/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.hc.core5.testing.nio;
  
  import java.io.IOException;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.atomic.AtomicReference;
  
  import org.apache.hc.core5.function.Callback;
  import org.apache.hc.core5.http.nio.command.ShutdownCommand;
  import org.apache.hc.core5.io.CloseMode;
  import org.apache.hc.core5.reactor.IOEventHandlerFactory;
  import org.apache.hc.core5.reactor.IOReactorConfig;
  import org.apache.hc.core5.reactor.IOReactorService;
  import org.apache.hc.core5.reactor.IOReactorStatus;
  import org.apache.hc.core5.reactor.IOSession;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.Asserts;
  import org.apache.hc.core5.util.TimeValue;
  
  abstract class IOReactorExecutor<T extends IOReactorService> implements AutoCloseable {
  
      enum Status { READY, RUNNING, TERMINATED }
  
      private final IOReactorConfig ioReactorConfig;
      private final ThreadFactory workerThreadFactory;
      private final AtomicReference<T> ioReactorRef;
      private final AtomicReference<Status> status;
  
      IOReactorExecutor(final IOReactorConfig ioReactorConfig, final ThreadFactory workerThreadFactory) {
          super();
          this.ioReactorConfig = ioReactorConfig != null ? ioReactorConfig : IOReactorConfig.DEFAULT;
          this.workerThreadFactory = workerThreadFactory;
          this.ioReactorRef = new AtomicReference<>(null);
          this.status = new AtomicReference<>(Status.READY);
      }
  
      abstract T createIOReactor(
              IOEventHandlerFactory ioEventHandlerFactory,
              IOReactorConfig ioReactorConfig,
              ThreadFactory threadFactory,
              Callback<IOSession> sessionShutdownCallback) throws IOException;
  
      protected void execute(final IOEventHandlerFactory ioEventHandlerFactory) throws IOException {
          Args.notNull(ioEventHandlerFactory, "Handler factory");
          if (ioReactorRef.compareAndSet(null, createIOReactor(
                  ioEventHandlerFactory,
                  ioReactorConfig,
                  workerThreadFactory,
                  ShutdownCommand.GRACEFUL_NORMAL_CALLBACK))) {
              if (status.compareAndSet(Status.READY, Status.RUNNING)) {
                  ioReactorRef.get().start();
              }
          } else {
              throw new IllegalStateException("I/O reactor has already been started");
          }
      }
  
      private T ensureRunning() {
          final T ioReactor = ioReactorRef.get();
          Asserts.check(ioReactor != null, "I/O reactor has not been started");
          return ioReactor;
      }
  
      T reactor() {
          return ensureRunning();
      }
  
      public IOReactorStatus getStatus() {
          final T ioReactor = ioReactorRef.get();
          return ioReactor != null ? ioReactor.getStatus() : IOReactorStatus.INACTIVE;
      }
  
      public void awaitShutdown(final TimeValue waitTime) throws InterruptedException {
         Args.notNull(waitTime, "Wait time");
         final T ioReactor = ioReactorRef.get();
         if (ioReactor != null) {
             ioReactor.awaitShutdown(waitTime);
         }
     }
 
     public void initiateShutdown() {
         final T ioReactor = ioReactorRef.get();
         if (ioReactor != null) {
             if (status.compareAndSet(Status.RUNNING, Status.TERMINATED)) {
                 ioReactor.initiateShutdown();
             }
         }
     }
 
     public void shutdown(final TimeValue graceTime) {
         Args.notNull(graceTime, "Grace time");
         final T ioReactor = ioReactorRef.get();
         if (ioReactor != null) {
             if (status.compareAndSet(Status.RUNNING, Status.TERMINATED)) {
                 ioReactor.initiateShutdown();
             }
             try {
                 ioReactor.awaitShutdown(graceTime);
             } catch (final InterruptedException ex) {
                 Thread.currentThread().interrupt();
             }
             ioReactor.close(CloseMode.IMMEDIATE);
         }
     }
 
     @Override
     public void close() throws Exception {
         shutdown(TimeValue.ofSeconds(5));
     }
 
 }