Validate workflow rule writes

MeetingAssistant/Workflow/MeetingWorkflowEngine.cs

@@ -3,7 +3,6 @@ using System.Globalization;
 using System.Text.RegularExpressions;
 using MeetingAssistant.MeetingNotes;
 using NCalc;
-using RazorLight;
 
 namespace MeetingAssistant.Workflow;
 
@@ -30,10 +29,6 @@ public sealed class NoopMeetingWorkflowEngine : IMeetingWorkflowEngine
 
 public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
 {
-    private static readonly Regex EmailAddressPattern = new(
-        @"(?<![A-Za-z0-9.!#$%&'*+/=?^_`{|}~-])(?<local>[A-Za-z0-9.!#$%&'*+/=?^_`{|}~-]+)@(?<domain>(?:[A-Za-z0-9](?:[A-Za-z0-9-]{0,61}[A-Za-z0-9])?\.)+[A-Za-z]{2,63})(?![A-Za-z0-9-])",
-        RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase);
-
     private static readonly string[] ParameterNames =
     [
         "meeting.attendees.count",
@@ -51,9 +46,7 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
     private readonly IMeetingNoteStore meetingNoteStore;
     private readonly IMeetingArtifactStore meetingArtifactStore;
     private readonly ILogger<MeetingWorkflowEngine> logger;
-    private readonly RazorLightEngine razorEngine = new RazorLightEngineBuilder()
-        .UseNoProject()
-        .Build();
+    private readonly MeetingWorkflowTemplateRenderer templateRenderer = new();
 
     public MeetingWorkflowEngine(
         IMeetingWorkflowRulesProvider rulesProvider,
@@ -256,63 +249,7 @@ public sealed class MeetingWorkflowEngine : IMeetingWorkflowEngine
         string template,
         MeetingWorkflowTemplateModel model)
     {
-        if (!ContainsRazorTemplateSyntax(template))
-        {
-            return template;
-        }
-
-        return await razorEngine.CompileRenderStringAsync(
-            Guid.NewGuid().ToString("N"),
-            EscapeEmailAddressAtSigns(template),
-            model);
-    }
-
-    private static bool ContainsRazorTemplateSyntax(string value)
-    {
-        if (!value.Contains('@', StringComparison.Ordinal))
-        {
-            return false;
-        }
-
-        var emailAtSigns = EmailAddressPattern
-            .Matches(value)
-            .Select(match => match.Index + match.Value.IndexOf('@', StringComparison.Ordinal))
-            .ToHashSet();
-
-        for (var index = 0; index < value.Length; index++)
-        {
-            if (value[index] != '@')
-            {
-                continue;
-            }
-
-            if (index + 1 < value.Length && value[index + 1] == '@')
-            {
-                index++;
-                continue;
-            }
-
-            if (emailAtSigns.Contains(index))
-            {
-                continue;
-            }
-
-            return true;
-        }
-
-        return false;
-    }
-
-    private static string EscapeEmailAddressAtSigns(string value)
-    {
-        if (!value.Contains('@', StringComparison.Ordinal))
-        {
-            return value;
-        }
-
-        return EmailAddressPattern.Replace(
-            value,
-            match => match.Value.Replace("@", "@@", StringComparison.Ordinal));
+        return await templateRenderer.RenderAsync(template, model);
     }
 
     private static bool SetProperty(