using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using System.Collections.Immutable;
using System.Text;

namespace GeneratorLib;

[Generator(LanguageNames.CSharp)]
public class HelloWorldGenerator : IIncrementalGenerator
{
	public void Initialize(IncrementalGeneratorInitializationContext context)
	{
		var provider = context.SyntaxProvider.CreateSyntaxProvider(
		static (syntaxNode, _) => syntaxNode is ClassDeclarationSyntax,
		static (generatorSyntaxContext, _) => (ClassDeclarationSyntax)generatorSyntaxContext.Node)
		.Where(static node => node != null);

		var compilation = context.CompilationProvider.Combine(provider.Collect());

		context.RegisterSourceOutput(compilation, ExecuteHelloWorldGeneration);
	}

	private static void ExecuteHelloWorldGeneration(SourceProductionContext context, (Compilation compilation, ImmutableArray<ClassDeclarationSyntax> classDeclarationSyntax) compilationProvider)
	{
		const string hintName = "HelloWorld.g.cs";
		string sourceText = new StringBuilder()
			.AppendLine("namespace HelloNamespace")
			.AppendLine("{")
			.AppendLine("\tpublic class HelloWorld")
			.AppendLine("\t{")
			.AppendLine("\t\tpublic static void SayHello()")
			.AppendLine("\t\t{")
			.AppendLine("\t\t\tConsole.WriteLine(\"Hello, World!\");")
			.AppendLine("\t\t}")
			.AppendLine("\t}")
			.AppendLine("}")
			.ToString();

		context.AddSource(hintName, sourceText);
	}
}