/*
 * 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.core;

import java.io.IOException;
import java.util.Collection;
import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.transforms.DoFn.WindowedContext;
import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
import org.apache.beam.sdk.util.WindowedValue;
import org.apache.beam.sdk.values.TupleTag;

/**
 * Context for the current execution. This is guaranteed to exist during processing,
 * but does not necessarily persist between different batches of work.
 */
public interface ExecutionContext {
  /**
   * Returns the {@link StepContext} associated with the given step.
   */
  StepContext getOrCreateStepContext(String stepName, String transformName);

  /**
   * Returns a collection view of all of the {@link StepContext}s.
   */
  Collection<? extends StepContext> getAllStepContexts();

  /**
   * Hook for subclasses to implement that will be called whenever
   * {@link WindowedContext#output(TupleTag, Object)} is called.
   */
  void noteOutput(WindowedValue<?> output);

  /**
   * Hook for subclasses to implement that will be called whenever
   * {@link WindowedContext#output(TupleTag, Object)} is called.
   */
  void noteOutput(TupleTag<?> tag, WindowedValue<?> output);

  /**
   * Per-step, per-key context used for retrieving state.
   */
  public interface StepContext {

    /**
     * The name of the step.
     */
    String getStepName();

    /**
     * The name of the transform for the step.
     */
    String getTransformName();

    /**
     * Hook for subclasses to implement that will be called whenever
     * {@link WindowedContext#output}
     * is called.
     */
    void noteOutput(WindowedValue<?> output);

    /**
     * Hook for subclasses to implement that will be called whenever
     * {@link WindowedContext#output}
     * is called.
     */
    void noteOutput(TupleTag<?> tag, WindowedValue<?> output);

    /**
     * Writes the given {@code PCollectionView} data to a globally accessible location.
     */
    <T, W extends BoundedWindow> void writePCollectionViewData(
        TupleTag<?> tag,
        Iterable<WindowedValue<T>> data,
        Coder<Iterable<WindowedValue<T>>> dataCoder,
        W window,
        Coder<W> windowCoder)
            throws IOException;

    StateInternals stateInternals();

    TimerInternals timerInternals();
  }
}