import sys
from typing import Any  # noqa:F401
from typing import Iterator  # noqa:F401
from typing import List  # noqa:F401
from typing import Optional  # noqa:F401
from typing import Set  # noqa:F401
from typing import Tuple  # noqa:F401
from typing import Type  # noqa:F401
from typing import Union  # noqa:F401

import wrapt

from ddtrace.internal.utils.attrdict import AttrDict
from ddtrace.internal.utils.cache import cached


NoneType = type(None)

PY = sys.version_info


def _maybe_slots(obj):
    # type: (Any) -> Union[Tuple[str], List[str]]
    try:
        slots = object.__getattribute__(obj, "__slots__")
        if isinstance(slots, str):
            return (slots,)
        return slots
    except AttributeError:
        return []


@cached()
def _slots(_type):
    # type: (Type) -> Set[str]
    return {_ for cls in object.__getattribute__(_type, "__mro__") for _ in _maybe_slots(cls)}


def get_slots(obj):
    # type: (Any) -> Set[str]
    """Get the object's slots."""
    return _slots(type(obj))


def _isinstance(obj, types):
    # type: (Any, Union[Type, Tuple[Union[Type, Tuple[Any, ...]], ...]]) -> bool
    # DEV: isinstance falls back to calling __getattribute__ which could cause
    # side effects.
    return issubclass(type(obj), types)


IS_312_OR_NEWER = PY >= (3, 12)


class SafeObjectProxy(wrapt.ObjectProxy):
    """Object proxy to make sure we don't call unsafe code.

    Access to the wrapped object is denied to prevent any potential
    side-effects. Arbitrary objects are essentially converted into attribute
    dictionaries. Callable objects are made uncallable to prevent accidental
    calls that can also trigger side-effects.
    """

    def __call__(self, *args, **kwargs):
        # type: (Any, Any) -> Optional[Any]
        raise RuntimeError("Cannot call safe object")

    def __getattribute__(self, name):
        # type: (str) -> Any
        if name == "__wrapped__":
            if not IS_312_OR_NEWER:
                raise AttributeError("Access denied")
            else:
                return super(SafeObjectProxy, self).__wrapped__
        return super(SafeObjectProxy, self).__getattribute__(name)

    def __getattr__(self, name):
        # type: (str) -> Any
        if name == "__wrapped__":
            if IS_312_OR_NEWER:
                raise AttributeError("Access denied")
            else:
                return super(SafeObjectProxy, self).__wrapped__
        return type(self).safe(super(SafeObjectProxy, self).__getattr__(name))

    def __getitem__(self, item):
        # type: (Any) -> Any
        return type(self).safe(super(SafeObjectProxy, self).__getitem__(item))

    def __iter__(self):
        # type: () -> Any
        return iter(type(self).safe(_) for _ in super(SafeObjectProxy, self).__iter__())

    def items(self):
        # type: () -> Iterator[Tuple[Any, Any]]
        return (
            (type(self).safe(k), type(self).safe(v)) for k, v in super(SafeObjectProxy, self).__getattr__("items")()
        )

    # Custom object representations might cause side-effects
    def __str__(self):
        return object.__repr__(self)

    __repr__ = __str__

    @classmethod
    def safe(cls, obj):
        # type: (Any) -> Optional[Any]
        """Turn an object into a safe proxy."""
        _type = type(obj)
        if _isinstance(obj, type):
            try:
                if obj.__module__ == "builtins":
                    # We are assuming that builtin types are safe
                    return obj
            except AttributeError:
                # No __module__ attribute. We'll use caution
                pass

        elif _type in {str, int, float, bool, NoneType, bytes, complex}:
            # We are assuming that scalar builtin type instances are safe
            return obj

        try:
            return cls(AttrDict(object.__getattribute__(obj, "__dict__")))
        except AttributeError:
            pass

        slots = get_slots(obj)
        if slots:
            # Handle slots objects
            return cls(AttrDict({k: object.__getattribute__(obj, k) for k in slots}))

        return cls(obj)
