Ghost/ghost/admin/app/components/modal-post-history.js

import Component from '@glimmer/component';
import RestoreRevisionModal from '../components/modals/restore-revision';
import diff from 'node-htmldiff';
import {action} from '@ember/object';
import {inject as service} from '@ember/service';
import {tracked} from '@glimmer/tracking';

function checkFinishedRendering(element, done) {
    let last = element.innerHTML;
    function check() {
        let html = element.innerHTML;
        if (html === last) {
            done();
        } else {
            last = html;
            setTimeout(check, 50);
        }
    }

    setTimeout(check, 50);
}

export default class ModalPostHistory extends Component {
  @service notifications;
  @service modals;
  @service feature;
  constructor() {
      super(...arguments);
      this.post = this.args.model.post;
      this.editorAPI = this.args.model.editorAPI;
      this.toggleSettingsMenu = this.args.toggleSettingsMenu;
  }
  @tracked selectedHTML = `<h1>loading...</h1>`;
  @tracked diffHtml = null;
  @tracked showDifferences = this.feature.get('postDiffing'); // should default to true in future
  @tracked selectedRevisionIndex = 0;

  get selectedRevision() {
      return this.revisionList[this.selectedRevisionIndex];
  }

  get comparisonRevision() {
      return this.revisionList[this.selectedRevisionIndex + 1] || this.selectedRevision;
  }

  get previousTitle() {
      return this.comparisonRevision.title || this.post.get('title');
  }

  get currentTitle() {
      return this.selectedRevision.title || this.post.get('title');
  }

  get revisionList() {
      return this.post.get('postRevisions').toArray().reverse().map((revision, index) => {
          return {
              lexical: revision.get('lexical'),
              selected: index === this.selectedRevisionIndex,
              latest: index === 0,
              createdAt: revision.get('createdAt'),
              title: revision.get('title'),
              author: {
                  name: revision.get('author.name')
              }
          };
      });
  }

  @action
  onInsert() {
      this.updateDiff();
  }

  @action
  handleClick(index) {
      this.selectedRevisionIndex = index;
      this.updateDiff();
  }

  @action
  registerSelectedEditorApi(api) {
      this.selectedEditor = api;
  }

  @action
  registerComparisonEditorApi(api) {
      this.comparisonEditor = api;
  }

  @action
  closeModal() {
      this.args.closeModal();
  }

  stripInitialPlaceholder(html) {
      //TODO: we should probably add a data attribute to Koenig and grab that instead
      const regex = /<div\b[^>]*>(\s*Begin writing your post\.\.\.\s*)<\/div>/i;
      const strippedHtml = html.replace(regex, '');
      return strippedHtml;
  }

  @action
  restoreRevision(index) {
      const revision = this.revisionList[index];
      this.modals.open(RestoreRevisionModal, {
          post: this.post,
          revision,
          updateTitle: () => {
              this.post.titleScratch = revision.title;
          },
          updateEditor: () => {
              const state = this.editorAPI.editorInstance.parseEditorState(revision.lexical);
              this.editorAPI.editorInstance.setEditorState(state);
          },
          closePostHistoryModal: () => {
              this.closeModal();
              this.toggleSettingsMenu();
          }
      });
  }

  @action
  toggleDifferences() {
      this.showDifferences = !this.showDifferences;
  }

  get cardConfig() {
      return {
          post: this.args.model
      };
  }

  calculateHTMLDiff(previousHTML, currentHTML) {
      const result = diff(previousHTML, currentHTML);
      const div = document.createElement('div');
      div.innerHTML = result;
      this.diffCards(div);
      return div.innerHTML;
  }

  diffCards(div) {
      const cards = div.querySelectorAll('div[data-kg-card]');
      for (const card of cards) {
          const hasChanges = !!card.querySelectorAll('del').length || !!card.querySelectorAll('ins').length;
          if (hasChanges) {
              const delCard = card.cloneNode(true);
              const insCard = card.cloneNode(true);

              const ins = document.createElement('ins');
              const del = document.createElement('del');

              delCard.querySelectorAll('ins').forEach((el) => {
                  el.remove();
              });
              insCard.querySelectorAll('del').forEach((el) => {
                  el.remove();
              });
              delCard.querySelectorAll('del').forEach((el) => {
                  el.parentNode.appendChild(el.firstChild);
                  el.remove();
              });
              insCard.querySelectorAll('ins').forEach((el) => {
                  el.parentNode.appendChild(el.firstChild);
                  el.remove();
              });

              ins.appendChild(insCard);
              del.appendChild(delCard);

              card.parentNode.appendChild(del);
              card.parentNode.appendChild(ins);
              card.remove();
          }
      }
  }

  updateDiff() {
      if (this.comparisonEditor && this.selectedEditor) {
          let comparisonState = this.comparisonEditor.editorInstance.parseEditorState(this.comparisonRevision.lexical);
          let selectedState = this.selectedEditor.editorInstance.parseEditorState(this.selectedRevision.lexical);

          this.comparisonEditor.editorInstance.setEditorState(comparisonState);
          this.selectedEditor.editorInstance.setEditorState(selectedState);
      }

      let previous = document.querySelector('.gh-post-history-hidden-lexical.previous');
      let current = document.querySelector('.gh-post-history-hidden-lexical.current');

      let previousDone = false;
      let currentDone = false;

      let updateIfBothDone = () => {
          if (previousDone && currentDone) {
              this.diffHtml = this.calculateHTMLDiff(this.stripInitialPlaceholder(previous.innerHTML), this.stripInitialPlaceholder(current.innerHTML));
              this.selectedHTML = this.stripInitialPlaceholder(current.innerHTML);
          }
      };

      checkFinishedRendering(previous, () => {
          previous.querySelectorAll('[contenteditable]').forEach((el) => {
              el.setAttribute('contenteditable', false);
          });
          previousDone = true;
          updateIfBothDone();
      });

      checkFinishedRendering(current, () => {
          current.querySelectorAll('[contenteditable]').forEach((el) => {
              el.setAttribute('contenteditable', false);
          });
          currentDone = true;
          updateIfBothDone();
      });
  }
}