import sqlite3 from 'sqlite3';
import { open, Database } from 'sqlite';

let db: Database | null = null;

/**
 * Opens a read-only connection to the webserver's visitors.db.
 * Returns null if the DB doesn't exist yet (webserver hasn't created it).
 * Retries on each call until the DB becomes available.
 */
export async function getVisitorsDb(): Promise<Database | null> {
  if (db) return db;

  try {
    db = await open({
      filename: '/server_storage/visitors.db',
      driver: sqlite3.Database,
      mode: sqlite3.OPEN_READONLY,
    });
    return db;
  } catch {
    // DB doesn't exist yet — don't cache the failure so we retry next time
    return null;
  }
}