#!/usr/bin/env python3
"""How many concurrent INTERACTIVE (`docker exec -i`) sessions does this host take?

Trivial non-interactive execs succeed 8-way, but the Phew SLA checker's 5-way
interactive test failed with

    failed to open stdin fifo: error creating fifo ... -stdin: no such file
    No such exec instance: <id>

which is a containerd exec-session limit, not a checker bug. Interactive execs
allocate a fifo + a tracked exec instance, so they hit a ceiling that plain
`docker exec <c> true` never approaches.

    python3 panel/exec_probe_i.py [container] [N]
"""
import subprocess
import sys
import time
from concurrent.futures import ThreadPoolExecutor

CONT = sys.argv[1] if len(sys.argv) > 1 else "phew_container_team1"
N = int(sys.argv[2]) if len(sys.argv) > 2 else 8


def interactive(i: int) -> tuple[int, str]:
    """Mimic the checker: `exec -i`, write a line, read the reply, exit."""
    p = subprocess.Popen(
        ["docker", "exec", "-i", CONT, "sh", "-c",
         "echo $$; read line; echo \"got:$line\""],
        stdin=subprocess.PIPE, stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT, text=True, bufsize=0)
    try:
        out, _ = p.communicate("hello\n", timeout=45)
    except subprocess.TimeoutExpired:
        p.kill()
        out = "TIMEOUT"
    return p.returncode, (out or "").strip().replace("\n", " | ")[:150]


def main() -> None:
    print(f"container={CONT}  N={N} interactive execs")
    ok = 0
    with ThreadPoolExecutor(max_workers=N) as ex:
        for rc, out in ex.map(interactive, range(N)):
            if rc == 0 and "got:hello" in out:
                ok += 1
            else:
                print(f"  FAIL rc={rc}: {out}")
    print(f"  {ok}/{N} interactive execs OK")
    print("RESULT:", "PASS" if ok == N else f"limit reached at {ok}/{N}")


if __name__ == "__main__":
    main()