class Tasks

class Tasks extends InstallTasks {
    
    /**
     * Minimum required MySQL version.
     *
     * 5.7.8 is the minimum version that supports the JSON datatype.
     * @see https://dev.mysql.com/doc/refman/5.7/en/json.html
     */
    const MYSQL_MINIMUM_VERSION = '5.7.8';
    
    /**
     * Minimum required MariaDB version.
     *
     * 10.3.7 is the first stable (GA) release in the 10.3 series.
     * @see https://mariadb.com/kb/en/changes-improvements-in-mariadb-103/#list-of-all-mariadb-103-releases
     */
    const MARIADB_MINIMUM_VERSION = '10.3.7';
    
    /**
     * The PDO driver name for MySQL and equivalent databases.
     *
     * @var string
     */
    protected $pdoDriver = 'mysql';
    
    /**
     * Constructs a \Drupal\mysql\Driver\Database\mysql\Install\Tasks object.
     */
    public function __construct() {
        $this->tasks[] = [
            'arguments' => [],
            'function' => 'ensureInnoDbAvailable',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function name() {
        try {
            if (!$this->isConnectionActive() || !$this->getConnection() instanceof Connection) {
                throw new ConnectionNotDefinedException('The database connection is not active or not a MySql connection');
            }
            if ($this->getConnection()
                ->isMariaDb()) {
                return $this->t('MariaDB');
            }
            return $this->t('MySQL, Percona Server, or equivalent');
        } catch (ConnectionNotDefinedException $e) {
            return $this->t('MySQL, MariaDB, Percona Server, or equivalent');
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function minimumVersion() {
        if ($this->getConnection()
            ->isMariaDb()) {
            return static::MARIADB_MINIMUM_VERSION;
        }
        return static::MYSQL_MINIMUM_VERSION;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function connect() {
        try {
            // This doesn't actually test the connection.
            Database::setActiveConnection();
            // Now actually do a check.
            Database::getConnection();
            $this->pass('Drupal can CONNECT to the database ok.');
        } catch (\Exception $e) {
            // Attempt to create the database if it is not found.
            if ($e->getCode() == Connection::DATABASE_NOT_FOUND) {
                // Remove the database string from connection info.
                $connection_info = Database::getConnectionInfo();
                $database = $connection_info['default']['database'];
                unset($connection_info['default']['database']);
                // In order to change the Database::$databaseInfo array, need to remove
                // the active connection, then re-add it with the new info.
                Database::removeConnection('default');
                Database::addConnectionInfo('default', 'default', $connection_info['default']);
                try {
                    // Now, attempt the connection again; if it's successful, attempt to
                    // create the database.
                    Database::getConnection()->createDatabase($database);
                    Database::closeConnection();
                    // Now, restore the database config.
                    Database::removeConnection('default');
                    $connection_info['default']['database'] = $database;
                    Database::addConnectionInfo('default', 'default', $connection_info['default']);
                    // Check the database connection.
                    Database::getConnection();
                    $this->pass('Drupal can CONNECT to the database ok.');
                } catch (DatabaseNotFoundException $e) {
                    // Still no dice; probably a permission issue. Raise the error to the
                    // installer.
                    $this->fail(t('Database %database not found. The server reports the following message when attempting to create the database: %error.', [
                        '%database' => $database,
                        '%error' => $e->getMessage(),
                    ]));
                }
            }
            else {
                // Database connection failed for some other reason than a non-existent
                // database.
                $this->fail(t('Failed to connect to your database server. The server reports the following message: %error.<ul><li>Is the database server running?</li><li>Does the database exist or does the database user have sufficient privileges to create the database?</li><li>Have you entered the correct database name?</li><li>Have you entered the correct username and password?</li><li>Have you entered the correct database hostname and port number?</li></ul>', [
                    '%error' => $e->getMessage(),
                ]));
                return FALSE;
            }
        }
        return TRUE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormOptions(array $database) {
        $form = parent::getFormOptions($database);
        if (empty($form['advanced_options']['port']['#default_value'])) {
            $form['advanced_options']['port']['#default_value'] = '3306';
        }
        $form['advanced_options']['isolation_level'] = [
            '#type' => 'select',
            '#title' => $this->t('Transaction isolation level'),
            '#options' => [
                'READ COMMITTED' => $this->t('READ COMMITTED'),
                'REPEATABLE READ' => $this->t('REPEATABLE READ'),
                '' => $this->t('Use database default'),
            ],
            '#default_value' => $database['isolation_level'] ?? 'READ COMMITTED',
            '#description' => $this->t('The recommended database transaction level for Drupal is "READ COMMITTED". For more information, see the <a href=":performance_doc">setting MySQL transaction isolation level</a> page.', [
                ':performance_doc' => 'https://www.drupal.org/docs/system-requirements/setting-the-mysql-transaction-isolation-level',
            ]),
        ];
        return $form;
    }
    
    /**
     * Ensure that InnoDB is available.
     */
    public function ensureInnoDbAvailable() {
        $engines = Database::getConnection()->query('SHOW ENGINES')
            ->fetchAllKeyed();
        if (isset($engines['MyISAM']) && $engines['MyISAM'] == 'DEFAULT' && !isset($engines['InnoDB'])) {
            $this->fail(t('The MyISAM storage engine is not supported.'));
        }
    }

}