from typing import Iterable

from mypy_extensions import trait

from mypy.types import (
    Type, SyntheticTypeVisitor, AnyType, UninhabitedType, NoneType, ErasedType, DeletedType,
    TypeVarType, LiteralType, Instance, CallableType, TupleType, TypedDictType, UnionType,
    Overloaded, TypeType, CallableArgument, UnboundType, TypeList, StarType, EllipsisType,
    PlaceholderType, PartialType, RawExpressionType, TypeAliasType, ParamSpecType, Parameters,
    UnpackType, TypeVarTupleType,
)


@trait
class TypeTraverserVisitor(SyntheticTypeVisitor[None]):
    """Visitor that traverses all components of a type"""

    # Atomic types

    def visit_any(self, t: AnyType) -> None:
        pass

    def visit_uninhabited_type(self, t: UninhabitedType) -> None:
        pass

    def visit_none_type(self, t: NoneType) -> None:
        pass

    def visit_erased_type(self, t: ErasedType) -> None:
        pass

    def visit_deleted_type(self, t: DeletedType) -> None:
        pass

    def visit_type_var(self, t: TypeVarType) -> None:
        # Note that type variable values and upper bound aren't treated as
        # components, since they are components of the type variable
        # definition. We want to traverse everything just once.
        pass

    def visit_param_spec(self, t: ParamSpecType) -> None:
        pass

    def visit_parameters(self, t: Parameters) -> None:
        self.traverse_types(t.arg_types)

    def visit_type_var_tuple(self, t: TypeVarTupleType) -> None:
        pass

    def visit_literal_type(self, t: LiteralType) -> None:
        t.fallback.accept(self)

    # Composite types

    def visit_instance(self, t: Instance) -> None:
        self.traverse_types(t.args)

    def visit_callable_type(self, t: CallableType) -> None:
        # FIX generics
        self.traverse_types(t.arg_types)
        t.ret_type.accept(self)
        t.fallback.accept(self)

    def visit_tuple_type(self, t: TupleType) -> None:
        self.traverse_types(t.items)
        t.partial_fallback.accept(self)

    def visit_typeddict_type(self, t: TypedDictType) -> None:
        self.traverse_types(t.items.values())
        t.fallback.accept(self)

    def visit_union_type(self, t: UnionType) -> None:
        self.traverse_types(t.items)

    def visit_overloaded(self, t: Overloaded) -> None:
        self.traverse_types(t.items)

    def visit_type_type(self, t: TypeType) -> None:
        t.item.accept(self)

    # Special types (not real types)

    def visit_callable_argument(self, t: CallableArgument) -> None:
        t.typ.accept(self)

    def visit_unbound_type(self, t: UnboundType) -> None:
        self.traverse_types(t.args)

    def visit_type_list(self, t: TypeList) -> None:
        self.traverse_types(t.items)

    def visit_star_type(self, t: StarType) -> None:
        t.type.accept(self)

    def visit_ellipsis_type(self, t: EllipsisType) -> None:
        pass

    def visit_placeholder_type(self, t: PlaceholderType) -> None:
        self.traverse_types(t.args)

    def visit_partial_type(self, t: PartialType) -> None:
        pass

    def visit_raw_expression_type(self, t: RawExpressionType) -> None:
        pass

    def visit_type_alias_type(self, t: TypeAliasType) -> None:
        self.traverse_types(t.args)

    def visit_unpack_type(self, t: UnpackType) -> None:
        t.type.accept(self)

    # Helpers

    def traverse_types(self, types: Iterable[Type]) -> None:
        for typ in types:
            typ.accept(self)
