"""
 Copyright (c) 2022, salesforce.com, inc.
 All rights reserved.
 SPDX-License-Identifier: BSD-3-Clause
 For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/BSD-3-Clause
"""

import datetime
import functools
import os

import torch
import torch.distributed as dist
import timm.models.hub as timm_hub


def setup_for_distributed(is_master):
    """
    This function disables printing when not in master process
    """
    import builtins as __builtin__

    builtin_print = __builtin__.print

    def print(*args, **kwargs):
        force = kwargs.pop("force", False)
        if is_master or force:
            builtin_print(*args, **kwargs)

    __builtin__.print = print


def is_dist_avail_and_initialized():
    if not dist.is_available():
        return False
    if not dist.is_initialized():
        return False
    return True


def get_world_size():
    if not is_dist_avail_and_initialized():
        return 1
    return dist.get_world_size()


def get_rank():
    if not is_dist_avail_and_initialized():
        return 0
    return dist.get_rank()


def is_main_process():
    return get_rank() == 0


def init_distributed_mode(args):
    if "RANK" in os.environ and "WORLD_SIZE" in os.environ:
        args.rank = int(os.environ["RANK"])
        args.world_size = int(os.environ["WORLD_SIZE"])
        args.gpu = int(os.environ["LOCAL_RANK"])
    elif "SLURM_PROCID" in os.environ:
        args.rank = int(os.environ["SLURM_PROCID"])
        args.gpu = args.rank % torch.cuda.device_count()
    else:
        print("Not using distributed mode")
        args.distributed = False
        return

    args.distributed = True

    torch.cuda.set_device(args.gpu)
    args.dist_backend = "nccl"
    print(
        "| distributed init (rank {}, world {}): {}".format(
            args.rank, args.world_size, args.dist_url
        ),
        flush=True,
    )
    torch.distributed.init_process_group(
        backend=args.dist_backend,
        init_method=args.dist_url,
        world_size=args.world_size,
        rank=args.rank,
        timeout=datetime.timedelta(
            days=365
        ),  # allow auto-downloading and de-compressing
    )
    torch.distributed.barrier()
    setup_for_distributed(args.rank == 0)


def get_dist_info():
    if torch.__version__ < "1.0":
        initialized = dist._initialized
    else:
        initialized = dist.is_initialized()
    if initialized:
        rank = dist.get_rank()
        world_size = dist.get_world_size()
    else:  # non-distributed training
        rank = 0
        world_size = 1
    return rank, world_size


def main_process(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        rank, _ = get_dist_info()
        if rank == 0:
            return func(*args, **kwargs)

    return wrapper


def download_cached_file(url, check_hash=True, progress=False):
    """
    Download a file from a URL and cache it locally. If the file already exists, it is not downloaded again.
    If distributed, only the main process downloads the file, and the other processes wait for the file to be downloaded.
    """

    def get_cached_file_path():
        # a hack to sync the file path across processes
        parts = torch.hub.urlparse(url)
        filename = os.path.basename(parts.path)
        # TODO: If we want to fix cache directory, use TORCH_HOME=/output env variable
        # Set the TORCH_HOME environment variable by "export TORCH_HOME=/output/torch"
        # os.environ['TORCH_HOME'] = '/output'
        cached_file = os.path.join(timm_hub.get_cache_dir(), filename)

        return cached_file

    if is_main_process():
        timm_hub.download_cached_file(url, check_hash, progress)

    if is_dist_avail_and_initialized():
        dist.barrier()

    return get_cached_file_path()
