namespace Compiler;

public sealed class TypeResolver(string fileName)
{
    private readonly Dictionary<string, NubTypeStruct> structTypes = [];

    public List<NubTypeStruct> GetAllStructs() => structTypes.Values.ToList();
    public NubTypeStruct? GetNamedStruct(string name) => structTypes.GetValueOrDefault(name);

    public static TypeResolver Create(string fileName, Ast ast, out List<Diagnostic> diagnostics)
    {
        diagnostics = [];
        var resolver = new TypeResolver(fileName);

        foreach (var structDef in ast.Structs)
        {
            if (resolver.structTypes.ContainsKey(structDef.Name.Ident))
            {
                diagnostics.Add(Diagnostic.Error($"Duplicate struct: {structDef.Name.Ident}").At(fileName, structDef.Name).Build());
                continue;
            }

            resolver.structTypes.Add(structDef.Name.Ident, new NubTypeStruct());
        }

        foreach (var structDef in ast.Structs)
        {
            var structType = resolver.structTypes[structDef.Name.Ident];

            try
            {
                structType.ResolveFields(structDef.Fields.Select(f => new NubTypeStruct.Field(f.Name.Ident, resolver.Resolve(f.Type))).ToList());
            }
            catch (CompileException e)
            {
                diagnostics.Add(e.Diagnostic);
            }
        }

        return resolver;
    }

    public NubType Resolve(NodeType node)
    {
        return node switch
        {
            NodeTypeBool type => new NubTypeBool(),
            NodeTypeCustom type => ResolveStruct(type),
            NodeTypeFunc type => new NubTypeFunc(type.Parameters.Select(Resolve).ToList(), Resolve(type.ReturnType)),
            NodeTypePointer type => new NubTypePointer(Resolve(type.To)),
            NodeTypeSInt type => new NubTypeSInt(type.Width),
            NodeTypeUInt type => new NubTypeUInt(type.Width),
            NodeTypeString type => new NubTypeString(),
            NodeTypeVoid type => new NubTypeVoid(),
            _ => throw new ArgumentOutOfRangeException(nameof(node))
        };
    }

    private NubTypeStruct ResolveStruct(NodeTypeCustom type)
    {
        var structType = structTypes.GetValueOrDefault(type.Name.Ident);
        if (structType == null)
            throw new CompileException(Diagnostic.Error($"Unknown custom type: {type}").At(fileName, type).Build());

        return structType;
    }
}