Make the generated files more friendly to code cleanup functionality of Visual Studio (#753)

* Add #nullable enable and a header to generated files to exclude it from code clean up.
More info: https://github.com/dotnet/roslyn/blob/70e158ba6c2c99bd3c3fc0754af0dbf82a6d353d/docs/features/nullable-reference-types.md#generated-code

* Added note about update_all_dependencies.ps1 and fixed version.

Co-authored-by: Ali Sanjabi <[email protected]>

Author: asanjabi

src/HassModel/NetDaemon.HassModel.CodeGenerator/Generator.cs

@@ -1,5 +1,9 @@
-using System.Runtime.CompilerServices;
+using Microsoft.CodeAnalysis.CSharp;
+
 using NetDaemon.Client.HomeAssistant.Model;
+
+using System.Runtime.CompilerServices;
+
 using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
 
 [assembly: InternalsVisibleTo("NetDaemon.Daemon.Tests")]
@@ -9,7 +13,7 @@ namespace NetDaemon.HassModel.CodeGenerator;
 internal static class Generator
 {
     public static string GenerateCode(CodeGenerationSettings codeGenerationSettings, IReadOnlyCollection<HassState> entities, IReadOnlyCollection<HassServiceDomain> services)
-    { 
+    {
         var code = CreateCompilationUnitSyntax(codeGenerationSettings, entities, services);
         return code.ToFullString();
     }
@@ -35,9 +39,13 @@ internal static IEnumerable<CompilationUnitSyntax> CreateCompilationUnitSyntaxPe
         {
             units.Add(CompilationUnit()
                 .AddUsings(UsingDirective(ParseName("System")))
+                .WithLeadingTrivia(TriviaHelper.GetFileHeader())
                 .AddUsings(UsingDirective(ParseName("System.Collections.Generic")))
                 .AddUsings(UsingNamespaces.OrderBy(s => s).Select(u => UsingDirective(ParseName(u))).ToArray())
-                .AddMembers(NamespaceDeclaration(ParseName(codeGenerationSettings.Namespace)).NormalizeWhitespace().AddMembers(x))
+                .AddMembers(NamespaceDeclaration(ParseName(codeGenerationSettings.Namespace))
+                                .AppendTrivia(Trivia(NullableDirectiveTrivia(Token(SyntaxKind.EnableKeyword), true)))
+                                .NormalizeWhitespace()
+                                .AddMembers(x))
                 .NormalizeWhitespace(Tab.ToString(), eol: "\n"));
         });
 
@@ -51,11 +59,13 @@ internal static CompilationUnitSyntax CreateCompilationUnitSyntax(CodeGeneration
 
         var code = CompilationUnit()
             .AddUsings(UsingDirective(ParseName("System")))
+            .WithLeadingTrivia(TriviaHelper.GetFileHeader())
             .AddUsings(UsingDirective(ParseName("System.Collections.Generic")))
             .AddUsings(UsingNamespaces.OrderBy(s => s).Select(u => UsingDirective(ParseName(u))).ToArray());
 
         var namespaceDeclaration = NamespaceDeclaration(ParseName(codeGenerationSettings.Namespace)).NormalizeWhitespace();
 
+        namespaceDeclaration = namespaceDeclaration.AppendTrivia(Trivia(NullableDirectiveTrivia(Token(SyntaxKind.EnableKeyword), true)));
         namespaceDeclaration = namespaceDeclaration.AddMembers(EntitiesGenerator.Generate(codeGenerationSettings, orderedEntities).ToArray());
         namespaceDeclaration = namespaceDeclaration.AddMembers(ServicesGenerator.Generate(orderedServiceDomains).ToArray());
         namespaceDeclaration = namespaceDeclaration.AddMembers(ExtensionMethodsGenerator.Generate(orderedServiceDomains, entities).ToArray());

src/HassModel/NetDaemon.HassModel.CodeGenerator/Helpers/TriviaHelper.cs

@@ -0,0 +1,36 @@
+using System.Reflection;
+
+using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
+
+namespace NetDaemon.HassModel.CodeGenerator.Helpers;
+internal static class TriviaHelper
+{
+    internal static string GeneratorVersion = Assembly.GetAssembly(typeof(Generator))!.GetName().Version!.ToString();
+    internal static SyntaxTrivia[] GetFileHeader()
+    {
+        string headerText = @$"
+        //------------------------------------------------------------------------------
+        // <auto-generated>
+        // Generated using NetDaemon CodeGenerator nd-codegen v{GeneratorVersion}
+        //
+        // *** Make sure the version of the codegen tool and your nugets Joysoftware.NetDaemon.* have the same version.***
+        // You can use following command to keep it up to date with the latest version:
+        //   dotnet tool update JoySoftware.NetDaemon.HassModel.CodeGen
+        //
+        // To update this file with latest entities run this command in your project directory: 
+        //   dotnet tool run nd-codegen
+        //
+        // In the template projects we provided a convenience powershell script that will update
+        // the codegen and nugets to latest versions update_all_dependencies.ps1.
+        //
+        // For more information: https://netdaemon.xyz/docs/v3/hass_model/hass_model_codegen
+        // For more information about NetDaemon: https://netdaemon.xyz/  
+        // </auto-generated>
+        //------------------------------------------------------------------------------";
+
+        var lines = headerText.Split('\n', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+
+        SyntaxTrivia[] header = lines.SelectMany(l => new[] { Comment(l), LineFeed }).ToArray();
+        return header;
+    }
+}