# mypy: allow-untyped-defs
import functools
import time
from typing import Any, Callable, Dict, List, TypeVar
from typing_extensions import ParamSpec
from uuid import uuid4

import torch.distributed.c10d_logger as c10d_logger
from torch.distributed.checkpoint.logging_handlers import DCP_LOGGER_NAME


__all__: List[str] = []

global _dcp_logger
_dcp_logger = c10d_logger._get_or_create_logger(DCP_LOGGER_NAME)

_T = TypeVar("_T")
_P = ParamSpec("_P")


def _msg_dict_from_dcp_method_args(*args, **kwargs) -> Dict[str, Any]:
    """
    Extracts log data from dcp method args
    """
    msg_dict = {}

    # checkpoint ID can be passed in through the serializer or through the checkpoint id directly
    storage_writer = kwargs.get("storage_writer", None)
    storage_reader = kwargs.get("storage_reader", None)
    planner = kwargs.get("planner", None)

    checkpoint_id = kwargs.get("checkpoint_id", None)
    if not checkpoint_id and (serializer := storage_writer or storage_reader):
        checkpoint_id = getattr(serializer, "checkpoint_id", None)

    msg_dict["checkpoint_id"] = (
        str(checkpoint_id) if checkpoint_id is not None else checkpoint_id
    )

    # Uniquely identify a _dcp_method_logger wrapped function call.
    msg_dict["uuid"] = str(uuid4().int)

    if storage_writer:
        msg_dict["storage_writer"] = storage_writer.__class__.__name__

    if storage_reader:
        msg_dict["storage_reader"] = storage_reader.__class__.__name__

    if planner:
        msg_dict["planner"] = planner.__class__.__name__

    return msg_dict


def _get_msg_dict(func_name, *args, **kwargs) -> Dict[str, Any]:
    msg_dict = _msg_dict_from_dcp_method_args(*args, **kwargs)
    msg_dict.update(c10d_logger._get_msg_dict(func_name, **msg_dict))

    return msg_dict


def _dcp_method_logger(
    log_exceptions: bool = False, **wrapper_kwargs: Any
) -> Callable[[Callable[_P, _T]], Callable[_P, _T]]:  # pyre-ignore
    """This method decorator logs the start, end, and exception of wrapped events."""

    def decorator(func: Callable[_P, _T]):
        @functools.wraps(func)
        def wrapper(*args: _P.args, **kwargs: _P.kwargs) -> _T:
            msg_dict = _get_msg_dict(
                func.__name__, *args, **{**wrapper_kwargs, **kwargs}
            )

            # log start event
            msg_dict["event"] = "start"
            t0 = time.time_ns()
            msg_dict["time"] = t0
            msg_dict["log_exceptions"] = log_exceptions
            _dcp_logger.debug(msg_dict)

            # exceptions
            try:
                result = func(*args, **kwargs)
            except BaseException as error:
                if log_exceptions:
                    msg_dict["event"] = "exception"
                    msg_dict["error"] = f"{error}"
                    msg_dict["time"] = time.time_ns()
                    _dcp_logger.error(msg_dict)
                raise

            # end event
            msg_dict["event"] = "end"
            t1 = time.time_ns()
            msg_dict["time"] = time.time_ns()
            msg_dict["times_spent"] = t1 - t0
            _dcp_logger.debug(msg_dict)

            return result

        return wrapper

    return decorator