ProxyUrlTransformer (#1361)

* ProxyUrlTransformer

* tests

* Update src/WireMock.Net.Shared/Settings/ProxyUrlReplaceSettings.cs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

src/WireMock.Net.Minimal/Http/WebhookSender.cs

@@ -11,24 +11,17 @@ using Stef.Validation;
 using WireMock.Models;
 using WireMock.Settings;
 using WireMock.Transformers;
-using WireMock.Transformers.Handlebars;
-using WireMock.Transformers.Scriban;
 using WireMock.Types;
 using WireMock.Util;
 
 namespace WireMock.Http;
 
-internal class WebhookSender
+internal class WebhookSender(WireMockServerSettings settings)
 {
     private const string ClientIp = "::1";
     private static readonly ThreadLocal<Random> Random = new(() => new Random(DateTime.UtcNow.Millisecond));
 
-    private readonly WireMockServerSettings _settings;
-
-    public WebhookSender(WireMockServerSettings settings)
-    {
-        _settings = Guard.NotNull(settings);
-    }
+    private readonly WireMockServerSettings _settings = Guard.NotNull(settings);
 
     public async Task<HttpResponseMessage> SendAsync(
         HttpClient client,
@@ -49,24 +42,7 @@ internal class WebhookSender
         string requestUrl;
         if (webhookRequest.UseTransformer == true)
         {
-            ITransformer transformer;
-            switch (webhookRequest.TransformerType)
-            {
-                case TransformerType.Handlebars:
-                    var factoryHandlebars = new HandlebarsContextFactory(_settings);
-                    transformer = new Transformer(_settings, factoryHandlebars);
-                    break;
-
-                case TransformerType.Scriban:
-                case TransformerType.ScribanDotLiquid:
-                    var factoryDotLiquid = new ScribanContextFactory(_settings.FileSystemHandler, webhookRequest.TransformerType);
-                    transformer = new Transformer(_settings, factoryDotLiquid);
-                    break;
-
-                default:
-                    throw new NotImplementedException($"TransformerType '{webhookRequest.TransformerType}' is not supported.");
-            }
-
+            var transformer = TransformerFactory.Create(webhookRequest.TransformerType, _settings);
             bodyData = transformer.TransformBody(mapping, originalRequestMessage, originalResponseMessage, webhookRequest.BodyData, webhookRequest.TransformerReplaceNodeOptions);
             headers = transformer.TransformHeaders(mapping, originalRequestMessage, originalResponseMessage, webhookRequest.Headers);
             requestUrl = transformer.TransformString(mapping, originalRequestMessage, originalResponseMessage, webhookRequest.Url);

src/WireMock.Net.Minimal/Proxy/ProxyHelper.cs

@@ -13,16 +13,10 @@ using WireMock.Util;
 
 namespace WireMock.Proxy;
 
-internal class ProxyHelper
+internal class ProxyHelper(WireMockServerSettings settings)
 {
-    private readonly WireMockServerSettings _settings;
-    private readonly ProxyMappingConverter _proxyMappingConverter;
-
-    public ProxyHelper(WireMockServerSettings settings)
-    {
-        _settings = Guard.NotNull(settings);
-        _proxyMappingConverter = new ProxyMappingConverter(settings, new GuidUtils(), new DateTimeUtils());
-    }
+    private readonly WireMockServerSettings _settings = Guard.NotNull(settings);
+    private readonly ProxyMappingConverter _proxyMappingConverter = new(settings, new GuidUtils(), new DateTimeUtils());
 
     public async Task<(IResponseMessage Message, IMapping? Mapping)> SendAsync(
         IMapping? mapping,
@@ -39,18 +33,7 @@ internal class ProxyHelper
         var requiredUri = new Uri(url);
 
         // Create HttpRequestMessage
-        var replaceSettings = proxyAndRecordSettings.ReplaceSettings;
-        string proxyUrl;
-        if (replaceSettings is not null)
-        {
-            var stringComparison = replaceSettings.IgnoreCase ? StringComparison.OrdinalIgnoreCase : StringComparison.Ordinal;
-            proxyUrl = url.Replace(replaceSettings.OldValue, replaceSettings.NewValue, stringComparison);
-        }
-        else
-        {
-            proxyUrl = url;
-        }
-
+        var proxyUrl = proxyAndRecordSettings.ReplaceSettings != null ? ProxyUrlTransformer.Transform(_settings, proxyAndRecordSettings.ReplaceSettings, url) : url;
         var httpRequestMessage = HttpRequestMessageHelper.Create(requestMessage, proxyUrl);
 
