#!/usr/bin/env python3
"""Independent, dependency-free Pulse liveness check for an external monitor."""

from __future__ import annotations

import argparse
import sys
from urllib.error import HTTPError, URLError
from urllib.parse import urlparse
from urllib.request import HTTPRedirectHandler, Request, build_opener


class NoRedirectHandler(HTTPRedirectHandler):
    def redirect_request(self, req, fp, code, msg, headers, newurl):
        return None

def check(url: str, timeout: float = 5.0) -> tuple[bool, str]:
    parsed = urlparse(url)
    if parsed.scheme not in {"http", "https"} or not parsed.hostname or parsed.username or parsed.password:
        return False, "endpoint must be an http(s) URL without embedded credentials"
    if timeout < 1 or timeout > 30:
        return False, "timeout must be between 1 and 30 seconds"
    request = Request(url, headers={"Accept": "text/plain", "User-Agent": "pulse-deadman/1"}, method="GET")
    try:
        with build_opener(NoRedirectHandler).open(request, timeout=timeout) as response:
            body = response.read(64).decode("utf-8", errors="replace").strip()
            if response.status != 200 or body != "ok":
                return False, f"unexpected liveness response ({response.status})"
    except HTTPError as error:
        return False, f"liveness returned HTTP {error.code}"
    except (URLError, TimeoutError, OSError) as error:
        return False, f"liveness request failed ({error.__class__.__name__})"
    return True, "ok"


def main() -> int:
    parser = argparse.ArgumentParser(description="Check Pulse /healthz from an independent monitor")
    parser.add_argument("url", help="HTTPS URL to Pulse /healthz")
    parser.add_argument("--timeout", type=float, default=5.0)
    args = parser.parse_args()
    ok, message = check(args.url, args.timeout)
    print(message)
    return 0 if ok else 1


if __name__ == "__main__":
    sys.exit(main())