up

src/Notifier/StellaOps.Notifier/StellaOps.Notifier.Worker/Processing/SimpleTemplateRenderer.cs

@@ -0,0 +1,100 @@
+using System.Text.Json.Nodes;
+using System.Text.RegularExpressions;
+using StellaOps.Notify.Models;
+
+namespace StellaOps.Notifier.Worker.Processing;
+
+/// <summary>
+/// Simple Handlebars-like template renderer supporting {{property}} and {{#each}} blocks.
+/// </summary>
+public sealed partial class SimpleTemplateRenderer : INotifyTemplateRenderer
+{
+    private static readonly Regex PlaceholderPattern = PlaceholderRegex();
+    private static readonly Regex EachBlockPattern = EachBlockRegex();
+
+    public string Render(NotifyTemplate template, JsonNode? payload)
+    {
+        ArgumentNullException.ThrowIfNull(template);
+
+        var body = template.Body;
+        if (string.IsNullOrWhiteSpace(body))
+        {
+            return string.Empty;
+        }
+
+        // Process {{#each}} blocks first
+        body = ProcessEachBlocks(body, payload);
+
+        // Then substitute simple placeholders
+        body = SubstitutePlaceholders(body, payload);
+
+        return body;
+    }
+
+    private static string ProcessEachBlocks(string body, JsonNode? payload)
+    {
+        return EachBlockPattern.Replace(body, match =>
+        {
+            var collectionPath = match.Groups[1].Value.Trim();
+            var innerTemplate = match.Groups[2].Value;
+
+            var collection = ResolvePath(payload, collectionPath);
+            if (collection is not JsonObject obj)
+            {
+                return string.Empty;
+            }
+
+            var results = new List<string>();
+            foreach (var (key, value) in obj)
+            {
+                var itemResult = innerTemplate
+                    .Replace("{{@key}}", key)
+                    .Replace("{{this}}", value?.ToString() ?? string.Empty);
+                results.Add(itemResult);
+            }
+
+            return string.Join(string.Empty, results);
+        });
+    }
+
+    private static string SubstitutePlaceholders(string body, JsonNode? payload)
+    {
+        return PlaceholderPattern.Replace(body, match =>
+        {
+            var path = match.Groups[1].Value.Trim();
+            var resolved = ResolvePath(payload, path);
+            return resolved?.ToString() ?? string.Empty;
+        });
+    }
+
+    private static JsonNode? ResolvePath(JsonNode? root, string path)
+    {
+        if (root is null || string.IsNullOrWhiteSpace(path))
+        {
+            return null;
+        }
+
+        var segments = path.Split('.');
+        var current = root;
+
+        foreach (var segment in segments)
+        {
+            if (current is JsonObject obj && obj.TryGetPropertyValue(segment, out var next))
+            {
+                current = next;
+            }
+            else
+            {
+                return null;
+            }
+        }
+
+        return current;
+    }
+
+    [GeneratedRegex(@"\{\{([^#/}]+)\}\}", RegexOptions.Compiled)]
+    private static partial Regex PlaceholderRegex();
+
+    [GeneratedRegex(@"\{\{#each\s+([^}]+)\}\}(.*?)\{\{/each\}\}", RegexOptions.Compiled | RegexOptions.Singleline)]
+    private static partial Regex EachBlockRegex();
+}