"""subprocess.run replacement for running untrusted model programs on Windows.

Two Windows traps make subprocess.run(..., timeout=) hang forever on a stuck program:
  * in a venv, python.exe is a launcher that starts the real interpreter as a child; the timeout kills only the
    launcher and the child keeps the pipes open;
  * Popen.communicate writes `input` synchronously before it starts waiting, so a program that stops reading a large
    input blocks the write and the timeout is never checked.
run() feeds stdin from a temporary file and kills the whole process tree on timeout, then raises
subprocess.TimeoutExpired like subprocess.run."""
import os
import subprocess
import tempfile


def run(cmd, input=None, timeout=None, capture_output=True, text=False, encoding=None, errors=None, **kw):
    kw.setdefault("creationflags", getattr(subprocess, "CREATE_NO_WINDOW", 0))
    fin, path = subprocess.DEVNULL, None
    if input is not None:
        fd, path = tempfile.mkstemp(suffix=".in")
        with os.fdopen(fd, "wb") as f:
            f.write(input if isinstance(input, bytes) else input.encode(encoding or "utf-8"))
        fin = open(path, "rb")
    try:
        p = subprocess.Popen(cmd, stdin=fin, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=text,
                             encoding=encoding, errors=errors, **kw)
        try:
            out, err = p.communicate(timeout=timeout)
        except subprocess.TimeoutExpired:
            subprocess.run(["taskkill", "/F", "/T", "/PID", str(p.pid)], capture_output=True)
            try:
                p.communicate(timeout=10)
            except subprocess.TimeoutExpired:
                pass
            raise subprocess.TimeoutExpired(cmd, timeout)
        return subprocess.CompletedProcess(cmd, p.returncode, out, err)
    finally:
        if path:
            fin.close()
            try:
                os.remove(path)
            except OSError:
                pass