/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.bootstrap;
  
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ChannelHandler;
  import io.netty.channel.ChannelOption;
  import io.netty.channel.ChannelPromise;
  import io.netty.channel.DefaultChannelPromise;
  import io.netty.channel.EventLoop;
  import io.netty.channel.EventLoopGroup;
  import io.netty.channel.ReflectiveChannelFactory;
  import io.netty.util.AttributeKey;
  import io.netty.util.concurrent.EventExecutor;
  import io.netty.util.concurrent.GlobalEventExecutor;
  import io.netty.util.internal.ObjectUtil;
  import io.netty.util.internal.SocketUtils;
  import io.netty.util.internal.StringUtil;
  import io.netty.util.internal.logging.InternalLogger;
  
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  import java.net.SocketAddress;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  
  /**
   * {@link AbstractBootstrap} is a helper class that makes it easy to bootstrap a {@link Channel}. It support
   * method-chaining to provide an easy way to configure the {@link AbstractBootstrap}.
   *
   * <p>When not used in a {@link ServerBootstrap} context, the {@link #bind()} methods are useful for connectionless
   * transports such as datagram (UDP).</p>
   */
  public abstract class AbstractBootstrap<B extends AbstractBootstrap<B, C>, C extends Channel> implements Cloneable {
      @SuppressWarnings("unchecked")
      private static final Map.Entry<ChannelOption<?>, Object>[] EMPTY_OPTION_ARRAY = new Map.Entry[0];
      @SuppressWarnings("unchecked")
      private static final Map.Entry<AttributeKey<?>, Object>[] EMPTY_ATTRIBUTE_ARRAY = new Map.Entry[0];
  
      volatile EventLoopGroup group;
      @SuppressWarnings("deprecation")
      private volatile ChannelFactory<? extends C> channelFactory;
      private volatile SocketAddress localAddress;
  
      // The order in which ChannelOptions are applied is important they may depend on each other for validation
      // purposes.
      private final Map<ChannelOption<?>, Object> options = new LinkedHashMap<ChannelOption<?>, Object>();
      private final Map<AttributeKey<?>, Object> attrs = new ConcurrentHashMap<AttributeKey<?>, Object>();
      private volatile ChannelHandler handler;
      private volatile ClassLoader extensionsClassLoader;
  
      AbstractBootstrap() {
          // Disallow extending from a different package.
      }
  
      AbstractBootstrap(AbstractBootstrap<B, C> bootstrap) {
          group = bootstrap.group;
          channelFactory = bootstrap.channelFactory;
          handler = bootstrap.handler;
          localAddress = bootstrap.localAddress;
          synchronized (bootstrap.options) {
              options.putAll(bootstrap.options);
          }
          attrs.putAll(bootstrap.attrs);
          extensionsClassLoader = bootstrap.extensionsClassLoader;
      }
  
      /**
       * The {@link EventLoopGroup} which is used to handle all the events for the to-be-created
       * {@link Channel}
       */
      public B group(EventLoopGroup group) {
          ObjectUtil.checkNotNull(group, "group");
          if (this.group != null) {
              throw new IllegalStateException("group set already");
          }
          this.group = group;
          return self();
      }
 
     @SuppressWarnings("unchecked")
     private B self() {
         return (B) this;
     }
 
     /**
      * The {@link Class} which is used to create {@link Channel} instances from.
      * You either use this or {@link #channelFactory(io.netty.channel.ChannelFactory)} if your
      * {@link Channel} implementation has no no-args constructor.
      */
     public B channel(Class<? extends C> channelClass) {
         return channelFactory(new ReflectiveChannelFactory<C>(
                 ObjectUtil.checkNotNull(channelClass, "channelClass")
         ));
     }
 
     /**
      * @deprecated Use {@link #channelFactory(io.netty.channel.ChannelFactory)} instead.
      */
     @Deprecated
     public B channelFactory(ChannelFactory<? extends C> channelFactory) {
         ObjectUtil.checkNotNull(channelFactory, "channelFactory");
         if (this.channelFactory != null) {
             throw new IllegalStateException("channelFactory set already");
         }
 
         this.channelFactory = channelFactory;
         return self();
     }
 
     /**
      * {@link io.netty.channel.ChannelFactory} which is used to create {@link Channel} instances from
      * when calling {@link #bind()}. This method is usually only used if {@link #channel(Class)}
      * is not working for you because of some more complex needs. If your {@link Channel} implementation
      * has a no-args constructor, its highly recommend to just use {@link #channel(Class)} to
      * simplify your code.
      */
     @SuppressWarnings({ "unchecked", "deprecation" })
     public B channelFactory(io.netty.channel.ChannelFactory<? extends C> channelFactory) {
         return channelFactory((ChannelFactory<C>) channelFactory);
     }
 
