, and must be checked, despite not
  // being nullable here
  @Override
  public NativeReader<?> create(
      CloudObject spec,
      @Nullable Coder<?> coder,
      PipelineOptions options,
      @Nullable DataflowExecutionContext executionContext,
      DataflowOperationContext operationContext)
      throws Exception {

    checkArgument(options != null, "options must not be null");
    @SuppressWarnings({"rawtypes", "unchecked"})
    Coder<WindowedValue<KV<Object, Iterable<Object>>>> typedCoder = (Coder) coder;
    return createTyped(spec, typedCoder, options, executionContext, operationContext);
  }

  public <K, V> GroupingShuffleReader<K, V> createTyped(
      CloudObject spec,
      @Nullable Coder<WindowedValue<KV<K, Iterable<V>>>> coder,
      PipelineOptions options,
      @Nullable DataflowExecutionContext executionContext,
      DataflowOperationContext operationContext)
      throws Exception {
    if (shouldUseGroupingShuffleReaderWithFaultyBytesReadCounter(options)) {
      return new GroupingShuffleReaderWithFaultyBytesReadCounter<K, V>(
          options,
          decodeBase64(getString(spec, WorkerPropertyNames.SHUFFLE_READER_CONFIG)),
          getString(spec, WorkerPropertyNames.START_SHUFFLE_POSITION, null),
          getString(spec, WorkerPropertyNames.END_SHUFFLE_POSITION, null),
          coder,
          (BatchModeExecutionContext) executionContext,
          operationContext,
          getBoolean(spec, PropertyNames.SORT_VALUES, false));
    }

    return new GroupingShuffleReader<K, V>(
        options,
        decodeBase64(getString(spec, WorkerPropertyNames.SHUFFLE_READER_CONFIG)),
        getString(spec, WorkerPropertyNames.START_SHUFFLE_POSITION, null),
        getString(spec, WorkerPropertyNames.END_SHUFFLE_POSITION, null),
        coder,
        (BatchModeExecutionContext) executionContext,
        operationContext,
        ShuffleReadCounterFactory.INSTANCE,
        getBoolean(spec, PropertyNames.SORT_VALUES, false));
  }

  /** Returns true if we should inject errors in the shuffle read bytes counter for testing. */
  private static boolean shouldUseGroupingShuffleReaderWithFaultyBytesReadCounter(
      PipelineOptions options) {
    return DataflowRunner.hasExperiment(
        options.as(DataflowPipelineDebugOptions.class), "inject_shuffle_read_count_error");
  }
}