import logging
import os
import random

import numpy as np
import torch
import torch.distributed as dist
import torch.multiprocessing as mp
from mmcv.runner import get_dist_info


def init_dist(launcher, backend='nccl', **kwargs):
    if mp.get_start_method(allow_none=True) is None:
        mp.set_start_method('spawn')
    if launcher == 'pytorch':
        _init_dist_pytorch(backend, **kwargs)
    elif launcher == 'mpi':
        _init_dist_mpi(backend, **kwargs)
    elif launcher == 'slurm':
        _init_dist_slurm(backend, **kwargs)
    else:
        raise ValueError('Invalid launcher type: {}'.format(launcher))


def _init_dist_pytorch(backend, **kwargs):
    # TODO: use local_rank instead of rank % num_gpus
    rank = int(os.environ['RANK'])
    num_gpus = torch.cuda.device_count()
    torch.cuda.set_device(rank % num_gpus)
    dist.init_process_group(backend=backend, **kwargs)


def _init_dist_mpi(backend, **kwargs):
    raise NotImplementedError


def _init_dist_slurm(backend, **kwargs):
    proc_id = int(os.environ['SLURM_PROCID'])
    ntasks = int(os.environ['SLURM_NTASKS'])
    node_list = os.environ['SLURM_NODELIST']
    num_gpus = torch.cuda.device_count()
    torch.cuda.set_device(proc_id % num_gpus)
    if '[' in node_list:
        beg = node_list.find('[')
        pos1 = node_list.find('-', beg)
        if pos1 < 0:
            pos1 = 1000
        pos2 = node_list.find(',', beg)
        if pos2 < 0:
            pos2 = 1000
        node_list = node_list[:min(pos1, pos2)].replace('[', '')
    addr = node_list[8:].replace('-', '.')
    os.environ['MASTER_PORT'] = str(kwargs['port'])
    os.environ['MASTER_ADDR'] = addr
    os.environ['WORLD_SIZE'] = str(ntasks)
    os.environ['RANK'] = str(proc_id)
    if backend == 'nccl':
        dist.init_process_group(backend='nccl')
    else:
        dist.init_process_group(
            backend='gloo', rank=proc_id, world_size=ntasks)
    rank = dist.get_rank()
    world_size = dist.get_world_size()
    return rank, world_size


def set_random_seed(seed):
    random.seed(seed)
    np.random.seed(seed)
    torch.manual_seed(seed)
    torch.cuda.manual_seed_all(seed)


def get_root_logger(log_level=logging.INFO):
    logger = logging.getLogger()
    if not logger.hasHandlers():
        logging.basicConfig(
            format='%(asctime)s - %(levelname)s - %(message)s',
            level=log_level)
    rank, _ = get_dist_info()
    if rank != 0:
        logger.setLevel('ERROR')
    return logger