import os
import warnings
from enum import Enum

from ._version import __version__, __version_tuple__  # noqa: F401

__array_api_version__ = "2022.12"


class BackendType(Enum):
    Numba = "Numba"
    Finch = "Finch"


_ENV_VAR_NAME = "SPARSE_BACKEND"

if _ENV_VAR_NAME in os.environ:
    warnings.warn("Selectable backends feature in `sparse` might change in the future.", FutureWarning, stacklevel=1)
    _backend_name = os.environ[_ENV_VAR_NAME]
else:
    _backend_name = BackendType.Numba.value

if _backend_name not in {BackendType.Numba.value, BackendType.Finch.value}:
    warnings.warn(f"Invalid backend identifier: {_backend_name}. Selecting Numba backend.", UserWarning, stacklevel=1)
    BACKEND = BackendType.Numba
else:
    BACKEND = BackendType[_backend_name]

del _backend_name

if BackendType.Finch == BACKEND:
    from sparse.finch_backend import *  # noqa: F403
    from sparse.finch_backend import __all__
else:
    from sparse.numba_backend import *  # noqa: F403
    from sparse.numba_backend import (  # noqa: F401
        __all__,
        _common,
        _compressed,
        _coo,
        _dok,
        _io,
        _numba_extension,
        _settings,
        _slicing,
        _sparse_array,
        _umath,
        _utils,
    )