class ConfigBase

abstract class ConfigBase implements RefinableCacheableDependencyInterface {
    use DependencySerializationTrait;
    use RefinableCacheableDependencyTrait;
    
    /**
     * The name of the configuration object.
     *
     * @var string
     */
    protected $name;
    
    /**
     * The data of the configuration object.
     *
     * @var array
     */
    protected $data = [];
    
    /**
     * The maximum length of a configuration object name.
     *
     * Many filesystems (including HFS, NTFS, and ext4) have a maximum file name
     * length of 255 characters. To ensure that no configuration objects
     * incompatible with this limitation are created, we enforce a maximum name
     * length of 250 characters (leaving 5 characters for the file extension).
     *
     * @see http://wikipedia.org/wiki/Comparison_of_file_systems
     *
     * Configuration objects not stored on the filesystem should still be
     * restricted in name length so name can be used as a cache key.
     */
    const MAX_NAME_LENGTH = 250;
    
    /**
     * Returns the name of this configuration object.
     *
     * @return string
     *   The name of the configuration object.
     */
    public function getName() {
        return $this->name;
    }
    
    /**
     * Sets the name of this configuration object.
     *
     * @param string $name
     *   The name of the configuration object.
     *
     * @return $this
     *   The configuration object.
     */
    public function setName($name) {
        $this->name = $name;
        return $this;
    }
    
    /**
     * Validates the configuration object name.
     *
     * @param string $name
     *   The name of the configuration object.
     *
     * @throws \Drupal\Core\Config\ConfigNameException
     *
     * @see Config::MAX_NAME_LENGTH
     */
    public static function validateName($name) {
        // The name must be namespaced by owner.
        if (strpos($name, '.') === FALSE) {
            throw new ConfigNameException("Missing namespace in Config object name {$name}.");
        }
        // The name must be shorter than Config::MAX_NAME_LENGTH characters.
        if (strlen($name) > self::MAX_NAME_LENGTH) {
            throw new ConfigNameException("Config object name {$name} exceeds maximum allowed length of " . static::MAX_NAME_LENGTH . " characters.");
        }
        // The name must not contain any of the following characters:
        // : ? * < > " ' / \
        if (preg_match('/[:?*<>"\'\\/\\\\]/', $name)) {
            throw new ConfigNameException("Invalid character in Config object name {$name}.");
        }
    }
    
    /**
     * Gets data from this configuration object.
     *
     * @param string $key
     *   A string that maps to a key within the configuration data.
     *   For instance in the following configuration array:
     *   @code
     *   array(
     *     'foo' => array(
     *       'bar' => 'baz',
     *     ),
     *   );
     *   @endcode
     *   A key of 'foo.bar' would return the string 'baz'. However, a key of 'foo'
     *   would return array('bar' => 'baz').
     *   If no key is specified, then the entire data array is returned.
     *
     * @return mixed
     *   The data that was requested.
     */
    public function get($key = '') {
        if (empty($key)) {
            return $this->data;
        }
        else {
            $parts = explode('.', $key);
            if (count($parts) == 1) {
                return $this->data[$key] ?? NULL;
            }
            else {
                $value = NestedArray::getValue($this->data, $parts, $key_exists);
                return $key_exists ? $value : NULL;
            }
        }
    }
    
    /**
     * Replaces the data of this configuration object.
     *
     * @param array $data
     *   The new configuration data.
     *
     * @return $this
     *   The configuration object.
     *
     * @throws \Drupal\Core\Config\ConfigValueException
     *   If any key in $data in any depth contains a dot.
     */
    public function setData(array $data) {
        $data = $this->castSafeStrings($data);
        $this->validateKeys($data);
        $this->data = $data;
        return $this;
    }
    
    /**
     * Sets a value in this configuration object.
     *
     * @param string $key
     *   Identifier to store value in configuration.
     * @param mixed $value
     *   Value to associate with identifier.
     *
     * @return $this
     *   The configuration object.
     *
     * @throws \Drupal\Core\Config\ConfigValueException
     *   If $value is an array and any of its keys in any depth contains a dot.
     */
    public function set($key, $value) {
        $value = $this->castSafeStrings($value);
        // The dot/period is a reserved character; it may appear between keys, but
        // not within keys.
        if (is_array($value)) {
            $this->validateKeys($value);
        }
        $parts = explode('.', $key);
        if (count($parts) == 1) {
            $this->data[$key] = $value;
        }
        else {
            NestedArray::setValue($this->data, $parts, $value);
        }
        return $this;
    }
    
    /**
     * Validates all keys in a passed in config array structure.
     *
     * @param array $data
     *   Configuration array structure.
     *
     * @return null
     *
     * @throws \Drupal\Core\Config\ConfigValueException
     *   If any key in $data in any depth contains a dot.
     */
    protected function validateKeys(array $data) {
        foreach ($data as $key => $value) {
            if (strpos($key, '.') !== FALSE) {
                throw new ConfigValueException("{$key} key contains a dot which is not supported.");
            }
            if (is_array($value)) {
                $this->validateKeys($value);
            }
        }
    }
    
    /**
     * Unsets a value in this configuration object.
     *
     * @param string $key
     *   Name of the key whose value should be unset.
     *
     * @return $this
     *   The configuration object.
     */
    public function clear($key) {
        $parts = explode('.', $key);
        if (count($parts) == 1) {
            unset($this->data[$key]);
        }
        else {
            NestedArray::unsetValue($this->data, $parts);
        }
        return $this;
    }
    
    /**
     * Merges data into a configuration object.
     *
     * @param array $data_to_merge
     *   An array containing data to merge.
     *
     * @return $this
     *   The configuration object.
     */
    public function merge(array $data_to_merge) {
        // Preserve integer keys so that configuration keys are not changed.
        $this->setData(NestedArray::mergeDeepArray([
            $this->data,
            $data_to_merge,
        ], TRUE));
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheContexts() {
        return $this->cacheContexts;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheTags() {
        return Cache::mergeTags([
            'config:' . $this->name,
        ], $this->cacheTags);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheMaxAge() {
        return $this->cacheMaxAge;
    }
    
    /**
     * Casts any objects that implement MarkupInterface to string.
     *
     * @param mixed $data
     *   The configuration data.
     *
     * @return mixed
     *   The data with any safe strings cast to string.
     */
    protected function castSafeStrings($data) {
        if ($data instanceof MarkupInterface) {
            $data = (string) $data;
        }
        elseif (is_array($data)) {
            array_walk_recursive($data, function (&$value) {
                if ($value instanceof MarkupInterface) {
                    $value = (string) $value;
                }
            });
        }
        return $data;
    }

}