trait MigrationConfigurationTrait

trait MigrationConfigurationTrait {
    
    /**
     * The config factory service.
     *
     * @var \Drupal\Core\Config\ConfigFactoryInterface
     */
    protected $configFactory;
    
    /**
     * The migration plugin manager service.
     *
     * @var \Drupal\migrate\Plugin\MigrationPluginManagerInterface
     */
    protected $migrationPluginManager;
    
    /**
     * The state service.
     *
     * @var \Drupal\Core\State\StateInterface
     */
    protected $state;
    
    /**
     * The follow-up migration tags.
     *
     * @var string[]
     */
    protected $followUpMigrationTags;
    
    /**
     * Gets the database connection for the source Drupal database.
     *
     * @param array $database
     *   Database array representing the source Drupal database.
     *
     * @return \Drupal\Core\Database\Connection
     *   The database connection for the source Drupal database.
     */
    protected function getConnection(array $database) {
        // Set up the connection.
        Database::addConnectionInfo('upgrade', 'default', $database);
        $connection = Database::getConnection('default', 'upgrade');
        return $connection;
    }
    
    /**
     * Gets the system data from the system table of the source Drupal database.
     *
     * @param \Drupal\Core\Database\Connection $connection
     *   Database connection to the source Drupal database.
     *
     * @return array
     *   The system data from the system table of the source Drupal database.
     */
    protected function getSystemData(Connection $connection) {
        $system_data = [];
        try {
            $results = $connection->select('system', 's', [
                'fetch' => \PDO::FETCH_ASSOC,
            ])
                ->fields('s')
                ->execute();
            foreach ($results as $result) {
                $system_data[$result['type']][$result['name']] = $result;
            }
        } catch (DatabaseExceptionWrapper $e) {
            // The table might not exist for example in tests.
        }
        return $system_data;
    }
    
    /**
     * Creates the necessary state entries for SqlBase::getDatabase() to work.
     *
     * The state entities created here have to exist before migration plugin
     * instances are created so that derivers such as
     * \Drupal\taxonomy\Plugin\migrate\D6TermNodeDeriver can access the source
     * database.
     *
     * @param array $database
     *   The source database settings.
     * @param string $drupal_version
     *   The Drupal version.
     *
     * @see \Drupal\migrate\Plugin\migrate\source\SqlBase::getDatabase()
     */
    protected function createDatabaseStateSettings(array $database, $drupal_version) {
        $database_state['key'] = 'upgrade';
        $database_state['database'] = $database;
        $database_state_key = 'migrate_drupal_' . $drupal_version;
        $state = $this->getState();
        $state->set($database_state_key, $database_state);
        $state->set('migrate.fallback_state_key', $database_state_key);
    }
    
    /**
     * Gets the migrations for import.
     *
     * @param string $database_state_key
     *   The state key.
     * @param int $drupal_version
     *   The version of Drupal we're getting the migrations for.
     *
     * @return \Drupal\migrate\Plugin\MigrationInterface[]
     *   The migrations for import.
     */
    protected function getMigrations($database_state_key, $drupal_version) {
        $version_tag = 'Drupal ' . $drupal_version;
        
