"""Pair this Pi with the backend.

Usage:
    python -m client.pair --backend https://backend.example.com [--code XYZ12345]

Called from install.sh after it prompts the user for the code.
"""
import argparse
import socket

import requests

from client.config import Config, save_config
from client.log import get_logger

_log = get_logger("pair")

CLIENT_VERSION = "0.1.0"


def pair(*, backend: str, code: str | None, hostname: str) -> None:
    backend = backend.rstrip("/")
    if not code:
        code = input("Pairing code: ").strip()
    if not code:
        raise SystemExit("no pairing code supplied")

    url = f"{backend}/api/pair"
    payload = {"code": code, "hostname": hostname, "client_version": CLIENT_VERSION}
    _log.info("POST %s code=%s hostname=%s", url, code, hostname)

    try:
        resp = requests.post(url, json=payload, timeout=30)
    except requests.RequestException as exc:
        raise SystemExit(f"pair request failed: {exc}") from exc

    if resp.status_code != 200:
        try:
            err = resp.json().get("error", resp.text)
        except ValueError:
            err = resp.text
        raise SystemExit(f"/api/pair returned {resp.status_code}: {err}")

    body = resp.json()
    cfg = Config(
        device_id=str(body["device_id"]),
        device_token=str(body["device_token"]),
        backend_ws=str(body["backend_ws"]),
    )
    save_config(cfg)
    _log.info("paired device %s; config saved", cfg.device_id)


def main() -> None:
    parser = argparse.ArgumentParser(description="Pair this Pi with the backend.")
    parser.add_argument("--backend", required=True, help="Backend base URL (https://...)")
    parser.add_argument("--code", default=None, help="Pairing code (prompted if omitted)")
    parser.add_argument(
        "--hostname",
        default=socket.gethostname(),
        help="Hostname reported to the backend (defaults to socket.gethostname())",
    )
    args = parser.parse_args()
    pair(backend=args.backend, code=args.code, hostname=args.hostname)


if __name__ == "__main__":
    main()