/*
 * 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:
 *
 *   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 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.internal.SocketUtils;
import io.netty.util.AttributeKey;
import io.netty.util.concurrent.EventExecutor;
import io.netty.util.concurrent.GlobalEventExecutor;
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.Collections;
import java.util.LinkedHashMap;
import java.util.Map;

AbstractBootstrap is a helper class that makes it easy to bootstrap a Channel. It support method-chaining to provide an easy way to configure the AbstractBootstrap. 
When not used in a ServerBootstrap context, the bind() methods are useful for connectionless transports such as datagram (UDP).
/**
 * {@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 {

    volatile EventLoopGroup group;
    @SuppressWarnings("deprecation")
    private volatile ChannelFactory<? extends C> channelFactory;
    private volatile SocketAddress localAddress;
    private final Map<ChannelOption<?>, Object> options = new LinkedHashMap<ChannelOption<?>, Object>();
    private final Map<AttributeKey<?>, Object> attrs = new LinkedHashMap<AttributeKey<?>, Object>();
    private volatile ChannelHandler handler;

    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);
        }
        synchronized (bootstrap.attrs) {
            attrs.putAll(bootstrap.attrs);
        }
    }

    
The EventLoopGroup which is used to handle all the events for the to-be-created Channel /**
     * The {@link EventLoopGroup} which is used to handle all the events for the to-be-created
     * {@link Channel}
     */
    public B group(EventLoopGroup group) {
        if (group == null) {
            throw new NullPointerException("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 Class which is used to create Channel instances from. You either use this or channelFactory(ChannelFactory) if your Channel implementation has no no-args constructor. /**
     * 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) {
        if (channelClass == null) {
            throw new NullPointerException("channelClass");
        }
        return channelFactory(new ReflectiveChannelFactory<C>(channelClass));
    }

    
Deprecated:
Use channelFactory(ChannelFactory) instead./**
     * @deprecated Use {@link #channelFactory(io.netty.channel.ChannelFactory)} instead.
     */
    @Deprecated
    public B channelFactory(ChannelFactory<? extends C> channelFactory) {
        if (channelFactory == null) {
            throw new NullPointerException("channelFactory");
        }
        if (this.channelFactory != null) {
            throw new IllegalStateException("channelFactory set already");
        }

        this.channelFactory = channelFactory;
        return self();
    }

    
ChannelFactory which is used to create Channel instances from when calling bind(). This method is usually only used if channel(Class) is not working for you because of some more complex needs. If your Channel implementation has a no-args constructor, its highly recommend to just use channel(Class) for simplify your code. /**
     * {@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)} for
     * simplify your code.
     */
    @SuppressWarnings({ "unchecked", "deprecation" })
    public B channelFactory(io.netty.channel.ChannelFactory<? extends C> channelFactory) {
        return channelFactory((ChannelFactory<C>) channelFactory);
    }

    
The SocketAddress which is used to bind the local "end" to. /**
     * The {@link SocketAddress} which is used to bind the local "end" to.
     */
    public B localAddress(SocketAddress localAddress) {
        this.localAddress = localAddress;
        return self();
    }

    
See Also:
localAddress(SocketAddress)/**
     * @see #localAddress(SocketAddress)
     */
    public B localAddress(int inetPort) {
        return localAddress(new InetSocketAddress(inetPort));
    }

    
See Also:
localAddress(SocketAddress)/**
     * @see #localAddress(SocketAddress)
     */
    public B localAddress(String inetHost, int inetPort) {
        return localAddress(SocketUtils.socketAddress(inetHost, inetPort));
    }

    
See Also:
localAddress(SocketAddress)/**
     * @see #localAddress(SocketAddress)
     */
    public B localAddress(InetAddress inetHost, int inetPort) {
        return localAddress(new InetSocketAddress(inetHost, inetPort));
    }

    
Allow to specify a ChannelOption which is used for the Channel instances once they got created. Use a value of null to remove a previous set ChannelOption. /**
     * 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) {
        if (option == null) {
            throw new NullPointerException("option");
        }
        if (value == null) {
            synchronized (options) {
                options.remove(option);
            }
        } else {
            synchronized (options) {
                options.put(option, value);
            }
        }
        return self();
    }

    
Allow to specify an initial attribute of the newly created Channel. If the value is null, the attribute of the specified key is removed. /**
     * 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) {
        if (key == null) {
            throw new NullPointerException("key");
        }
        if (value == null) {
            synchronized (attrs) {
                attrs.remove(key);
            }
        } else {
            synchronized (attrs) {
                attrs.put(key, value);
            }
        }
        return self();
    }

    
Validate all the parameters. Sub-classes may override this, but should
call the super method in that case.
/**
     * 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 Channels with similar settings. Please note that this method does not clone the EventLoopGroup deeply but shallowly, making the group a shared resource. /**
     * 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 Channel and register it with an EventLoop. /**
     * Create a new {@link Channel} and register it with an {@link EventLoop}.
     */
    public ChannelFuture register() {
        validate();
        return initAndRegister();
    }

    
Create a new Channel and bind it. /**
     * 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 Channel and bind it. /**
     * Create a new {@link Channel} and bind it.
     */
    public ChannelFuture bind(int inetPort) {
        return bind(new InetSocketAddress(inetPort));
    }

    
Create a new Channel and bind it. /**
     * Create a new {@link Channel} and bind it.
     */
    public ChannelFuture bind(String inetHost, int inetPort) {
        return bind(SocketUtils.socketAddress(inetHost, inetPort));
    }

    
Create a new Channel and bind it. /**
     * Create a new {@link Channel} and bind it.
     */
    public ChannelFuture bind(InetAddress inetHost, int inetPort) {
        return bind(new InetSocketAddress(inetHost, inetPort));
    }

    
Create a new Channel and bind it. /**
     * Create a new {@link Channel} and bind it.
     */
    public ChannelFuture bind(SocketAddress localAddress) {
        validate();
        if (localAddress == null) {
            throw new NullPointerException("localAddress");
        }
        return doBind(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);
        }

        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;

    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 ChannelHandler to use for serving the requests. /**
     * the {@link ChannelHandler} to use for serving the requests.
     */
    public B handler(ChannelHandler handler) {
        if (handler == null) {
            throw new NullPointerException("handler");
        }
        this.handler = handler;
        return self();
    }

    
Returns the configured EventLoopGroup or null if non is configured yet. 
Deprecated:
Use config() instead./**
     * 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 AbstractBootstrapConfig object that can be used to obtain the current config of the bootstrap. /**
     * Returns the {@link AbstractBootstrapConfig} object that can be used to obtain the current config
     * of the bootstrap.
     */
    public abstract AbstractBootstrapConfig<B, C> config();

    static <K, V> Map<K, V> copiedMap(Map<K, V> map) {
        final Map<K, V> copied;
        synchronized (map) {
            if (map.isEmpty()) {
                return Collections.emptyMap();
            }
            copied = new LinkedHashMap<K, V>(map);
        }
        return Collections.unmodifiableMap(copied);
    }

    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() {
        return copiedMap(options);
    }

    final Map<AttributeKey<?>, Object> attrs() {
        return copiedMap(attrs);
    }

    static void setChannelOptions(
            Channel channel, Map<ChannelOption<?>, Object> options, InternalLogger logger) {
        for (Map.Entry<ChannelOption<?>, Object> e: options.entrySet()) {
            setChannelOption(channel, e.getKey(), e.getValue(), logger);
        }
    }

    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;
        }
    }
}