class StorableConfigBase

abstract class StorableConfigBase extends ConfigBase {
    
    /**
     * The storage used to load and save this configuration object.
     *
     * @var \Drupal\Core\Config\StorageInterface
     */
    protected $storage;
    
    /**
     * The config schema wrapper object for this configuration object.
     *
     * @var \Drupal\Core\Config\Schema\Element
     */
    protected $schemaWrapper;
    
    /**
     * The typed config manager.
     *
     * @var \Drupal\Core\Config\TypedConfigManagerInterface
     */
    protected $typedConfigManager;
    
    /**
     * Whether the configuration object is new or has been saved to the storage.
     *
     * @var bool
     */
    protected $isNew = TRUE;
    
    /**
     * The data of the configuration object.
     *
     * @var array
     */
    protected $originalData = [];
    
    /**
     * Saves the configuration object.
     *
     * Must invalidate the cache tags associated with the configuration object.
     *
     * @param bool $has_trusted_data
     *   Set to TRUE if the configuration data has already been checked to ensure
     *   it conforms to schema. Generally this is only used during module and
     *   theme installation.
     *
     * @return $this
     *
     * @see \Drupal\Core\Config\ConfigInstaller::createConfiguration()
     */
    public abstract function save($has_trusted_data = FALSE);
    
    /**
     * Deletes the configuration object.
     *
     * Must invalidate the cache tags associated with the configuration object.
     *
     * @return $this
     */
    public abstract function delete();
    
    /**
     * Initializes a configuration object with pre-loaded data.
     *
     * @param array $data
     *   Array of loaded data for this configuration object.
     *
     * @return $this
     *   The configuration object.
     */
    public function initWithData(array $data) {
        $this->isNew = FALSE;
        $this->data = $data;
        $this->originalData = $this->data;
        return $this;
    }
    
    /**
     * Returns whether this configuration object is new.
     *
     * @return bool
     *   TRUE if this configuration object does not exist in storage.
     */
    public function isNew() {
        return $this->isNew;
    }
    
    /**
     * Retrieves the storage used to load and save this configuration object.
     *
     * @return \Drupal\Core\Config\StorageInterface
     *   The configuration storage object.
     */
    public function getStorage() {
        return $this->storage;
    }
    
    /**
     * Gets the schema wrapper for the whole configuration object.
     *
     * The schema wrapper is dependent on the configuration name and the whole
     * data structure, so if the name or the data changes in any way, the wrapper
     * should be reset.
     *
     * @return \Drupal\Core\Config\Schema\Element
     */
    protected function getSchemaWrapper() {
        if (!isset($this->schemaWrapper)) {
            $this->schemaWrapper = $this->typedConfigManager
                ->createFromNameAndData($this->name, $this->data);
        }
        return $this->schemaWrapper;
    }
    
    /**
     * Validate the values are allowed data types.
     *
     * @param string $key
     *   A string that maps to a key within the configuration data.
     * @param string $value
     *   Value to associate with the key.
     *
     * @return null
     *
     * @throws \Drupal\Core\Config\UnsupportedDataTypeConfigException
     *   If the value is unsupported in configuration.
     */
    protected function validateValue($key, $value) {
        // Minimal validation. Should not try to serialize resources or non-arrays.
        if (is_array($value)) {
            foreach ($value as $nested_value_key => $nested_value) {
                $this->validateValue($key . '.' . $nested_value_key, $nested_value);
            }
        }
        elseif ($value !== NULL && !is_scalar($value)) {
            throw new UnsupportedDataTypeConfigException("Invalid data type for config element {$this->getName()}:{$key}");
        }
    }
    
    /**
     * Casts the value to correct data type using the configuration schema.
     *
     * @param string $key
     *   A string that maps to a key within the configuration data.
     * @param string $value
     *   Value to associate with the key.
     *
     * @return mixed
     *   The value cast to the type indicated in the schema.
     *
     * @throws \Drupal\Core\Config\UnsupportedDataTypeConfigException
     *   If the value is unsupported in configuration.
     */
    protected function castValue($key, $value) {
        $element = $this->getSchemaWrapper()
            ->get($key);
        // Do not cast value if it is unknown or defined to be ignored.
        if ($element && ($element instanceof Undefined || $element instanceof Ignore)) {
            // Do validate the value (may throw UnsupportedDataTypeConfigException)
            // to ensure unsupported types are not supported in this case either.
            $this->validateValue($key, $value);
            return $value;
        }
        if (is_scalar($value) || $value === NULL) {
            if ($element && $element instanceof PrimitiveInterface) {
                // Special handling for integers and floats since the configuration
                // system is primarily concerned with saving values from the Form API
                // we have to special case the meaning of an empty string for numeric
                // types. In PHP this would be casted to a 0 but for the purposes of
                // configuration we need to treat this as a NULL.
                $empty_value = $value === '' && ($element instanceof IntegerInterface || $element instanceof FloatInterface);
                if ($value === NULL || $empty_value) {
                    $value = NULL;
                }
                else {
                    $value = $element->getCastedValue();
                }
            }
        }
        else {
            // Throw exception on any non-scalar or non-array value.
            if (!is_array($value)) {
                throw new UnsupportedDataTypeConfigException("Invalid data type for config element {$this->getName()}:{$key}");
            }
            // Recurse into any nested keys.
            foreach ($value as $nested_value_key => $nested_value) {
                $value[$nested_value_key] = $this->castValue($key . '.' . $nested_value_key, $nested_value);
            }
            if ($element instanceof Sequence) {
                $data_definition = $element->getDataDefinition();
                if ($data_definition instanceof SequenceDataDefinition) {
                    // Apply any sorting defined on the schema.
                    switch ($data_definition->getOrderBy()) {
                        case 'key':
                            ksort($value);
                            break;
                        case 'value':
                            // The PHP documentation notes that "Be careful when sorting
                            // arrays with mixed types values because sort() can produce
                            // unpredictable results". There is no risk here because
                            // \Drupal\Core\Config\StorableConfigBase::castValue() has
                            // already cast all values to the same type using the
                            // configuration schema.
                            sort($value);
                            break;
                    }
                }
            }
        }
        return $value;
    }

}