class FilterFormat

class FilterFormat extends ConfigEntityBase implements FilterFormatInterface, EntityWithPluginCollectionInterface {
    
    /**
     * Unique machine name of the format.
     *
     * @todo Rename to $id.
     *
     * @var string
     */
    protected $format;
    
    /**
     * Unique label of the text format.
     *
     * Since text formats impact a site's security, two formats with the same
     * label but different filter configuration would impose a security risk.
     * Therefore, each text format label must be unique.
     *
     * @todo Rename to $label.
     *
     * @var string
     */
    protected $name;
    
    /**
     * Weight of this format in the text format selector.
     *
     * The first/lowest text format that is accessible for a user is used as
     * default format.
     *
     * @var int
     */
    protected $weight = 0;
    
    /**
     * List of user role IDs to grant access to use this format on initial creation.
     *
     * This property is always empty and unused for existing text formats.
     *
     * Default configuration objects of modules and installation profiles are
     * allowed to specify a list of user role IDs to grant access to.
     *
     * This property only has an effect when a new text format is created and the
     * list is not empty. By default, no user role is allowed to use a new format.
     *
     * @var array
     */
    protected $roles;
    
    /**
     * Configured filters for this text format.
     *
     * An associative array of filters assigned to the text format, keyed by the
     * instance ID of each filter and using the properties:
     * - id: The plugin ID of the filter plugin instance.
     * - provider: The name of the provider that owns the filter.
     * - status: (optional) A Boolean indicating whether the filter is
     *   enabled in the text format. Defaults to FALSE.
     * - weight: (optional) The weight of the filter in the text format. Defaults
     *   to 0.
     * - settings: (optional) An array of configured settings for the filter.
     *
     * Use FilterFormat::filters() to access the actual filters.
     *
     * @var array
     */
    protected $filters = [];
    
    /**
     * Holds the collection of filters that are attached to this format.
     *
     * @var \Drupal\filter\FilterPluginCollection
     */
    protected $filterCollection;
    
    /**
     * {@inheritdoc}
     */
    public function id() {
        return $this->format;
    }
    
    /**
     * {@inheritdoc}
     */
    public function filters($instance_id = NULL) {
        if (!isset($this->filterCollection)) {
            $this->filterCollection = new FilterPluginCollection(\Drupal::service('plugin.manager.filter'), $this->filters);
            $this->filterCollection
                ->sort();
        }
        if (isset($instance_id)) {
            return $this->filterCollection
                ->get($instance_id);
        }
        return $this->filterCollection;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPluginCollections() {
        return [
            'filters' => $this->filters(),
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function setFilterConfig($instance_id, array $configuration) {
        $this->filters[$instance_id] = $configuration;
        if (isset($this->filterCollection)) {
            $this->filterCollection
                ->setInstanceConfiguration($instance_id, $configuration);
        }
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function toArray() {
        $properties = parent::toArray();
        // The 'roles' property is only used during install and should never
        // actually be saved.
        unset($properties['roles']);
        return $properties;
    }
    
    /**
     * {@inheritdoc}
     */
    public function disable() {
        if ($this->isFallbackFormat()) {
            throw new \LogicException("The fallback text format '{$this->id()}' cannot be disabled.");
        }
        parent::disable();
        // Allow modules to react on text format deletion.
        \Drupal::moduleHandler()->invokeAll('filter_format_disable', [
            $this,
        ]);
        // Clear the filter cache whenever a text format is disabled.
        filter_formats_reset();
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function preSave(EntityStorageInterface $storage) {
        // Ensure the filters have been sorted before saving.
        $this->filters()
            ->sort();
        parent::preSave($storage);
        assert(is_string($this->label()), 'Filter format label is expected to be a string.');
        $this->name = trim($this->label());
    }
    
    /**
     * {@inheritdoc}
     */
    public function postSave(EntityStorageInterface $storage, $update = TRUE) {
        parent::postSave($storage, $update);
        // Clear the static caches of filter_formats() and others.
        filter_formats_reset();
        if (!$update && !$this->isSyncing()) {
            // Default configuration of modules and installation profiles is allowed
            // to specify a list of user roles to grant access to for the new format;
            // apply the defined user role permissions when a new format is inserted
            // and has a non-empty $roles property.
            // Note: user_role_change_permissions() triggers a call chain back into
            // \Drupal\filter\FilterPermissions::permissions() and lastly
            // filter_formats(), so its cache must be reset upfront.
            if (($roles = $this->get('roles')) && ($permission = $this->getPermissionName())) {
                foreach (user_roles() as $rid => $name) {
                    $enabled = in_array($rid, $roles, TRUE);
                    user_role_change_permissions($rid, [
                        $permission => $enabled,
                    ]);
                }
            }
        }
    }
    
