/**
 * @file
 * CKEditor 5 implementation of {@link Drupal.editors} API.
 */

((Drupal, debounce, CKEditor5, $, once) => {
  /**
   * The CKEditor 5 instances.
   *
   * @type {Map}
   */
  Drupal.CKEditor5Instances = new Map();

  /**
   * The callback functions.
   *
   * @type {Map}
   */
  const callbacks = new Map();

  /**
   * List of element ids with the required attribute.
   *
   * @type {Set}
   */
  const required = new Set();

  /**
   * Get the value of the (deep) property on name from scope.
   *
   * @param {object} scope
   *  Object used to search for the function.
   * @param {string} name
   *  The path to access in the scope object.
   *
   * @return {null|function}
   *  The corresponding function from the scope object.
   */
  function findFunc(scope, name) {
    if (!scope) {
      return null;
    }
    const parts = name.includes('.') ? name.split('.') : name;

    if (parts.length > 1) {
      return findFunc(scope[parts.shift()], parts);
    }
    return typeof scope[parts[0]] === 'function' ? scope[parts[0]] : null;
  }

  /**
   * Transform a config key in a callback function or execute the function
   * to dynamically build the configuration entry.
   *
   * @param {object} config
   *  The plugin configuration object.
   *
   * @return {null|function|*}
   *  Resulting configuration value.
   */
  function buildFunc(config) {
    const { func } = config;
    // Assuming a global object.
    const fn = findFunc(window, func.name);
    if (typeof fn === 'function') {
      const result = func.invoke ? fn(...func.args) : fn;
      return result;
    }
    return null;
  }

  /**
   * Converts a string representing regexp to a RegExp object.
   *
   * @param {Object} config
   *   An object containing configuration.
   * @param {string} config.pattern
   *   The regexp pattern that is used to create the RegExp object.
   *
   * @return {RegExp}
   *   Regexp object built from the string regexp.
   */
  function buildRegexp(config) {
    const { pattern } = config.regexp;

    const main = pattern.match(/\/(.+)\/.*/)[1];
    const options = pattern.match(/\/.+\/(.*)/)[1];

    return new RegExp(main, options);
  }

  /**
   * Casts configuration items to correct types.
   *
   * @param {Object} config
   *   The config object.
   * @return {Object}
   *   The config object with items transformed to correct type.
   */
  function processConfig(config) {
    /**
     * Processes an array in config recursively.
     *
     * @param {Array} config
     *   An array that should be processed recursively.
     * @return {Array}
     *   An array that has been processed recursively.
     */
    function processArray(config) {
      return config.map((item) => {
        if (typeof item === 'object') {
          return processConfig(item);
        }

        return item;
      });
    }

    return Object.entries(config).reduce((processed, [key, value]) => {
      if (typeof value === 'object') {
        // Check for null values.
        if (!value) {
          return processed;
        }
        if (value.hasOwnProperty('func')) {
          processed[key] = buildFunc(value);
        } else if (value.hasOwnProperty('regexp')) {
          processed[key] = buildRegexp(value);
        } else if (Array.isArray(value)) {
          processed[key] = processArray(value);
        } else {
          processed[key] = processConfig(value);
        }
      } else {
        processed[key] = value;
      }

      return processed;
    }, {});
  }

  /**
   * Set an id to a data-attribute for registering this element instance.
   *
   * @param {Element} element
   *   An element that should receive unique ID.
   *
   * @return {string}
   *   The id to use for this element.
   */
  const setElementId = (element) => {
    const id = Math.random().toString().slice(2, 9);
    element.setAttribute('data-ckeditor5-id', id);

    return id;
  };

  /**
   * Return a unique selector for the element.
   *
   * @param {HTMLElement} element
   *   An element which unique ID should be retrieved.
   *
   * @return {string}
   *   The id to use for this element.
   */
  const getElementId = (element) => element.getAttribute('data-ckeditor5-id');

  /**
   * Select CKEditor 5 plugin classes to include.
   *
   * Found in the CKEditor 5 global JavaScript object as {package.Class}.
   *
   * @param {Array} plugins
   *  List of package and Class name of plugins
   *
   * @return {Array}
   *   List of JavaScript Classes to add in the extraPlugins property of config.
   */
  function selectPlugins(plugins) {
    return plugins.map((pluginDefinition) => {
      const [build, name] = pluginDefinition.split('.');
      if (CKEditor5[build] && CKEditor5[build][name]) {
        return CKEditor5[build][name];
      }

      // eslint-disable-next-line no-console
      console.warn(`Failed to load ${build} - ${name}`);
      return null;
    });
  }

