using System;
using System.Collections.Generic;
using Microsoft.Extensions.DependencyInjection;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.OperationModel;
using OpcLabs.EasyOpc.UA.Services;

namespace OpcLabsQuickTest
{
   class Program
   {
      private static Dictionary<string, string> _lastStates = new Dictionary<string, string>();
      private static EasyUAClient _client;
      private static IEasyUAClientConnectionMonitoring _clientConnectionMonitoring;

      static void Main(string[] args)
      {
         Console.WriteLine("OPC UA Subscription Test");
         Console.WriteLine("========================\n");

         // Configure your OPC UA server endpoint
         string endpointUrl = "opc.tcp://localhost:49320"; // Change to your server

         // Configure the nodes you want to monitor
         var monitoredItems = new[]
         {
                new EasyUAMonitoredItemArguments(null, endpointUrl, "ns=2;Data Type Examples.8 Bit Device.S Registers2.String1", 1000),
                new EasyUAMonitoredItemArguments(null, endpointUrl, "ns=2;Data Type Examples.8 Bit Device.K Registers.FloatArray1", 1000),
                new EasyUAMonitoredItemArguments(null, endpointUrl, "ns=2;Data Type Examples.8 Bit Device.K Registers.Long2", 1000)
            };

         _client = new EasyUAClient();

         // Obtain the client connection monitoring service
         _clientConnectionMonitoring = _client.GetService<IEasyUAClientConnectionMonitoring>();
         if (_clientConnectionMonitoring == null)
         {
            Console.WriteLine("The client connection monitoring service is not available.");
            return;
         }

         // Hook events
         _client.DataChangeNotification += Client_DataChangeNotification;
         _clientConnectionMonitoring.ServerConditionChanged += Client_ServerConditionChanged;

         Console.WriteLine("Subscribing to nodes...\n");
         _client.SubscribeMultipleMonitoredItems(monitoredItems);

         Console.WriteLine("Monitoring for changes. Press Enter to exit...\n");
         Console.ReadLine();

         Dispose();

         Console.WriteLine("Done.");
      }

      /// <summary>
      /// Disposes of the OPC client and cleans up resources
      /// </summary>
      private static void Dispose()
      {
         if (_client != null)
         {
            try
            {
               Console.WriteLine("\nDisposing client...");

               // Unsubscribe from events
               _client.DataChangeNotification -= Client_DataChangeNotification;
               if (_clientConnectionMonitoring != null)
               {
                  _clientConnectionMonitoring.ServerConditionChanged -= Client_ServerConditionChanged;
               }

               // Unsubscribe from all monitored items
               _client.UnsubscribeAllMonitoredItems();

               // Dispose the client
               _client.Dispose();
               _client = null;
               _clientConnectionMonitoring = null;
            }
            catch (Exception ex)
            {
               Console.WriteLine($"Error during disposal: {ex.Message}");
            }
         }
      }

      /// <summary>
      /// Event handler for Server Condition Changed
      /// </summary>
      /// <param name="sender">sending object</param>
      /// <param name="e">server condition changed event args</param>
      private static void Client_ServerConditionChanged(object sender, EasyUAServerConditionChangedEventArgs e)
      {
         try
         {
            // Display the event
            Console.WriteLine(e);
         }
         catch (Exception exception)
         {
            // Log the exception but don't let it propagate
            Console.WriteLine($"[ERROR] Exception in ServerConditionChanged handler: {exception.Message}");
         }
      }

      private static void Client_DataChangeNotification(object sender, EasyUADataChangeNotificationEventArgs e)
      {
         string nodeId = e.Arguments.NodeDescriptor.NodeId.ToString();
         string timestamp = DateTime.Now.ToString("HH:mm:ss.fff");

         if (e.Succeeded)
         {
            string currentState = e.AttributeData.StatusCode.ToString();

            // Check if state changed
            if (_lastStates.TryGetValue(nodeId, out string lastState))
            {
               if (lastState != currentState)
               {
                  Console.WriteLine($"[{timestamp}] STATE CHANGED: {nodeId}");
                  Console.WriteLine($"              Old State: {lastState}");
                  Console.WriteLine($"              New State: {currentState}");
               }
            }
            else
            {
               Console.WriteLine($"[{timestamp}] INITIAL STATE: {nodeId} = {currentState}");
            }

            _lastStates[nodeId] = currentState;

            // Print value change
            Console.WriteLine($"[{timestamp}] {nodeId} = {e.AttributeData.Value} (Quality: {currentState})");
         }
         else
         {
            Console.WriteLine($"[{timestamp}] ERROR: {nodeId} - {e.ErrorMessageBrief}");
         }
      }
   }
}