#!/usr/bin/env python3
import os
import signal
import subprocess
import sys
import time

if len(sys.argv) < 4 or sys.argv[2] != "--":
    raise SystemExit("usage: MeasureProcess.py LOG -- COMMAND [ARGS...]")

log_path = sys.argv[1]
command = sys.argv[3:]
os.makedirs(os.path.dirname(log_path) or ".", exist_ok=True)
start = time.monotonic()
with open(log_path, "wb") as log_file:
    process = subprocess.Popen(command, stdout=log_file, stderr=subprocess.STDOUT,
                               start_new_session=True)
    max_hwm_kib = 0
    max_rss_kib = 0
    max_pid = process.pid
    max_name = ""
    deadline = start + 1800.0
    while process.poll() is None:
        if time.monotonic() >= deadline:
            os.killpg(process.pid, signal.SIGTERM)
            try:
                process.wait(timeout=10)
            except subprocess.TimeoutExpired:
                os.killpg(process.pid, signal.SIGKILL)
                process.wait()
            print("MONITOR_TIMEOUT_SECONDS=1800", file=log_file, flush=True)
            break
        stat_by_pid = {}
        for entry in os.scandir("/proc"):
            if not entry.name.isdigit():
                continue
            pid = int(entry.name)
            try:
                with open(f"/proc/{pid}/stat", "r", encoding="ascii") as stat_file:
                    fields = stat_file.read().rsplit(")", 1)[1].split()
                ppid = int(fields[1])
                stat_by_pid[pid] = ppid
            except (OSError, ValueError, IndexError):
                continue
        descendants = {process.pid}
        changed = True
        while changed:
            changed = False
            for pid, ppid in stat_by_pid.items():
                if ppid in descendants and pid not in descendants:
                    descendants.add(pid)
                    changed = True
        for pid in descendants:
            try:
                with open(f"/proc/{pid}/status", "r", encoding="ascii") as status_file:
                    status = status_file.read().splitlines()
                values = {line.split(":", 1)[0]: line.split(":", 1)[1].strip()
                          for line in status if ":" in line}
                hwm = int(values.get("VmHWM", "0 kB").split()[0])
                rss = int(values.get("VmRSS", "0 kB").split()[0])
                name = values.get("Name", "")
            except (OSError, ValueError, IndexError):
                continue
            if hwm > max_hwm_kib:
                max_hwm_kib, max_pid, max_name = hwm, pid, name
            max_rss_kib = max(max_rss_kib, rss)
        time.sleep(0.05)
    result = process.wait()
    elapsed = time.monotonic() - start
    for line in (
        f"MONITOR_EXIT_CODE={result}",
        f"MONITOR_WALL_SECONDS={elapsed:.3f}",
        f"MONITOR_PEAK_PROCESS_HWM_KIB={max_hwm_kib}",
        f"MONITOR_PEAK_PROCESS_PID={max_pid}",
        f"MONITOR_PEAK_PROCESS_NAME={max_name}",
        f"MONITOR_MAX_SAMPLED_PROCESS_RSS_KIB={max_rss_kib}",
    ):
        log_file.write((line + "\n").encode("utf-8"))
raise SystemExit(result)