     /**
      * The {@link SocketAddress} which is used to bind the local "end" to.
      */
     public B localAddress(SocketAddress localAddress) {
         this.localAddress = localAddress;
         return self();
     }
 
     /**
      * @see #localAddress(SocketAddress)
      */
     public B localAddress(int inetPort) {
         return localAddress(new InetSocketAddress(inetPort));
     }
 
     /**
      * @see #localAddress(SocketAddress)
      */
     public B localAddress(String inetHost, int inetPort) {
         return localAddress(SocketUtils.socketAddress(inetHost, inetPort));
     }
 
     /**
      * @see #localAddress(SocketAddress)
      */
     public B localAddress(InetAddress inetHost, int inetPort) {
         return localAddress(new InetSocketAddress(inetHost, inetPort));
     }
 
     /**
      * Allow to specify a {@link ChannelOption} which is used for the {@link Channel} instances once they got
      * created. Use a value of {@code null} to remove a previous set {@link ChannelOption}.
      */
     public <T> B option(ChannelOption<T> option, T value) {
         ObjectUtil.checkNotNull(option, "option");
         synchronized (options) {
             if (value == null) {
                 options.remove(option);
             } else {
                 options.put(option, value);
             }
         }
         return self();
     }
 
     /**
      * Allow to specify an initial attribute of the newly created {@link Channel}.  If the {@code value} is
      * {@code null}, the attribute of the specified {@code key} is removed.
      */
     public <T> B attr(AttributeKey<T> key, T value) {
         ObjectUtil.checkNotNull(key, "key");
         if (value == null) {
             attrs.remove(key);
         } else {
             attrs.put(key, value);
         }
         return self();
     }
 
     /**
      * Load {@link ChannelInitializerExtension}s using the given class loader.
      * <p>
      * By default, the extensions will be loaded by the same class loader that loaded this bootstrap class.
      *
      * @param classLoader The class loader to use for loading {@link ChannelInitializerExtension}s.
      * @return This bootstrap.
      */
     public B extensionsClassLoader(ClassLoader classLoader) {
         extensionsClassLoader = classLoader;
         return self();
     }
 
     /**
      * Validate all the parameters. Sub-classes may override this, but should
      * call the super method in that case.
      */
     public B validate() {
         if (group == null) {
             throw new IllegalStateException("group not set");
         }
         if (channelFactory == null) {
             throw new IllegalStateException("channel or channelFactory not set");
         }
         return self();
     }
 
     /**
      * Returns a deep clone of this bootstrap which has the identical configuration.  This method is useful when making
      * multiple {@link Channel}s with similar settings.  Please note that this method does not clone the
      * {@link EventLoopGroup} deeply but shallowly, making the group a shared resource.
      */
     @Override
     @SuppressWarnings("CloneDoesntDeclareCloneNotSupportedException")
     public abstract B clone();
 
     /**
      * Create a new {@link Channel} and register it with an {@link EventLoop}.
      */
     public ChannelFuture register() {
         validate();
         return initAndRegister();
     }
 
     /**
      * Create a new {@link Channel} and bind it.
      */
     public ChannelFuture bind() {
         validate();
         SocketAddress localAddress = this.localAddress;
         if (localAddress == null) {
             throw new IllegalStateException("localAddress not set");
         }
         return doBind(localAddress);
     }
 
     /**
      * Create a new {@link Channel} and bind it.
      */
     public ChannelFuture bind(int inetPort) {
         return bind(new InetSocketAddress(inetPort));
     }
 
     /**
      * Create a new {@link Channel} and bind it.
      */
     public ChannelFuture bind(String inetHost, int inetPort) {
         return bind(SocketUtils.socketAddress(inetHost, inetPort));
     }
 
     /**
      * Create a new {@link Channel} and bind it.
      */
     public ChannelFuture bind(InetAddress inetHost, int inetPort) {
         return bind(new InetSocketAddress(inetHost, inetPort));
     }
 
