feat(centralui): protocol selector + MxGateway editor in DataConnectionForm

Adds an OPC UA | MxGateway protocol dropdown (create-time; locked read-only on
edit), branches the primary/backup endpoint editors, serializer, and validator
by protocol, and persists DataConnection.Protocol accordingly. Updates form
tests: protocol dropdown present on create + MxGateway save round-trips typed
JSON with Protocol=MxGateway.

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Pages/Design/DataConnectionForm.razor

@@ -49,17 +49,45 @@
                         </select>
                     }
                 </div>
+                <div class="mb-2">
+                    <label class="form-label small">Protocol</label>
+                    @if (_protocolLocked)
+                    {
+                        <input type="text"
+                               class="form-control form-control-plaintext form-control-sm"
+                               readonly
+                               value="@_protocol" />
+                        <div class="form-text">Protocol is locked after creation.</div>
+                    }
+                    else
+                    {
+                        <select class="form-select form-select-sm" @bind="_protocol">
+                            <option value="OpcUa">OPC UA</option>
+                            <option value="MxGateway">MxGateway</option>
+                        </select>
+                    }
+                </div>
                 <div class="mb-3">
                     <label class="form-label small">Name</label>
                     <input type="text" class="form-control form-control-sm" @bind="_formName" />
                 </div>
 
                 <h6 class="text-muted mt-3">Primary endpoint</h6>
-                <OpcUaEndpointEditor Title="Primary Endpoint"
+                @if (_protocol == "MxGateway")
-                                     IdPrefix="primary"
+                {
-                                     Config="_primaryConfig"
+                    <MxGatewayEndpointEditor Title="Primary Endpoint"
-                                     IsLegacy="_primaryIsLegacy"
+                                             IdPrefix="primary"
-                                     Errors="_primaryErrors" />
+                                             Config="_primaryMx"
+                                             Errors="_primaryErrors" />
+                }
+                else
+                {
+                    <OpcUaEndpointEditor Title="Primary Endpoint"
+                                         IdPrefix="primary"
+                                         Config="_primaryConfig"
+                                         IsLegacy="_primaryIsLegacy"
+                                         Errors="_primaryErrors" />
+                }
 
                 <h6 class="text-muted mt-3">
                     Backup endpoint
@@ -77,11 +105,21 @@
                 }
                 else
                 {
-                    <OpcUaEndpointEditor Title="Backup Endpoint"
+                    @if (_protocol == "MxGateway")
-                                         IdPrefix="backup"
+                    {
-                                         Config="_backupConfig"
+                        <MxGatewayEndpointEditor Title="Backup Endpoint"
-                                         IsLegacy="_backupIsLegacy"
+                                                 IdPrefix="backup"
-                                         Errors="_backupErrors" />
+                                                 Config="_backupMx"
+                                                 Errors="_backupErrors" />
+                    }
+                    else
+                    {
+                        <OpcUaEndpointEditor Title="Backup Endpoint"
+                                             IdPrefix="backup"
+                                             Config="_backupConfig"
+                                             IsLegacy="_backupIsLegacy"
+                                             Errors="_backupErrors" />
+                    }
                     <div class="mb-2">
                         <label class="form-label small">Failover Retry Count</label>
                         <input type="number" class="form-control form-control-sm" style="max-width: 120px;"
@@ -118,8 +156,12 @@
     private string _siteName = string.Empty;
     private bool _siteLocked;
     private string _formName = string.Empty;
+    private string _protocol = "OpcUa";
+    private bool _protocolLocked;
     private OpcUaEndpointConfig _primaryConfig = new();
     private OpcUaEndpointConfig _backupConfig = new();
+    private MxGatewayEndpointConfig _primaryMx = new();
+    private MxGatewayEndpointConfig _backupMx = new();
     private bool _primaryIsLegacy;
     private bool _backupIsLegacy;
     private bool _showBackup;
@@ -143,17 +185,10 @@
                     _siteName = _sites.FirstOrDefault(s => s.Id == _formSiteId)?.Name ?? $"Site {_formSiteId}";
                     _siteLocked = true;
                     _formName = _editingConnection.Name;
+                    _protocol = string.IsNullOrWhiteSpace(_editingConnection.Protocol) ? "OpcUa" : _editingConnection.Protocol;
+                    _protocolLocked = true;
 
