/**
 * @file
 * A Backbone View acting as a controller for CKEditor toolbar configuration.
 */

(function($, Drupal, Backbone, CKEDITOR, _) {
  Drupal.ckeditor.ControllerView = Backbone.View.extend(
    /** @lends Drupal.ckeditor.ControllerView# */ {
      /**
       * @type {object}
       */
      events: {},

      /**
       * Backbone View acting as a controller for CKEditor toolbar configuration.
       *
       * @constructs
       *
       * @augments Backbone.View
       */
      initialize() {
        this.getCKEditorFeatures(
          this.model.get('hiddenEditorConfig'),
          this.disableFeaturesDisallowedByFilters.bind(this),
        );

        // Push the active editor configuration to the textarea.
        this.model.listenTo(
          this.model,
          'change:activeEditorConfig',
          this.model.sync,
        );
        this.listenTo(this.model, 'change:isDirty', this.parseEditorDOM);
      },

      /**
       * Converts the active toolbar DOM structure to an object representation.
       *
       * @param {Drupal.ckeditor.ConfigurationModel} model
       *   The state model for the CKEditor configuration.
       * @param {bool} isDirty
       *   Tracks whether the active toolbar DOM structure has been changed.
       *   isDirty is toggled back to false in this method.
       * @param {object} options
       *   An object that includes:
       * @param {bool} [options.broadcast]
       *   A flag that controls whether a CKEditorToolbarChanged event should be
       *   fired for configuration changes.
       *
       * @fires event:CKEditorToolbarChanged
       */
      parseEditorDOM(model, isDirty, options) {
        if (isDirty) {
          const currentConfig = this.model.get('activeEditorConfig');

          // Process the rows.
          const rows = [];
          this.$el
            .find('.ckeditor-active-toolbar-configuration')
            .children('.ckeditor-row')
            .each(function() {
              const groups = [];
              // Process the button groups.
              $(this)
                .find('.ckeditor-toolbar-group')
                .each(function() {
                  const $group = $(this);
                  const $buttons = $group.find('.ckeditor-button');
                  if ($buttons.length) {
                    const group = {
                      name: $group.attr(
                        'data-drupal-ckeditor-toolbar-group-name',
                      ),
                      items: [],
                    };
                    $group
                      .find('.ckeditor-button, .ckeditor-multiple-button')
                      .each(function() {
                        group.items.push(
                          $(this).attr('data-drupal-ckeditor-button-name'),
                        );
                      });
                    groups.push(group);
                  }
                });
              if (groups.length) {
                rows.push(groups);
              }
            });
          this.model.set('activeEditorConfig', rows);
          // Mark the model as clean. Whether or not the sync to the textfield
          // occurs depends on the activeEditorConfig attribute firing a change
          // event. The DOM has at least been processed and posted, so as far as
          // the model is concerned, it is clean.
          this.model.set('isDirty', false);

          // Determine whether we should trigger an event.
          if (options.broadcast !== false) {
            const prev = this.getButtonList(currentConfig);
            const next = this.getButtonList(rows);
            if (prev.length !== next.length) {
              this.$el
                .find('.ckeditor-toolbar-active')
                .trigger('CKEditorToolbarChanged', [
                  prev.length < next.length ? 'added' : 'removed',
                  _.difference(
                    _.union(prev, next),
                    _.intersection(prev, next),
                  )[0],
                ]);
            }
          }
        }
      },

      /**
       * Asynchronously retrieve the metadata for all available CKEditor features.
       *
       * In order to get a list of all features needed by CKEditor, we create a
       * hidden CKEditor instance, then check the CKEditor's "allowedContent"
       * filter settings. Because creating an instance is expensive, a callback
       * must be provided that will receive a hash of {@link Drupal.EditorFeature}
       * features keyed by feature (button) name.
       *
       * @param {object} CKEditorConfig
       *   An object that represents the configuration settings for a CKEditor
       *   editor component.
       * @param {function} callback
       *   A function to invoke when the instanceReady event is fired by the
       *   CKEditor object.
       */
      getCKEditorFeatures(CKEditorConfig, callback) {
        const getProperties = function(CKEPropertiesList) {
          return _.isObject(CKEPropertiesList) ? _.keys(CKEPropertiesList) : [];
        };

        const convertCKERulesToEditorFeature = function(
          feature,
          CKEFeatureRules,
        ) {
          for (let i = 0; i < CKEFeatureRules.length; i++) {
            const CKERule = CKEFeatureRules[i];
            const rule = new Drupal.EditorFeatureHTMLRule();