     /**
      * Create a new {@link Channel} and bind it.
      */
     public ChannelFuture bind(SocketAddress localAddress) {
         validate();
         return doBind(ObjectUtil.checkNotNull(localAddress, "localAddress"));
     }
 
     private ChannelFuture doBind(final SocketAddress localAddress) {
         final ChannelFuture regFuture = initAndRegister();
         final Channel channel = regFuture.channel();
         if (regFuture.cause() != null) {
             return regFuture;
         }
 
         if (regFuture.isDone()) {
             // At this point we know that the registration was complete and successful.
             ChannelPromise promise = channel.newPromise();
             doBind0(regFuture, channel, localAddress, promise);
             return promise;
         } else {
             // Registration future is almost always fulfilled already, but just in case it's not.
             final PendingRegistrationPromise promise = new PendingRegistrationPromise(channel);
             regFuture.addListener(new ChannelFutureListener() {
                 @Override
                 public void operationComplete(ChannelFuture future) throws Exception {
                     Throwable cause = future.cause();
                     if (cause != null) {
                         // Registration on the EventLoop failed so fail the ChannelPromise directly to not cause an
                         // IllegalStateException once we try to access the EventLoop of the Channel.
                         promise.setFailure(cause);
                     } else {
                         // Registration was successful, so set the correct executor to use.
                         // See https://github.com/netty/netty/issues/2586
                         promise.registered();
 
                         doBind0(regFuture, channel, localAddress, promise);
                     }
                 }
             });
             return promise;
         }
     }
 
     final ChannelFuture initAndRegister() {
         Channel channel = null;
         try {
             channel = channelFactory.newChannel();
             init(channel);
         } catch (Throwable t) {
             if (channel != null) {
                 // channel can be null if newChannel crashed (eg SocketException("too many open files"))
                 channel.unsafe().closeForcibly();
                 // as the Channel is not registered yet we need to force the usage of the GlobalEventExecutor
                 return new DefaultChannelPromise(channel, GlobalEventExecutor.INSTANCE).setFailure(t);
             }
             // as the Channel is not registered yet we need to force the usage of the GlobalEventExecutor
             return new DefaultChannelPromise(new FailedChannel(), GlobalEventExecutor.INSTANCE).setFailure(t);
         }
 
         final ChannelFuture regFuture = config().group().register(channel);
         if (regFuture.cause() != null) {
             if (channel.isRegistered()) {
                 channel.close();
             } else {
                 channel.unsafe().closeForcibly();
             }
         }
 
         // If we are here and the promise is not failed, it's one of the following cases:
         // 1) If we attempted registration from the event loop, the registration has been completed at this point.
         //    i.e. It's safe to attempt bind() or connect() now because the channel has been registered.
         // 2) If we attempted registration from the other thread, the registration request has been successfully
         //    added to the event loop's task queue for later execution.
         //    i.e. It's safe to attempt bind() or connect() now:
         //         because bind() or connect() will be executed *after* the scheduled registration task is executed
         //         because register(), bind(), and connect() are all bound to the same thread.
 
         return regFuture;
     }
 
     abstract void init(Channel channel) throws Exception;
 
     Collection<ChannelInitializerExtension> getInitializerExtensions() {
         ClassLoader loader = extensionsClassLoader;
         if (loader == null) {
             loader = getClass().getClassLoader();
         }
         return ChannelInitializerExtensions.getExtensions().extensions(loader);
     }
 
     private static void doBind0(
             final ChannelFuture regFuture, final Channel channel,
             final SocketAddress localAddress, final ChannelPromise promise) {
 
         // This method is invoked before channelRegistered() is triggered.  Give user handlers a chance to set up
         // the pipeline in its channelRegistered() implementation.
         channel.eventLoop().execute(new Runnable() {
             @Override
             public void run() {
                 if (regFuture.isSuccess()) {
                     channel.bind(localAddress, promise).addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
                 } else {
                     promise.setFailure(regFuture.cause());
                 }
             }
         });
     }
 
     /**
      * the {@link ChannelHandler} to use for serving the requests.
      */
     public B handler(ChannelHandler handler) {
         this.handler = ObjectUtil.checkNotNull(handler, "handler");
         return self();
     }
 
