using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Text;

namespace GameCult.Caching.MessagePack.Generator
{
    [Generator]
    public class CultDocumentMessagePackGenerator : IIncrementalGenerator
    {
        public void Initialize(IncrementalGeneratorInitializationContext context)
        {
            var documentTypes = context.SyntaxProvider
                .CreateSyntaxProvider(
                    static (node, _) => node is ClassDeclarationSyntax cds && cds.AttributeLists.Count > 0,
                    static (ctx, _) => ctx.SemanticModel.GetDeclaredSymbol(ctx.Node) as INamedTypeSymbol)
                .Where(static symbol => symbol is not null)!
                .Select((symbol, _) => symbol!)
                .Where(static symbol => symbol.GetAttributes().Any(attribute =>
                    attribute.AttributeClass?.ToDisplayString() == "GameCult.Caching.CultDocumentAttribute"));

            context.RegisterSourceOutput(documentTypes.Collect(), (spc, types) =>
            {
                var builder = new StringBuilder();
                builder.AppendLine("// <auto-generated/>");
                builder.AppendLine("#nullable enable");
                builder.AppendLine("using MessagePack.Formatters;");
                builder.AppendLine("namespace GameCult.Caching.MessagePack");
                builder.AppendLine("{");
                builder.AppendLine("    public static partial class GeneratedCultDocumentResolvers");
                builder.AppendLine("    {");
                builder.AppendLine("        public static IMessagePackFormatter<T>? GetFormatter<T>()");
                builder.AppendLine("        {");
                builder.AppendLine("            return null;");
                builder.AppendLine("        }");
                builder.AppendLine("    }");
                builder.AppendLine("}");
                spc.AddSource("GeneratedCultDocumentResolvers.g.cs", SourceText.From(builder.ToString(), Encoding.UTF8));
            });
        }
    }
}