From fb926fbf737ce278ab9fec58dd5aa416792df2e6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20H=C3=A4kli?= <ville.hakli@iki.fi>
Date: Wed, 29 Nov 2023 04:08:33 +0200
Subject: [PATCH] feat: allow configuring Liquid parser (#18)

---
 .../FluentEmail.Liquid/LiquidRenderer.cs      |  1 +
 .../LiquidRendererOptions.cs                  |  5 +++
 test/FluentEmail.Liquid.Tests/LiquidTests.cs  | 34 ++++++++++++++++++-
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/src/Renderers/FluentEmail.Liquid/LiquidRenderer.cs b/src/Renderers/FluentEmail.Liquid/LiquidRenderer.cs
index fe53645a..1d7d2725 100644
--- a/src/Renderers/FluentEmail.Liquid/LiquidRenderer.cs
+++ b/src/Renderers/FluentEmail.Liquid/LiquidRenderer.cs
@@ -19,6 +19,7 @@ public LiquidRenderer(IOptions<LiquidRendererOptions> options)
         {
             _options = options;
             _parser = new LiquidParser();
+            _options.Value.ConfigureParser?.Invoke(_parser);
         }
 
         public string Parse<T>(string template, T model, bool isHtml = true)
diff --git a/src/Renderers/FluentEmail.Liquid/LiquidRendererOptions.cs b/src/Renderers/FluentEmail.Liquid/LiquidRendererOptions.cs
index f1debd78..ad477118 100644
--- a/src/Renderers/FluentEmail.Liquid/LiquidRendererOptions.cs
+++ b/src/Renderers/FluentEmail.Liquid/LiquidRendererOptions.cs
@@ -30,5 +30,10 @@ public class LiquidRendererOptions
         /// Set custom Template Options for Fluid 
         /// </summary>
         public TemplateOptions TemplateOptions { get; set; } = new TemplateOptions();
+
+        /// <summary>
+        /// Allows configuring parser
+        /// </summary>
+        public Action<LiquidParser>? ConfigureParser { get; set; }
     }
 }
diff --git a/test/FluentEmail.Liquid.Tests/LiquidTests.cs b/test/FluentEmail.Liquid.Tests/LiquidTests.cs
index 2d53e3b9..7300f200 100644
--- a/test/FluentEmail.Liquid.Tests/LiquidTests.cs
+++ b/test/FluentEmail.Liquid.Tests/LiquidTests.cs
@@ -1,9 +1,13 @@
 using System;
 using System.IO;
 using System.Reflection;
+using System.Text.Encodings.Web;
+using System.Threading.Tasks;
+
 using FluentEmail.Core;
 
 using Fluid;
+using Fluid.Ast;
 
 using Microsoft.Extensions.FileProviders;
 using Microsoft.Extensions.Options;
@@ -27,12 +31,14 @@ public void SetUp()
 
         private static void SetupRenderer(
             IFileProvider fileProvider = null,
-            Action<TemplateContext, object> configureTemplateContext = null)
+            Action<TemplateContext, object> configureTemplateContext = null,
+            Action<LiquidParser> configureParser = null)
         {
             var options = new LiquidRendererOptions
             {
                 FileProvider = fileProvider,
                 ConfigureTemplateContext = configureTemplateContext,
+                ConfigureParser = configureParser
             };
             Email.DefaultRenderer = new LiquidRenderer(Options.Create(options));
         }
@@ -181,6 +187,32 @@ public void Should_be_able_to_use_embedded_layout()
             Assert.AreEqual($"<h2>Hello!</h2>{Environment.NewLine}<div>{Environment.NewLine}sup LUKE here is a list 123</div>", email.Data.Body);
         }
 
+        [Test]
+        public void Should_be_able_to_configure_parser()
+        {
+            SetupRenderer(
+                new EmbeddedFileProvider(typeof(LiquidTests).Assembly, "FluentEmail.Liquid.Tests.EmailTemplates"),
+                configureParser: parser => parser.RegisterExpressionTag("testTag", TestTag)
+            );
+
+            const string template = "sup {{ Name }} here is a custom tag: {% testTag 'test' %}";
+
+            var email = Email
+                .From(FromEmail)
+                .To(ToEmail)
+                .Subject(Subject)
+                .UsingTemplate(template, new ViewModel { Name = "LUKE" });
+
+            Assert.AreEqual("sup LUKE here is a custom tag: Hello from custom tag test", email.Data.Body);
+
+            static async ValueTask<Completion> TestTag(Expression pathExpression, TextWriter writer, TextEncoder encoder, TemplateContext context)
+            {
+                var tagParameterValue = await pathExpression.EvaluateAsync(context);
+                await writer.WriteAsync($"Hello from custom tag {tagParameterValue.ToStringValue()}");
+                return Completion.Normal;
+            }
+        }
+
         private class ViewModel
         {
             public string Name { get; set; }