"""Generate NUT (Network UPS Tools) configuration files.

Called by entrypoint.sh before the NUT daemons start.  Reads config either from
environment variables (legacy NUT_MANAGED=1 path) or from a JSON file written
by the FabledScryer settings page (/data/nut_managed.json).

Environment variables (used when no --from-file is given):
  NUT_DRIVER       NUT driver (default: snmp-ups)
                     snmp-ups    — any UPS with SNMP management card (APC, Eaton,
                                   CyberPower, Tripp Lite, Liebert, ...)
                     netxml-ups  — Eaton Network Management Card (XML/HTTP)
  NUT_UPS_NAME     Name exposed by upsd (default: ups)
                   Must match 'ups_name' in the UPS plugin settings.
  NUT_UPS_HOST     IP address or hostname of the UPS management card (required)
  NUT_SNMP_COMMUNITY  SNMP community string (default: public) [snmp-ups only]
  NUT_SNMP_VERSION    SNMP version: v1, v2c (default: v1) [snmp-ups only]
  NUT_USERNAME     Optional upsd username for authenticated access
  NUT_PASSWORD     Optional upsd password

JSON file format (--from-file path):
  {
    "ups_host": "192.168.1.x",   // required
    "driver": "snmp-ups",
    "ups_name": "ups",
    "snmp_community": "public",
    "snmp_version": "v1",
    "username": "",
    "password": ""
  }
"""
import json
import os
import sys
from pathlib import Path

NUT_CONF_DIR = Path("/etc/nut")
NUT_MANAGED_JSON = Path("/data/nut_managed.json")


def _env(key: str, default: str = "") -> str:
    return os.environ.get(key, default).strip()


def write_configs(cfg: dict | None = None) -> None:
    """Write NUT config files.  If cfg is given, use it; otherwise fall back to env vars."""
    NUT_CONF_DIR.mkdir(parents=True, exist_ok=True)

    if cfg is not None:
        driver    = cfg.get("driver", "snmp-ups").strip()
        ups_name  = cfg.get("ups_name", "ups").strip()
        ups_host  = cfg.get("ups_host", "").strip()
        community = cfg.get("snmp_community", "public").strip()
        snmp_ver  = cfg.get("snmp_version", "v1").strip()
        username  = cfg.get("username", "").strip()
        password  = cfg.get("password", "").strip()
    else:
        driver    = _env("NUT_DRIVER", "snmp-ups")
        ups_name  = _env("NUT_UPS_NAME", "ups")
        ups_host  = _env("NUT_UPS_HOST")
        community = _env("NUT_SNMP_COMMUNITY", "public")
        snmp_ver  = _env("NUT_SNMP_VERSION", "v1")
        username  = _env("NUT_USERNAME")
        password  = _env("NUT_PASSWORD")

    if not ups_host:
        print("[nut_setup] ERROR: NUT_UPS_HOST is required", file=sys.stderr)
        sys.exit(1)

    # ── nut.conf ───────────────────────────────────────────────────────────────
    (NUT_CONF_DIR / "nut.conf").write_text("MODE=standalone\n")

    # ── ups.conf ───────────────────────────────────────────────────────────────
    ups_block = [f"[{ups_name}]"]
    ups_block.append(f"    driver = {driver}")

    if driver == "netxml-ups":
        # Eaton: port is a URL
        ups_block.append(f"    port = http://{ups_host}")
    else:
        # snmp-ups and others: port is the IP/hostname
        ups_block.append(f"    port = {ups_host}")
        if driver == "snmp-ups":
            ups_block.append(f"    community = {community}")
            ups_block.append(f"    snmp_version = {snmp_ver}")

    ups_block.append(f'    desc = "Network UPS at {ups_host}"')
    (NUT_CONF_DIR / "ups.conf").write_text("\n".join(ups_block) + "\n")

    # ── upsd.conf ──────────────────────────────────────────────────────────────
    (NUT_CONF_DIR / "upsd.conf").write_text("LISTEN 127.0.0.1 3493\n")

    # ── upsd.users ─────────────────────────────────────────────────────────────
    if username and password:
        users_content = (
            f"[{username}]\n"
            f"    password = {password}\n"
            f"    upsmon primary\n"
        )
    else:
        users_content = "# No users configured — unauthenticated access\n"
    users_path = NUT_CONF_DIR / "upsd.users"
    users_path.write_text(users_content)
    users_path.chmod(0o640)

    print(
        f"[nut_setup] Config written: driver={driver} host={ups_host} ups_name={ups_name}"
    )


if __name__ == "__main__":
    try:
        cfg = None
        if "--from-file" in sys.argv:
            idx = sys.argv.index("--from-file")
            json_path = Path(sys.argv[idx + 1])
            with json_path.open() as f:
                cfg = json.load(f)
        write_configs(cfg)
    except Exception as exc:
        print(f"[nut_setup] ERROR: {exc}", file=sys.stderr)
        sys.exit(1)