from __future__ import annotations

import importlib as _importlib
import os as _os

from cupy_backends.cuda.api import runtime as _runtime

if not _runtime.is_hip:
    from cuda import pathfinder as _pathfinder


# All submodules are already made lazily loaded (and they should continue
# remaining so). The problem we are solving is we want to load the required
# C library before the submodule that needs it is imported. This list of
# submodules are supported by the pathfinder.
#
# Note: Do NOT add "nvrtc" here. It is run-time linked instead of dynamically
# linked, so its loading is further deferred (to inside SoftLink).
_submodules = (
    'cublas', 'cusolver', 'cusparse', 'curand', 'nccl', 'cutensor',
    'cusparselt',
)
_submodules_runtime_link = (
    'nvrtc', 'nvtx'
)


def __getattr__(name):
    if not _runtime.is_hip and name in _submodules:
        try:
            pathfinder_name = name
            if name == 'cusparselt':
                pathfinder_name = 'cusparseLt'
            _pathfinder.load_nvidia_dynamic_lib(pathfinder_name)
        except _pathfinder.DynamicLibNotFoundError as e:
            if (not (_os.environ.get('READTHEDOCS') == 'True') and
                    not (_os.environ.get('CUPY_CI') is not None)):
                raise ImportError(str(e)) from e

    if name in (_submodules + _submodules_runtime_link):
        return _importlib.import_module(f'cupy_backends.cuda.libs.{name}')

    raise AttributeError(
        f"module {__name__!r} has no attribute {name!r}")