"""Keep child processes from popping console windows on Windows.

The UI worker launches training jobs with pythonw.exe and DETACHED_PROCESS so
they survive the UI shutting down (see ui/cron/actions/startJob.ts). That
leaves the job with no console at all, and Windows hands a brand new console
-- with a visible window -- to any console program launched from a process
that has none. MSVC during a torch/triton compile, git during a HF download
and ffmpeg would each flash a window on the user's desktop.

Defaulting those spawns to CREATE_NO_WINDOW suppresses the flash. This is a
no-op unless we are on Windows *and* have no console, so running run.py from a
terminal behaves exactly as it did before.
"""

import subprocess
import sys

CREATE_NEW_CONSOLE = 0x00000010
DETACHED_PROCESS = 0x00000008
CREATE_NO_WINDOW = 0x08000000

# creationflags is the 14th positional parameter of Popen.__init__ after self.
_CREATIONFLAGS_POSITION = 14

_patched = False


def _has_console():
    import ctypes

    return bool(ctypes.windll.kernel32.GetConsoleWindow())


def suppress_child_consoles():
    """Make CREATE_NO_WINDOW the default for subprocesses, where it matters."""
    global _patched
    if _patched or sys.platform != "win32":
        return
    try:
        if _has_console():
            return
    except Exception:
        # Never let a console tweak take down a training run.
        return

    original_init = subprocess.Popen.__init__

    def patched_init(self, *args, **kwargs):
        if len(args) >= _CREATIONFLAGS_POSITION:
            # Passed positionally; leave the caller's choice alone.
            return original_init(self, *args, **kwargs)
        flags = kwargs.get("creationflags", 0)
        if not flags & (CREATE_NEW_CONSOLE | DETACHED_PROCESS | CREATE_NO_WINDOW):
            kwargs["creationflags"] = flags | CREATE_NO_WINDOW
        return original_init(self, *args, **kwargs)

    subprocess.Popen.__init__ = patched_init
    _patched = True