pferd/PFERD/utils.py

import asyncio
import getpass
import sys
import threading
from abc import ABC, abstractmethod
from contextlib import AsyncExitStack
from types import TracebackType
from typing import Any, Callable, Dict, Generic, Optional, Type, TypeVar
from urllib.parse import parse_qs, urlencode, urlsplit, urlunsplit

import bs4

T = TypeVar("T")


async def in_daemon_thread(func: Callable[..., T], *args: Any, **kwargs: Any) -> T:
    loop = asyncio.get_running_loop()
    future: asyncio.Future[T] = asyncio.Future()

    def thread_func() -> None:
        result = func()
        loop.call_soon_threadsafe(future.set_result, result)

    threading.Thread(target=thread_func, daemon=True).start()

    return await future


async def ainput(prompt: str) -> str:
    return await in_daemon_thread(lambda: input(prompt))


async def agetpass(prompt: str) -> str:
    return await in_daemon_thread(lambda: getpass.getpass(prompt))


def soupify(data: bytes) -> bs4.BeautifulSoup:
    """
    Parses HTML to a beautifulsoup object.
    """

    return bs4.BeautifulSoup(data, "html.parser")


def url_set_query_param(url: str, param: str, value: str) -> str:
    """
    Set a query parameter in an url, overwriting existing ones with the same name.
    """
    scheme, netloc, path, query, fragment = urlsplit(url)
    query_parameters = parse_qs(query)
    query_parameters[param] = [value]
    new_query_string = urlencode(query_parameters, doseq=True)

    return urlunsplit((scheme, netloc, path, new_query_string, fragment))


def url_set_query_params(url: str, params: Dict[str, str]) -> str:
    """
    Sets multiple query parameters in an url, overwriting existing ones.
    """
    result = url

    for key, val in params.items():
        result = url_set_query_param(result, key, val)

    return result


async def prompt_yes_no(query: str, default: Optional[bool]) -> bool:
    """
    Asks the user a yes/no question and returns their choice.
    """

    if default is True:
        query += " [Y/n] "
    elif default is False:
        query += " [y/N] "
    else:
        query += " [y/n] "

    while True:
        response = (await ainput(query)).strip().lower()
        if response == "y":
            return True
        elif response == "n":
            return False
        elif response == "" and default is not None:
            return default

        print("Please answer with 'y' or 'n'.")


class ReusableAsyncContextManager(ABC, Generic[T]):
    def __init__(self) -> None:
        self._active = False
        self._stack = AsyncExitStack()

    @abstractmethod
    async def _on_aenter(self) -> T:
        pass

    async def __aenter__(self) -> T:
        if self._active:
            raise RuntimeError("Nested or otherwise concurrent usage is not allowed")

        self._active = True
        await self._stack.__aenter__()

        # See https://stackoverflow.com/a/13075071
        try:
            result: T = await self._on_aenter()
        except:  # noqa: E722 do not use bare 'except'
            if not await self.__aexit__(*sys.exc_info()):
                raise

        return result

    async def __aexit__(
            self,
            exc_type: Optional[Type[BaseException]],
            exc_value: Optional[BaseException],
            traceback: Optional[TracebackType],
    ) -> Optional[bool]:
        if not self._active:
            raise RuntimeError("__aexit__ called too many times")

        result = await self._stack.__aexit__(exc_type, exc_value, traceback)
        self._active = False
        return result