juju-php/SQL/migration.abstract.class.php

<?php
	namespace Juju\SQL;
	require_once(realpath(dirname(__DIR__).'/sql.class.php'));
	use Juju\{SQL, Settings};

	abstract class Migration {
		public abstract static function up();
		public abstract static function down();
		public abstract static function change();

		const MIGRATE_UP = 'up';
		const MIGRATE_DOWN = 'down';
		private static $sql;

		final public static function version(){
			$name = get_called_class();
			return substr($name, strrpos($name, '\\') + 1);
		}
		final public static function version_table(){
			if(!class_exists("Juju\\Settings")){
				throw new \Exception("Settings not loaded");
			}
			return Settings::get('db.versions');
		}
		final public static function installed(){
			return self::$sql->query(
				"select count(1) count ".
				"from `".self::version_table()."` ".
				"where version = ?",
				's',
				static::version()
			)->assoc_result['count'] == 1;
		}
		final public static function migrations(){
			$migrations = array_filter(get_declared_classes(), function($class){
				return 0 === strpos($class, "Migration\\");
			});
			sort($migrations);
			return $migrations;
		}
		final public static function migrate(string $direction, int $amount = 1){
			if($amount < 1){
				throw new \Exception("Migration amount must be a positive integer");
			}
			$table = self::version_table();
			$sql = self::$sql;
			if(count($sql->query("show tables like '{$table}'")->assoc_results) == 0){
				$sql->query("CREATE TABLE `{$table}` (version varchar(100) NOT NULL, primary key (version))")->execute();
			}
			switch($direction){
				case self::MIGRATE_UP:
					foreach(self::migrations() as $migration){
						if(!$migration::installed()){
							$migration::up();
							$sql->query(
								"insert into `{$table}` set version = ?",
								's',
								$migration::version()
							)->execute();
							if(--$amount == 0){
								break;
							}
						}
					}
				break;
				case self::MIGRATE_DOWN:
					foreach(array_reverse(self::migrations()) as $migration){
						if($migration::installed()){
							$migration::down();
							$sql->query(
								"delete from `{$table}` where version = ?",
								's',
								$migration::version()
							)->execute();
							if(--$amount == 0){
								break;
							}
						}
					}
				break;
				default:
					throw new \Exception("Invalid migration direction '{$direction}'");
			}
		}
		final public static function migrate_all(string $direction){
			self::migrate($direction, count(self::migrations()));
		}
		final public static function bind(string $dsn){
			self::$sql = SQL::FromDSN($dsn);
		}
		final public static function release(){
			$sql = self::$sql;
			unset($sql);
			self::$sql = null;
		}
	}
?>