Refactor HttpBrowserCapability to support this[]

src/Microsoft.AspNetCore.SystemWebAdapters.CoreServices/SystemWebAdaptersExtensions.cs

@@ -18,7 +18,7 @@ public static ISystemWebAdapterBuilder AddSystemWebAdapters(this IServiceCollect
         services.AddHttpContextAccessor();
         services.AddSingleton<IHttpRuntime>(_ => HttpRuntimeFactory.Create());
         services.AddSingleton<Cache>();
-        services.AddSingleton<BrowserCapabilitiesFactory>();
+        services.AddSingleton<IBrowserCapabilitiesFactory, BrowserCapabilitiesFactory>();
         services.AddTransient<IStartupFilter, HttpContextStartupFilter>();
 
         return new SystemWebAdapterBuilder(services)

src/Microsoft.AspNetCore.SystemWebAdapters/Adapters/IBrowserCapabilitiesFactory.cs

@@ -0,0 +1,11 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.SystemWebAdapters;
+
+#if NET6_0_OR_GREATER
+public interface IBrowserCapabilitiesFactory
+{
+    IHttpBrowserCapabilityFeature Create(HttpRequestCore request);
+}
+#endif

src/Microsoft.AspNetCore.SystemWebAdapters/Adapters/IHttpBrowserCapabilityFeature.cs

@@ -0,0 +1,11 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.SystemWebAdapters;
+
+#if NET6_0_OR_GREATER
+public interface IHttpBrowserCapabilityFeature
+{
+    string? this[string key] { get; }
+}
+#endif

src/Microsoft.AspNetCore.SystemWebAdapters/Configuration/BrowserCapabilitiesFactory.cs

@@ -1,7 +1,12 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Collections.Generic;
+using System.Diagnostics;
 using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.SystemWebAdapters;
+using Microsoft.Extensions.Caching.Memory;
+using Microsoft.Extensions.DependencyInjection;
 
 namespace System.Web.Configuration;
 
@@ -18,7 +23,7 @@ namespace System.Web.Configuration;
 ///   to do custom stuff. These are not implemented in the framework and are potentially added by uses. For now, we don't
 ///   support that pattern.
 /// </summary>
-internal class BrowserCapabilitiesFactory
+internal sealed class BrowserCapabilitiesFactory : IBrowserCapabilitiesFactory
 {
     // Func will return true if we want to end the processing of further funcs
     private readonly Func<string, ParsedBrowserResult, bool>[] _processList;
@@ -40,7 +45,30 @@ public BrowserCapabilitiesFactory()
         };
     }
 
-    public ParsedBrowserResult Process(string userAgent)
+    IHttpBrowserCapabilityFeature IBrowserCapabilitiesFactory.Create(HttpRequestCore request)
+    {
+        var userAgent = request.Headers.UserAgent;
+
+        if (string.IsNullOrWhiteSpace(userAgent))
+        {
+            return EmptyBrowserFeatures.Instance;
+        }
+        else if (request.HttpContext.RequestServices.GetService<IMemoryCache>() is { } cache)
+        {
+            return cache.GetOrCreate<IHttpBrowserCapabilityFeature>(userAgent, entry =>
+            {
+                entry.SlidingExpiration = TimeSpan.FromMinutes(2);
+
+                return Parse(userAgent);
+            });
+        }
+        else
+        {
+            return Parse(userAgent);
+        }
+    }
+
+    public IHttpBrowserCapabilityFeature Parse(string userAgent)
     {
         var dictionary = new ParsedBrowserResult();
 
@@ -621,7 +649,23 @@ private bool UcbrowserProcess(string userAgent, ParsedBrowserResult dictionary)
         return false;
     }
 
