import inspect
import re
from functools import partial
from typing import Callable


def is_async(func) -> bool:
    return inspect.iscoroutinefunction(_unpartial(func))


def _unpartial(func: Callable) -> Callable:
    while isinstance(func, partial):
        func = func.func
    return func


def describe(func: Callable) -> str:
    if _is_a_lambda(func):
        return _content_of(func)
    return _unpartial(func).__name__


def _is_a_lambda(func: Callable) -> bool:
    lambda_template = lambda: 0  # noqa: E731
    return (
        isinstance(func, type(lambda_template))
        and func.__name__ == lambda_template.__name__
    )


def _content_of(lambda_func: Callable) -> str:
    source_line = inspect.getsource(lambda_func)
    r = re.search(r"lambda[^:]*:\s*(.+)\s*\)", source_line)
    assert r is not None
    return r.group(1)
