import { ClientBase, Pool, PoolClient } from 'pg';
import {
  IsolationLevel,
  Parameter,
  SQLFragment,
  TxnClient,
  param,
  transaction,
} from 'zapatos/db';

export type DbClient = Pool | TxnClient<IsolationLevel>;

/**
 * Iterates through pgSettings properties, composes and runs a single SELECT
 * query to execute set_config for each property.
 */
export const setPgSettingsConfig = async (
  pgSettings: { [key: string]: string } = {},
  txn: Pool | TxnClient<IsolationLevel> | PoolClient | ClientBase,
): Promise<void> => {
  let literal = 'SELECT ';
  const params: Parameter<string>[] = [];
  for (const property in pgSettings) {
    if (!Object.prototype.hasOwnProperty.call(pgSettings, property)) {
      continue;
    }
    params.push(param(property), param(pgSettings[property]));
    literal += 'set_config($, $, TRUE), ';
  }
  if (params.length > 0) {
    await new SQLFragment(`${literal.slice(0, -2)};`.split('$'), params).run(
      txn,
    );
    // eslint-disable-next-line @typescript-eslint/no-explicit-any -- for debug purposes add the applied PG settings to the transaction object
    (txn as any)._debugPgSettings = pgSettings;
  }
};

/**
 * Creates a transaction and sets pg settings before executing queries.
 * The applied pgSettings are added to the field "_debugPgSettings" in the transaction object for debug purposes.
 * @param pool - DB pool instance or PG/Zapatos client.
 * @param isolationLevel - Transaction isolation level.
 * @param pgSettings - Settings to be set before queries are executed.
 * @param callback - Callback where queries are executed.
 */
export const transactionWithContext = async <T>(
  pool: DbClient,
  isolationLevel: IsolationLevel,
  pgSettings: { [key: string]: string } = {},
  callback: (client: TxnClient<IsolationLevel>) => Promise<T>,
): Promise<T> => {
  return transaction(pool, isolationLevel, async (txn) => {
    await setPgSettingsConfig(pgSettings, txn);
    return callback(txn);
  });
};