using Opc.Ua;   // Install-Package OPCFoundation.NetStandard.Opc.Ua
using Opc.Ua.Client;
using Opc.Ua.Configuration;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Net;

namespace MyHomework
{
  class Program
  {
    static void Main(string[] args)
    {

        Console.WriteLine("Step 1 - Create application configuration and certificate.");
        var config = new ApplicationConfiguration()
        {
            ApplicationName = "MyHomework",
            ApplicationUri = Utils.Format(@"urn:{0}:MyHomework", System.Net.Dns.GetHostName()),
            ApplicationType = ApplicationType.Client,
            SecurityConfiguration = new SecurityConfiguration {
                ApplicationCertificate = new CertificateIdentifier { StoreType = @"Directory", StorePath = @"%CommonApplicationData%\OPC Foundation\CertificateStores\MachineDefault", SubjectName = Utils.Format(@"CN={0}, DC={1}", "MyHomework", System.Net.Dns.GetHostName()) },
                TrustedIssuerCertificates = new CertificateTrustList { StoreType = @"Directory", StorePath = @"%CommonApplicationData%\OPC Foundation\CertificateStores\UA Certificate Authorities" },
                TrustedPeerCertificates = new CertificateTrustList { StoreType = @"Directory", StorePath = @"%CommonApplicationData%\OPC Foundation\CertificateStores\UA Applications" },
                RejectedCertificateStore = new CertificateTrustList { StoreType = @"Directory", StorePath = @"%CommonApplicationData%\OPC Foundation\CertificateStores\RejectedCertificates" },
                AutoAcceptUntrustedCertificates = true,
                AddAppCertToTrustedStore = true
            },
            TransportConfigurations = new TransportConfigurationCollection(),
            TransportQuotas = new TransportQuotas { OperationTimeout = 15000 },
            ClientConfiguration = new ClientConfiguration { DefaultSessionTimeout = 60000 },
            TraceConfiguration = new TraceConfiguration()
        };
        config.Validate(ApplicationType.Client).GetAwaiter().GetResult();
        if (config.SecurityConfiguration.AutoAcceptUntrustedCertificates)
        {
            config.CertificateValidator.CertificateValidation += (s, e) => { e.Accept = (e.Error.StatusCode == StatusCodes.BadCertificateUntrusted); };
        }

        var application = new ApplicationInstance
        {
            ApplicationName = "MyHomework",
            ApplicationType = ApplicationType.Client,
            ApplicationConfiguration = config
        };
        application.CheckApplicationInstanceCertificate(false, 2048).GetAwaiter().GetResult();

        var selectedEndpoint = CoreClientUtils.SelectEndpoint("opc.tcp://" + Dns.GetHostName() + ":48010", useSecurity: true, operationTimeout: 15000);

        Console.WriteLine($"Step 2 - Create a session with your server: {selectedEndpoint.EndpointUrl} ");
        using (var session = Session.Create(config, new ConfiguredEndpoint(null, selectedEndpoint, EndpointConfiguration.Create(config)), false, "", 60000, null, null).GetAwaiter().GetResult())
        {
            Console.WriteLine("Step 3 - Browse the server namespace.");
            ReferenceDescriptionCollection refs;
            Byte[] cp;
            session.Browse(null, null, ObjectIds.ObjectsFolder, 0u, BrowseDirection.Forward, ReferenceTypeIds.HierarchicalReferences, true, (uint)NodeClass.Variable | (uint)NodeClass.Object | (uint)NodeClass.Method, out cp, out refs);
            Console.WriteLine("DisplayName: BrowseName, NodeClass");
            foreach (var rd in refs)
            {
                Console.WriteLine("{0}: {1}, {2}", rd.DisplayName, rd.BrowseName, rd.NodeClass);
                ReferenceDescriptionCollection nextRefs;
                byte[] nextCp;
                session.Browse(null, null, ExpandedNodeId.ToNodeId(rd.NodeId, session.NamespaceUris), 0u, BrowseDirection.Forward, ReferenceTypeIds.HierarchicalReferences, true, (uint)NodeClass.Variable | (uint)NodeClass.Object | (uint)NodeClass.Method, out nextCp, out nextRefs);
                foreach (var nextRd in nextRefs)
                {
                    Console.WriteLine("+ {0}: {1}, {2}", nextRd.DisplayName, nextRd.BrowseName, nextRd.NodeClass);
                }
            }

            Console.WriteLine("Step 4 - Create a subscription. Set a faster publishing interval if you wish.");
            var subscription = new Subscription(session.DefaultSubscription) { PublishingInterval = 1000 };

            Console.WriteLine("Step 5 - Add a list of items you wish to monitor to the subscription.");
            var list = new List<MonitoredItem> { new MonitoredItem(subscription.DefaultItem) { DisplayName = "ServerStatusCurrentTime", StartNodeId = "i=2258" } };
            list.ForEach(i => i.Notification += OnNotification);
            subscription.AddItems(list);

            Console.WriteLine("Step 6 - Add the subscription to the session.");
            session.AddSubscription(subscription);
            subscription.Create();

            Console.WriteLine("Press any key to remove subscription...");
            Console.ReadKey(true);
        }

        Console.WriteLine("Press any key to exit...");
        Console.ReadKey(true);
    }

    private static void OnNotification(MonitoredItem item, MonitoredItemNotificationEventArgs e)
    {
        foreach (var value in item.DequeueValues())
        {
            Console.WriteLine("{0}: {1}, {2}, {3}", item.DisplayName, value.Value, value.SourceTimestamp, value.StatusCode);
        }
    }

  }
}