-    private struct RegexResult
+    private sealed class ParsedBrowserResult : Dictionary<string, string?>, IHttpBrowserCapabilityFeature
+    {
+        public ParsedBrowserResult()
+            : base(StringComparer.OrdinalIgnoreCase)
+        {
+        }
+
+        [Conditional("NotNeededYet")]
+        [Diagnostics.CodeAnalysis.SuppressMessage("Performance", "CA1822:Mark members as static", Justification = "Retained in case we need the data later")]
+        public void AddBrowser(string browser)
+        {
+        }
+
+        string? IHttpBrowserCapabilityFeature.this[string key] => TryGetValue(key, out var value) ? value : null;
+    }
+
+    private readonly struct RegexResult
     {
         private readonly Match? _match;
         private readonly Match? _match2;
@@ -655,7 +699,7 @@ public RegexResult(Match? match, Match? match2)
         }
     }
 
-    private class RegexWorker
+    private sealed class RegexWorker
     {
         private readonly Regex _regex;
         private readonly Regex? _regex2;
@@ -673,4 +717,11 @@ public RegexWorker(string pattern, string? pattern2 = null)
         public RegexResult Process(string userAgent)
             => new(_regex?.Match(userAgent), _regex2?.Match(userAgent));
     }
+
+    private sealed class EmptyBrowserFeatures : IHttpBrowserCapabilityFeature
+    {
+        public static IHttpBrowserCapabilityFeature Instance { get; } = new EmptyBrowserFeatures();
+
+        public string? this[string key] => null;
+    }
 }

src/Microsoft.AspNetCore.SystemWebAdapters/Configuration/HttpCapabilitiesBase.cs

@@ -1,28 +1,92 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Globalization;
+using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.SystemWebAdapters;
+using Microsoft.Extensions.DependencyInjection;
+
 namespace System.Web.Configuration;
 
 public class HttpCapabilitiesBase
 {
-    private readonly ParsedBrowserResult _data;
+    private readonly HttpContextCore _context;
+
+    private FeatureReference<IHttpBrowserCapabilityFeature> _capability;
+
+    private protected HttpCapabilitiesBase(HttpContextCore context)
+    {
+        _context = context;
+        _capability = FeatureReference<IHttpBrowserCapabilityFeature>.Default;
+    }
 
-    private protected HttpCapabilitiesBase(BrowserCapabilitiesFactory factory, string userAgent)
+    private IHttpBrowserCapabilityFeature Capability
     {
-        _data = factory.Process(userAgent);
+        get
+        {
+            if (_capability.Fetch(_context.Features) is { } existing)
+            {
+                return existing;
+            }
+
+            return _capability.Update(_context.Features, _context.RequestServices.GetRequiredService<IBrowserCapabilitiesFactory>().Create(_context.Request));
+        }
     }
 
-    public string? Browser => _data["browser"];
+    public string? Browser => Capability["browser"];
+
+    public string? Version => Capability["version"];
+
+    public int MajorVersion => GetInt("majorversion");
+
+    public double MinorVersion => GetDouble("minorversion");
+
+    public string? Platform => Capability["platform"];
 
-    public string? Version => _data["version"];
+    public bool Crawler => GetBoolean("crawler");
 
-    public int MajorVersion => _data.GetInt("majorversion");
+    public string? Type => Capability["type"];
 
-    public double MinorVersion => _data.GetDouble("minorversion");
+    public string? PreferredRequestEncoding => Capability["preferredRequestEncoding"];
 
-    public string? Platform => _data["platform"];
+    public string? this[string key] => Capability[key];
 
-    public bool Crawler => _data.GetBoolean("crawler");
+    public bool IsMobileDevice => GetBoolean("isMobileDevice");
 
