// Centralized, per-user configuration store.
//
// Multi-user: every setting (Ollama, E-Mail, CalDAV, API-Token) is owned by a
// user. The values live in the SQLite app_state table (key prefixed "cfg:"),
// now keyed by (user_id, key). The /einstellungen page edits the *current* user's
// values; the libs (mailer, caldav, chat, documents) read through config.get() /
// config.ollama() at call time, picking up the current user from the per-request
// context (lib/context.js). An edit therefore takes effect immediately, scoped
// to the user who made it — no restart, no .env file.
//
// On first start of an install that previously used .env, init() migrates any
// still-present env value into the *admin* user's config once. After that the
// database is the single source of truth; process.env is only a fallback for keys
// that were never saved.

const { currentUser } = require('./context');

const DEFAULTS = {
  // Ollama Cloud (KI text generation + chat).
  OLLAMA_API_KEY: '',
  OLLAMA_MODEL: 'gpt-oss:120b',
  OLLAMA_HOST: 'https://ollama.com',
  OLLAMA_TIMEOUT_MS: '300000',
  // E-Mail (SMTP submission + IMAP receive).
  MAIL_HOST: '',
  MAIL_SMTP_PORT: '587',
  MAIL_IMAP_PORT: '993',
  MAIL_USER: '',
  MAIL_PASSWORD: '',
  MAIL_FROM_NAME: '',
  MAIL_FROM: '',
  MAIL_IMAP_MAILBOX: 'INBOX',
  MAIL_POLL_MS: '180000',
  // Bewerbungskalender (CalDAV, z. B. SOGo).
  CALDAV_URL: '',
  CALDAV_ALARM_MIN: '60',
  CALDAV_POLL_MS: '300000',
  // REST-API für Drittanbietersoftware (/api/v1, Header X-API-Key).
  API_TOKEN: '',
};

// UI metadata for the /einstellungen page: grouped sections with input types.
// `secret` fields render as password inputs with a reveal toggle.
const FIELDS = [
  {
    titel: 'Ollama Cloud (KI-Generierung + Chat)',
    beschreibung: 'Steuerung der KI, die Bewerbungsunterlagen erzeugt und den KI-Chat beantwortet. Ohne API-Schlüssel sind diese Funktionen deaktiviert.',
    items: [
      { key: 'OLLAMA_API_KEY', label: 'API-Schlüssel', secret: true, help: 'Schlüssel von https://ollama.com/settings/keys' },
      { key: 'OLLAMA_MODEL', label: 'Modell', help: 'Standard: gpt-oss:120b' },
      { key: 'OLLAMA_HOST', label: 'Host', help: 'Standard: https://ollama.com — lokaler Ollama: http://localhost:11434' },
      { key: 'OLLAMA_TIMEOUT_MS', label: 'Timeout (ms)', help: 'Standard: 300000 (5 Min.)' },
    ],
  },
  {
    titel: 'E-Mail (SMTP-Versand + IMAP-Empfang)',
    beschreibung: 'Versand läuft über den eigenen Mailserver (DKIM/SPF/DMARC-Alignment). Ohne Host/Benutzer/Passwort ist der E-Mail-Teil deaktiviert. Pro Benutzer eigenes Postfach.',
    items: [
      { key: 'MAIL_HOST', label: 'SMTP/IMAP Host' },
      { key: 'MAIL_SMTP_PORT', label: 'SMTP-Port', help: '587 = STARTTLS, 465 = implicit TLS' },
      { key: 'MAIL_IMAP_PORT', label: 'IMAP-Port', help: 'Standard: 993 (implicit TLS)' },
      { key: 'MAIL_USER', label: 'Benutzername (Login)', help: 'Auch CalDAV-Login' },
      { key: 'MAIL_PASSWORD', label: 'Passwort', secret: true, help: 'Auch CalDAV-Passwort' },
      { key: 'MAIL_FROM_NAME', label: 'Absendername' },
      { key: 'MAIL_FROM', label: 'Absenderadresse', help: 'Leer = Benutzername' },
      { key: 'MAIL_IMAP_MAILBOX', label: 'IMAP-Postfach', help: 'Standard: INBOX' },
      { key: 'MAIL_POLL_MS', label: 'Abrufintervall (ms)', help: 'Standard: 180000 (3 Min.) — greift nach Neustart' },
    ],
  },
  {
    titel: 'Bewerbungskalender (CalDAV)',
    beschreibung: 'Voll-URL der Kalender-Sammlung (mit abschließendem /). Authentifizierung läuft über MAIL_USER/MAIL_PASSWORD. Ohne URL sind die Kalender-Funktionen deaktiviert.',
    items: [
      { key: 'CALDAV_URL', label: 'Kalender-URL', help: 'z. B. https://mail.example.com/SOGo/dav/name@…/Calendar/XXXX/' },
      { key: 'CALDAV_ALARM_MIN', label: 'Erinnerung (Minuten vor Termin)', help: 'Standard: 60' },
      { key: 'CALDAV_POLL_MS', label: 'Sync-Intervall (ms)', help: 'Standard: 300000 (5 Min.) — greift nach Neustart' },
    ],
  },
  {
    titel: 'REST-API für Drittanbietersoftware',
    beschreibung: 'Ist ein Token gesetzt, ist /api/v1 für diesen Benutzer aktiv und erwartet den Wert im Header „X-API-Key“. Anfragen operieren auf den Daten dieses Benutzers. Ohne Token antwortet die API (bis auf /health) mit 503. Swagger unter /swagger.',
    items: [
      { key: 'API_TOKEN', label: 'API-Token (X-API-Key)', secret: true, help: 'Leer = API deaktiviert' },
    ],
  },
];

const PREFIX = 'cfg:';

