Add more function mappings for MQTTnet Server.

Source/MQTTnet.Server/Mqtt/MqttClientDisconnectedHandler.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Threading.Tasks;
+using IronPython.Runtime;
+using Microsoft.Extensions.Logging;
+using MQTTnet.Server.Scripting;
+
+namespace MQTTnet.Server.Mqtt
+{
+    public class MqttClientDisconnectedHandler : IMqttServerClientDisconnectedHandler
+    {
+        private readonly PythonScriptHostService _pythonScriptHostService;
+        private readonly ILogger _logger;
+
+        public MqttClientDisconnectedHandler(PythonScriptHostService pythonScriptHostService, ILogger<MqttClientDisconnectedHandler> logger)
+        {
+            _pythonScriptHostService = pythonScriptHostService ?? throw new ArgumentNullException(nameof(pythonScriptHostService));
+            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        }
+
+        public Task HandleClientDisconnectedAsync(MqttServerClientDisconnectedEventArgs eventArgs)
+        {
+            try
+            {
+                var pythonEventArgs = new PythonDictionary
+                {
+                    { "client_id", eventArgs.ClientId },
+                    { "type", PythonConvert.Pythonfy(eventArgs.DisconnectType) }
+                };
+
+                _pythonScriptHostService.InvokeOptionalFunction("on_client_disconnected", pythonEventArgs);
+            }
+            catch (Exception exception)
+            {
+                _logger.LogError(exception, "Error while handling client disconnected event.");
+            }
+
+            return Task.CompletedTask;
+        }
+    }
+}