import asyncio
from concurrent.futures import Executor
from typing import AsyncGenerator, AsyncIterable, Generator, Iterable, TypeVar

T = TypeVar('T')


async def iter2asynciter(
        iterable: Iterable[T],
        *,
        loop: asyncio.AbstractEventLoop = None,
        executor: Executor = None) -> AsyncGenerator[T, None]:
    if loop is None:
        loop = asyncio.get_running_loop()
    sentinel = object()
    iterator = iter(iterable)

    future = loop.run_in_executor(executor, next, iterator, sentinel)
    while True:
        v = await future
        if v is sentinel:
            break
        future = loop.run_in_executor(executor, next, iterator, sentinel)
        yield v


def asynciter2iter(
        asynciterable: AsyncIterable[T],
        *,
        loop: asyncio.AbstractEventLoop) -> Generator[T, None, None]:
    asynciterator = asynciterable.__aiter__()

    future = asyncio.run_coroutine_threadsafe(asynciterator.__anext__(), loop)
    while True:
        try:
            v = future.result()
        except StopAsyncIteration:
            break
        else:
            future = asyncio.run_coroutine_threadsafe(asynciterator.__anext__(), loop)
            yield v