Merge pull request #191 from PhyxionNL/issue-188

Fixes #188

src/Smidge/TagHelpers/SmidgeLinkTagHelper.cs

@@ -1,47 +1,36 @@
+using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Text.Encodings.Web;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Html;
 using Microsoft.AspNetCore.Mvc.Rendering;
 using Microsoft.AspNetCore.Razor.TagHelpers;
-using Microsoft.AspNetCore.Mvc.TagHelpers;
-using System.Collections.Generic;
-using System;
 
 namespace Smidge.TagHelpers
 {
     [HtmlTargetElement("link", Attributes = HrefAttributeName, TagStructure = TagStructure.WithoutEndTag)]
     public class SmidgeLinkTagHelper : TagHelper
     {
-        private const string HrefIncludeAttributeName = "asp-href-include";
-        private const string HrefExcludeAttributeName = "asp-href-exclude";
-        private const string FallbackHrefAttributeName = "asp-fallback-href";
-        private const string SuppressFallbackIntegrityAttributeName = "asp-suppress-fallback-integrity";
-        private const string FallbackHrefIncludeAttributeName = "asp-fallback-href-include";
-        private const string FallbackHrefExcludeAttributeName = "asp-fallback-href-exclude";
-        private const string FallbackTestClassAttributeName = "asp-fallback-test-class";
-        private const string FallbackTestPropertyAttributeName = "asp-fallback-test-property";
-        private const string FallbackTestValueAttributeName = "asp-fallback-test-value";
-        private const string AppendVersionAttributeName = "asp-append-version";
         private const string HrefAttributeName = "href";
+        private readonly IBundleManager _bundleManager;
+        private readonly HtmlEncoder _encoder;
 
-        private readonly HashSet<string> _invalid = new()
+        private readonly HashSet<string> _invalidAttributes = new()
         {
-            HrefIncludeAttributeName,
-            HrefExcludeAttributeName,
-            FallbackHrefAttributeName,
-            FallbackHrefIncludeAttributeName,
-            FallbackTestClassAttributeName,
-            FallbackTestPropertyAttributeName,
-            SuppressFallbackIntegrityAttributeName,
-            FallbackHrefExcludeAttributeName,
-            FallbackTestValueAttributeName,
-            AppendVersionAttributeName
+            "asp-href-include",
+            "asp-href-exclude",
+            "asp-fallback-href",
+            "asp-fallback-href-exclude",
+            "asp-fallback-test-class",
+            "asp-fallback-test-property",
+            "asp-fallback-test-value",
+            "asp-suppress-fallback-integrity",
+            "asp-suppress-fallback-integrity",
+            "asp-append-version"
         };
+
         private readonly SmidgeHelper _smidgeHelper;
-        private readonly IBundleManager _bundleManager;
-        private readonly HtmlEncoder _encoder;
 
         public SmidgeLinkTagHelper(SmidgeHelper smidgeHelper, IBundleManager bundleManager, HtmlEncoder encoder)
         {
@@ -50,28 +39,28 @@ public SmidgeLinkTagHelper(SmidgeHelper smidgeHelper, IBundleManager bundleManag
             _encoder = encoder;
         }
 
+        [HtmlAttributeName("debug")]
+        public bool Debug { get; set; }
+
         /// <summary>
-        /// TODO: Need to figure out why we need this. If the order is default and executes 'after' the 
+        /// TODO: Need to figure out why we need this. If the order is default and executes 'after' the
         /// default tag helpers like the script tag helper and url resolution tag helper, the url resolution
-        /// doesn't actually work, it simply doesn't get passed through. Not sure if this is a bug or if I'm 
+        /// doesn't actually work, it simply doesn't get passed through. Not sure if this is a bug or if I'm
         /// doing it wrong. In the meantime, setting this to execute before the defaults works.
         /// </summary>
         public override int Order => -2000;
 
         [HtmlAttributeName(HrefAttributeName)]
         public string Source { get; set; }
 
-        [HtmlAttributeName("debug")]
-        public bool Debug { get; set; }
-
         public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
         {
             if (string.IsNullOrWhiteSpace(Source))
             {
                 return;
             }
 
-            var exists = _bundleManager.Exists(Source);
+            bool exists = _bundleManager.Exists(Source);
 
             // Pass through attribute that is also a well-known HTML attribute.
             // this is required to make sure that other tag helpers executing against this element have
@@ -83,29 +72,32 @@ public override async Task ProcessAsync(TagHelperContext context, TagHelperOutpu
                 return;
             }
 
-            if (context.AllAttributes.Any(x => _invalid.Contains(x.Name)))
+            if (context.AllAttributes.Any(x => _invalidAttributes.Contains(x.Name)))
+            {
+                return;
+            }
+
+            if (context.AllAttributes.TryGetAttribute("as", out TagHelperAttribute attribute) && attribute.Value is not "style")
             {
-                throw new InvalidOperationException("Smidge tag helpers do not support the ASP.NET tag helpers: " + string.Join(", ", _invalid));
+                return;
             }
 
-            var result = (await _smidgeHelper.GenerateCssUrlsAsync(Source, Debug)).ToArray();
-            var currAttr = output.Attributes.ToDictionary(x => x.Name, x => x.Value);
-            using (var writer = new StringWriter())
+            var attributes = output.Attributes.ToDictionary(x => x.Name, x => x.Value);
+            await using (var writer = new StringWriter())
             {
-                foreach (var s in result)
+                foreach (var url in await _smidgeHelper.GenerateCssUrlsAsync(Source, Debug))
                 {
-                    var builder = new TagBuilder(output.TagName)
-                    {
-                        TagRenderMode = TagRenderMode.SelfClosing
-                    };
-                    builder.MergeAttributes(currAttr);
-                    builder.Attributes["href"] = s;
+                    var builder = new TagBuilder(output.TagName) { TagRenderMode = TagRenderMode.SelfClosing };
+                    builder.MergeAttributes(attributes);
+                    builder.Attributes["href"] = url;
 
                     builder.WriteTo(writer, _encoder);
                 }
-                writer.Flush();
+
+                await writer.FlushAsync();
                 output.PostElement.SetHtmlContent(new HtmlString(writer.ToString()));
             }
+
             //This ensures the original tag is not written.
             output.TagName = null;
         }