-    public bool IsMobileDevice => _data.GetBoolean("isMobileDevice");
+    private int GetInt(string key) => int.TryParse(Capability[key], NumberStyles.Integer, CultureInfo.InvariantCulture, out var result) ? result : throw new HttpUnhandledException($"Invalid string from browser capabilities '{key}'");
+
+    private bool GetBoolean(string key) => bool.TryParse(Capability[key], out var result) && result;
+
+    private double GetDouble(string key)
+    {
+        const NumberStyles Style = NumberStyles.Float | NumberStyles.AllowDecimalPoint;
+
+        var value = Capability[key];
+
+        if (value is not null)
+        {
+            if (double.TryParse(value, Style, CultureInfo.InvariantCulture, out var result))
+            {
+                return result;
+            }
+
+            // Handle if there's more than one decimal i.e. .4.1 -> .4
+            var firstDecimal = value.IndexOf('.', StringComparison.Ordinal);
+
+            if (firstDecimal != -1)
+            {
+                var nextDecimal = value.IndexOf('.', firstDecimal + 1);
+
+                if (nextDecimal != -1)
+                {
+                    if (double.TryParse(value.AsSpan()[..nextDecimal], Style, CultureInfo.InvariantCulture, out var result2))
+                    {
+                        return result2;
+                    }
+                }
+            }
+        }
+
+        throw new HttpUnhandledException($"Invalid string from browser capabilities '{key}'");
+    }
 }

src/Microsoft.AspNetCore.SystemWebAdapters/Generated/ExcludedApis.txt

@@ -14,3 +14,6 @@ T:Microsoft.AspNetCore.SystemWebAdapters.SessionState.ISessionState
 
 # We manually type forward this only for .NET 4.7.2+
 T:System.Web.SameSiteMode
+
+T:Microsoft.AspNetCore.SystemWebAdapters.IBrowserCapabilitiesFactory
+T:Microsoft.AspNetCore.SystemWebAdapters.IHttpBrowserCapabilityFeature

src/Microsoft.AspNetCore.SystemWebAdapters/Generated/Ref.Standard.cs

@@ -525,9 +525,12 @@ internal HttpCapabilitiesBase() { }
         public string Browser { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public bool Crawler { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public bool IsMobileDevice { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public string this[string key] { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public int MajorVersion { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public double MinorVersion { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public string Platform { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public string PreferredRequestEncoding { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
+        public string Type { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
         public string Version { get { throw new System.PlatformNotSupportedException("Only supported when running on ASP.NET Core or System.Web");} }
     }
 }

src/Microsoft.AspNetCore.SystemWebAdapters/HttpBrowserCapabilities.cs

@@ -7,8 +7,8 @@ namespace System.Web;
 
 public class HttpBrowserCapabilities : HttpCapabilitiesBase
 {
-    internal HttpBrowserCapabilities(BrowserCapabilitiesFactory factory, string userAgent)
-        : base(factory, userAgent)
+    internal HttpBrowserCapabilities(HttpContextCore core)
+        : base(core)
     {
     }
 }

src/Microsoft.AspNetCore.SystemWebAdapters/HttpRequest.cs

@@ -196,25 +196,7 @@ public bool IsLocal
 
         public string? UserHostName => _request.HttpContext.Connection.RemoteIpAddress?.ToString();
 
-        public HttpBrowserCapabilities Browser
-        {
-            get
-            {
-                if (_browser is null)
-                {
-                    var factory = _request.HttpContext.RequestServices.GetService<BrowserCapabilitiesFactory>();
-
-                    if (factory is null)
-                    {
-                        throw new InvalidOperationException("Browser capabilities requires AddSystemWebAdapters() to be called on service collection");
-                    }
-
-                    _browser = new(factory, _request.Headers.UserAgent);
-                }
-
-                return _browser;
-            }
-        }
+        public HttpBrowserCapabilities Browser => _browser ??= new(_request.HttpContext);
 
         public string? this[string key] => Params[key];
 

test/Microsoft.AspNetCore.SystemWebAdapters.Tests/Configuration/BrowserCapabilitiesFactoryTests.cs

@@ -20,7 +20,7 @@ public void VerifyCapabilities(TestData data)
         var browserFactory = new BrowserCapabilitiesFactory();
 
         // Act
-        var result = browserFactory.Process(data.UserAgent);
+        var result = browserFactory.Parse(data.UserAgent);
 
         // Assert
         Assert.Equal(data.Browser, result["browser"]);