# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang)
#
# See ../../LICENSE for clarification regarding multiple authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


import os

import torch
from torch import distributed as dist


def setup_dist(rank, world_size, master_port=None, use_ddp_launch=False):
    """
    rank and world_size are used only if use_ddp_launch is False.
    """
    if "MASTER_ADDR" not in os.environ:
        os.environ["MASTER_ADDR"] = "localhost"

    if "MASTER_PORT" not in os.environ:
        os.environ["MASTER_PORT"] = "12354" if master_port is None else str(master_port)

    if use_ddp_launch is False:
        dist.init_process_group("nccl", rank=rank, world_size=world_size)
        torch.cuda.set_device(rank)
    else:
        dist.init_process_group("nccl")


def cleanup_dist():
    dist.destroy_process_group()


def get_world_size():
    if "WORLD_SIZE" in os.environ:
        return int(os.environ["WORLD_SIZE"])
    if dist.is_available() and dist.is_initialized():
        return dist.get_world_size()
    else:
        return 1


def get_rank():
    if "RANK" in os.environ:
        return int(os.environ["RANK"])
    elif dist.is_available() and dist.is_initialized():
        return dist.get_rank()
    else:
        return 0


def get_local_rank():
    return int(os.environ.get("LOCAL_RANK", 0))
