# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.

# This source code is licensed under the license found in the
# LICENSE file in the root directory of this source tree.
# --------------------------------------------------------
# References:
# DeiT: https://github.com/facebookresearch/deit
# BEiT: https://github.com/microsoft/unilm/tree/master/beit
# --------------------------------------------------------

import builtins
import datetime
import os
import glob
import time
from collections import defaultdict, deque
from pathlib import Path
import subprocess

import torch
import torch.distributed as dist
from torch import inf
from torch.distributed.fsdp.sharded_grad_scaler import ShardedGradScaler
from torch.distributed.fsdp import (
    FullyShardedDataParallel as FSDP,
    StateDictType,
    FullStateDictConfig,
)
from torch.distributed._shard.api import load_with_process_group

from fairscale.nn.model_parallel import initialize as fs_init

from types import TracebackType
from typing import Any, Optional
import torch
import torch.nn as nn

class SmoothedValue(object):
    """Track a series of values and provide access to smoothed values over a
    window or the global series average.
    """

    def __init__(self, window_size=20, fmt=None):
        if fmt is None:
            fmt = "{median:.4f} ({global_avg:.4f})"
        self.deque = deque(maxlen=window_size)
        self.total = 0.0
        self.count = 0
        self.fmt = fmt

    def update(self, value, n=1):
        self.deque.append(value)
        self.count += n
        self.total += value * n

    def synchronize_between_processes(self):
        """
        Warning: does not synchronize the deque!
        """
        if not is_dist_avail_and_initialized():
            return
        t = torch.tensor([self.count, self.total], dtype=torch.float64, device='cuda')
        dist.barrier()
        dist.all_reduce(t)
        t = t.tolist()
        self.count = int(t[0])
        self.total = t[1]

    @property
    def median(self):
        d = torch.tensor(list(self.deque))
        return d.median().item()

    @property
    def avg(self):
        d = torch.tensor(list(self.deque), dtype=torch.float32)
        return d.mean().item()

    @property
    def global_avg(self):
        return self.total / self.count

    @property
    def max(self):
        return max(self.deque)

    @property
    def value(self):
        return self.deque[-1]

    def __str__(self):
        return self.fmt.format(
            median=self.median,
            avg=self.avg,
            global_avg=self.global_avg,
            max=self.max,
            value=self.value)


class MetricLogger(object):
    def __init__(self, delimiter="\t"):
        self.meters = defaultdict(SmoothedValue)
        self.delimiter = delimiter

    def update(self, **kwargs):
        for k, v in kwargs.items():
            if v is None:
                continue
            if isinstance(v, torch.Tensor):
                v = v.item()
            assert isinstance(v, (float, int))
            self.meters[k].update(v)

    def __getattr__(self, attr):
        if attr in self.meters:
            return self.meters[attr]
        if attr in self.__dict__:
            return self.__dict__[attr]
        raise AttributeError("'{}' object has no attribute '{}'".format(
            type(self).__name__, attr))

    def __str__(self):
        loss_str = []
        for name, meter in self.meters.items():
            loss_str.append(
                "{}: {}".format(name, str(meter))
            )
        return self.delimiter.join(loss_str)

    def synchronize_between_processes(self):
        for meter in self.meters.values():
            meter.synchronize_between_processes()

    def add_meter(self, name, meter):
        self.meters[name] = meter

    def log_every(self, iterable, print_freq, header=None, start_iter=0):
        i = start_iter
        if not header:
            header = ''
        start_time = time.time()
        end = time.time()
        iter_time = SmoothedValue(fmt='{avg:.4f}')
        data_time = SmoothedValue(fmt='{avg:.4f}')
        log_msg = [
            header,
            '[{0' + '}/{1}]',
            '{meters}',
            'time: {time}',
            'data: {data}'
        ]
        if torch.cuda.is_available():
            log_msg.append('max mem: {memory:.0f}')
        log_msg = self.delimiter.join(log_msg)
        MB = 1024.0 * 1024.0
        for obj in iterable:
            data_time.update(time.time() - end)
            yield obj
            iter_time.update(time.time() - end)
            if i % print_freq == 0:
                try:
                    total_len = len(iterable)
                except:
                    total_len = "unknown"
                if torch.cuda.is_available():
                    print(log_msg.format(
                        i, total_len,
                        meters=str(self),
                        time=str(iter_time), data=str(data_time),
                        memory=torch.cuda.max_memory_allocated() / MB))
                else:
                    print(log_msg.format(
                        i, total_len,
                        meters=str(self),
                        time=str(iter_time), data=str(data_time)))
            i += 1
            end = time.time()
        total_time = time.time() - start_time
        total_time_str = str(datetime.timedelta(seconds=int(total_time)))
        print('{} Total time: {} ({:.4f} s / it)'.format(
            header, total_time_str, total_time / len(iterable)))


