Added extensibility model for interception of messages.

Jabbot/Bot.cs

@@ -1,7 +1,9 @@
 using System;
-using System.Linq;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.ComponentModel.Composition.Hosting;
+using System.Linq;
+using Jabbot.MessageHandlers;
 using SignalR.Client.Hubs;
 
 namespace Jabbot
@@ -136,20 +138,31 @@ public void ShutDown()
 
         private void ProcessMessage(dynamic message)
         {
+
+            string content = message.Content;
+            string name = message.User.Name;
+
+            // Ignore replies from self
+            if (name.Equals(_name, StringComparison.OrdinalIgnoreCase))
+            {
+                return;
+            }
+
+            // We're going to process commands for the bot here
+            var chatMessage = new ChatMessage(content, name);
+
             if (MessageReceived != null)
             {
-                string content = message.Content;
-                string name = message.User.Name;
+                MessageReceived(chatMessage);
+            }
 
-                // Ignore replies from self
-                if (name.Equals(_name, StringComparison.OrdinalIgnoreCase))
+            foreach (var handler in GetMessageHandlers())
+            {
+                // Stop at the first one that handled the message
+                if (handler.Handle(chatMessage, this))
                 {
-                    return;
+                    break;
                 }
-
-                // We're going to process commands for the bot here
-                var chatMessage = new ChatMessage(content, name);
-                MessageReceived(chatMessage);
             }
         }
 
@@ -160,7 +173,7 @@ private void OnLeave(dynamic user)
 
         private void OnJoin(dynamic user)
         {
-            AddUser(user);   
+            AddUser(user);
         }
 
         private void RemoveUser(dynamic user)
@@ -181,5 +194,12 @@ private void AddUser(dynamic user)
             };
         }
 
+        private IList<IMessageHandler> GetMessageHandlers()
+        {
+            // TODO: Allow passing a directory where we look for commands that get added/removed dynamically
+            var container = new CompositionContainer(new AssemblyCatalog(typeof(Bot).Assembly));
+            return container.GetExportedValues<IMessageHandler>().ToList();
+        }
+
     }
 }

Jabbot/Jabbot.csproj

@@ -38,6 +38,7 @@
       <HintPath>..\packages\SignalR.Client.0.3.6\lib\net40\SignalR.Client.dll</HintPath>
     </Reference>
     <Reference Include="System" />
+    <Reference Include="System.ComponentModel.Composition" />
     <Reference Include="System.Core" />
     <Reference Include="System.Xml.Linq" />
     <Reference Include="System.Data.DataSetExtensions" />
@@ -49,6 +50,7 @@
     <Compile Include="Bot.cs" />
     <Compile Include="ChatMessage.cs" />
     <Compile Include="ChatUser.cs" />
+    <Compile Include="MessageHandlers\IMessageHandler.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>

Jabbot/MessageHandlers/IMessageHandler.cs

@@ -0,0 +1,20 @@
+using System.ComponentModel.Composition;
+
+namespace Jabbot.MessageHandlers
+{
+    /// <summary>
+    /// Extension point for bots. When an incoming message comes in, a message handler
+    /// will get a change to do something with it.
+    /// </summary>
+    [InheritedExport]
+    public interface IMessageHandler
+    {
+        /// <summary>
+        /// Allows the user to handle a message incoming from the bot's room
+        /// </summary>
+        /// <param name="message">Incoming message</param>
+        /// <param name="bot">bot instance</param>
+        /// <returns>true if handled, false if not</returns>
+        bool Handle(ChatMessage message, Bot bot);
+    }
+}