#!/usr/bin/env python3
"""simple.py — check whether a list of sites is reachable and how fast they respond.

Usage:
    python simple.py [sites.txt]

The config file is a plain-text list of URLs, one per line.
Lines starting with '#' and blank lines are ignored.
Exits 0 if all sites responded, 1 if any failed.
"""

import sys
import time
import urllib.error
import urllib.request

_TIMEOUT = 10  # seconds


def load_sites(path: str) -> list[str]:
    """Return URLs from a plain-text config file (one per line, # comments)."""
    urls = []
    with open(path) as f:
        for raw in f:
            line = raw.strip()
            if not line or line.startswith("#"):
                continue
            # Take only the first token so future 'url  key=value' annotations
            # (e.g. budget=200ms) don't break the URL.
            urls.append(line.split()[0])
    return urls


def check_site(url: str) -> tuple[bool, float, str]:
    """Probe url and return (ok, elapsed_ms, error_message).

    The body is fully read so the elapsed time includes transfer, not just TTFB.
    """
    t0 = time.perf_counter()
    try:
        with urllib.request.urlopen(url, timeout=_TIMEOUT) as resp:
            resp.read()
        elapsed = (time.perf_counter() - t0) * 1000
        return True, elapsed, ""
    except urllib.error.HTTPError as exc:
        elapsed = (time.perf_counter() - t0) * 1000
        # Show the full "HTTP Error CODE: REASON" so the status code is visible.
        return False, elapsed, str(exc)
    except urllib.error.URLError as exc:
        elapsed = (time.perf_counter() - t0) * 1000
        # URLError.reason is either a string or another exception.
        reason = str(exc.reason) if exc.reason else str(exc)
        return False, elapsed, reason
    except Exception as exc:  # noqa: BLE001 — catch-all for unexpected errors
        elapsed = (time.perf_counter() - t0) * 1000
        return False, elapsed, str(exc)


def main(argv: list[str]) -> int:
    config = argv[0] if argv else "sites.txt"

    try:
        urls = load_sites(config)
    except FileNotFoundError:
        print(f"error: config file not found: {config}", file=sys.stderr)
        return 1
    except OSError as exc:
        print(f"error: cannot read config file: {exc}", file=sys.stderr)
        return 1

    if not urls:
        print("error: no URLs found in config file", file=sys.stderr)
        return 1

    any_failed = False
    for url in urls:
        ok, elapsed_ms, err = check_site(url)
        if ok:
            print(f"OK     {elapsed_ms:8.2f} ms  {url}")
        else:
            any_failed = True
            print(f"FAIL   ({err})  {url}")

    return 1 if any_failed else 0


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))