-                    (_primaryConfig, _primaryIsLegacy) =
+                    LoadConfig(_editingConnection);
-                        OpcUaEndpointConfigSerializer.Deserialize(_editingConnection.PrimaryConfiguration);
-
-                    if (!string.IsNullOrWhiteSpace(_editingConnection.BackupConfiguration))
-                    {
-                        (_backupConfig, _backupIsLegacy) =
-                            OpcUaEndpointConfigSerializer.Deserialize(_editingConnection.BackupConfiguration);
-                        _showBackup = true;
-                        _formFailoverRetryCount = _editingConnection.FailoverRetryCount;
-                    }
                 }
             }
             else if (SiteId.HasValue)
@@ -177,32 +212,80 @@
         }
     }
 
+    private void LoadConfig(DataConnection conn)
+    {
+        if (_protocol == "MxGateway")
+        {
+            _primaryMx = MxGatewayEndpointConfigSerializer.Deserialize(conn.PrimaryConfiguration);
+            if (!string.IsNullOrWhiteSpace(conn.BackupConfiguration))
+            {
+                _backupMx = MxGatewayEndpointConfigSerializer.Deserialize(conn.BackupConfiguration);
+                _showBackup = true;
+                _formFailoverRetryCount = conn.FailoverRetryCount;
+            }
+        }
+        else
+        {
+            (_primaryConfig, _primaryIsLegacy) =
+                OpcUaEndpointConfigSerializer.Deserialize(conn.PrimaryConfiguration);
+            if (!string.IsNullOrWhiteSpace(conn.BackupConfiguration))
+            {
+                (_backupConfig, _backupIsLegacy) =
+                    OpcUaEndpointConfigSerializer.Deserialize(conn.BackupConfiguration);
+                _showBackup = true;
+                _formFailoverRetryCount = conn.FailoverRetryCount;
+            }
+        }
+    }
+
     private async Task SaveConnection()
     {
         _formError = null;
         if (_formSiteId == 0) { _formError = "Site is required."; return; }
         if (string.IsNullOrWhiteSpace(_formName)) { _formError = "Name is required."; return; }
 
-        _primaryErrors = OpcUaEndpointConfigValidator.Validate(_primaryConfig, "Primary.");
+        string primaryJson;
-        _backupErrors = _showBackup
+        string? backupJson;
-            ? OpcUaEndpointConfigValidator.Validate(_backupConfig, "Backup.")
-            : null;
 
-        if (!_primaryErrors.IsValid || (_backupErrors is { IsValid: false }))
+        if (_protocol == "MxGateway")
         {
-            _formError = "Fix the errors below before saving.";
+            _primaryErrors = MxGatewayEndpointConfigValidator.Validate(_primaryMx, "Primary.");
-            return;
+            _backupErrors = _showBackup
-        }
+                ? MxGatewayEndpointConfigValidator.Validate(_backupMx, "Backup.")
+                : null;
 
-        var primaryJson = OpcUaEndpointConfigSerializer.Serialize(_primaryConfig);
+            if (!_primaryErrors.IsValid || (_backupErrors is { IsValid: false }))
-        var backupJson = _showBackup ? OpcUaEndpointConfigSerializer.Serialize(_backupConfig) : null;
+            {
+                _formError = "Fix the errors below before saving.";
+                return;
+            }
+
+            primaryJson = MxGatewayEndpointConfigSerializer.Serialize(_primaryMx);
+            backupJson = _showBackup ? MxGatewayEndpointConfigSerializer.Serialize(_backupMx) : null;
+        }
+        else
+        {
+            _primaryErrors = OpcUaEndpointConfigValidator.Validate(_primaryConfig, "Primary.");
+            _backupErrors = _showBackup
+                ? OpcUaEndpointConfigValidator.Validate(_backupConfig, "Backup.")
+                : null;
+
+            if (!_primaryErrors.IsValid || (_backupErrors is { IsValid: false }))
+            {
+                _formError = "Fix the errors below before saving.";
+                return;
+            }
+
+            primaryJson = OpcUaEndpointConfigSerializer.Serialize(_primaryConfig);
+            backupJson = _showBackup ? OpcUaEndpointConfigSerializer.Serialize(_backupConfig) : null;
+        }
 
