feat(lmxproxy): phase 2 — host core (MxAccessClient, SessionManager, SubscriptionManager)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lmxproxy/src/ZB.MOM.WW.LmxProxy.Host/MxAccess/MxAccessClient.EventHandlers.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Collections.Generic;
+using ArchestrA.MxAccess;
+using Serilog;
+using ZB.MOM.WW.LmxProxy.Host.Domain;
+
+namespace ZB.MOM.WW.LmxProxy.Host.MxAccess
+{
+    public sealed partial class MxAccessClient
+    {
+        /// <summary>
+        ///     Callback invoked by the SubscriptionManager when it needs to deliver
+        ///     data change events. Set by the SubscriptionManager during initialization.
+        /// </summary>
+        public Action<string, Vtq>? OnTagValueChanged { get; set; }
+
+        /// <summary>
+        ///     COM event handler for MxAccess OnDataChange events.
+        ///     Called on the STA thread when a subscribed tag value changes.
+        ///     Signature matches the ArchestrA.MxAccess ILMXProxyServerEvents interface.
+        /// </summary>
+        private void OnDataChange(
+            int hLMXServerHandle,
+            int phItemHandle,
+            object pvItemValue,
+            int pwItemQuality,
+            object pftItemTimeStamp,
+            ref MXSTATUS_PROXY[] ItemStatus)
+        {
+            try
+            {
+                var quality = MapQuality(pwItemQuality);
+                var timestamp = ConvertTimestamp(pftItemTimeStamp);
+                var vtq = new Vtq(pvItemValue, timestamp, quality);
+
+                // We don't have the address from the COM callback — the reference code
+                // looks it up from _subscriptionsByHandle. For the v2 design, the
+                // SubscriptionManager's global handler receives (address, vtq) via
+                // OnTagValueChanged. The actual address resolution will be implemented
+                // when the full subscription tracking is wired up on windev.
+
+                // Route to the SubscriptionManager's global handler
+                OnTagValueChanged?.Invoke(phItemHandle.ToString(), vtq);
+            }
+            catch (Exception ex)
+            {
+                Log.Error(ex, "Error processing OnDataChange event for handle {Handle}", phItemHandle);
+            }
+        }
+
+        /// <summary>
+        ///     COM event handler for MxAccess OnWriteComplete events.
+        ///     Signature matches the ArchestrA.MxAccess ILMXProxyServerEvents interface.
+        /// </summary>
+        private void OnWriteComplete(
+            int hLMXServerHandle,
+            int phItemHandle,
+            ref MXSTATUS_PROXY[] ItemStatus)
+        {
+            // Write completion is currently fire-and-forget.
+            // Log for diagnostics.
+            try
+            {
+                Log.Debug("WriteCompleted: handle {Handle}", phItemHandle);
+            }
+            catch (Exception ex)
+            {
+                Log.Error(ex, "Error processing OnWriteComplete event for handle {Handle}", phItemHandle);
+            }
+        }
+
+        /// <summary>
+        ///     Converts a timestamp object to DateTime in UTC.
+        /// </summary>
+        private static DateTime ConvertTimestamp(object timestamp)
+        {
+            if (timestamp is DateTime dt)
+            {
+                return dt.Kind == DateTimeKind.Utc ? dt : dt.ToUniversalTime();
+            }
+
+            return DateTime.UtcNow;
+        }
+    }
+}