// This KEPServerEX/UA example shows how to obtain "data nodes" under the "Objects" node, recursively.
//
// Find all latest examples here: https://www.doc-that.com/files/onlinedocs/OPCLabs-ConnectivityStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-ConnectivityStudio-CSharp .
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using System;
using System.Diagnostics;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.AddressSpace;
using OpcLabs.EasyOpc.UA.AddressSpace.Standard;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples.Specialized
{
    partial class Kepware_KEPServerEX_UA
    {
        public static void BrowseDataNodes()
        {
            UAEndpointDescriptor endpointDescriptor = "opc.tcp://localhost:49320";  // default KEPServerEX/UA endpoint 

            // Instantiate the client object
            var client = new EasyUAClient();

            try
            {
                BrowseFromNode(client, endpointDescriptor, UAObjectIds.ObjectsFolder, level:0);
            }
            catch (UAException uaException)
            {
                Console.WriteLine($"*** Failure: {uaException.GetBaseException().Message}");
            }
        }

        private static void BrowseFromNode(
            EasyUAClient client,
            UAEndpointDescriptor endpointDescriptor,
            UANodeDescriptor parentNodeDescriptor,
            int level)
        {
            Debug.Assert(!(client is null));
            Debug.Assert(!(endpointDescriptor is null));
            Debug.Assert(!(parentNodeDescriptor is null));

            // Obtain all node elements under parentNodeDescriptor
            UANodeElementCollection nodeElementCollection = 
                client.BrowseDataNodes(endpointDescriptor, parentNodeDescriptor);
            // Remark: BrowseDataNodes(...) may throw UAException; we handle it in the calling method.

            foreach (UANodeElement nodeElement in nodeElementCollection)
            {
                Debug.Assert(!(nodeElement is null));

                Console.Write(new string(' ', level*2));    // indent
                Console.WriteLine(nodeElement);

                // Browse recursively into the node.
                // The UANodeElement has an implicit conversion to UANodeDescriptor.
                BrowseFromNode(client, endpointDescriptor, nodeElement, level + 1);

                // Note that the number of nodes you obtain through recursive browsing may be very large, or even infinite.
                // Production code should contain appropriate safeguards for these cases.
            }
        }
    }
}