class MysqlRequirements

class MysqlRequirements {
    use StringTranslationTrait;
    
    /**
     * Implements hook_runtime_requirements().
     */
    public function runtime() : array {
        $requirements = [];
        // Test with MySql databases.
        if (Database::isActiveConnection()) {
            $connection = Database::getConnection();
            // Only show requirements when MySQL is the default database connection.
            if (!($connection->driver() === 'mysql' && $connection->getProvider() === 'mysql')) {
                return [];
            }
            $query = $connection->isMariaDb() ? 'SELECT @@SESSION.tx_isolation' : 'SELECT @@SESSION.transaction_isolation';
            $isolation_level = $connection->query($query)
                ->fetchField();
            $tables_missing_primary_key = [];
            $tables = $connection->schema()
                ->findTables('%');
            foreach ($tables as $table) {
                $primary_key_column = Database::getConnection()->query("SHOW KEYS FROM {" . $table . "} WHERE Key_name = 'PRIMARY'")
                    ->fetchAllAssoc('Column_name');
                if (empty($primary_key_column)) {
                    $tables_missing_primary_key[] = $table;
                }
            }
            $description = [];
            if ($isolation_level == 'READ-COMMITTED') {
                if (empty($tables_missing_primary_key)) {
                    $severity_level = RequirementSeverity::OK;
                }
                else {
                    $severity_level = RequirementSeverity::Error;
                }
            }
            else {
                if ($isolation_level == 'REPEATABLE-READ') {
                    $severity_level = RequirementSeverity::Warning;
                }
                else {
                    $severity_level = RequirementSeverity::Error;
                    $description[] = $this->t('This is not supported by Drupal.');
                }
                $description[] = $this->t('The recommended level for Drupal is "READ COMMITTED".');
            }
            if (!empty($tables_missing_primary_key)) {
                $description[] = $this->t('For this to work correctly, all tables must have a primary key. The following table(s) do not have a primary key: @tables.', [
                    '@tables' => implode(', ', $tables_missing_primary_key),
                ]);
            }
            $description[] = $this->t('See the <a href=":performance_doc">setting MySQL transaction isolation level</a> page for more information.', [
                ':performance_doc' => 'https://www.drupal.org/docs/system-requirements/setting-the-mysql-transaction-isolation-level',
            ]);
            $requirements['mysql_transaction_level'] = [
                'title' => $this->t('Transaction isolation level'),
                'severity' => $severity_level,
                'value' => $isolation_level,
                'description' => Markup::create(implode(' ', $description)),
            ];
        }
        return $requirements;
    }

}