from __future__ import annotations

import time
from contextlib import contextmanager

from loguru import logger

class PerfTimer:
    """性能计时器，用于测量代码段执行耗时"""

    def __init__(self, name: str = "") -> None:
        self.name = name
        self._start = 0.0
        self._elapsed = 0.0

    def start(self) -> PerfTimer:
        """启动计时器"""
        self._start = time.perf_counter()
        return self

    def stop(self) -> float:
        """停止计时器并返回耗时（秒）"""
        self._elapsed = time.perf_counter() - self._start
        return self._elapsed

    @property
    def elapsed_ms(self) -> float:
        """返回已记录耗时（毫秒）"""
        return self._elapsed * 1000


@contextmanager
def measure(name: str = ""):
    """上下文管理器：进入时计时，退出时记录耗时日志"""
    timer = PerfTimer(name).start()
    yield timer
    elapsed = timer.stop()
    if name:
        logger.debug("{} took {:.1f}ms", name, timer.elapsed_ms)