import { pathToFileURL } from 'node:url';
import { monthRange, openReadOnlyStore } from './db.mjs';

export function readMetrics(args, env = process.env) {
  if (args.length !== 2 || args[0] !== '--month') throw new Error('Invalid arguments');
  const month = args[1];
  monthRange(month);
  const store = openReadOnlyStore(env.DB_PATH);
  try { return { month, monthlyVisitors: store.monthlyVisitors(month), arrivals: store.arrivalCount() }; }
  finally { store.close(); }
}

if (process.argv[1] && import.meta.url === pathToFileURL(process.argv[1]).href) {
  try { process.stdout.write(`${JSON.stringify(readMetrics(process.argv.slice(2)))}\n`); }
  catch { process.stderr.write('Metrics unavailable; check --month YYYY-MM and existing DB_PATH\n'); process.exitCode = 1; }
}