import logging
import warnings

# May help avoid undefined symbol errors https://pytorch.org/cppdocs/notes/faq.html#undefined-symbol-errors-from-pytorch-aten
import torch

# For optimizers and normalization there is no Python fallback.
# Absence of cuda backend is a hard error.
# I would like the errors from importing fused_adam_cuda or fused_layer_norm_cuda
# to be triggered lazily, because if someone has installed with --cpp_ext and --cuda_ext
# so they expect those backends to be available, but for some reason they actually aren't
# available (for example because they built improperly in a way that isn't revealed until
# load time) the error message is timely and visible.
from . import optimizers
from . import normalization


__all__ = ["optimizers", "normalization"]


def check_cudnn_version_and_warn(global_option: str, required_cudnn_version: int) -> bool:
    cudnn_available = torch.backends.cudnn.is_available()
    cudnn_version = torch.backends.cudnn.version() if cudnn_available else None
    if not (cudnn_available and (cudnn_version >= required_cudnn_version)):
        warnings.warn(
            f"`{global_option}` depends on cuDNN {required_cudnn_version} or later, "
            f"but {'cuDNN is not available' if not cudnn_available else cudnn_version}"
        )
        return False
    return True


class DeprecatedFeatureWarning(FutureWarning):
    pass


def deprecated_warning(msg: str) -> None:
    if (
        not torch.distributed.is_available
        or not torch.distributed.is_initialized()
        or (torch.distributed.is_initialized() and torch.distributed.get_rank() == 0)
    ):
        warnings.warn(msg, DeprecatedFeatureWarning)