async function authenticate(credentials) { const { email, password } = credentials; const user = await findUserByEmail(email); if (!user || !await verifyHash(password, user.hash)) { throw new AuthError("Invalid credentials"); } const token = signToken({ sub: user.id, role: user.role, exp: Date.now() + 86400000 }); await session.create(user.id, token); return { token, user: sanitize(user) }; } class EventEmitter { #listeners = new Map(); on(event, callback) { if (!this.#listeners.has(event)) { this.#listeners.set(event, []); } this.#listeners.get(event).push(callback); return this; } emit(event, ...args) { const handlers = this.#listeners.get(event); if (handlers) { handlers.forEach(fn => fn(...args)); } } } function debounce(fn, delay = 300) { let timer; return (...args) => { clearTimeout(timer); timer = setTimeout(() => fn(...args), delay); }; } async function* paginate(query, size = 20) { let offset = 0; while (true) { const rows = await query({ limit: size, offset }); if (rows.length === 0) break; yield rows; offset += size; } } const memoize = (fn) => { const cache = new Map(); return (...args) => { const key = JSON.stringify(args); if (cache.has(key)) return cache.get(key); const result = fn(...args); cache.set(key, result); return result; }; };