            // Tags.
            const tags = getProperties(CKERule.elements);
            rule.required.tags = CKERule.propertiesOnly ? [] : tags;
            rule.allowed.tags = tags;
            // Attributes.
            rule.required.attributes = getProperties(
              CKERule.requiredAttributes,
            );
            rule.allowed.attributes = getProperties(CKERule.attributes);
            // Styles.
            rule.required.styles = getProperties(CKERule.requiredStyles);
            rule.allowed.styles = getProperties(CKERule.styles);
            // Classes.
            rule.required.classes = getProperties(CKERule.requiredClasses);
            rule.allowed.classes = getProperties(CKERule.classes);
            // Raw.
            rule.raw = CKERule;

            feature.addHTMLRule(rule);
          }
        };

        // Create hidden CKEditor with all features enabled, retrieve metadata.
        // @see \Drupal\ckeditor\Plugin\Editor\CKEditor::buildConfigurationForm().
        const hiddenCKEditorID = 'ckeditor-hidden';
        if (CKEDITOR.instances[hiddenCKEditorID]) {
          CKEDITOR.instances[hiddenCKEditorID].destroy(true);
        }
        // Load external plugins, if any.
        const hiddenEditorConfig = this.model.get('hiddenEditorConfig');
        if (hiddenEditorConfig.drupalExternalPlugins) {
          const externalPlugins = hiddenEditorConfig.drupalExternalPlugins;
          Object.keys(externalPlugins || {}).forEach(pluginName => {
            CKEDITOR.plugins.addExternal(
              pluginName,
              externalPlugins[pluginName],
              '',
            );
          });
        }
        CKEDITOR.inline($(`#${hiddenCKEditorID}`).get(0), CKEditorConfig);

        // Once the instance is ready, retrieve the allowedContent filter rules
        // and convert them to Drupal.EditorFeature objects.
        CKEDITOR.once('instanceReady', e => {
          if (e.editor.name === hiddenCKEditorID) {
            // First collect all CKEditor allowedContent rules.
            const CKEFeatureRulesMap = {};
            const rules = e.editor.filter.allowedContent;
            let rule;
            let name;
            for (let i = 0; i < rules.length; i++) {
              rule = rules[i];
              name = rule.featureName || ':(';
              if (!CKEFeatureRulesMap[name]) {
                CKEFeatureRulesMap[name] = [];
              }
              CKEFeatureRulesMap[name].push(rule);
            }

            // Now convert these to Drupal.EditorFeature objects. And track which
            // buttons are mapped to which features.
            // @see getFeatureForButton()
            const features = {};
            const buttonsToFeatures = {};
            Object.keys(CKEFeatureRulesMap).forEach(featureName => {
              const feature = new Drupal.EditorFeature(featureName);
              convertCKERulesToEditorFeature(
                feature,
                CKEFeatureRulesMap[featureName],
              );
              features[featureName] = feature;
              const command = e.editor.getCommand(featureName);
              if (command) {
                buttonsToFeatures[command.uiItems[0].name] = featureName;
              }
            });

            callback(features, buttonsToFeatures);
          }
        });
      },

      /**
       * Retrieves the feature for a given button from featuresMetadata. Returns
       * false if the given button is in fact a divider.
       *
       * @param {string} button
       *   The name of a CKEditor button.
       *
       * @return {object}
       *   The feature metadata object for a button.
       */
      getFeatureForButton(button) {
        // Return false if the button being added is a divider.
        if (button === '-') {
          return false;
        }

        // Get a Drupal.editorFeature object that contains all metadata for
        // the feature that was just added or removed. Not every feature has
        // such metadata.
        let featureName = this.model.get('buttonsToFeatures')[
          button.toLowerCase()
        ];
        // Features without an associated command do not have a 'feature name' by
        // default, so we use the lowercased button name instead.
        if (!featureName) {
          featureName = button.toLowerCase();
        }
        const featuresMetadata = this.model.get('featuresMetadata');
        if (!featuresMetadata[featureName]) {
          featuresMetadata[featureName] = new Drupal.EditorFeature(featureName);
          this.model.set('featuresMetadata', featuresMetadata);
        }
        return featuresMetadata[featureName];
      },

      /**
       * Checks buttons against filter settings; disables disallowed buttons.
       *
       * @param {object} features
       *   A map of {@link Drupal.EditorFeature} objects.
       * @param {object} buttonsToFeatures
       *   Object containing the button-to-feature mapping.
       *
       * @see Drupal.ckeditor.ControllerView#getFeatureForButton
       */
      disableFeaturesDisallowedByFilters(features, buttonsToFeatures) {
        this.model.set('featuresMetadata', features);
        // Store the button-to-feature mapping. Needs to happen only once, because
        // the same buttons continue to have the same features; only the rules for
        // specific features may change.
        // @see getFeatureForButton()
        this.model.set('buttonsToFeatures', buttonsToFeatures);

        // Ensure that toolbar configuration changes are broadcast.
        this.broadcastConfigurationChanges(this.$el);

