Godot.Sharp.Extended/SceneGenerator.cs

using System.Collections.Generic;
using System.IO;
using System.Text;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Text;

namespace Godot.Sharp.Extended.Generators;

[Generator]
public class SceneGenerator : IIncrementalGenerator
{
    public void Initialize(IncrementalGeneratorInitializationContext context)
    {
        var scenes = context.AdditionalTextsProvider
            .Where(text => text.Path.EndsWith(".tscn"));

        context.RegisterSourceOutput(
            context.CompilationProvider.Combine(scenes.Collect()).Combine(context.AnalyzerConfigOptionsProvider),
            (ctx, t) => GenerateCode(ctx, t.Left.Left, t.Left.Right, t.Right));
    }

    private void GenerateCode(
        SourceProductionContext context,
        Compilation compilation,
        IEnumerable<AdditionalText> scenes,
        AnalyzerConfigOptionsProvider optionsProvider)
    {
        optionsProvider.GlobalOptions.TryGetValue("build_property.projectdir", out var projectDirectory);

        var allMethods = new StringBuilder();
        foreach (var scene in scenes)
        {
            var directory = Path.GetDirectoryName(scene.Path);
            var name = Path.GetFileNameWithoutExtension(scene.Path);
            var relativePath = scene.Path.Replace(projectDirectory ?? "", "").Replace("\\", "/");
            allMethods.AppendLine(
                $$"""
                    public static T New{{name.ToPascalCase()}}<T>() where T : Node {
                        var packedScene = GD.Load<PackedScene>("res://{{relativePath}}");
                        return packedScene.Instance<T>();
                    }
                  """);
            
            var code =
                $$"""
                  // <auto-generated />
                  
                  using System;
                  using Godot;
                  
                  namespace Godot.Sharp.Extended;
                  
                  public class Scenes
                  {
                  {{allMethods}}
                  }
                  """;
            
            context.AddSource("Godot.Sharp.Extended.Scenes.g.cs", SourceText.From(code, Encoding.UTF8));
        }
    }

}