def setup_for_distributed(is_master):
    """
    This function disables printing when not in master process
    """
    builtin_print = builtins.print

    def print(*args, **kwargs):
        force = kwargs.pop('force', False)
#        force = force or (get_world_size() > 8)
        if is_master or force:
            now = datetime.datetime.now().time()
            builtin_print('[{}] '.format(now), end='')  # print with time stamp
            builtin_print(*args, **kwargs)

    builtins.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 save_on_master(*args, **kwargs):
    if is_main_process():
        torch.save(*args, **kwargs)

def init_distributed_mode(args):
    if args.dist_on_itp:
        args.rank = int(os.environ['OMPI_COMM_WORLD_RANK'])
        args.world_size = int(os.environ['OMPI_COMM_WORLD_SIZE'])
        args.gpu = int(os.environ['OMPI_COMM_WORLD_LOCAL_RANK'])
        args.dist_url = "tcp://%s:%s" % (os.environ['MASTER_ADDR'], os.environ['MASTER_PORT'])
        os.environ['LOCAL_RANK'] = str(args.gpu)
        os.environ['RANK'] = str(args.rank)
        os.environ['WORLD_SIZE'] = str(args.world_size)
        # ["RANK", "WORLD_SIZE", "MASTER_ADDR", "MASTER_PORT", "LOCAL_RANK"]
    elif '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:
        os.environ['MASTER_PORT'] = '8994'
        while 'MASTER_ADDR' not in os.environ or len(os.environ['MASTER_ADDR'].strip()) == 0:
            os.environ['MASTER_ADDR'] = subprocess.check_output('sinfo -Nh -n %s | head -n 1 | awk \'{print $1}\'' % os.environ['SLURM_NODELIST'], shell=True, ).decode().strip()
            time.sleep(1)
        print(os.environ['MASTER_ADDR'])
        args.world_size = int(os.environ['SLURM_NPROCS'])
        args.rank = int(os.environ['SLURM_PROCID'])
        args.gpu = args.rank % torch.cuda.device_count()
        args.local_rank = args.gpu
        os.environ['LOCAL_RANK'] = str(args.gpu)
        os.environ['WORLD_SIZE'] = str(args.world_size)
        os.environ['RANK'] = str(args.rank)
    else:
        print('Not using distributed mode')
        setup_for_distributed(is_master=True)  # hack
        args.distributed = False
        return

    args.distributed = True

    torch.cuda.set_device(args.gpu)
    args.dist_backend = 'nccl'
    print('| distributed init (rank {}): {}, gpu {}'.format(
        args.rank, args.dist_url, args.gpu), flush=True)
    torch.distributed.init_process_group(backend=args.dist_backend, init_method=args.dist_url,
                                         world_size=args.world_size, rank=args.rank)
    torch.distributed.barrier()
    setup_for_distributed(args.rank == 0)


def init_distributed_mode1(args):
    if args.dist_on_itp:
        args.rank = int(os.environ['OMPI_COMM_WORLD_RANK'])
        args.world_size = int(os.environ['OMPI_COMM_WORLD_SIZE'])
        args.gpu = int(os.environ['OMPI_COMM_WORLD_LOCAL_RANK'])
        args.dist_url = "tcp://%s:%s" % (os.environ['MASTER_ADDR'], os.environ['MASTER_PORT'])
        os.environ['LOCAL_RANK'] = str(args.gpu)
        os.environ['RANK'] = str(args.rank)
        os.environ['WORLD_SIZE'] = str(args.world_size)
        # ["RANK", "WORLD_SIZE", "MASTER_ADDR", "MASTER_PORT", "LOCAL_RANK"]
    elif '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')
        setup_for_distributed(is_master=True)  # hack
        args.distributed = False
        return