         try
         {
             if (_editingConnection != null)
             {
                 _editingConnection.Name = _formName.Trim();
-                _editingConnection.Protocol = "OpcUa";
+                _editingConnection.Protocol = _protocol;
                 _editingConnection.PrimaryConfiguration = primaryJson;
                 _editingConnection.BackupConfiguration = backupJson;
                 _editingConnection.FailoverRetryCount = _showBackup ? _formFailoverRetryCount : 3;
@@ -210,7 +293,7 @@
             }
             else
             {
-                var conn = new DataConnection(_formName.Trim(), "OpcUa", _formSiteId)
+                var conn = new DataConnection(_formName.Trim(), _protocol, _formSiteId)
                 {
                     PrimaryConfiguration = primaryJson,
                     BackupConfiguration = backupJson,
@@ -233,6 +316,7 @@
     {
         _showBackup = false;
         _backupConfig = new OpcUaEndpointConfig();
+        _backupMx = new MxGatewayEndpointConfig();
         _backupIsLegacy = false;
         _formFailoverRetryCount = 3;
     }

tests/ZB.MOM.WW.ScadaBridge.CentralUI.Tests/DataConnectionFormTests.cs

@@ -44,12 +44,55 @@ public class DataConnectionFormTests : BunitContext
     }
 
     [Fact]
-    public void NoProtocolDropdown_IsRendered()
+    public void ProtocolDropdown_IsRendered_OnCreate_WithBothProtocols()
     {
         var cut = RenderForCreateSite(1);
-        Assert.DoesNotContain("Custom", cut.Markup);
         var labels = cut.FindAll("label").Select(l => l.TextContent.Trim()).ToList();
-        Assert.DoesNotContain(labels, l => l == "Protocol");
+        Assert.Contains(labels, l => l == "Protocol");
+
+        // The protocol select offers OPC UA and MxGateway.
+        var optionTexts = cut.FindAll("option").Select(o => o.TextContent.Trim()).ToList();
+        Assert.Contains("OPC UA", optionTexts);
+        Assert.Contains("MxGateway", optionTexts);
+    }
+
+    [Fact]
+    public async Task Save_MxGateway_PersistsTypedJsonAndProtocolMxGateway()
+    {
+        DataConnection? captured = null;
+        await _siteRepo.AddDataConnectionAsync(
+            Arg.Do<DataConnection>(d => captured = d));
+
+        var cut = RenderForCreateSite(1);
+
+        // Switch protocol to MxGateway — re-renders with the MxGateway editor.
+        cut.FindAll("select")
+           .First(s => s.QuerySelectorAll("option").Any(o => o.TextContent.Trim() == "MxGateway"))
+           .Change("MxGateway");
+
+        // Name (skip readonly Site plaintext input; MxGateway editor inputs carry placeholders).
+        cut.FindAll("input[type='text']")
+           .First(i => !i.HasAttribute("readonly") && i.GetAttribute("placeholder") is null)
+           .Change("MX-1");
+        // Gateway endpoint
+        cut.FindAll("input[type='text']")
+           .First(i => i.GetAttribute("placeholder")?.StartsWith("http://") == true)
+           .Change("http://gw:5000");
+        // API key (password input)
+        cut.FindAll("input[type='password']")
+           .First(i => i.GetAttribute("placeholder")?.Contains("API key") == true)
+           .Change("secret");
+
+        await cut.FindAll("button")
+                 .First(b => b.TextContent.Trim() == "Save").ClickAsync(new());
+
+        Assert.NotNull(captured);
+        Assert.Equal("MxGateway", captured!.Protocol);
+        Assert.NotNull(captured.PrimaryConfiguration);
+
+        using var doc = JsonDocument.Parse(captured.PrimaryConfiguration!);
+        Assert.Equal("http://gw:5000",
+            doc.RootElement.GetProperty("endpoint").GetString());
     }
 
     [Fact]