using Opc.Ua;
using Opc.Ua.Client;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;

namespace Xylem.Common.Hardware.Plc.Siemens.Client.TestbenchAdapter
{
    [Guid("C027D79A-7133-404A-8015-6F5D626B5FA1"),
    ComVisible(true),
    InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
    public interface ITestbenchAdapter : IDisposable
    {
        void Disconnect();
        void Connect(string url);
        dynamic ReadValueVar(string Register);
        void WriteValue(object Value, string Register);

        string WriteValueErrorMsg(object Value, string Register);

    }

    [Guid("A20D9680-7DFB-4CBD-AB88-7C7ACFE34D36"),
    ComVisible(true),
    InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]

    public interface ITestbenchAdapterEvents
    {
        void onErrorOccur(string description, string source);
        void onLog(string text, string source);

    }
    [Guid("01565BB8-477E-49FC-834B-5C99C16F2883"),
    ComVisible(true),
    ClassInterface(ClassInterfaceType.None),
    ComSourceInterfaces(typeof(ITestbenchAdapterEvents))]
    public class Vb6Testbench : ITestbenchAdapter
    {
        private Session mySession;
        private Subscription mySubscription;
        private UAClientHelperAPI myClientHelperAPI;
        private EndpointDescription mySelectedEndpoint;


        private string myUrl = "";

        public Vb6Testbench()
        {

            myClientHelperAPI = new UAClientHelperAPI();
        }


        [ComVisible(false)]
        public delegate void ErrorHandler(string description, string source);
        public event ErrorHandler onErrorOccur;

        [ComVisible(false)]
        public delegate void LogHandler(string text);
        public event LogHandler onLog;





        public void Setup(string url)
        {
            myUrl = url;
        }
        public void Disconnect()
        {
            if (mySession != null && !mySession.Disposed)
            {
                try
                {
                    mySubscription.Delete(true);
                }
                catch
                {
                    //ignore
                    ;
                }

                myClientHelperAPI.Disconnect();
                mySession = myClientHelperAPI.Session;

            }
        }

        public void Connect(string tmpurl)
        {
            Setup(tmpurl);
            if (tmpurl != "none")
            {
                EndpointDescriptionCollection endpoints = myClientHelperAPI.GetEndpoints(myUrl);
                foreach (var endpoint in endpoints)
                {
                    if (mySession == null || mySession.Disposed)
                    {
                        try
                        {
                            myClientHelperAPI.KeepAliveNotification += new KeepAliveEventHandler(Notification_KeepAlive);
                            //myClientHelperAPI.CertificateValidationNotification += new CertificateValidationEventHandler(Notification_ServerCertificate);

                            myClientHelperAPI.Connect(endpoint, false, "", "");
                            mySession = myClientHelperAPI.Session;

                        }
                        catch (Exception ex)
                        {
                            onErrorOccur?.Invoke(ex.Message, ex.StackTrace);
                        }
                    }
                }
            }
        }

        private void Notification_KeepAlive(Session sender, KeepAliveEventArgs e)
        {
            try
            {
                // check for events from discarded sessions.
                if (!Object.ReferenceEquals(sender, mySession))
                {
                    return;
                }

                // check for disconnected session.
                if (ServiceResult.IsBad(e.Status))
                {
                    // try reconnecting using the existing session state
                    mySession.Reconnect();
                }
            }
            catch (Exception ex)
            {
                onErrorOccur?.Invoke(ex.Message, ex.StackTrace);
            }
        }



        public dynamic ReadValueVar(string Register)
        {
            var RetryLeft = 4;
            var exs = new List<Exception>();
            if (!mySession.Connected)
            {
                mySession.Reconnect();
            }

            while (RetryLeft >= 1)
            {
                try
                {
                    return myClientHelperAPI.ReadValue(Register);
                }
                catch (Exception ex)
                {
                    exs.Add(ex);
                    if (!mySession.Connected)
                    {
                        mySession.Reconnect();
                    }
                    else
                    {
                        RetryLeft = 0;
                    }
                }
                RetryLeft = RetryLeft--;
            }
            if (exs.Any())
            {
                throw new AggregateException("Cannot Read Value from OPC", exs);
            }
            else
            {
                throw new ApplicationException("Cannot Read Value from OPC");
            }

        }

        public string WriteValueErrorMsg(object Value, string Register)
        {
            
            try
            {
                if (!mySession.Connected)
                {
                    mySession.Reconnect();
                }
                myClientHelperAPI.WriteValues(new List<object>() { Value }, new List<string>() { Register });
            }
            catch (Exception ex)
            {
                return ex.Message;

            }
            return "";

        }

        public void WriteValue(object Value, string Register)
        {
            var RetryLeft = 4;
            var exs = new List<Exception>();


            while (RetryLeft >= 1)
            {
                try
                {
                    if (!mySession.Connected)
                    {
                        mySession.Reconnect();
                    }
                    myClientHelperAPI.WriteValues(new List<object>() { Value }, new List<string>() { Register });
                    break;
                }
                catch (Exception ex)
                {
                    exs.Add(ex);

                }
                RetryLeft = RetryLeft--;
            }
            if (exs.Any())
            {
                throw new AggregateException("writeValue to OPC  failed", exs);
            }
        }
        public void Dispose()
        {
            Disconnect();
        }


    }
}