import { readFile } from "node:fs/promises";
import type Database from "better-sqlite3";
import { upsertDevices, type DiscoveredDevice } from "../db/index.js";

interface RawEntry {
  ip: string;
  mac: string;
  state: string;
}

// Reads the JSON file produced by scripts/discover-devices.sh (a systemd timer
// on the deploy host, not this process) and labels each entry against the
// known-device list from config/hosts.yaml. See docs/device-discovery.md.
export async function refreshDevices(
  db: Database.Database,
  filePath: string,
  knownDevices: Map<string, string>
): Promise<void> {
  let raw: RawEntry[];
  try {
    raw = JSON.parse(await readFile(filePath, "utf8"));
  } catch (err) {
    // Missing file (timer hasn't run yet, or not deployed on this host) isn't
    // fatal — just means no device data this cycle.
    if ((err as NodeJS.ErrnoException).code === "ENOENT") return;
    throw err;
  }

  const devices: DiscoveredDevice[] = raw.map((entry) => ({
    ip: entry.ip,
    mac: entry.mac,
    knownName: knownDevices.get(entry.ip) ?? null,
  }));

  upsertDevices(db, devices);
}