import asyncio
from greenletio.core import await_


def wait_to_read(fd):
    event = asyncio.Event()
    asyncio.get_event_loop().add_reader(fd, event.set)
    await_(event.wait())
    asyncio.get_event_loop().remove_reader(fd)


def wait_to_write(fd):
    event = asyncio.Event()
    asyncio.get_event_loop().add_writer(fd, event.set)
    await_(event.wait())
    asyncio.get_event_loop().remove_writer(fd)


def wait_many(read_list, write_list, timeout=None):
    readers = []
    writers = []
    event = asyncio.Event()

    def _reader_callback(fd):
        if fd not in readers:  # pragma: no branch
            readers.append(fd)
        event.set()

    def _writer_callback(fd):
        if fd not in writers:  # pragma: no branch
            writers.append(fd)
        event.set()

    for fd in read_list:
        asyncio.get_event_loop().add_reader(fd, _reader_callback, fd)
    for fd in write_list:
        asyncio.get_event_loop().add_writer(fd, _writer_callback, fd)
    try:
        await_(asyncio.wait_for(event.wait(), timeout))
    except asyncio.TimeoutError:  # pragma: no cover
        pass
    for fd in read_list:
        asyncio.get_event_loop().remove_reader(fd)
    for fd in write_list:
        asyncio.get_event_loop().remove_writer(fd)
    return readers, writers