// Shared helpers for the UHPPOTE hardware test scripts.
// Run directly against the device (independent of the HTTP server).
//
//   node apps/server/scripts/uhppote-listen.mjs
//   node apps/server/scripts/uhppote-relay.mjs
//
// Env overrides:
//   UHPPOTE_SERIAL   controller serial   (default 225088491)
//   UHPPOTE_HOST     controller IP       (default 10.0.10.3)
//   UHPPOTE_BCAST    Config broadcast    (default derived from HOST subnet)
//   HOST_IP          this host's IP the controller pushes events to
//                    (default: auto-detected interface on the controller's subnet)

import { networkInterfaces } from "node:os";
import { createRequire } from "node:module";

const require = createRequire(import.meta.url);
const uhppoted = require("uhppoted");

export const SERIAL = Number(process.env.UHPPOTE_SERIAL ?? 225088491);
export const HOST = process.env.UHPPOTE_HOST ?? "10.0.10.3";

/** Subnet-directed broadcast for the interface that owns `ip`. */
function broadcastForHost(ip) {
  const o = ip.split(".").map(Number);
  for (const ifaces of Object.values(networkInterfaces())) {
    for (const i of ifaces ?? []) {
      if (i.family !== "IPv4" || i.internal) continue;
      const a = i.address.split(".").map(Number);
      const m = i.netmask.split(".").map(Number);
      if (o.every((x, k) => (x & m[k]) === (a[k] & m[k]))) {
        return a.map((x, k) => (x & m[k]) | (~m[k] & 0xff)).join(".");
      }
    }
  }
  return "255.255.255.255";
}

/** This host's own IP on the controller's subnet (where it should push events). */
export function hostIpOnControllerSubnet(ip = HOST) {
  if (process.env.HOST_IP) return process.env.HOST_IP;
  const o = ip.split(".").map(Number);
  for (const ifaces of Object.values(networkInterfaces())) {
    for (const i of ifaces ?? []) {
      if (i.family !== "IPv4" || i.internal) continue;
      const a = i.address.split(".").map(Number);
      const m = i.netmask.split(".").map(Number);
      if (o.every((x, k) => (x & m[k]) === (a[k] & m[k]))) return i.address;
    }
  }
  return null;
}

export const BCAST = process.env.UHPPOTE_BCAST ?? broadcastForHost(HOST);

export function makeCtx(timeoutMs = 5000) {
  return {
    config: new uhppoted.Config(
      "parking",
      "0.0.0.0",
      `${BCAST}:60000`,
      "0.0.0.0:60001",
      timeoutMs,
      [],
      false,
    ),
    locale: "en-US",
  };
}

export const controller = { id: SERIAL, address: HOST, protocol: "udp" };
export { uhppoted };