    args.distributed = True

    torch.cuda.set_device(args.gpu)
    args.dist_backend = 'nccl'
    print('| distributed init (rank {}): {}, gpu {}'.format(
        args.rank, args.dist_url, args.gpu), flush=True)
    torch.distributed.init_process_group(backend=args.dist_backend, init_method=args.dist_url,
                                         world_size=args.world_size, rank=args.rank)
    torch.distributed.barrier()
    setup_for_distributed(args.rank == 0)


class NativeScalerWithGradNormCount:
    state_dict_key = "amp_scaler"

    def __init__(self, args):
        self._scaler = ShardedGradScaler(enabled=args.precision in ["fp16"])

    def __call__(self, loss, optimizer, model, clip_grad=None, parameters=None, create_graph=False, update_grad=True):
        if update_grad:
            self._scaler.scale(loss).backward(create_graph=create_graph)
            if clip_grad is not None:
                assert parameters is not None
                self._scaler.unscale_(optimizer)  # unscale the gradients of optimizer's assigned params in-place
                # norm = torch.nn.utils.clip_grad_norm_(parameters, clip_grad)
                norm = model.clip_grad_norm_(clip_grad)
            else:
                raise NotImplementedError("please set clip_grad to a very large value if you do not want to clip.")
                self._scaler.unscale_(optimizer)
                norm = get_grad_norm_(parameters)
            self._scaler.step(optimizer)
            self._scaler.update()
        else:
            with model.no_sync():
                self._scaler.scale(loss).backward(create_graph=create_graph)
            norm = None
        return norm

    def state_dict(self):
        return self._scaler.state_dict()

    def load_state_dict(self, state_dict):
        self._scaler.load_state_dict(state_dict)


def get_grad_norm_(parameters, norm_type: float = 2.0) -> torch.Tensor:
    if isinstance(parameters, torch.Tensor):
        parameters = [parameters]
    parameters = [p for p in parameters if p.grad is not None]
    norm_type = float(norm_type)
    if len(parameters) == 0:
        return torch.tensor(0.)
    device = parameters[0].grad.device
    if norm_type == inf:
        total_norm = max(p.grad.detach().abs().max().to(device) for p in parameters)
    else:
        total_norm = torch.norm(torch.stack([torch.norm(p.grad.detach(), norm_type).to(device) for p in parameters]), norm_type)
    return total_norm


def save_model(output_dir, args, epoch, iteration, model, optimizer, loss_scaler, dataset_state):
    save_dir = os.path.join(output_dir, f"epoch_{epoch}_iter_{iteration:09d}")
    os.makedirs(save_dir, exist_ok=True)
    with FSDP.state_dict_type(model, StateDictType.SHARDED_STATE_DICT):
        to_save = {
            "model": model.state_dict(),
            "optimizer": optimizer.state_dict(),
            "iter": iteration,
            "epoch": epoch,
            "scaler": loss_scaler.state_dict(),
            "args": args,
            "dataset_state": dataset_state,
        }
        save_path = os.path.join(
            save_dir,
            f"checkpoint.{dist.get_rank():05d}-of-{dist.get_world_size():05d}.pth",
        )
        torch.save(to_save, save_path)

    if args.save_consolidated:
        mp_rank = fs_init.get_model_parallel_rank()
        mp_world_size = fs_init.get_model_parallel_world_size()
        consolidated_model_save_path = os.path.join(
            save_dir,
            f"consolidated.{mp_rank:02d}-of-{mp_world_size:02d}.pth",
        )
        with FSDP.state_dict_type(
            model,
            StateDictType.FULL_STATE_DICT,
            FullStateDictConfig(rank0_only=True, offload_to_cpu=True),
        ):
            save_dtype = {
                "fp16": torch.float16,
                "bf16": torch.bfloat16,
                "tf32": torch.float32,
            }[args.precision]
            consolidated_model_state_dict = {
                k: v.to(save_dtype) for k, v in model.state_dict().items()
            }
        if fs_init.get_data_parallel_rank() == 0:
            torch.save(consolidated_model_state_dict, consolidated_model_save_path)
    
