discourse/app/assets/javascripts/discourse/controllers/quote-button.js.es6

import DiscourseController from 'discourse/controllers/controller';
import loadScript from 'discourse/lib/load-script';

export default DiscourseController.extend({
  needs: ['topic', 'composer'],

  _loadSanitizer: function() {
    loadScript('defer/html-sanitizer-bundle');
  }.on('init'),

  //  If the buffer is cleared, clear out other state (post)
  bufferChanged: function() {
    if (this.blank('buffer')) this.set('post', null);
  }.observes('buffer'),

  // Save the currently selected text and displays the
  //  "quote reply" button
  selectText(postId) {
    // anonymous users cannot "quote-reply"
    if (!this.currentUser) return;

    // don't display the "quote-reply" button if we can't reply
    const topicDetails = this.get('controllers.topic.model.details');
    if (!(topicDetails.get('can_reply_as_new_topic') || topicDetails.get('can_create_post'))) {
      return;
    }

    const selection = window.getSelection();
    // no selections
    if (selection.isCollapsed) return;

    // retrieve the selected range
    const range = selection.getRangeAt(0),
          cloned = range.cloneRange(),
          $ancestor = $(range.commonAncestorContainer);

    if ($ancestor.closest('.cooked').length === 0) {
      this.set('buffer', '');
      return;
    }

    const selectedText = Discourse.Utilities.selectedText();
    if (this.get('buffer') === selectedText) return;

    // we need to retrieve the post data from the posts collection in the topic controller
    const postStream = this.get('controllers.topic.model.postStream');
    this.set('post', postStream.findLoadedPost(postId));
    this.set('buffer', selectedText);

    // create a marker element
    const markerElement = document.createElement("span");
    // containing a single invisible character
    markerElement.appendChild(document.createTextNode("\u{feff}"));

    // collapse the range at the beginning/end of the selection
    range.collapse(!Discourse.Mobile.isMobileDevice);
    // and insert it at the start of our selection range
    range.insertNode(markerElement);

    // retrieve the position of the marker
    const markerOffset = $(markerElement).offset(),
          $quoteButton = $('.quote-button');

    // remove the marker
    markerElement.parentNode.removeChild(markerElement);

    // work around Chrome that would sometimes lose the selection
    const sel = window.getSelection();
    sel.removeAllRanges();
    sel.addRange(cloned);

    // move the quote button above the marker
    Em.run.schedule('afterRender', function() {
      let topOff = markerOffset.top;
      let leftOff = markerOffset.left;

      if (Discourse.Mobile.isMobileDevice) {
        topOff = topOff + 20;
        leftOff = Math.min(leftOff + 10, $(window).width() - $quoteButton.outerWidth());
      } else {
        topOff = topOff - $quoteButton.outerHeight() - 5;
      }

      $quoteButton.offset({ top: topOff, left: leftOff });
    });
  },

  quoteText() {

    const post = this.get('post');

    // If we can't create a post, delegate to reply as new topic
    if (!this.get('controllers.topic.model.details.can_create_post')) {
      this.get('controllers.topic').send('replyAsNewTopic', post);
      return;
    }

    const composerController = this.get('controllers.composer');
    const composerOpts = {
      action: Discourse.Composer.REPLY,
      draftKey: this.get('post.topic.draft_key')
    };

    if(post.get('post_number') === 1) {
      composerOpts.topic = post.get("topic");
    } else {
      composerOpts.post = post;
    }

    // If the composer is associated with a different post, we don't change it.
    const composerPost = composerController.get('content.post');
    if (composerPost && (composerPost.get('id') !== this.get('post.id'))) {
      composerOpts.post = composerPost;
    }

    const buffer = this.get('buffer');
    const quotedText = Discourse.Quote.build(post, buffer);
    composerOpts.quote = quotedText;
    if (composerController.get('content.viewOpen') || composerController.get('content.viewDraft')) {
      composerController.appendBlockAtCursor(quotedText.trim());
    } else {
      composerController.open(composerOpts);
    }
    this.set('buffer', '');
    return false;
  },

  deselectText() {
    // clear selected text
    window.getSelection().removeAllRanges();
    // clean up the buffer
    this.set('buffer', '');
  }

});