/*
 * Licensed 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.dag.app;


import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import com.google.protobuf.Message;
import org.apache.hadoop.service.AbstractService;
import org.apache.tez.service.TezTestServiceProtocolBlockingPB;
import org.apache.tez.service.impl.TezTestServiceProtocolClientImpl;
import org.apache.tez.test.service.rpc.TezTestServiceProtocolProtos.RunContainerRequestProto;
import org.apache.tez.test.service.rpc.TezTestServiceProtocolProtos.RunContainerResponseProto;
import org.apache.tez.test.service.rpc.TezTestServiceProtocolProtos.SubmitWorkRequestProto;
import org.apache.tez.test.service.rpc.TezTestServiceProtocolProtos.SubmitWorkResponseProto;

public class TezTestServiceCommunicator extends AbstractService {

  private final ConcurrentMap<String, TezTestServiceProtocolBlockingPB> hostProxies;
  private final ListeningExecutorService executor;

  // TODO Convert this into a singleton
  public TezTestServiceCommunicator(int numThreads) {
    super(TezTestServiceCommunicator.class.getSimpleName());
    ExecutorService localExecutor = Executors.newFixedThreadPool(numThreads,
        new ThreadFactoryBuilder().setNameFormat("TezTestServiceCommunicator #%2d").build());
    this.hostProxies = new ConcurrentHashMap<String, TezTestServiceProtocolBlockingPB>();
    executor = MoreExecutors.listeningDecorator(localExecutor);
  }

  @Override
  public void serviceStop() {
    executor.shutdownNow();
  }


  public void runContainer(RunContainerRequestProto request, String host, int port,
                           final ExecuteRequestCallback<RunContainerResponseProto> callback) {
    ListenableFuture<RunContainerResponseProto> future = executor.submit(new RunContainerCallable(request, host, port));
    Futures.addCallback(future, new FutureCallback<RunContainerResponseProto>() {
      @Override
      public void onSuccess(RunContainerResponseProto result) {
        callback.setResponse(result);
      }

      @Override
      public void onFailure(Throwable t) {
        callback.indicateError(t);
      }
    });

  }

  public void submitWork(SubmitWorkRequestProto request, String host, int port,
                         final ExecuteRequestCallback<SubmitWorkResponseProto> callback) {
    ListenableFuture<SubmitWorkResponseProto> future = executor.submit(new SubmitWorkCallable(request, host, port));
    Futures.addCallback(future, new FutureCallback<SubmitWorkResponseProto>() {
      @Override
      public void onSuccess(SubmitWorkResponseProto result) {
        callback.setResponse(result);
      }

      @Override
      public void onFailure(Throwable t) {
        callback.indicateError(t);
      }
    });

  }


  private class RunContainerCallable implements Callable<RunContainerResponseProto> {

    final String hostname;
    final int port;
    final RunContainerRequestProto request;

    private RunContainerCallable(RunContainerRequestProto request, String hostname, int port) {
      this.hostname = hostname;
          this.port = port;
      this.request = request;
    }

    @Override
    public RunContainerResponseProto call() throws Exception {
      return getProxy(hostname, port).runContainer(null, request);
    }
  }

  private class SubmitWorkCallable implements Callable<SubmitWorkResponseProto> {
    final String hostname;
    final int port;
    final SubmitWorkRequestProto request;

    private SubmitWorkCallable(SubmitWorkRequestProto request, String hostname, int port) {
      this.hostname = hostname;
      this.port = port;
      this.request = request;
    }

    @Override
    public SubmitWorkResponseProto call() throws Exception {
      return getProxy(hostname, port).submitWork(null, request);
    }
  }

  public interface ExecuteRequestCallback<T extends Message> {
    void setResponse(T response);
    void indicateError(Throwable t);
  }

  private TezTestServiceProtocolBlockingPB getProxy(String hostname, int port) {
    String hostId = getHostIdentifier(hostname, port);

    TezTestServiceProtocolBlockingPB proxy = hostProxies.get(hostId);
    if (proxy == null) {
      proxy = new TezTestServiceProtocolClientImpl(getConfig(), hostname, port);
      TezTestServiceProtocolBlockingPB proxyOld = hostProxies.putIfAbsent(hostId, proxy);
      if (proxyOld != null) {
        // TODO Shutdown the new proxy.
        proxy = proxyOld;
      }
    }
    return proxy;
  }

  private String getHostIdentifier(String hostname, int port) {
    return hostname + ":" + port;
  }
}