    # remove previous ckpts
    ckpts = glob.glob(os.path.join(output_dir, "iter_*")) + glob.glob(os.path.join(output_dir, "epoch_*"))
    ckpts.sort()
    if len(ckpts)>2 and not args.keep_all:
        for ckpt in ckpts[:-2]:
            print('del', ckpt)
            os.system(f'rm {ckpt} -rf')

def load_model(args, model, optimizer, loss_scaler):
    start_iter = 0
    start_epoch = 0
    if args.auto_resume:
        ckpt_dirs = glob.glob(os.path.join(args.output_dir, "iter_*")) + glob.glob(os.path.join(args.output_dir, "epoch_*"))
        ckpt_dirs.sort()
        if len(ckpt_dirs) > 0:
            args.resume = ckpt_dirs[-1]
    if args.resume:
        print("Resume checkpoint %s" % args.resume)
        local_checkpoint_path = os.path.join(
            args.resume,
            f"checkpoint.{dist.get_rank():05d}-of-{dist.get_world_size():05d}.pth",
        )
        with load_with_process_group(fs_init.get_data_parallel_group()):
            checkpoint = torch.load(local_checkpoint_path, map_location='cpu')
        with FSDP.state_dict_type(model, StateDictType.SHARDED_STATE_DICT):
            model.load_state_dict(checkpoint['model'])
        optimizer.load_state_dict(checkpoint['optimizer'])
        loss_scaler.load_state_dict(checkpoint['scaler'])
        start_iter = int(checkpoint['iter']) + 1
        if 'epoch' in checkpoint:
            start_epoch = int(checkpoint['epoch'])
    return start_epoch, start_iter
    
def all_reduce_mean(x):
    world_size = get_world_size()
    if world_size > 1:
        if isinstance(x, torch.Tensor):
            x_reduce = x.clone().cuda()
        else:
            x_reduce = torch.tensor(x).cuda()
        dist.all_reduce(x_reduce)
        x_reduce /= world_size
        return x_reduce.item()
    else:
        return x


def add_weight_decay(model, weight_decay=1e-5, skip_list=()):
    decay = []
    no_decay = []
    for name, param in model.named_parameters():
        if not param.requires_grad:
            continue  # frozen weights
        #if len(param.shape) == 1 or name.endswith(".bias") or name in skip_list:
        if name.endswith(".bias") or name.endswith("norm.weight"):
            no_decay.append(param)
        else:
            decay.append(param)
    return [
        {'params': no_decay, 'weight_decay': 0.},
        {'params': decay, 'weight_decay': weight_decay}]




class default_tensor_type:
    _tensor_type_stack = [(torch.float, "cpu")]
    
    def __init__(
        self,
        dtype: Optional[torch.dtype] = None,
        device: Optional[str] = None,
    ) -> None:
        # Only limited combinations are supported.
        assert device is None or device in ["cpu", "cuda"]
        assert dtype is None or dtype in [torch.float, torch.bfloat16, torch.half]
        self.dtype, self.device = dtype, device
    
    def __enter__(self) -> None:
        dtype, device = self.dtype, self.device
        if dtype is None:
            dtype = default_tensor_type._tensor_type_stack[-1][0]
        if device is None:
            device = default_tensor_type._tensor_type_stack[-1][1]
        default_tensor_type._tensor_type_stack.append((dtype, device))
        
        # We use all 3 calls since the new apis (set_default_device, set_default_dtype)
        # seems to be ineffective sometimes (e.g., set_default_device is ineffective to
        # torch.Tensor calls).
        torch.set_default_tensor_type(default_tensor_type.get_tensor_type(dtype, device))
        torch.set_default_device(device)
        torch.set_default_dtype(dtype)

    def __exit__(
        self,
        exc_type: Optional[type[BaseException]],
        exc_val: Optional[BaseException],
        exc_tb: Optional[TracebackType],
    ) -> None:
        default_tensor_type._tensor_type_stack.pop()
        dtype, device = default_tensor_type._tensor_type_stack[-1]

        torch.set_default_tensor_type(default_tensor_type.get_tensor_type(dtype, device))
        torch.set_default_device(device)
        torch.set_default_dtype(dtype)

    @staticmethod
    def get_tensor_type(dtype: torch.dtype, device: str) -> Any:
        return {
            (torch.float, "cpu"): torch.FloatTensor,
            (torch.bfloat16, "cpu"): torch.BFloat16Tensor,
            (torch.half, "cpu"): torch.HalfTensor,
            (torch.float, "cuda"): torch.cuda.FloatTensor,
            (torch.bfloat16, "cuda"): torch.cuda.BFloat16Tensor,
            (torch.half, "cuda"): torch.cuda.HalfTensor,
        }[(dtype, device)]