         // Call the URL

src/WireMock.Net.Minimal/Proxy/ProxyUrlTransformer.cs

@@ -0,0 +1,21 @@
+// Copyright © WireMock.Net
+
+using System;
+using WireMock.Settings;
+using WireMock.Transformers;
+
+namespace WireMock.Proxy;
+
+internal static class ProxyUrlTransformer
+{
+    internal static string Transform(WireMockServerSettings settings, ProxyUrlReplaceSettings replaceSettings, string url)
+    {
+        if (!replaceSettings.UseTransformer)
+        {
+            return url.Replace(replaceSettings.OldValue, replaceSettings.NewValue, replaceSettings.IgnoreCase ? StringComparison.OrdinalIgnoreCase : StringComparison.Ordinal);
+        }
+        
+        var transformer = TransformerFactory.Create(replaceSettings.TransformerType, settings);
+        return transformer.Transform(replaceSettings.TransformTemplate, url);
+    }
+}

src/WireMock.Net.Minimal/ResponseBuilders/Response.cs

@@ -272,25 +272,8 @@ public partial class Response : IResponseBuilder
                 }
             }
 
-            ITransformer responseMessageTransformer;
-            switch (TransformerType)
-            {
-                case TransformerType.Handlebars:
-                    var factoryHandlebars = new HandlebarsContextFactory(settings);
-                    responseMessageTransformer = new Transformer(settings, factoryHandlebars);
-                    break;
-
-                case TransformerType.Scriban:
-                case TransformerType.ScribanDotLiquid:
-                    var factoryDotLiquid = new ScribanContextFactory(settings.FileSystemHandler, TransformerType);
-                    responseMessageTransformer = new Transformer(settings, factoryDotLiquid);
-                    break;
-
-                default:
-                    throw new NotSupportedException($"TransformerType '{TransformerType}' is not supported.");
-            }
-
-            return (responseMessageTransformer.Transform(mapping, requestMessage, responseMessage, UseTransformerForBodyAsFile, TransformerReplaceNodeOptions), null);
+            var transformer = TransformerFactory.Create(TransformerType, settings);
+            return (transformer.Transform(mapping, requestMessage, responseMessage, UseTransformerForBodyAsFile, TransformerReplaceNodeOptions), null);
         }
 
         if (!UseTransformer && ResponseMessage.BodyData?.BodyAsFileIsCached == true && responseMessage.BodyData?.BodyAsFile is not null)

src/WireMock.Net.Minimal/Transformers/ITransformer.cs

@@ -6,7 +6,7 @@ using WireMock.Util;
 
 namespace WireMock.Transformers;
 
-interface ITransformer
+internal interface ITransformer
 {
     ResponseMessage Transform(IMapping mapping, IRequestMessage requestMessage, IResponseMessage original, bool useTransformerForBodyAsFile, ReplaceNodeOptions options);
 
@@ -15,4 +15,6 @@ interface ITransformer
     IDictionary<string, WireMockList<string>> TransformHeaders(IMapping mapping, IRequestMessage originalRequestMessage, IResponseMessage originalResponseMessage, IDictionary<string, WireMockList<string>>? headers);
 
     string TransformString(IMapping mapping, IRequestMessage originalRequestMessage, IResponseMessage originalResponseMessage, string? value);
+
+    string Transform(string template, object? model);
 }

src/WireMock.Net.Minimal/Transformers/ITransformerContextFactory.cs

@@ -1,9 +1,8 @@
 // Copyright © WireMock.Net
 
-namespace WireMock.Transformers
+namespace WireMock.Transformers;
+
+internal interface ITransformerContextFactory
 {
-    interface ITransformerContextFactory
-    {
-        ITransformerContext Create();
-    }
+    ITransformerContext Create();
 }

src/WireMock.Net.Minimal/Transformers/Transformer.cs

@@ -75,6 +75,11 @@ internal class Transformer : ITransformer
         return transformerContext.ParseAndRender(value, model);
     }
 
+    public string Transform(string template, object? model)
+    {
+        return model is null ? string.Empty : _factory.Create().ParseAndRender(template, model);
+    }
+
     public ResponseMessage Transform(IMapping mapping, IRequestMessage requestMessage, IResponseMessage original, bool useTransformerForBodyAsFile, ReplaceNodeOptions options)
     {
         var responseMessage = new ResponseMessage();

src/WireMock.Net.Minimal/Transformers/TransformerFactory.cs

@@ -0,0 +1,30 @@
+// Copyright © WireMock.Net
+
+using System;
+using WireMock.Settings;
+using WireMock.Transformers.Handlebars;
+using WireMock.Transformers.Scriban;
+using WireMock.Types;
+
+namespace WireMock.Transformers;
+
+internal static class TransformerFactory
+{
+    internal static ITransformer Create(TransformerType transformerType, WireMockServerSettings settings)
+    {
+        switch (transformerType)
+        {
+            case TransformerType.Handlebars:
+                var factoryHandlebars = new HandlebarsContextFactory(settings);
+                return new Transformer(settings, factoryHandlebars);
+                
+            case TransformerType.Scriban:
+            case TransformerType.ScribanDotLiquid:
+                var factoryDotLiquid = new ScribanContextFactory(settings.FileSystemHandler, transformerType);
+                return new Transformer(settings, factoryDotLiquid);
+
+            default:
+                throw new NotSupportedException($"{nameof(TransformerType)} '{transformerType}' is not supported.");
+        }
+    }
+}

src/WireMock.Net.Shared/Settings/ProxyUrlReplaceSettings.cs

@@ -1,5 +1,8 @@
 // Copyright © WireMock.Net
 
+using System.Diagnostics.CodeAnalysis;
+using WireMock.Types;
+
 namespace WireMock.Settings;
 
