"""DNSMasq state collector."""

from copy import deepcopy
from datetime import UTC, datetime
from pathlib import Path
from typing import Any

from lib import schema
from lib.common import compute_pending, run_proc, strip_apply_meta
from lib.dnsmasq import DEFAULT_CFG, get_config
from lib.state import _now_iso, register_collector


def _collect_dnsmasq() -> schema.DnsmasqState:
    """Collect dnsmasq status, config, and leases.

    Returns:
        Dict containing config, service status, leases, and timestamp.
    """
    DNSMASQ_CONF = "/etc/dnsmasq.d/vacuum-wall.conf"
    LEASE_FILE = "/var/lib/misc/dnsmasq.leases"

    # Load config (lib defaults; fall back to them when the file is broken)
    try:
        cfg = get_config()
    except Exception:
        cfg = deepcopy(DEFAULT_CFG)

    # Service status
    service_active = False
    try:
        proc = run_proc(["systemctl", "is-active", "dnsmasq"], sudo=True)
        service_active = proc.stdout.strip() == "active"
    except Exception:
        pass

    # Leases
    leases: list[dict[str, Any]] = []
    try:
        result = run_proc(["cat", LEASE_FILE], sudo=True, check=True)
        for line in result.stdout.splitlines():
            line = line.strip()
            if not line or line.startswith("#"):
                continue
            parts = line.split()
            if len(parts) < 3:
                continue
            try:
                ts = datetime.fromtimestamp(int(parts[0]), tz=UTC)
            except (ValueError, OSError):
                ts = None
            leases.append(
                {
                    "expires": ts.isoformat() if ts else "",
                    "mac": parts[1],
                    "ip": parts[2],
                    "hostname": parts[3] if len(parts) > 3 else "",
                    "interface": parts[4] if len(parts) > 4 else "",
                }
            )
    except Exception:
        pass

    # Check config file on disk
    conf_exists = Path(DNSMASQ_CONF).is_file()

    pending_changes, pending_diff = compute_pending(cfg)
    safe_cfg = strip_apply_meta(cfg)

    return {
        "config": safe_cfg,
        "status": {
            "service_active": service_active,
            "config_file_exists": conf_exists,
            "active_leases": len(leases),
            "pending_changes": pending_changes,
            "pending_diff": pending_diff,
        },
        "leases": leases,
        "timestamp": _now_iso(),
    }


register_collector("dnsmasq", _collect_dnsmasq)
# dnsmasq has no volatile fields — leases change slowly enough to treat as structural