/**
 * 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.tez.runtime.library.shuffle.common;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.hadoop.classification.InterfaceAudience.Private;
import org.apache.tez.runtime.library.common.InputAttemptIdentifier;

@Private
public abstract class FetchedInput {
  
  public static enum Type {
    WAIT, // TODO NEWTEZ Implement this, only if required.
    MEMORY,
    DISK,
  }
  
  protected static enum State {
    PENDING, COMMITTED, ABORTED, FREED
  }

  private static AtomicInteger ID_GEN = new AtomicInteger(0);

  protected InputAttemptIdentifier inputAttemptIdentifier;
  protected final long actualSize;
  protected final long compressedSize;
  protected final Type type;
  protected final FetchedInputCallback callback;
  protected final int id;
  protected State state;

  public FetchedInput(Type type, long actualSize, long compressedSize,
      InputAttemptIdentifier inputAttemptIdentifier,
      FetchedInputCallback callbackHandler) {
    this.type = type;
    this.actualSize = actualSize;
    this.compressedSize = compressedSize;
    this.inputAttemptIdentifier = inputAttemptIdentifier;
    this.callback = callbackHandler;
    this.id = ID_GEN.getAndIncrement();
    this.state = State.PENDING;
  }

  public Type getType() {
    return this.type;
  }

  public long getActualSize() {
    return this.actualSize;
  }
  
  public long getCompressedSize() {
    return this.compressedSize;
  }

  public InputAttemptIdentifier getInputAttemptIdentifier() {
    return this.inputAttemptIdentifier;
  }

  /**
   * Inform the Allocator about a committed resource.
   * This should be called by commit
   */
  public void notifyFetchComplete() {
    this.callback.fetchComplete(this);
  }
  
  /**
   * Inform the Allocator about a failed resource.
   * This should be called by abort
   */
  public void notifyFetchFailure() {
    this.callback.fetchFailed(this);
  }
  
  /**
   * Inform the Allocator about a completed resource being released.
   * This should be called by free
   */
  public void notifyFreedResource() {
    this.callback.freeResources(this);
  }
  
  /**
   * Returns the output stream to be used to write fetched data. Users are
   * expected to close the OutputStream when they're done
   */
  public abstract OutputStream getOutputStream() throws IOException;

  /**
   * Return an input stream to be used to read the previously fetched data.
   * Users are expected to close the InputStream when they're done
   */
  public abstract InputStream getInputStream() throws IOException;

  /**
   * Commit the output. Should be idempotent
   */
  public abstract void commit() throws IOException;

  /**
   * Abort the output. Should be idempotent
   */
  public abstract void abort() throws IOException;

  /**
   * Called when this input has been consumed, so that resources can be
   * reclaimed.
   */
  public abstract void free();
  
  @Override
  public int hashCode() {
    return id;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj)
      return true;
    if (obj == null)
      return false;
    if (getClass() != obj.getClass())
      return false;
    FetchedInput other = (FetchedInput) obj;
    if (id != other.id)
      return false;
    return true;
  }
}