 /// <summary>
@@ -8,17 +11,35 @@ namespace WireMock.Settings;
 public class ProxyUrlReplaceSettings
 {
     /// <summary>
-    /// The old path value to be replaced by the new path value
+    /// The old path value to be replaced by the new path value.
     /// </summary>
-    public string OldValue { get; set; } = null!;
+    public string? OldValue { get; set; }
 
     /// <summary>
-    /// The new path value to replace the old value with
+    /// The new path value to replace the old value with.
     /// </summary>
-    public string NewValue { get; set; } = null!;
+    public string? NewValue { get; set; }
 
     /// <summary>
     /// Defines if the case should be ignored when replacing.
     /// </summary>
     public bool IgnoreCase { get; set; }
+
+    /// <summary>
+    /// Holds the transformation template used when <see cref="UseTransformer"/> is true.
+    /// </summary>
+    public string? TransformTemplate { get; set; }
+
+    /// <summary>
+    /// Use Transformer.
+    /// </summary>
+    [MemberNotNullWhen(true, nameof(TransformTemplate))]
+    [MemberNotNullWhen(false, nameof(OldValue))]
+    [MemberNotNullWhen(false, nameof(NewValue))]
+    public bool UseTransformer => !string.IsNullOrEmpty(TransformTemplate);
+
+    /// <summary>
+    /// The transformer type, in case <see cref="UseTransformer"/> is set to <c>true</c>.
+    /// </summary>
+    public TransformerType TransformerType { get; set; } = TransformerType.Handlebars;
 }

test/WireMock.Net.Tests/Proxy/ProxyUrlTransformerTests.cs

@@ -0,0 +1,98 @@
+using System.Globalization;
+using Moq;
+using WireMock.Handlers;
+using WireMock.Proxy;
+using WireMock.Settings;
+using WireMock.Types;
+using Xunit;
+
+namespace WireMock.Net.Tests.Proxy;
+
+public class ProxyUrlTransformerTests
+{
+    private readonly Mock<IFileSystemHandler> _fileSystemHandlerMock = new();
+
+    [Fact]
+    public void Transform_WithUseTransformerFalse_PerformsSimpleReplace_CaseSensitive()
+    {
+        // Arrange
+        var settings = new WireMockServerSettings
+        {
+            FileSystemHandler = _fileSystemHandlerMock.Object,
+            Culture = CultureInfo.InvariantCulture
+        };
+
+        var replaceSettings = new ProxyUrlReplaceSettings
+        {
+            TransformTemplate = null,
+            OldValue = "/old",
+            NewValue = "/new",
+            IgnoreCase = false
+        };
+
+        var url = "http://example.com/old/path";
+        var expected = "http://example.com/new/path";
+
+        // Act
+        var actual = ProxyUrlTransformer.Transform(settings, replaceSettings, url);
+
+        // Assert
+        Assert.Equal(expected, actual);
+    }
+
+    [Fact]
+    public void Transform_WithUseTransformerFalse_PerformsSimpleReplace_IgnoreCase()
+    {
+        // Arrange
+        var settings = new WireMockServerSettings
+        {
+            FileSystemHandler = _fileSystemHandlerMock.Object,
+            Culture = CultureInfo.InvariantCulture
+        };
+
+        var replaceSettings = new ProxyUrlReplaceSettings
+        {
+            TransformTemplate = null, // UseTransformer == false
+            OldValue = "/OLD",
+            NewValue = "/new",
+            IgnoreCase = true
+        };
+
+        var url = "http://example.com/old/path"; // lowercase 'old' but OldValue is uppercase
+        var expected = "http://example.com/new/path";
+
+        // Act
+        var actual = ProxyUrlTransformer.Transform(settings, replaceSettings, url);
+
+        // Assert
+        Assert.Equal(expected, actual);
+    }
+
+    [Fact]
+    public void Transform_WithUseTransformerTrue_UsesTransformer_ToTransformUrl()
+    {
+        // Arrange
+        var settings = new WireMockServerSettings
+        {
+            FileSystemHandler = _fileSystemHandlerMock.Object,
+            Culture = CultureInfo.InvariantCulture
+        };
+
+        // Handlebars is the default TransformerType; the TransformTemplate uses the model directly.
+        var replaceSettings = new ProxyUrlReplaceSettings
+        {
+            TransformTemplate = "{{this}}-transformed",
+            // TransformerType defaults to Handlebars but set explicitly for clarity.
+            TransformerType = TransformerType.Handlebars
+        };
+
+        var url = "http://example.com/path";
+        var expected = "http://example.com/path-transformed";
+
+        // Act
+        var actual = ProxyUrlTransformer.Transform(settings, replaceSettings, url);
+
+        // Assert
+        Assert.Equal(expected, actual);
+    }
+}