        // Initialization: not all of the default toolbar buttons may be allowed
        // by the current filter settings. Remove any of the default toolbar
        // buttons that require more permissive filter settings. The remaining
        // default toolbar buttons are marked as "added".
        let existingButtons = [];
        // Loop through each button group after flattening the groups from the
        // toolbar row arrays.
        const buttonGroups = _.flatten(this.model.get('activeEditorConfig'));
        for (let i = 0; i < buttonGroups.length; i++) {
          // Pull the button names from each toolbar button group.
          const buttons = buttonGroups[i].items;
          for (let k = 0; k < buttons.length; k++) {
            existingButtons.push(buttons[k]);
          }
        }
        // Remove duplicate buttons.
        existingButtons = _.unique(existingButtons);
        // Prepare the active toolbar and available-button toolbars.
        for (let n = 0; n < existingButtons.length; n++) {
          const button = existingButtons[n];
          const feature = this.getFeatureForButton(button);
          // Skip dividers.
          if (feature === false) {
            continue;
          }

          if (Drupal.editorConfiguration.featureIsAllowedByFilters(feature)) {
            // Existing toolbar buttons are in fact "added features".
            this.$el
              .find('.ckeditor-toolbar-active')
              .trigger('CKEditorToolbarChanged', ['added', existingButtons[n]]);
          } else {
            // Move the button element from the active the active toolbar to the
            // list of available buttons.
            $(
              `.ckeditor-toolbar-active li[data-drupal-ckeditor-button-name="${button}"]`,
            )
              .detach()
              .appendTo(
                '.ckeditor-toolbar-disabled > .ckeditor-toolbar-available > ul',
              );
            // Update the toolbar value field.
            this.model.set({ isDirty: true }, { broadcast: false });
          }
        }
      },

      /**
       * Sets up broadcasting of CKEditor toolbar configuration changes.
       *
       * @param {jQuery} $ckeditorToolbar
       *   The active toolbar DOM element wrapped in jQuery.
       */
      broadcastConfigurationChanges($ckeditorToolbar) {
        const view = this;
        const hiddenEditorConfig = this.model.get('hiddenEditorConfig');
        const getFeatureForButton = this.getFeatureForButton.bind(this);
        const getCKEditorFeatures = this.getCKEditorFeatures.bind(this);
        $ckeditorToolbar
          .find('.ckeditor-toolbar-active')
          // Listen for CKEditor toolbar configuration changes. When a button is
          // added/removed, call an appropriate Drupal.editorConfiguration method.
          .on(
            'CKEditorToolbarChanged.ckeditorAdmin',
            (event, action, button) => {
              const feature = getFeatureForButton(button);

              // Early-return if the button being added is a divider.
              if (feature === false) {
                return;
              }

              // Trigger a standardized text editor configuration event to indicate
              // whether a feature was added or removed, so that filters can react.
              const configEvent =
                action === 'added' ? 'addedFeature' : 'removedFeature';
              Drupal.editorConfiguration[configEvent](feature);
            },
          )
          // Listen for CKEditor plugin settings changes. When a plugin setting is
          // changed, rebuild the CKEditor features metadata.
          .on(
            'CKEditorPluginSettingsChanged.ckeditorAdmin',
            (event, settingsChanges) => {
              // Update hidden CKEditor configuration.
              Object.keys(settingsChanges || {}).forEach(key => {
                hiddenEditorConfig[key] = settingsChanges[key];
              });

              // Retrieve features for the updated hidden CKEditor configuration.
              getCKEditorFeatures(hiddenEditorConfig, features => {
                // Trigger a standardized text editor configuration event for each
                // feature that was modified by the configuration changes.
                const featuresMetadata = view.model.get('featuresMetadata');
                Object.keys(features || {}).forEach(name => {
                  const feature = features[name];
                  if (
                    featuresMetadata.hasOwnProperty(name) &&
                    !_.isEqual(featuresMetadata[name], feature)
                  ) {
                    Drupal.editorConfiguration.modifiedFeature(feature);
                  }
                });
                // Update the CKEditor features metadata.
                view.model.set('featuresMetadata', features);
              });
            },
          );
      },

      /**
       * Returns the list of buttons from an editor configuration.
       *
       * @param {object} config
       *   A CKEditor configuration object.
       *
       * @return {Array}
       *   A list of buttons in the CKEditor configuration.
       */
      getButtonList(config) {
        const buttons = [];
        // Remove the rows.
        config = _.flatten(config);

        // Loop through the button groups and pull out the buttons.
        config.forEach(group => {
          group.items.forEach(button => {
            buttons.push(button);
          });
        });

        // Remove the dividing elements if any.
        return _.without(buttons, '-');
      },
    },
  );
})(jQuery, Drupal, Backbone, CKEDITOR, _);