  /**
   * Process a group of CSS rules.
   *
   * @param {CSSGroupingRule} rulesGroup
   *  A complete stylesheet or a group of nested rules like @media.
   */
  function processRules(rulesGroup) {
    try {
      // eslint-disable-next-line no-use-before-define
      [...rulesGroup.cssRules].forEach(ckeditor5SelectorProcessing);
    } catch (e) {
      // eslint-disable-next-line no-console
      console.warn(
        `Stylesheet ${rulesGroup.href} not included in CKEditor reset due to the browser's CORS policy.`,
      );
    }
  }

  /**
   * Processes CSS rules dynamically to account for CKEditor 5 in off canvas.
   *
   * This is achieved by doing the following steps:
   * - Adding a donut scope to off canvas rules, so they don't apply within the
   *   editor element.
   * - Editor specific rules (i.e. those with .ck* selectors) are duplicated and
   *   prefixed with the off canvas selector to ensure they have higher
   *   specificity over the off canvas reset.
   *
   * The donut scope prevents off canvas rules from applying to the CKEditor 5
   * editor element. Transforms a:
   *  - #drupal-off-canvas strong
   * rule into:
   *  - #drupal-off-canvas strong:not([data-drupal-ck-style-fence] *)
   *
   * This means that the rule applies to all <strong> elements inside
   * #drupal-off-canvas, except for <strong> elements who have a with a parent
   * with the "data-drupal-ck-style-fence" attribute.
   *
   * For example:
   * <div id="drupal-off-canvas">
   *   <p>
   *     <strong>Off canvas reset</strong>
   *   </p>
   *   <p data-drupal-ck-style-fence>
   *     <!--
   *       this strong elements matches the `[data-drupal-ck-style-fence] *`
   *       selector and is excluded from the off canvas reset rule.
   *     -->
   *     <strong>Off canvas reset NOT applied.</strong>
   *   </p>
   * </div>
   *
   * The donut scope does not prevent CSS inheritance. There is CSS that resets
   * following properties to prevent inheritance: background, border,
   * box-sizing, margin, padding, position, text-decoration, transition,
   * vertical-align and word-wrap.
   *
   * All .ck* CSS rules are duplicated and prefixed with the off canvas selector
   * To ensure they have higher specificity and are not reset too aggressively.
   *
   * @param {CSSRule} rule
   *  A single CSS rule to be analysed and changed if necessary.
   */
  function ckeditor5SelectorProcessing(rule) {
    // Handle nested rules in @media, @support, etc.
    if (rule.cssRules) {
      processRules(rule);
    }
    if (!rule.selectorText) {
      return;
    }
    const offCanvasId = '#drupal-off-canvas';
    const CKEditorClass = '.ck';
    const styleFence = '[data-drupal-ck-style-fence]';
    if (
      rule.selectorText.includes(offCanvasId) ||
      rule.selectorText.includes(CKEditorClass)
    ) {
      rule.selectorText = rule.selectorText
        .split(/,/g)
        .map((selector) => {
          // Only change rules that include #drupal-off-canvas in the selector.
          if (selector.includes(offCanvasId)) {
            return `${selector.trim()}:not(${styleFence} *)`;
          }
          // Duplicate CKEditor 5 styles with higher specificity for proper
          // display in off canvas elements.
          if (selector.includes(CKEditorClass)) {
            // Return both rules to avoid replacing the existing rules.
            return [
              selector.trim(),
              selector
                .trim()
                .replace(
                  CKEditorClass,
                  `${offCanvasId} ${styleFence} ${CKEditorClass}`,
                ),
            ];
          }
          return selector;
        })
        .flat()
        .join(', ');
    }
  }

  /**
   * Adds CSS to ensure proper styling of CKEditor 5 inside off-canvas dialogs.
   *
   * @param {HTMLElement} element
   *   The element the editor is attached to.
   */
  function offCanvasCss(element) {
    const fenceName = 'data-drupal-ck-style-fence';
    const editor = Drupal.CKEditor5Instances.get(
      element.getAttribute('data-ckeditor5-id'),
    );
    editor.ui.view.element.setAttribute(fenceName, '');
    // Only proceed if the styles haven't been added yet.
    if (once('ckeditor5-off-canvas-reset', 'body').length) {
      // For all rules on the page, add the donut scope for
      // rules containing the #drupal-off-canvas selector.
      [...document.styleSheets].forEach(processRules);

      const prefix = `#drupal-off-canvas-wrapper [${fenceName}]`;
      // Additional styles that need to be explicity added in addition to the
      // prefixed versions of existing css in `existingCss`.
      const addedCss = [
        `${prefix} .ck.ck-content {display:block;min-height:5rem;}`,
        `${prefix} .ck.ck-content * {display:initial;background:initial;color:initial;padding:initial;}`,
        `${prefix} .ck.ck-content li {display:list-item}`,
        `${prefix} .ck.ck-content ol li {list-style-type: decimal}`,
        `${prefix} .ck[contenteditable], ${prefix} .ck[contenteditable] * {-webkit-user-modify: read-write;-moz-user-modify: read-write;}`,
      ];

      const prefixedCss = [...addedCss].join('\n');