    /**
     * Returns if this format is the fallback format.
     *
     * The fallback format can never be disabled. It must always be available.
     *
     * @return bool
     *   TRUE if this format is the fallback format, FALSE otherwise.
     */
    public function isFallbackFormat() {
        $fallback_format = \Drupal::config('filter.settings')->get('fallback_format');
        return $this->id() == $fallback_format;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPermissionName() {
        return !$this->isFallbackFormat() ? 'use text format ' . $this->id() : FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFilterTypes() {
        $filter_types = [];
        $filters = $this->filters();
        foreach ($filters as $filter) {
            if ($filter->status) {
                $filter_types[] = $filter->getType();
            }
        }
        return array_unique($filter_types);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getHtmlRestrictions() {
        // Ignore filters that are disabled or don't have HTML restrictions.
        $filters = array_filter($this->filters()
            ->getAll(), function ($filter) {
            if (!$filter->status) {
                return FALSE;
            }
            if ($filter->getType() === FilterInterface::TYPE_HTML_RESTRICTOR && $filter->getHTMLRestrictions() !== FALSE) {
                return TRUE;
            }
            return FALSE;
        });
        if (empty($filters)) {
            return FALSE;
        }
        else {
            // From the set of remaining filters (they were filtered by array_filter()
            // above), collect the list of tags and attributes that are allowed by all
            // filters, i.e. the intersection of all allowed tags and attributes.
            $restrictions = array_reduce($filters, function ($restrictions, $filter) {
                $new_restrictions = $filter->getHTMLRestrictions();
                if (isset($new_restrictions['forbidden_tags'])) {
                    @trigger_error('forbidden_tags for FilterInterface::getHTMLRestrictions() is deprecated in drupal:9.4.0 and is removed from drupal:10.0.0', E_USER_DEPRECATED);
                }
                // The first filter with HTML restrictions provides the initial set.
                if (!isset($restrictions)) {
                    return $new_restrictions;
                }
                else {
                    // Track the union of forbidden tags.
                    if (isset($new_restrictions['forbidden_tags'])) {
                        if (!isset($restrictions['forbidden_tags'])) {
                            $restrictions['forbidden_tags'] = $new_restrictions['forbidden_tags'];
                        }
                        else {
                            $restrictions['forbidden_tags'] = array_unique(array_merge($restrictions['forbidden_tags'], $new_restrictions['forbidden_tags']));
                        }
                    }
                    // Track the intersection of allowed tags.
                    if (isset($restrictions['allowed'])) {
                        $intersection = $restrictions['allowed'];
                        foreach ($intersection as $tag => $attributes) {
                            // If the current tag is not allowed by the new filter, then it's
                            // outside of the intersection.
                            if (!array_key_exists($tag, $new_restrictions['allowed'])) {
                                // The exception is the asterisk (which applies to all tags): it
                                // does not need to be allowed by every filter in order to be
                                // used; not every filter needs attribute restrictions on all tags.
                                if ($tag === '*') {
                                    continue;
                                }
                                unset($intersection[$tag]);
                            }
                            else {
                                $current_attributes = $intersection[$tag];
                                $new_attributes = $new_restrictions['allowed'][$tag];
                                // The current intersection does not allow any attributes, never
                                // allow.
                                if (!is_array($current_attributes) && $current_attributes == FALSE) {
                                    continue;
                                }
                                elseif (!is_array($current_attributes) && $current_attributes == TRUE && ($new_attributes == FALSE || is_array($new_attributes))) {
                                    $intersection[$tag] = $new_attributes;
                                }
                                elseif (is_array($current_attributes) && $new_attributes == FALSE) {
                                    $intersection[$tag] = $new_attributes;
                                }
                                elseif (is_array($current_attributes) && $new_attributes == TRUE) {
                                    continue;
                                }
                                elseif ($current_attributes == $new_attributes) {
                                    continue;
                                }
                                else {
                                    $intersection[$tag] = array_intersect_key($intersection[$tag], $new_attributes);
                                    foreach (array_keys($intersection[$tag]) as $attribute_value) {
                                        $intersection[$tag][$attribute_value] = $intersection[$tag][$attribute_value] && $new_attributes[$attribute_value];
                                    }
                                }
                            }
                        }
                        $restrictions['allowed'] = $intersection;
                    }
                    return $restrictions;
                }
            }, NULL);
            // Simplification: if we have both allowed (intersected) and forbidden
            // (unioned) tags, then remove any allowed tags that are also forbidden.
            // Once complete, the list of allowed tags expresses all tag-level
            // restrictions, and the list of forbidden tags can be removed.
            if (isset($restrictions['allowed']) && isset($restrictions['forbidden_tags'])) {
                foreach ($restrictions['forbidden_tags'] as $tag) {
                    if (isset($restrictions['allowed'][$tag])) {
                        unset($restrictions['allowed'][$tag]);
                    }
                }
                unset($restrictions['forbidden_tags']);
            }
            // Simplification: if the only remaining allowed tag is the asterisk
            // (which contains attribute restrictions that apply to all tags), and
            // there are no forbidden tags, then effectively nothing is allowed.
            if (isset($restrictions['allowed'])) {
                if (count($restrictions['allowed']) === 1 && array_key_exists('*', $restrictions['allowed']) && !isset($restrictions['forbidden_tags'])) {
                    $restrictions['allowed'] = [];
                }
            }
            return $restrictions;
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function removeFilter($instance_id) {
        unset($this->filters[$instance_id]);
        $this->filterCollection
            ->removeInstanceId($instance_id);
    }
    
    /**
     * {@inheritdoc}
     */
    public function onDependencyRemoval(array $dependencies) {
        $changed = parent::onDependencyRemoval($dependencies);
        $filters = $this->filters();
        foreach ($filters as $filter) {
            // Remove disabled filters, so that this FilterFormat config entity can
            // continue to exist.
            if (!$filter->status && in_array($filter->provider, $dependencies['module'])) {
                $this->removeFilter($filter->getPluginId());
                $changed = TRUE;
            }
        }
        return $changed;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function calculatePluginDependencies(PluginInspectionInterface $instance) {
        // Only add dependencies for plugins that are actually configured. This is
        // necessary because the filter plugin collection will return all available
        // filter plugins.
        // @see \Drupal\filter\FilterPluginCollection::getConfiguration()
        if (isset($this->filters[$instance->getPluginId()])) {
            parent::calculatePluginDependencies($instance);
        }
    }

}