From 60a71f41409ab76fa031402962aa1b226313d583 Mon Sep 17 00:00:00 2001
From: "fabien.menager" <fabien.menager@repply.fr>
Date: Thu, 3 Aug 2023 21:16:25 +0200
Subject: [PATCH] Escape invalid identifiers for file constants

---
 src/ThisAssembly.Constants/Model.cs           | 34 ++++++++++++++++---
 .../Content/Docs/12. Readme (copy).txt        |  1 +
 src/ThisAssembly.Tests/Tests.cs               |  4 +++
 3 files changed, 35 insertions(+), 4 deletions(-)
 create mode 100644 src/ThisAssembly.Tests/Content/Docs/12. Readme (copy).txt

diff --git a/src/ThisAssembly.Constants/Model.cs b/src/ThisAssembly.Constants/Model.cs
index 25ec0b69..f8664985 100644
--- a/src/ThisAssembly.Constants/Model.cs
+++ b/src/ThisAssembly.Constants/Model.cs
@@ -3,6 +3,8 @@
 using System.Diagnostics;
 using System.Linq;
 using System.Reflection;
+using System.Text.RegularExpressions;
+using Microsoft.CodeAnalysis.CSharp;
 
 [DebuggerDisplay("Values = {RootArea.Values.Count}")]
 record Model(Area RootArea)
@@ -16,6 +18,27 @@ record Area(string Name, string Prefix)
 {
     public List<Area> NestedAreas { get; init; } = new();
     public List<Constant> Values { get; init; } = new();
+    
+    private static string EscapeIdentifier(string identifier)
+    {
+        if (string.IsNullOrWhiteSpace(identifier))
+        {
+            return "_";
+        }
+        
+        var replaced = identifier
+            .Select(c => SyntaxFacts.IsIdentifierPartCharacter(c) ? c : '_')
+            .ToArray();
+
+        var result = Regex.Replace(new string(replaced), "(_)+", "_");
+
+        if (!SyntaxFacts.IsIdentifierStartCharacter(result[0]))
+        {
+            result = "_" + result;
+        }  
+
+        return result;
+    }
 
     public static Area Load(List<Constant> constants, string rootArea = "Constants")
     {
@@ -24,15 +47,18 @@ public static Area Load(List<Constant> constants, string rootArea = "Constants")
         foreach (var constant in constants)
         {
             //  Splits: ([area].)*[name]
-            var parts = constant.Name.Split(new[] { "." }, StringSplitOptions.RemoveEmptyEntries);
+            var parts = constant.Name.Split(new[] { "." }, StringSplitOptions.RemoveEmptyEntries)
+                .Select(EscapeIdentifier)
+                .ToArray();
+            
             if (parts.Length <= 1)
             {
-                root.Values.Add(new Constant(constant.Name, constant.Value, constant.Comment));
+                root.Values.Add(constant with { Name = EscapeIdentifier(constant.Name) });
             }
             else
             {
                 var area = GetArea(root, parts.Take(parts.Length - 1));
-                var value = new Constant(parts.Skip(parts.Length - 1).First(), constant.Value, constant.Comment);
+                var value = constant with { Name = parts.Skip(parts.Length - 1).First() };
 
                 area.Values.Add(value);
             }
@@ -74,4 +100,4 @@ static Area GetArea(Area area, IEnumerable<string> areaPath)
 }
 
 [DebuggerDisplay("{Name} = {Value}")]
-record Constant(string Name, string? Value, string? Comment);
\ No newline at end of file
+record Constant(string Name, string? Value, string? Comment);
diff --git a/src/ThisAssembly.Tests/Content/Docs/12. Readme (copy).txt b/src/ThisAssembly.Tests/Content/Docs/12. Readme (copy).txt
new file mode 100644
index 00000000..5f282702
--- /dev/null
+++ b/src/ThisAssembly.Tests/Content/Docs/12. Readme (copy).txt	
@@ -0,0 +1 @@
+
\ No newline at end of file
diff --git a/src/ThisAssembly.Tests/Tests.cs b/src/ThisAssembly.Tests/Tests.cs
index 7a11d414..d9944274 100644
--- a/src/ThisAssembly.Tests/Tests.cs
+++ b/src/ThisAssembly.Tests/Tests.cs
@@ -35,6 +35,10 @@ public void CanUseConstants()
     public void CanUseFileConstants()
         => Assert.Equal(ThisAssembly.Constants.Content.Docs.License, Path.Combine("Content", "Docs", "License.md"));
 
+    [Fact]
+    public void CanUseFileConstantInvalidIdentifier()
+        => Assert.Equal(ThisAssembly.Constants.Content.Docs._12._Readme_copy_, Path.Combine("Content", "Docs", "12. Readme (copy).txt"));
+
     [Fact]
     public void CanUseFileConstantLinkedFile()
         => Assert.Equal(ThisAssembly.Constants.Included.Readme, Path.Combine("Included", "Readme.txt"));