        /** @var \Drupal\migrate\Plugin\MigrationInterface[] $all_migrations */
        $all_migrations = $this->getMigrationPluginManager()
            ->createInstancesByTag($version_tag);
        // Unset the node migrations that should not run based on the type of node
        // migration. That is, if this is a complete node migration then unset the
        // classic node migrations and if this is a classic node migration then
        // unset the complete node migrations.
        $type = NodeMigrateType::getNodeMigrateType(\Drupal::database(), $drupal_version);
        switch ($type) {
            case NodeMigrateType::NODE_MIGRATE_TYPE_COMPLETE:
                $patterns = '/(d' . $drupal_version . '_node:)|(d' . $drupal_version . '_node_translation:)|(d' . $drupal_version . '_node_revision:)|(d7_node_entity_translation:)/';
                break;
            case NodeMigrateType::NODE_MIGRATE_TYPE_CLASSIC:
                $patterns = '/(d' . $drupal_version . '_node_complete:)/';
                break;
        }
        foreach ($all_migrations as $key => $migrations) {
            if (preg_match($patterns, $key)) {
                unset($all_migrations[$key]);
            }
        }
        $migrations = [];
        foreach ($all_migrations as $migration) {
            // Skip migrations tagged with any of the follow-up migration tags. They
            // will be derived and executed after the migrations on which they depend
            // have been successfully executed.
            // @see Drupal\migrate_drupal\Plugin\MigrationWithFollowUpInterface
            if (!empty(array_intersect($migration->getMigrationTags(), $this->getFollowUpMigrationTags()))) {
                continue;
            }
            try {
                // @todo https://drupal.org/node/2681867 We should be able to validate
                //   the entire migration at this point.
                $source_plugin = $migration->getSourcePlugin();
                if ($source_plugin instanceof RequirementsInterface) {
                    $source_plugin->checkRequirements();
                }
                $destination_plugin = $migration->getDestinationPlugin();
                if ($destination_plugin instanceof RequirementsInterface) {
                    $destination_plugin->checkRequirements();
                }
                $migrations[] = $migration;
            } catch (RequirementsException $e) {
                // Migrations which are not applicable given the source and destination
                // site configurations (e.g., what modules are enabled) will be silently
                // ignored.
            }
        }
        return $migrations;
    }
    
    /**
     * Returns the follow-up migration tags.
     *
     * @return string[]
     */
    protected function getFollowUpMigrationTags() {
        if ($this->followUpMigrationTags === NULL) {
            $this->followUpMigrationTags = $this->getConfigFactory()
                ->get('migrate_drupal.settings')
                ->get('follow_up_migration_tags') ?: [];
        }
        return $this->followUpMigrationTags;
    }
    
    /**
     * Determines what version of Drupal the source database contains.
     *
     * @param \Drupal\Core\Database\Connection $connection
     *   The database connection object.
     *
     * @return string|false
     *   A string representing the major branch of Drupal core (e.g. '6' for
     *   Drupal 6.x), or FALSE if no valid version is matched.
     */
    public static function getLegacyDrupalVersion(Connection $connection) {
        // Don't assume because a table of that name exists, that it has the columns
        // we're querying. Catch exceptions and report that the source database is
        // not Drupal.
        // Drupal 5/6/7 can be detected by the schema_version in the system table.
        if ($connection->schema()
            ->tableExists('system')) {
            try {
                $version_string = $connection->query('SELECT [schema_version] FROM {system} WHERE [name] = :module', [
                    ':module' => 'system',
                ])
                    ->fetchField();
                if ($version_string && $version_string[0] == '1') {
                    if ((int) $version_string >= 1000) {
                        $version_string = '5';
                    }
                    else {
                        $version_string = FALSE;
                    }
                }
            } catch (DatabaseExceptionWrapper $e) {
                $version_string = FALSE;
            }
        }
        elseif ($connection->schema()
            ->tableExists('key_value')) {
            try {
                $result = $connection->query("SELECT [value] FROM {key_value} WHERE [collection] = :system_schema AND [name] = :module", [
                    ':system_schema' => 'system.schema',
                    ':module' => 'system',
                ])
                    ->fetchField();
                $version_string = unserialize($result);
            } catch (DatabaseExceptionWrapper $e) {
                $version_string = FALSE;
            }
        }
        else {
            $version_string = FALSE;
        }
        return $version_string ? substr($version_string, 0, 1) : FALSE;
    }
    
    /**
     * Gets the config factory service.
     *
     * @return \Drupal\Core\Config\ConfigFactoryInterface
     *   The config factory service.
     */
    protected function getConfigFactory() {
        if (!$this->configFactory) {
            $this->configFactory = \Drupal::service('config.factory');
        }
        return $this->configFactory;
    }
    
    /**
     * Gets the migration plugin manager service.
     *
     * @return \Drupal\migrate\Plugin\MigrationPluginManagerInterface
     *   The migration plugin manager service.
     */
    protected function getMigrationPluginManager() {
        if (!$this->migrationPluginManager) {
            $this->migrationPluginManager = \Drupal::service('plugin.manager.migration');
        }
        return $this->migrationPluginManager;
    }
    
    /**
     * Gets the state service.
     *
     * @return \Drupal\Core\State\StateInterface
     *   The state service.
     */
    protected function getState() {
        if (!$this->state) {
            $this->state = \Drupal::service('state');
        }
        return $this->state;
    }

}