<?php

/**
 * Vvveb
 *
 * Copyright (C) 2022  Ziadin Givan
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 */

namespace Vvveb\System;

class Db {
	/**
	 * Get or create a database driver instance for the given engine.
	 *
	 * @param  string $engine  The database engine identifier (e.g. 'Mysql').
	 *
	 * @return static|null     The driver instance, or null when $engine is falsy.
	 */
	public static function getInstance(string $engine = DB_ENGINE): ?object {
		static $inst = [];

		if (! $engine) {
			return null;
		}

		if (! isset($inst[$engine]) || $inst[$engine] === null) {
			$driverName = "\Vvveb\System\Db\\$engine";

			//if (class_exists($driverName)) {
			$inst[$engine] = new $driverName();
			/*
			} else {
				throw new \Exception("Error loading db driver '$driverName'!");
			}*/
		}

		return $inst[$engine];
	}
}
