Add preload order property and sort headers

Author: maraf

src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Streaming.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics;
+using System.Linq;
 using System.Runtime.InteropServices;
 using System.Text;
 using System.Text.Encodings.Web;
@@ -323,7 +324,7 @@ private void AppendWebAssemblyPreloadHeaders()
         var assets = _httpContext.GetEndpoint()?.Metadata.GetMetadata<ResourceAssetCollection>();
         if (assets != null)
         {
-            var headers = new List<string>();
+            var headers = new List<(string? Order, string Value)>();
             foreach (var asset in assets)
             {
                 if (asset.Properties == null)
@@ -347,6 +348,7 @@ private void AppendWebAssemblyPreloadHeaders()
                     continue;
                 }
 
+                string? order = null;
                 foreach (var property in asset.Properties)
                 {
                     if (property.Name.Equals("preloadas", StringComparison.OrdinalIgnoreCase))
@@ -365,15 +367,20 @@ private void AppendWebAssemblyPreloadHeaders()
                     {
                         header = String.Concat(header, "; integrity=\"", property.Value, "\"");
                     }
+                    else if (property.Name.Equals("preloadorder", StringComparison.OrdinalIgnoreCase))
+                    {
+                        order = property.Value;
+                    }
                 }
 
                 if (header != null)
                 {
-                    headers.Add(header);
+                    headers.Add((order, header));
                 }
             }
 
-            _httpContext.Response.Headers.Link = StringValues.Concat(_httpContext.Response.Headers.Link, headers.ToArray());
+            headers.Sort((a, b) => string.Compare(a.Order, b.Order, StringComparison.InvariantCulture));
+            _httpContext.Response.Headers.Link = StringValues.Concat(_httpContext.Response.Headers.Link, headers.Select(h => h.Value).ToArray());
         }
     }
 

src/Shared/Components/ResourceCollectionResolver.cs

@@ -46,13 +46,15 @@ public ResourceAssetCollection ResolveResourceCollection()
             string? preloadAs = null;
             string? preloadPriority = null;
             string? preloadCrossorigin = null;
+            string? preloadOrder = null;
 #else
             string label = null;
             string integrity = null;
             string preloadRel = null;
             string preloadAs = null;
             string preloadPriority = null;
             string preloadCrossorigin = null;
+            string preloadOrder = null;
 #endif
 
             // If there's a selector this means that this is an alternative representation for a resource, so skip it.
@@ -92,9 +94,14 @@ public ResourceAssetCollection ResolveResourceCollection()
                         preloadCrossorigin = property.Value;
                         foundProperties++;
                     }
+                    else if (property.Name.Equals("preloadorder", StringComparison.OrdinalIgnoreCase))
+                    {
+                        preloadOrder = property.Value;
+                        foundProperties++;
+                    }
                 }
 
-                AddResource(resources, descriptor, label, integrity, preloadRel, preloadAs, preloadPriority, preloadCrossorigin, foundProperties);
+                AddResource(resources, descriptor, label, integrity, preloadRel, preloadAs, preloadPriority, preloadCrossorigin, preloadOrder, foundProperties);
             }
         }
 
@@ -128,13 +135,15 @@ private static void AddResource(
         string? preloadAs,
         string? preloadPriority,
         string? preloadCrossorigin,
+        string? preloadOrder,
 #else
         string label,
         string integrity,
         string preloadRel,
         string preloadAs,
         string preloadPriority,
         string preloadCrossorigin,
+        string preloadOrder,
 #endif
     int foundProperties)
     {
@@ -166,6 +175,10 @@ private static void AddResource(
             {
                 properties[index++] = new ResourceAssetProperty("preloadcrossorigin", preloadCrossorigin);
             }
+            if (preloadOrder != null)
+            {
+                properties[index++] = new ResourceAssetProperty("preloadorder", preloadOrder);
+            }
 
             resources.Add(new ResourceAsset(descriptor.Route, properties));
         }