      // Create a new style tag with the prefixed styles added above.
      const offCanvasCssStyle = document.createElement('style');
      offCanvasCssStyle.textContent = prefixedCss;
      offCanvasCssStyle.setAttribute('id', 'ckeditor5-off-canvas-reset');
      document.body.appendChild(offCanvasCssStyle);
    }
  }

  /**
   * Integration of CKEditor 5 with the Drupal editor API.
   *
   * @namespace
   *
   * @see Drupal.editorAttach
   */
  Drupal.editors.ckeditor5 = {
    /**
     * Editor attach callback.
     *
     * @param {HTMLElement} element
     *   The element to attach the editor to.
     * @param {string} format
     *   The text format for the editor.
     */
    attach(element, format) {
      const { editorClassic } = CKEditor5;
      const { toolbar, plugins, config, language } = format.editorSettings;
      const extraPlugins = selectPlugins(plugins);
      const pluginConfig = processConfig(config);
      const editorConfig = {
        extraPlugins,
        toolbar,
        ...pluginConfig,
        // Language settings have a conflict between the editor localization
        // settings and the "language" plugin.
        language: { ...pluginConfig.language, ...language },
      };
      // Set the id immediately so that it is available when onChange is called.
      const id = setElementId(element);
      const { ClassicEditor } = editorClassic;

      ClassicEditor.create(element, editorConfig)
        .then((editor) => {
          // Save a reference to the initialized instance.
          Drupal.CKEditor5Instances.set(id, editor);

          // CKEditor 4 had a feature to remove the required attribute
          // see: https://www.drupal.org/project/drupal/issues/1954968
          if (element.hasAttribute('required')) {
            required.add(id);
            element.removeAttribute('required');
          }

          // Integrate CKEditor 5 viewport offset with Drupal displace.
          // @see \Drupal\Tests\ckeditor5\FunctionalJavascript\CKEditor5ToolbarTest
          // @see https://ckeditor.com/docs/ckeditor5/latest/api/module_core_editor_editorui-EditorUI.html#member-viewportOffset
          $(document).on(
            `drupalViewportOffsetChange.ckeditor5.${id}`,
            (event, offsets) => {
              editor.ui.viewportOffset = offsets;
            },
          );

          editor.model.document.on('change:data', () => {
            const callback = callbacks.get(id);
            if (callback) {
              if (editor.plugins.has('SourceEditing')) {
                // If the change:data is being called while in source editing
                // mode, it means that the form is being submitted. To avoid
                // race conditions, in this case the callback gets called
                // without decorating the callback with debounce.
                // @see https://www.drupal.org/i/3229174
                // @see Drupal.editorDetach
                if (editor.plugins.get('SourceEditing').isSourceEditingMode) {
                  callback();
                  return;
                }
              }

              // Marks the field as changed.
              // @see Drupal.editorAttach
              debounce(callback, 400)();
            }
          });

          const isOffCanvas = element.closest('#drupal-off-canvas');

          if (isOffCanvas) {
            offCanvasCss(element);
          }
        })
        .catch((error) => {
          // eslint-disable-next-line no-console
          console.info(
            'Debugging can be done with an unminified version of CKEditor by installing from the source file. Consult documentation at https://www.drupal.org/node/3258901',
          );
          // eslint-disable-next-line no-console
          console.error(error);
        });
    },

    /**
     * Editor detach callback.
     *
     * @param {HTMLElement} element
     *   The element to detach the editor from.
     * @param {string} format
     *   The text format used for the editor.
     * @param {string} trigger
     *   The event trigger for the detach.
     */
    detach(element, format, trigger) {
      const id = getElementId(element);
      const editor = Drupal.CKEditor5Instances.get(id);
      if (!editor) {
        return;
      }

      $(document).off(`drupalViewportOffsetChange.ckeditor5.${id}`);

      if (trigger === 'serialize') {
        editor.updateSourceElement();
      } else {
        element.removeAttribute('contentEditable');
        // Return the promise to allow external code to queue code to
        // execute after the destroy is complete.
        return editor
          .destroy()
          .then(() => {
            // Clean up stored references.
            Drupal.CKEditor5Instances.delete(id);
            callbacks.delete(id);
            if (required.has(id)) {
              element.setAttribute('required', 'required');
              required.delete(id);
            }
          })
          .catch((error) => {
            // eslint-disable-next-line no-console
            console.error(error);
          });
      }
    },

