"""
Utility module for timing function execution with log metadata preservation.
"""

import functools
import inspect
import time
from typing import Any, Callable, TypeVar, cast

from loguru import logger

# Type variable to preserve the signature of the decorated callable
F = TypeVar("F", bound=Callable[..., Any])


def timer(func: F) -> F:
    """
    Decorator that logs execution time and patches log records with original function metadata.
    """
    # Extract original function metadata to ensure logs point to the correct source
    func_name = func.__name__
    try:
        # Retrieve the source file path and the starting line number
        file_path = inspect.getsourcefile(func) or "unknown"
        _, line_no = inspect.getsourcelines(func)
    except Exception:
        file_path = "unknown"
        line_no = 0

    def patcher(record):
        """Modifies the log record to reflect the decorated function's location."""
        record["function"] = func_name
        record["file"].name = file_path.split("/")[-1]
        record["file"].path = file_path
        record["line"] = line_no

    @functools.wraps(func)
    async def async_wrapper(*args: Any, **kwargs: Any) -> Any:
        """Timer wrapper for asynchronous functions."""
        start_time = time.perf_counter()
        try:
            return await func(*args, **kwargs)
        finally:
            duration = time.perf_counter() - start_time
            # Use patch to inject metadata instead of relying on stack depth
            logger.patch(patcher).info(
                "========== cost={:.6f}s ==========",
                duration,
            )

    @functools.wraps(func)
    def sync_wrapper(*args: Any, **kwargs: Any) -> Any:
        """Timer wrapper for synchronous functions."""
        start_time = time.perf_counter()
        try:
            return func(*args, **kwargs)
        finally:
            duration = time.perf_counter() - start_time
            logger.patch(patcher).info(
                "========== cost={:.6f}s ==========",
                duration,
            )

    if inspect.iscoroutinefunction(func):
        return cast(F, async_wrapper)
    return cast(F, sync_wrapper)