// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

namespace SecureChat.Server
{
 using System;
 using System.Net;
 using DotNetty.Transport.Channels;
 using DotNetty.Transport.Channels.Groups;

 public class SecureChatServerHandler : SimpleChannelInboundHandler<string>
 {
 static volatile IChannelGroup group;

 public override void ChannelActive(IChannelHandlerContext contex)
 {
 IChannelGroup g = group;
 if (g == null)
 {
 lock (this)
 {
 if (group == null)
 {
 g = group = new DefaultChannelGroup(contex.Executor);
 }
 }
 }

 contex.WriteAndFlushAsync(string.Format("Welcome to {0} secure chat server!\n", Dns.GetHostName()));
 g.Add(contex.Channel);
 }

 class EveryOneBut : IChannelMatcher
 {
 readonly IChannelId id;

 public EveryOneBut(IChannelId id)
 {
 this.id = id;
 }

 public bool Matches(IChannel channel) => channel.Id != this.id;
 }

 protected override void ChannelRead0(IChannelHandlerContext contex, string msg)
 {
 //send message to all but this one
 string broadcast = string.Format("[{0}] {1}\n", contex.Channel.RemoteAddress, msg);
 string response = string.Format("[you] {0}\n", msg);
 group.WriteAndFlushAsync(broadcast, new EveryOneBut(contex.Channel.Id));
 contex.WriteAndFlushAsync(response);

 if (string.Equals("bye", msg, StringComparison.OrdinalIgnoreCase))
 {
 contex.CloseAsync();
 }
 }

 public override void ChannelReadComplete(IChannelHandlerContext ctx) => ctx.Flush();

 public override void ExceptionCaught(IChannelHandlerContext ctx, Exception e)
 {
 Console.WriteLine("{0}", e.StackTrace);
 ctx.CloseAsync();
 }

 public override bool IsSharable => true;
 }
}