// Per-user cache: Map<userId, Object<string,string>>. A user is loaded lazily on
// first access (ensureLoaded) and stays cached for the process lifetime. Edits
// via saveAll() update the cache in place so subsequent reads are consistent.
const cache = new Map(); // userId -> { key: value }
const loaded = new Set(); // userIds whose cfg rows have been read from the DB
let dbAllFn = null;
let dbRunFn = null;

function envOrDefault(key) {
  const e = process.env[key];
  return e && e.length ? e : DEFAULTS[key];
}

// Load one user's cfg rows from the DB into the cache. No-op if already loaded.
async function ensureLoaded(userId) {
  if (!userId || loaded.has(userId)) return;
  const rows = await dbAllFn('SELECT key, value FROM app_state WHERE user_id = ?', [userId]);
  const obj = Object.create(null);
  for (const r of rows) obj[r.key.slice(PREFIX.length)] = r.value;
  cache.set(userId, obj);
  loaded.add(userId);
}

// Drop the cached rows for a user so the next read reloads from the DB. Used
// after a direct DB write outside saveAll() (e.g. the one-time env migration).
function invalidate(userId) {
  loaded.delete(userId);
  cache.delete(userId);
}

// Synchronous read for the current user. Falls back to process.env (pre-migration
// / never saved) then to the built-in default. Outside a request context (boot)
// only the env/default fallback applies — callers that need a specific user must
// run inside the user context (see lib/context.js).
function get(key) {
  const u = currentUser();
  const userObj = u ? cache.get(u.id) : null;
  if (userObj && userObj[key] !== undefined) return userObj[key];
  return envOrDefault(key);
}

// All keys with their effective values for the current user — used by the
// settings UI. Must be called within a request context.
function getAll() {
  const out = {};
  for (const key of Object.keys(DEFAULTS)) out[key] = get(key);
  return out;
}

// Ollama bundle (shared by lib/documents.js + lib/chat.js), for the current user.
function ollama() {
  return {
    host: (get('OLLAMA_HOST') || 'https://ollama.com').replace(/\/+$/, ''),
    model: get('OLLAMA_MODEL') || 'gpt-oss:120b',
    timeoutMs: Number(get('OLLAMA_TIMEOUT_MS')) || 300000,
    apiKey: get('OLLAMA_API_KEY') || '',
  };
}

// Wire up DB helpers. The one-time .env migration now runs per-admin at boot
// from server.js (it needs the admin user id); this init only stores the fns.
async function init({ dbAll, dbRun }) {
  dbAllFn = dbAll;
  dbRunFn = dbRun;
}

// Persist every key for the current user (writes all rows, including empty
// strings, so a cleared field is stored as empty and no longer falls back to
// env/default). Must be called within a request context.
async function saveAll(values) {
  if (!dbRunFn) throw new Error('Konfigurationsspeicher nicht initialisiert.');
  const u = currentUser();
  if (!u) throw new Error('Kein Benutzerkontext für Konfigurationsspeicherung.');
  const obj = cache.get(u.id) || Object.create(null);
  for (const key of Object.keys(DEFAULTS)) {
    const v = values && values[key] != null ? String(values[key]) : '';
    await dbRunFn(
      'INSERT INTO app_state (user_id, key, value) VALUES (?, ?, ?) ON CONFLICT(user_id, key) DO UPDATE SET value = excluded.value',
      [u.id, PREFIX + key, v]
    );
    obj[key] = v;
  }
  cache.set(u.id, obj);
  loaded.add(u.id);
}

// Write a single key for an explicit user (used by the one-time env migration,
// which runs outside a request context). Updates the cache if loaded.
async function setForUser(userId, key, value) {
  if (!dbRunFn) throw new Error('Konfigurationsspeicher nicht initialisiert.');
  await dbRunFn(
    'INSERT INTO app_state (user_id, key, value) VALUES (?, ?, ?) ON CONFLICT(user_id, key) DO UPDATE SET value = excluded.value',
    [userId, PREFIX + key, String(value)]
  );
  if (loaded.has(userId)) {
    const obj = cache.get(userId) || Object.create(null);
    obj[key] = String(value);
    cache.set(userId, obj);
  }
}

module.exports = {
  DEFAULTS, FIELDS, PREFIX,
  get, getAll, ollama, init, saveAll, setForUser, ensureLoaded, invalidate,
};