# -*- coding: utf-8 -*-
# MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
#
# Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
import os

from ..logger import get_logger
from ..utils.deprecation import deprecated

_execution_strategy = os.getenv("MEGENGINE_EXECUTION_STRATEGY", "HEURISTIC")

if os.getenv("MEGENGINE_CONV_EXECUTION_STRATEGY") != None:
    get_logger().warning(
        "Environment variable `MEGENGINE_CONV_EXECUTION_STRATEGY` is deprecated, please use `MEGENGINE_EXECUTION_STRATEGY`"
    )


def get_execution_strategy() -> str:
    """
    Returns the execution strategy of :class:`~.Conv2d` and :func:'~.matmul'

    See :func:`~.set_execution_strategy` for possible return values
    """
    return _execution_strategy


def set_execution_strategy(option: str):
    """
    Sets the execution strategy of :class:`~.Conv2d` and :func:'~.matmul'

    :param option: Decides how :class:`~.Conv2d` and :func:'~.matmul' algorithms are chosen.
        Available values:

        * 'HEURISTIC' uses heuristic to choose the fastest algorithm.
        * 'PROFILE' runs possible algorithms on real device to find the best one.
        * 'PROFILE_HEURISTIC' uses profiling result and heuristic to choose the fastest algorithm.
        * 'PROFILE_REPRODUCIBLE' uses the fastest of profiling result that is also reproducible.
        * 'HEURISTIC_REPRODUCIBLE' uses heuristic to choose the fastest algorithm that is also reproducible.

        The default strategy is 'HEURISTIC'.

        It can also be set through the environment variable 'MEGENGINE_EXECUTION_STRATEGY'.
    """
    valid_option = (
        "HEURISTIC",
        "PROFILE",
        "PROFILE_HEURISTIC",
        "PROFILE_REPRODUCIBLE",
        "HEURISTIC_REPRODUCIBLE",
    )
    if not option in valid_option:
        raise ValueError("Valid option can only be one of {}".format(valid_option))

    global _execution_strategy  # pylint: disable=global-statement
    _execution_strategy = option


@deprecated(version="1.3", reason="use get_execution_strategy() instead")
def get_conv_execution_strategy() -> str:
    return get_execution_strategy()


@deprecated(version="1.3", reason="use set_execution_strategy() instead")
def set_conv_execution_strategy(option: str):
    return set_execution_strategy(option)