// ---------------------------------------------------------------------------
//  settings.js — editierbare Admin-Einstellungen (Domains, Webmail-Domain, Brand)
//
//  Liegt als JSON in der DMS-Config (persistent). Beim ersten Start aus den
//  ENV-Variablen (Deploy-Dialog) geseedet, danach in der Admin-UI editierbar.
// ---------------------------------------------------------------------------
import { promises as fs } from 'node:fs';
import path from 'node:path';

const CONFIG_DIR = process.env.CONFIG_DIR || '/config';
const FILE = path.join(CONFIG_DIR, 'admin-settings.json');

const isDomain = (s) => /^[^@\s]+\.[^@\s]+$/.test(s);
const envDomains = () =>
  (process.env.MAIL_DOMAINS || process.env.MAIL_DOMAIN || '').split(/[\s,]+/).filter(Boolean);

function seed() {
  const domains = envDomains();
  const primary = process.env.MAIL_DOMAIN || domains[0] || 'example.com';
  return {
    brand: process.env.BRAND || primary,
    fqdn: process.env.MAIL_FQDN || `mail.${primary}`,
    primaryDomain: primary,
    domains: domains.length ? domains : [primary],
    webmailFqdn: process.env.WEBMAIL_FQDN || `mail.${primary}`,
    adminFqdn: process.env.ADMIN_FQDN || `admin.${primary}`,
  };
}

let chain = Promise.resolve();
const withLock = (fn) => { const r = chain.then(fn, fn); chain = r.catch(() => {}); return r; };
const save = (s) => fs.writeFile(FILE, JSON.stringify(s, null, 2) + '\n', 'utf8');

export async function readSettings() {
  try {
    return { id: 'settings', ...JSON.parse(await fs.readFile(FILE, 'utf8')) };
  } catch (e) {
    if (e.code === 'ENOENT') { const s = seed(); await save(s); return { id: 'settings', ...s }; }
    throw e;
  }
}

export function writeSettings(patch) {
  return withLock(async () => {
    const { id, ...cur } = await readSettings();
    const next = { ...cur };
    // nur erlaubte Felder
    for (const k of ['brand', 'fqdn', 'primaryDomain', 'webmailFqdn', 'adminFqdn']) {
      if (typeof patch[k] === 'string' && patch[k].trim()) next[k] = patch[k].trim();
    }
    if (Array.isArray(patch.domains)) {
      next.domains = [...new Set(patch.domains.map((d) => String(d).trim()).filter(isDomain))];
    }
    await save(next);
    return { id: 'settings', ...next };
  });
}

export function addDomain(domain) {
  return withLock(async () => {
    domain = String(domain || '').trim().toLowerCase();
    if (!isDomain(domain)) { const e = new Error('Ungültige Domain.'); e.status = 400; throw e; }
    const { id, ...cur } = await readSettings();
    if (!cur.domains.includes(domain)) cur.domains.push(domain);
    await save(cur);
    return { id: 'settings', ...cur };
  });
}

export function removeDomain(domain) {
  return withLock(async () => {
    const { id, ...cur } = await readSettings();
    cur.domains = cur.domains.filter((d) => d !== domain);
    await save(cur);
    return { id: 'settings', ...cur };
  });
}