From 2ff138f1e8566b73c9278967b667fb9c1849ac33 Mon Sep 17 00:00:00 2001
From: Joseph Doherty <dohejw01@gmail.com>
Date: Thu, 28 May 2026 11:52:28 -0400
Subject: [PATCH] feat(templates): apply InstanceConnectionBinding override
 during flattening

---
 .../Flattening/FlatteningService.cs           |  3 +-
 .../ConnectionBindingOverrideTests.cs         | 83 +++++++++++++++++++
 2 files changed, 85 insertions(+), 1 deletion(-)
 create mode 100644 tests/ZB.MOM.WW.ScadaBridge.TemplateEngine.Tests/Flattening/ConnectionBindingOverrideTests.cs

diff --git a/src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Flattening/FlatteningService.cs b/src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Flattening/FlatteningService.cs
index aff9c2d2..de6c7f0d 100644
--- a/src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Flattening/FlatteningService.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Flattening/FlatteningService.cs
@@ -365,7 +365,8 @@ public class FlatteningService
             {
                 BoundDataConnectionId = connection.Id,
                 BoundDataConnectionName = connection.Name,
-                BoundDataConnectionProtocol = connection.Protocol
+                BoundDataConnectionProtocol = connection.Protocol,
+                DataSourceReference = binding.DataSourceReferenceOverride ?? existing.DataSourceReference
             };
         }
     }
diff --git a/tests/ZB.MOM.WW.ScadaBridge.TemplateEngine.Tests/Flattening/ConnectionBindingOverrideTests.cs b/tests/ZB.MOM.WW.ScadaBridge.TemplateEngine.Tests/Flattening/ConnectionBindingOverrideTests.cs
new file mode 100644
index 00000000..cfbe30f6
--- /dev/null
+++ b/tests/ZB.MOM.WW.ScadaBridge.TemplateEngine.Tests/Flattening/ConnectionBindingOverrideTests.cs
@@ -0,0 +1,83 @@
+using ZB.MOM.WW.ScadaBridge.Commons.Entities.Instances;
+using ZB.MOM.WW.ScadaBridge.Commons.Entities.Sites;
+using ZB.MOM.WW.ScadaBridge.Commons.Entities.Templates;
+using ZB.MOM.WW.ScadaBridge.Commons.Types.Enums;
+using ZB.MOM.WW.ScadaBridge.TemplateEngine.Flattening;
+
+namespace ZB.MOM.WW.ScadaBridge.TemplateEngine.Tests.Flattening;
+
+public class ConnectionBindingOverrideTests
+{
+    private readonly FlatteningService _sut = new();
+
+    private static Instance CreateInstance(string name = "TestInstance", int templateId = 1, int siteId = 1) =>
+        new(name) { Id = 1, TemplateId = templateId, SiteId = siteId };
+
+    private static Template CreateTemplate(int id, string name)
+    {
+        return new Template(name) { Id = id };
+    }
+
+    private static Template CreateTemplateWithDataSourcedAttribute(string attributeName, string dataSourceReference)
+    {
+        var template = CreateTemplate(1, "Base");
+        template.Attributes.Add(new TemplateAttribute(attributeName)
+        {
+            DataType = DataType.Double,
+            DataSourceReference = dataSourceReference
+        });
+        return template;
+    }
+
+    private static Dictionary<int, DataConnection> SingleConnection(int id = 1) =>
+        new()
+        {
+            [id] = new("OPC-Server1", "OpcUa", 1) { Id = id, PrimaryConfiguration = "opc.tcp://localhost:4840" }
+        };
+
+    [Fact]
+    public void Override_replaces_template_DataSourceReference_when_set()
+    {
+        var template = CreateTemplateWithDataSourcedAttribute("Speed", dataSourceReference: "TemplateDefault");
+        var instance = CreateInstance();
+        instance.ConnectionBindings.Add(new InstanceConnectionBinding("Speed")
+        {
+            DataConnectionId = 1,
+            DataSourceReferenceOverride = "ns=2;s=Pump1.Speed"
+        });
+
+        var result = _sut.Flatten(
+            instance,
+            [template],
+            new Dictionary<int, IReadOnlyList<TemplateComposition>>(),
+            new Dictionary<int, IReadOnlyList<Template>>(),
+            SingleConnection(id: 1));
+
+        Assert.True(result.IsSuccess);
+        var attr = result.Value.Attributes.Single(a => a.CanonicalName == "Speed");
+        Assert.Equal("ns=2;s=Pump1.Speed", attr.DataSourceReference);
+    }
+
+    [Fact]
+    public void Null_override_falls_back_to_template_default()
+    {
+        var template = CreateTemplateWithDataSourcedAttribute("Speed", dataSourceReference: "TemplateDefault");
+        var instance = CreateInstance();
+        instance.ConnectionBindings.Add(new InstanceConnectionBinding("Speed")
+        {
+            DataConnectionId = 1,
+            DataSourceReferenceOverride = null
+        });
+
+        var result = _sut.Flatten(
+            instance,
+            [template],
+            new Dictionary<int, IReadOnlyList<TemplateComposition>>(),
+            new Dictionary<int, IReadOnlyList<Template>>(),
+            SingleConnection(id: 1));
+
+        Assert.True(result.IsSuccess);
+        var attr = result.Value.Attributes.Single(a => a.CanonicalName == "Speed");
+        Assert.Equal("TemplateDefault", attr.DataSourceReference);
+    }
+}