    /**
     * Registers a callback which CKEditor 5 will call on change:data event.
     *
     * @param {HTMLElement} element
     *   The element where the change occurred.
     * @param {function} callback
     *   Callback called with the value of the editor.
     */
    onChange(element, callback) {
      callbacks.set(getElementId(element), callback);
    },

    /**
     * Attaches an inline editor to a DOM element.
     *
     * @param {HTMLElement} element
     *   The element to attach the editor to.
     * @param {object} format
     *   The text format used in the editor.
     * @param {string} [mainToolbarId]
     *   The id attribute for the main editor toolbar, if any.
     */
    attachInlineEditor(element, format, mainToolbarId) {
      const { editorDecoupled } = CKEditor5;
      const {
        toolbar,
        plugins,
        config: pluginConfig,
        language,
      } = format.editorSettings;
      const extraPlugins = selectPlugins(plugins);
      const config = {
        extraPlugins,
        toolbar,
        language,
        ...processConfig(pluginConfig),
      };
      const id = setElementId(element);
      const { DecoupledEditor } = editorDecoupled;

      DecoupledEditor.create(element, config)
        .then((editor) => {
          Drupal.CKEditor5Instances.set(id, editor);
          const toolbar = document.getElementById(mainToolbarId);
          toolbar.appendChild(editor.ui.view.toolbar.element);
          editor.model.document.on('change:data', () => {
            const callback = callbacks.get(id);
            if (callback) {
              // Allow modules to update EditorModel by providing the current data.
              debounce(callback, 400)(editor.getData());
            }
          });
        })
        .catch((error) => {
          // eslint-disable-next-line no-console
          console.error(error);
        });
    },
  };

  /**
   * Public API for Drupal CKEditor 5 integration.
   *
   * @namespace
   */
  Drupal.ckeditor5 = {
    /**
     * Variable storing the current dialog's save callback.
     *
     * @type {?function}
     */
    saveCallback: null,

    /**
     * Open a dialog for a Drupal-based plugin.
     *
     * This dynamically loads jQuery UI (if necessary) using the Drupal AJAX
     * framework, then opens a dialog at the specified Drupal path.
     *
     * @param {string} url
     *   The URL that contains the contents of the dialog.
     * @param {function} saveCallback
     *   A function to be called upon saving the dialog.
     * @param {object} dialogSettings
     *   An object containing settings to be passed to the jQuery UI.
     */
    openDialog(url, saveCallback, dialogSettings) {
      // Add a consistent dialog class.
      const classes = dialogSettings.dialogClass
        ? dialogSettings.dialogClass.split(' ')
        : [];
      classes.push('ui-dialog--narrow');
      dialogSettings.dialogClass = classes.join(' ');
      dialogSettings.autoResize =
        window.matchMedia('(min-width: 600px)').matches;
      dialogSettings.width = 'auto';

      const ckeditorAjaxDialog = Drupal.ajax({
        dialog: dialogSettings,
        dialogType: 'modal',
        selector: '.ckeditor5-dialog-loading-link',
        url,
        progress: { type: 'fullscreen' },
        submit: {
          editor_object: {},
        },
      });
      ckeditorAjaxDialog.execute();

      // Store the save callback to be executed when this dialog is closed.
      Drupal.ckeditor5.saveCallback = saveCallback;
    },
  };

  // Redirect on hash change when the original hash has an associated CKEditor 5.
  function redirectTextareaFragmentToCKEditor5Instance() {
    const hash = window.location.hash.substr(1);
    const element = document.getElementById(hash);
    if (element) {
      const editorID = getElementId(element);
      const editor = Drupal.CKEditor5Instances.get(editorID);
      if (editor) {
        // Give the CKEditor 5 instance an ID.
        editor.sourceElement.nextElementSibling.setAttribute(
          'id',
          `cke_${hash}`,
        );
        window.location.replace(`#cke_${hash}`);
      }
    }
  }

  $(window).on(
    'hashchange.ckeditor',
    redirectTextareaFragmentToCKEditor5Instance,
  );

  // Respond to new dialogs that are opened by CKEditor, closing the AJAX loader.
  $(window).on('dialog:beforecreate', () => {
    $('.ckeditor5-dialog-loading').animate(
      { top: '-40px' },
      function removeDialogLoading() {
        $(this).remove();
      },
    );
  });

  // Respond to dialogs that are saved, sending data back to CKEditor.
  $(window).on('editor:dialogsave', (e, values) => {
    if (Drupal.ckeditor5.saveCallback) {
      Drupal.ckeditor5.saveCallback(values);
    }
  });

  // Respond to dialogs that are closed, removing the current save handler.
  $(window).on('dialog:afterclose', () => {
    if (Drupal.ckeditor5.saveCallback) {
      Drupal.ckeditor5.saveCallback = null;
    }
  });
})(Drupal, Drupal.debounce, CKEditor5, jQuery, once);
