Merge CharCollection and UserDefinedCharCollection

Otherwise only CharCollection would work, and that's obsolete, now you can use either, but UserDefinedCharCollection takes priority

Author: nikolajlauridsen

src/Umbraco.Core/DependencyInjection/UmbracoBuilder.Configuration.cs

@@ -6,6 +6,7 @@
 using Microsoft.Extensions.Options;
 using Umbraco.Cms.Core.Configuration.Models;
 using Umbraco.Cms.Core.Configuration.Models.Validation;
+using Umbraco.Extensions;
 
 namespace Umbraco.Cms.Core.DependencyInjection
 {
@@ -78,23 +79,7 @@ public static IUmbracoBuilder AddConfiguration(this IUmbracoBuilder builder)
                 .AddUmbracoOptions<LegacyPasswordMigrationSettings>()
                 .AddUmbracoOptions<PackageMigrationSettings>();
 
-            builder.Services.Configure<RequestHandlerSettings>(options =>
-            {
-                var userDefinedReplacements = new List<CharItem>();
-                IEnumerable<IConfigurationSection> config = builder.Config
-                    .GetSection(
-                        $"{Constants.Configuration.ConfigRequestHandler}:{nameof(RequestHandlerSettings.CharCollection)}")
-                    .GetChildren();
-
-                foreach (IConfigurationSection section in config)
-                {
-                    var @char = section.GetValue<string>(nameof(CharItem.Char));
-                    var replacement = section.GetValue<string>(nameof(CharItem.Replacement));
-                    userDefinedReplacements.Add(new CharItem { Char = @char, Replacement = replacement });
-                }
-
-                options.UserDefinedCharCollection = userDefinedReplacements;
-            });
+            builder.Services.Configure<RequestHandlerSettings>(options => options.MergeReplacements(builder.Config));
 
             return builder;
         }

src/Umbraco.Core/Extensions/RequestHandlerSettingsExtension.cs

@@ -1,5 +1,7 @@
 using System.Collections.Generic;
 using System.Linq;
+using Microsoft.Extensions.Configuration;
+using Umbraco.Cms.Core;
 using Umbraco.Cms.Core.Configuration.Models;
 using Umbraco.Cms.Core.Configuration.UmbracoSettings;
 
@@ -11,34 +13,84 @@ namespace Umbraco.Extensions
     /// </summary>
     public static class RequestHandlerSettingsExtension
     {
+        /// <summary>
+        /// Get concatenated user and default character replacements
+        /// taking into account <see cref="RequestHandlerSettings.EnableDefaultCharReplacements"/>
+        /// </summary>
         public static IEnumerable<CharItem> GetCharReplacements(this RequestHandlerSettings requestHandlerSettings)
         {
-            if (!requestHandlerSettings.EnableDefaultCharReplacements)
+            if (requestHandlerSettings.EnableDefaultCharReplacements is false)
             {
                 return requestHandlerSettings.UserDefinedCharCollection ?? Enumerable.Empty<CharItem>();
             }
 
-            if (requestHandlerSettings.UserDefinedCharCollection == null || !requestHandlerSettings.UserDefinedCharCollection.Any())
+            if (requestHandlerSettings.UserDefinedCharCollection == null || requestHandlerSettings.UserDefinedCharCollection.Any() is false)
             {
                 return RequestHandlerSettings.DefaultCharCollection;
             }
 
-            foreach (CharItem defaultReplacement in RequestHandlerSettings.DefaultCharCollection)
+            return MergeUnique(requestHandlerSettings.UserDefinedCharCollection, RequestHandlerSettings.DefaultCharCollection);
+        }
+
+        /// <summary>
+        /// Merges CharCollection and UserDefinedCharCollection, prioritizing UserDefinedCharCollection
+        /// </summary>
+        internal static void MergeReplacements(this RequestHandlerSettings requestHandlerSettings, IConfiguration configuration)
+        {
+            string sectionKey = $"{Constants.Configuration.ConfigRequestHandler}:";
+
+            IEnumerable<CharItem> charCollection = GetReplacements(
+                configuration,
+                $"{sectionKey}{nameof(RequestHandlerSettings.CharCollection)}");
+
+            IEnumerable<CharItem> userDefinedCharCollection = GetReplacements(
+                configuration,
+                $"{sectionKey}{nameof(requestHandlerSettings.UserDefinedCharCollection)}");
+
+            IEnumerable<CharItem> mergedCollection = MergeUnique(userDefinedCharCollection, charCollection);
+
+            requestHandlerSettings.UserDefinedCharCollection = mergedCollection;
+        }
+
+        private static IEnumerable<CharItem> GetReplacements(IConfiguration configuration, string key)
+        {
+            var replacements = new List<CharItem>();
+            IEnumerable<IConfigurationSection> config = configuration.GetSection(key).GetChildren();
+
+            foreach (IConfigurationSection section in config)
             {
-                foreach (CharItem userReplacement in requestHandlerSettings.UserDefinedCharCollection)
+                var @char = section.GetValue<string>(nameof(CharItem.Char));
+                var replacement = section.GetValue<string>(nameof(CharItem.Replacement));
+                replacements.Add(new CharItem { Char = @char, Replacement = replacement });
+            }
+
+            return replacements;
+        }
+
+        /// <summary>
+        /// Merges two IEnumerable of CharItem without any duplicates, items in priorityReplacements will override those in alternativeReplacements
+        /// </summary>
+        private static IEnumerable<CharItem> MergeUnique(
+            IEnumerable<CharItem> priorityReplacements,
+            IEnumerable<CharItem> alternativeReplacements)
+        {
+            var priorityReplacementsList = priorityReplacements.ToList();
+            var alternativeReplacementsList = alternativeReplacements.ToList();
+
+            foreach (CharItem alternativeReplacement in alternativeReplacementsList)
+            {
+                foreach (CharItem priorityReplacement in priorityReplacementsList)
                 {
-                    if (userReplacement.Char == defaultReplacement.Char)
+                    if (priorityReplacement.Char == alternativeReplacement.Char)
                     {
-                        defaultReplacement.Replacement = userReplacement.Replacement;
+                        alternativeReplacement.Replacement = priorityReplacement.Replacement;
                     }
                 }
             }
 
-            IEnumerable<CharItem> mergedCollections =
-                RequestHandlerSettings.DefaultCharCollection.Union<CharItem>(
-                    requestHandlerSettings.UserDefinedCharCollection, new CharacterReplacementEqualityComparer());
-
-            return mergedCollections;
+            return priorityReplacementsList.Union<CharItem>(
+                alternativeReplacementsList,
+                new CharacterReplacementEqualityComparer());
         }
     }
 }