From 111290133463ac1d765e32599e4f7cab94b73145 Mon Sep 17 00:00:00 2001
From: Roger Howell <roger.howell@education.gov.uk>
Date: Thu, 8 Feb 2024 17:48:34 +0000
Subject: [PATCH] Switch urls from CamelCase to kebab-case

See also:
https://www.gov.uk/guidance/content-design/url-standards-for-gov-uk

https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/routing?view=aspnetcore-8.0#use-a-parameter-transformer-to-customize-token-replacement
---
 .../Program.cs                                | 10 +++++-
 .../SlugifyParameterTransformer.cs            | 33 +++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 src/ServiceAssessmentService/ServiceAssessmentService.WebApp/SlugifyParameterTransformer.cs

diff --git a/src/ServiceAssessmentService/ServiceAssessmentService.WebApp/Program.cs b/src/ServiceAssessmentService/ServiceAssessmentService.WebApp/Program.cs
index 37f9ee93..a3c527ee 100644
--- a/src/ServiceAssessmentService/ServiceAssessmentService.WebApp/Program.cs
+++ b/src/ServiceAssessmentService/ServiceAssessmentService.WebApp/Program.cs
@@ -7,6 +7,8 @@
 using ServiceAssessmentService.Application.Database;
 using ServiceAssessmentService.Application.UseCases;
 using ServiceAssessmentService.WebApp.Models;
+using Microsoft.AspNetCore.Mvc.ApplicationModels;
+using ServiceAssessmentService.WebApp;
 
 
 var builder = WebApplication.CreateBuilder(args);
@@ -26,7 +28,13 @@
     // By default, all incoming requests will be authorized according to the default policy.
     options.FallbackPolicy = options.DefaultPolicy;
 });
-builder.Services.AddRazorPages()
+
+builder.Services.AddRazorPages(options =>
+    {
+        // Convert CamelCase to kebab-case for page routes
+        // See also: https://www.gov.uk/guidance/content-design/url-standards-for-gov-uk
+        options.Conventions.Add(new PageRouteTransformerConvention(new SlugifyParameterTransformer()));
+    })
     .AddMicrosoftIdentityUI();
 
 // // Used for local accounts
diff --git a/src/ServiceAssessmentService/ServiceAssessmentService.WebApp/SlugifyParameterTransformer.cs b/src/ServiceAssessmentService/ServiceAssessmentService.WebApp/SlugifyParameterTransformer.cs
new file mode 100644
index 00000000..3d765818
--- /dev/null
+++ b/src/ServiceAssessmentService/ServiceAssessmentService.WebApp/SlugifyParameterTransformer.cs
@@ -0,0 +1,33 @@
+using System.Text.RegularExpressions;
+
+namespace ServiceAssessmentService.WebApp;
+
+/// <summary>
+/// This class is used to transform the URL parameters to lowercase and replace spaces with hyphens.
+///
+/// See also the GDS guidance on URL, which requires lowercase and dash-separated words
+/// https://www.gov.uk/guidance/content-design/url-standards-for-gov-uk
+/// 
+/// For example:
+/// <code>
+///     /AssessmentRequest/Details/1
+///     vs 
+///     /assessment-request/details/1
+/// </code>
+///
+/// Implementation is based on the following article:
+/// https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/routing?view=aspnetcore-8.0#use-a-parameter-transformer-to-customize-token-replacement
+/// </summary>
+public class SlugifyParameterTransformer : IOutboundParameterTransformer
+{
+    public string? TransformOutbound(object? value)
+    {
+        if (value == null) { return null; }
+
+        return Regex.Replace(value.ToString()!,
+            "([a-z])([A-Z])",
+            "$1-$2",
+            RegexOptions.CultureInvariant,
+            TimeSpan.FromMilliseconds(100)).ToLowerInvariant();
+    }
+}