from ctypes import pointer, windll
from ctypes.wintypes import BOOL, DWORD, HANDLE
from typing import List, Optional

from prot.prompt.win32_types import SECURITY_ATTRIBUTES

__all__ = ["wait_for_handles", "create_win32_event"]


WAIT_TIMEOUT = 0x00000102
INFINITE = -1


def wait_for_handles(
    handles: List[HANDLE], timeout: int = INFINITE
) -> Optional[HANDLE]:
    """
    Waits for multiple handles. (Similar to 'select') Returns the handle which is ready.
    Returns `None` on timeout.
    http://msdn.microsoft.com/en-us/library/windows/desktop/ms687025(v=vs.85).aspx

    Note that handles should be a list of `HANDLE` objects, not integers. See
    this comment in the patch by @quark-zju for the reason why:

        ''' Make sure HANDLE on Windows has a correct size

        Previously, the type of various HANDLEs are native Python integer
        types. The ctypes library will treat them as 4-byte integer when used
        in function arguments. On 64-bit Windows, HANDLE is 8-byte and usually
        a small integer. Depending on whether the extra 4 bytes are zero-ed out
        or not, things can happen to work, or break. '''

    This function returns either `None` or one of the given `HANDLE` objects.
    (The return value can be tested with the `is` operator.)
    """
    arrtype = HANDLE * len(handles)
    handle_array = arrtype(*handles)

    ret = windll.kernel32.WaitForMultipleObjects(
        len(handle_array), handle_array, BOOL(False), DWORD(timeout)
    )

    if ret == WAIT_TIMEOUT:
        return None
    else:
        return handles[ret]


def create_win32_event() -> HANDLE:
    """
    Creates a Win32 unnamed Event .
    http://msdn.microsoft.com/en-us/library/windows/desktop/ms682396(v=vs.85).aspx
    """
    return HANDLE(
        windll.kernel32.CreateEventA(
            pointer(SECURITY_ATTRIBUTES()),
            BOOL(True),  # Manual reset event.
            BOOL(False),  # Initial state.
            None,  # Unnamed event object.
        )
    )
