/**
 * Persistent token store backed by SQLite (better-sqlite3).
 *
 * Survives process restarts — Emby tokens remain valid across deploys
 * and container restarts, so users do not need to re-login after an
 * update. Tokens are stored in DATA_DIR/tokens.db (default: /app/data
 * inside the container, or ./data locally).
 *
 * Schema: tokens(userId TEXT PK, accessToken TEXT, createdAt INTEGER)
 *
 * Expired rows (older than TOKEN_TTL_DAYS) are pruned on startup and
 * once per hour, preventing unbounded growth.
 */

const Database = require('better-sqlite3');
const path = require('path');
const fs = require('fs');

const TOKEN_TTL_DAYS = 31; // slightly longer than max cookie lifetime
const DATA_DIR = process.env.DATA_DIR || path.join(__dirname, '../../data');

// Ensure data directory exists (non-root writable in container)
if (!fs.existsSync(DATA_DIR)) {
  fs.mkdirSync(DATA_DIR, { recursive: true });
}

const DB_PATH = path.join(DATA_DIR, 'tokens.db');
const db = new Database(DB_PATH);

// WAL mode for better concurrent read performance
db.pragma('journal_mode = WAL');
db.pragma('foreign_keys = ON');

db.exec(`
  CREATE TABLE IF NOT EXISTS tokens (
    userId      TEXT PRIMARY KEY,
    accessToken TEXT NOT NULL,
    createdAt   INTEGER NOT NULL DEFAULT (strftime('%s','now'))
  )
`);

const storeToken = db.prepare(
  `INSERT OR REPLACE INTO tokens (userId, accessToken, createdAt)
   VALUES (?, ?, strftime('%s','now'))`
);

const getTokenStmt = db.prepare(
  `SELECT accessToken FROM tokens WHERE userId = ?`
);

const clearTokenStmt = db.prepare(
  `DELETE FROM tokens WHERE userId = ?`
);

const pruneStmt = db.prepare(
  `DELETE FROM tokens WHERE createdAt < strftime('%s','now') - ?`
);

const TTL_SECONDS = TOKEN_TTL_DAYS * 24 * 60 * 60;

function prune() {
  const result = pruneStmt.run(TTL_SECONDS);
  if (result.changes > 0) {
    console.log(`[TokenStore] Pruned ${result.changes} expired token(s)`);
  }
}

// Prune on startup and every hour
prune();
setInterval(prune, 60 * 60 * 1000).unref();

module.exports = {
  storeToken(userId, accessToken) {
    storeToken.run(userId, accessToken);
  },
  getToken(userId) {
    const row = getTokenStmt.get(userId);
    return row ? { accessToken: row.accessToken } : null;
  },
  clearToken(userId) {
    clearTokenStmt.run(userId);
  }
};