# Copyright 2024 Bytedance Ltd. and/or its affiliates
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import datetime
import inspect
import logging
from contextlib import contextmanager
from typing import Any, Dict, Tuple

import torch
import torch.distributed as dist
from codetiming import Timer

from verl.utils.device import get_torch_device
from verl.utils.logger import DecoratorLoggerBase


def _get_current_mem_info(unit: str = "GB", precision: int = 2) -> Tuple[str]:
    """Get current memory usage."""
    assert unit in ["GB", "MB", "KB"]
    divisor = 1024**3 if unit == "GB" else 1024**2 if unit == "MB" else 1024
    mem_allocated = get_torch_device().memory_allocated()
    mem_reserved = get_torch_device().memory_reserved()
    # use get_torch_device().mem_get_info to profile device memory
    # since vllm's sleep mode works below pytorch
    # see https://github.com/vllm-project/vllm/pull/11743#issuecomment-2754338119
    mem_free, mem_total = get_torch_device().mem_get_info()
    mem_used = mem_total - mem_free
    mem_allocated = f"{mem_allocated / divisor:.{precision}f}"
    mem_reserved = f"{mem_reserved / divisor:.{precision}f}"
    mem_used = f"{mem_used / divisor:.{precision}f}"
    mem_total = f"{mem_total / divisor:.{precision}f}"
    return mem_allocated, mem_reserved, mem_used, mem_total


def log_gpu_memory_usage(head: str, logger: logging.Logger = None, level=logging.DEBUG, rank: int = 0):
    if (not dist.is_initialized()) or (rank is None) or (dist.get_rank() == rank):
        mem_allocated, mem_reserved, mem_used, mem_total = _get_current_mem_info()
        message = f"{head}, memory allocated (GB): {mem_allocated}, memory reserved (GB): {mem_reserved}, device memory used/total (GB): {mem_used}/{mem_total}"

        if logger is None:
            print(message)
        else:
            logger.log(msg=message, level=level)


class GPUMemoryLogger(DecoratorLoggerBase):
    """A decorator class to log GPU memory usage.

    Example:
        >>> from verl.utils.debug.performance import GPUMemoryLogger
        >>> @GPUMemoryLogger(role="actor")
        >>> def update_actor(self, batch):
        ...     # real actor update logics
        ...     return
    """

    def __init__(self, role: str, logger: logging.Logger = None, level=logging.DEBUG, log_only_rank_0: bool = True):
        if dist.is_initialized() and dist.get_world_size() > 1:
            rank = dist.get_rank()
        else:
            rank = 0
        super().__init__(role, logger, level, rank, log_only_rank_0)

    def __call__(self, decorated_function: callable):
        def f(*args, **kwargs):
            return self.log(decorated_function, *args, **kwargs)

        return f

    def log(self, func, *args, **kwargs):
        name = func.__name__
        mem_allocated, mem_reserved, mem_used, mem_total = _get_current_mem_info()
        message = f"Before {name}, memory allocated (GB): {mem_allocated}, memory reserved (GB): {mem_reserved}, device memory used/total (GB): {mem_used}/{mem_total}"
        self.logging_function(message)

        output = func(*args, **kwargs)

        mem_allocated, mem_reserved, mem_used, mem_total = _get_current_mem_info()
        message = f"After {name}, memory allocated (GB): {mem_allocated}, memory reserved (GB): {mem_reserved}, device memory used/total (GB): {mem_used}/{mem_total}"

        self.logging_function(message)
        return output


def log_print(ctn: Any):
    current_time = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")

    frame = inspect.currentframe().f_back
    function_name = frame.f_code.co_name
    line_number = frame.f_lineno
    file_name = frame.f_code.co_filename.split("/")[-1]
    print(f"[{current_time}-{file_name}:{line_number}:{function_name}]: {ctn}")


@contextmanager
def _timer(name: str, timing_raw: Dict[str, float]):
    """Context manager for timing code execution.

    This utility function measures the execution time of code within its context
    and accumulates the timing information in the provided dictionary.

    Args:
        name (str): The name/identifier for this timing measurement.
        timing_raw (Dict[str, float]): Dictionary to store timing information.

    Yields:
        None: This is a context manager that yields control back to the code block.
    """
    with Timer(name=name, logger=None) as timer:
        yield
    if name not in timing_raw:
        timing_raw[name] = 0
    timing_raw[name] += timer.last


def reduce_timing(timing_raw: Dict[str, float]) -> Dict[str, float]:
    """Reduce timing information across all processes.

    This function uses distributed communication to gather and sum the timing
    information from all processes in a distributed environment.

    Args:
        timing_raw (Dict[str, float]): Dictionary containing timing information.

    Returns:
        Dict[str, float]: Reduced timing information.
    """
    if not dist.is_initialized():
        return timing_raw

    key_list, timing_list = [], []
    for key in sorted(timing_raw.keys()):
        key_list.append(key)
        timing_list.append(timing_raw[key])
    timing_list = torch.tensor(timing_list, dtype=torch.float32, device=get_torch_device().current_device())
    torch.distributed.all_reduce(timing_list, op=torch.distributed.ReduceOp.AVG)
    timing_list = [tensor.item() for tensor in timing_list.to("cpu")]
    timing_generate = {key_list[i]: timing_list[i] for i in range(len(key_list))}
    return timing_generate
