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#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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#
#     http://www.apache.org/licenses/LICENSE-2.0
#
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import torch
from datetime import datetime
from modulus.distributed import DistributedManager


def create_ddp_group_tag(group_name: str = None) -> str:
    """Creates a common group tag for logging

    For some reason this does not work with multi-node. Seems theres a bug in PyTorch
    when one uses a distributed util before DDP

    Parameters
    ----------
    group_name : str, optional
        Optional group name prefix. If None will use "DDP_Group_", by default None

    Returns
    -------
    str
        Group tag
    """
    dist = DistributedManager()
    if dist.rank == 0:
        # Store time stamp as int tensor for broadcasting
        tint = lambda x: int(datetime.now().strftime(f"%{x}"))
        time_index = torch.IntTensor(
            [tint(x) for x in ["m", "d", "y", "H", "M", "S"]]
        ).to(dist.device)
    else:
        time_index = torch.IntTensor([0, 0, 0, 0, 0, 0]).to(dist.device)

    if torch.distributed.is_available():
        # Broadcast group ID to all processes
        torch.distributed.broadcast(time_index, src=0)

    time_string = f"{time_index[0]}/{time_index[1]}/{time_index[2]}_\
        {time_index[3]}-{time_index[4]}-{time_index[5]}"

    if group_name is None:
        group_name = "DDP_Group"
    return group_name + "_" + time_string
