class Map

class Map extends TypedData implements \IteratorAggregate, ComplexDataInterface {
    
    /**
     * The data definition.
     *
     * @var \Drupal\Core\TypedData\ComplexDataDefinitionInterface
     */
    protected $definition;
    
    /**
     * An array of values for the contained properties.
     *
     * @var array
     */
    protected $values = [];
    
    /**
     * The array of properties.
     *
     * @var \Drupal\Core\TypedData\TypedDataInterface[]
     */
    protected $properties = [];
    
    /**
     * {@inheritdoc}
     */
    public function getValue() {
        // Update the values and return them.
        foreach ($this->properties as $name => $property) {
            $definition = $property->getDataDefinition();
            if (!$definition->isComputed()) {
                $value = $property->getValue();
                // Only write NULL values if the whole map is not NULL.
                if (isset($this->values) || isset($value)) {
                    $this->values[$name] = $value;
                }
            }
        }
        return $this->values;
    }
    
    /**
     * Overrides \Drupal\Core\TypedData\TypedData::setValue().
     *
     * @param array|null $values
     *   An array of property values.
     * @param bool $notify
     *   (optional) Whether to notify the parent object of the change. Defaults to
     *   TRUE. If a property is updated from a parent object, set it to FALSE to
     *   avoid being notified again.
     */
    public function setValue($values, $notify = TRUE) {
        if (isset($values) && !is_array($values)) {
            throw new \InvalidArgumentException("Invalid values given. Values must be represented as an associative array.");
        }
        $this->values = $values;
        // Update any existing property objects.
        foreach ($this->properties as $name => $property) {
            $value = $values[$name] ?? NULL;
            $property->setValue($value, FALSE);
            // Remove the value from $this->values to ensure it does not contain any
            // value for computed properties.
            unset($this->values[$name]);
        }
        // Notify the parent of any changes.
        if ($notify && isset($this->parent)) {
            $this->parent
                ->onChange($this->name);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function getString() {
        $strings = [];
        foreach ($this->getProperties() as $property) {
            $strings[] = $property->getString();
        }
        // Remove any empty strings resulting from empty items.
        return implode(', ', array_filter($strings, 'mb_strlen'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function get($property_name) {
        if (!isset($this->properties[$property_name])) {
            $value = NULL;
            if (isset($this->values[$property_name])) {
                $value = $this->values[$property_name];
            }
            // If the property is unknown, this will throw an exception.
            $this->properties[$property_name] = $this->getTypedDataManager()
                ->getPropertyInstance($this, $property_name, $value);
        }
        return $this->properties[$property_name];
    }
    
    /**
     * {@inheritdoc}
     */
    public function set($property_name, $value, $notify = TRUE) {
        // Separate the writing in a protected method, such that onChange
        // implementations can make use of it.
        $this->writePropertyValue($property_name, $value);
        $this->onChange($property_name, $notify);
        return $this;
    }
    
    /**
     * Writes the value of a property without handling changes.
     *
     * Implementations of onChange() should use this method instead of set() in
     * order to avoid onChange() being triggered again.
     *
     * @param string $property_name
     *   The name of the property to be written.
     * @param $value
     *   The value to set.
     */
    protected function writePropertyValue($property_name, $value) {
        if ($this->definition
            ->getPropertyDefinition($property_name)) {
            $this->get($property_name)
                ->setValue($value, FALSE);
        }
        else {
            // Just set the plain value, which allows adding a new entry to the map.
            $this->values[$property_name] = $value;
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function getProperties($include_computed = FALSE) {
        $properties = [];
        foreach ($this->definition
            ->getPropertyDefinitions() as $name => $definition) {
            if ($include_computed || !$definition->isComputed()) {
                $properties[$name] = $this->get($name);
            }
        }
        return $properties;
    }
    
    /**
     * {@inheritdoc}
     */
    public function toArray() {
        $values = [];
        foreach ($this->getProperties() as $name => $property) {
            $values[$name] = $property->getValue();
        }
        return $values;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getIterator() {
        return new \ArrayIterator($this->getProperties());
    }
    
    /**
     * {@inheritdoc}
     */
    public function isEmpty() {
        foreach ($this->properties as $property) {
            $definition = $property->getDataDefinition();
            if (!$definition->isComputed() && $property->getValue() !== NULL) {
                return FALSE;
            }
        }
        if (isset($this->values)) {
            foreach ($this->values as $name => $value) {
                if (isset($value) && !isset($this->properties[$name])) {
                    return FALSE;
                }
            }
        }
        return TRUE;
    }
    
    /**
     * Magic method: Implements a deep clone.
     */
    public function __clone() {
        foreach ($this->properties as $name => $property) {
            $this->properties[$name] = clone $property;
            $this->properties[$name]
                ->setContext($name, $this);
        }
    }
    
    /**
     * {@inheritdoc}
     *
     * @param $property_name
     *   The name of the property.
     * @param bool $notify
     *   (optional) Whether to forward the notification to the parent. Defaults to
     *   TRUE. By passing FALSE, overrides of this method can re-use the logic
     *   of parent classes without triggering notification.
     */
    public function onChange($property_name, $notify = TRUE) {
        // Notify the parent of changes.
        if ($notify && isset($this->parent)) {
            $this->parent
                ->onChange($this->name);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function applyDefaultValue($notify = TRUE) {
        // Apply the default value of all properties.
        foreach ($this->getProperties() as $property) {
            $property->applyDefaultValue(FALSE);
        }
        return $this;
    }

}