from dataclasses import dataclass


class ADTMeta(type):
    def __new__(mcs, name, bases, namespace: dict):
        adtc_class = super().__new__(mcs, name, bases, namespace)
        if "__is_adt_variant__" in namespace:
            if namespace["__is_adt_variant__"]:
                return adtc_class

        for member_name, member in namespace.items():
            if isinstance(member, type):
                variant_class = dataclass(type(member_name, (adtc_class,), {
                    "__qualname__": f"{adtc_class.__qualname__}.{member_name}",
                    "__is_adt_variant__": True,
                    "__annotations__": member.__annotations__
                }))
                setattr(adtc_class, member_name, variant_class)

        annotations = namespace.pop("__annotations__", {})
        for variant_name, variant_annotation in annotations.items():
            variant_class = type(variant_name, (adtc_class,), {
                "__qualname__": f"{adtc_class.__qualname__}.{variant_name}",
                "__is_adt_variant__": True
            })

            if (variant_annotation is Ellipsis) or (variant_annotation is None):
                variant_class.__repr__ = lambda self: f"<{self.__class__.__qualname__}>"
            else:
                variant_class.__init__ = create_init(variant_class, variant_annotation)
                variant_class.__repr__ = lambda self: f"<{self.__class__.__qualname__} {repr(self.value)}>"
                variant_class.__match_args__ = ("value",)
            setattr(adtc_class, variant_name, variant_class)

        return adtc_class


def create_init(klass, annotation):
    def __init__(self: klass, value: annotation) -> None:
        self.value = value
    return __init__