import {
  ENSURE_TYPE as MSSQL_ENSURE_TYPE,
  GET_FOR_UPDATE as MSSQL_GET_FOR_UPDATE,
} from '../../providers/mssql/queries/numbers.js';
import {
  ENSURE_TYPE as SQLITE_ENSURE_TYPE,
  GET_FOR_UPDATE as SQLITE_GET_FOR_UPDATE,
} from '../../providers/sqlite3/queries/numbers.js';
import makeRunner from '../runner.js';

function formatNumber(prefix, padding, num) {
  const p = prefix ?? '';
  const nStr = String(num);
  const padded = padding > 0 ? nStr.padStart(padding, '0') : nStr;
  return `${p}${padded}`;
}

export default function peekNumber(provider) {
  const isSqlite = provider?.dialect === 'sqlite3';
  const ensureSql = isSqlite ? SQLITE_ENSURE_TYPE : MSSQL_ENSURE_TYPE;
  const getSql = isSqlite ? SQLITE_GET_FOR_UPDATE : MSSQL_GET_FOR_UPDATE;

  /**
   * Returns the next number for a company and type without consuming it.
   *
   * @param {number} companyId - The id of the company.
   * @param {string} type - The number type (e.g. `'entity'`, `'sku'`).
   * @param {object} [tx] - Optional transaction to run within.
   * @returns {Promise<string>} The next number.
   *
   * @example
   * const number = await store.numbers.peek(1, 'entity');
   * // => '1'
   */
  return async (companyId, type, tx) => {
    const doPeek = async (runner) => {
      const prefix = type === 'shipment' ? '-L-' : '';
      await runner.query(ensureSql, { companyId, type, prefix });
      const res = await runner.query(getSql, { companyId, type });
      const row = res.rows[0];
      if (!row) {
        throw new Error('Number type not found for company');
      }
      return formatNumber(row.prefix, row.padding, row.next);
    };

    if (tx) {
      return doPeek(makeRunner(provider, tx));
    }
    if (typeof provider?.transaction === 'function') {
      return provider.transaction(doPeek);
    }
    return doPeek(makeRunner(provider));
  };
}