     /**
      * Returns the configured {@link EventLoopGroup} or {@code null} if non is configured yet.
      *
      * @deprecated Use {@link #config()} instead.
      */
     @Deprecated
     public final EventLoopGroup group() {
         return group;
     }
 
     /**
      * Returns the {@link AbstractBootstrapConfig} object that can be used to obtain the current config
      * of the bootstrap.
      */
     public abstract AbstractBootstrapConfig<B, C> config();
 
     final Map.Entry<ChannelOption<?>, Object>[] newOptionsArray() {
         return newOptionsArray(options);
     }
 
     static Map.Entry<ChannelOption<?>, Object>[] newOptionsArray(Map<ChannelOption<?>, Object> options) {
         synchronized (options) {
             return new LinkedHashMap<ChannelOption<?>, Object>(options).entrySet().toArray(EMPTY_OPTION_ARRAY);
         }
     }
 
     final Map.Entry<AttributeKey<?>, Object>[] newAttributesArray() {
         return newAttributesArray(attrs0());
     }
 
     static Map.Entry<AttributeKey<?>, Object>[] newAttributesArray(Map<AttributeKey<?>, Object> attributes) {
         return attributes.entrySet().toArray(EMPTY_ATTRIBUTE_ARRAY);
     }
 
     final Map<ChannelOption<?>, Object> options0() {
         return options;
     }
 
     final Map<AttributeKey<?>, Object> attrs0() {
         return attrs;
     }
 
     final SocketAddress localAddress() {
         return localAddress;
     }
 
     @SuppressWarnings("deprecation")
     final ChannelFactory<? extends C> channelFactory() {
         return channelFactory;
     }
 
     final ChannelHandler handler() {
         return handler;
     }
 
     final Map<ChannelOption<?>, Object> options() {
         synchronized (options) {
             return copiedMap(options);
         }
     }
 
     final Map<AttributeKey<?>, Object> attrs() {
         return copiedMap(attrs);
     }
 
     static <K, V> Map<K, V> copiedMap(Map<K, V> map) {
         if (map.isEmpty()) {
             return Collections.emptyMap();
         }
         return Collections.unmodifiableMap(new HashMap<K, V>(map));
     }
 
     static void setAttributes(Channel channel, Map.Entry<AttributeKey<?>, Object>[] attrs) {
         for (Map.Entry<AttributeKey<?>, Object> e: attrs) {
             @SuppressWarnings("unchecked")
             AttributeKey<Object> key = (AttributeKey<Object>) e.getKey();
             channel.attr(key).set(e.getValue());
         }
     }
 
     static void setChannelOptions(
             Channel channel, Map.Entry<ChannelOption<?>, Object>[] options, InternalLogger logger) {
         for (Map.Entry<ChannelOption<?>, Object> e: options) {
             setChannelOption(channel, e.getKey(), e.getValue(), logger);
         }
     }
 
     @SuppressWarnings("unchecked")
     private static void setChannelOption(
             Channel channel, ChannelOption<?> option, Object value, InternalLogger logger) {
         try {
             if (!channel.config().setOption((ChannelOption<Object>) option, value)) {
                 logger.warn("Unknown channel option '{}' for channel '{}'", option, channel);
             }
         } catch (Throwable t) {
             logger.warn(
                     "Failed to set channel option '{}' with value '{}' for channel '{}'", option, value, channel, t);
         }
     }
 
     @Override
     public String toString() {
         StringBuilder buf = new StringBuilder()
             .append(StringUtil.simpleClassName(this))
             .append('(').append(config()).append(')');
         return buf.toString();
     }
 
     static final class PendingRegistrationPromise extends DefaultChannelPromise {
 
         // Is set to the correct EventExecutor once the registration was successful. Otherwise it will
         // stay null and so the GlobalEventExecutor.INSTANCE will be used for notifications.
         private volatile boolean registered;
 
         PendingRegistrationPromise(Channel channel) {
             super(channel);
         }
 
         void registered() {
             registered = true;
         }
 
         @Override
         protected EventExecutor executor() {
             if (registered) {
                 // If the registration was a success executor is set.
                 //
                 // See https://github.com/netty/netty/issues/2586
                 return super.executor();
             }
             // The registration failed so we can only use the GlobalEventExecutor as last resort to notify.
             return GlobalEventExecutor.INSTANCE;
         }
     }
 }