instrumental/app/javascript/mastodon/components/status_content.js

import React from 'react';
import ImmutablePropTypes from 'react-immutable-proptypes';
import PropTypes from 'prop-types';
import { isRtl } from '../rtl';
import { FormattedMessage } from 'react-intl';
import Permalink from './permalink';
import classnames from 'classnames';
import PollContainer from 'mastodon/containers/poll_container';
import Icon from 'mastodon/components/icon';
import { autoPlayGif } from 'mastodon/initial_state';
import { decode as decodeIDNA } from 'mastodon/utils/idna';

const MAX_HEIGHT = 642; // 20px * 32 (+ 2px padding at the top)

// Regex matching what "looks like a link", that is, something that starts with
// an optional "http://" or "https://" scheme and then what could look like a
// domain main, that is, at least two sequences of characters not including spaces
// and separated by "." or an homoglyph. The idea is not to match valid URLs or
// domain names, but what could be confused for a valid URL or domain name,
// especially to the untrained eye.

const h_confusables = 'h\u13c2\u1d58d\u1d4f1\u1d691\u0068\uff48\u1d525\u210e\u1d489\u1d629\u0570\u1d4bd\u1d65d\u1d421\u1d5c1\u1d5f5\u04bb\u1d559';
const t_confusables = 't\u1d42d\u1d5cd\u1d531\u1d565\u1d4c9\u1d669\u1d4fd\u1d69d\u0074\u1d461\u1d601\u1d495\u1d635\u1d599';
const p_confusables = 'p\u0440\u03c1\u1d52d\u1d631\u1d665\u1d429\uff50\u1d6e0\u1d45d\u1d561\u1d595\u1d71a\u1d699\u1d78e\u2ca3\u1d754\u1d6d2\u1d491\u1d7c8\u1d746\u1d4c5\u1d70c\u1d5c9\u0070\u1d780\u03f1\u1d5fd\u2374\u1d7ba\u1d4f9';
const s_confusables = 's\u1d530\u118c1\u1d494\u1d634\u1d4c8\u1d668\uabaa\u1d42c\u1d5cc\u1d460\u1d600\ua731\u0073\uff53\u1d564\u0455\u1d598\u1d4fc\u1d69c\u10448\u01bd';
const column_confusables = ':\u0903\u0a83\u0703\u1803\u05c3\u0704\u0589\u1809\ua789\u16ec\ufe30\u02d0\u2236\u02f8\u003a\uff1a\u205a\ua4fd';
const slash_confusables = '/\u2041\u2f03\u2044\u2cc6\u27cb\u30ce\u002f\u2571\u31d3\u3033\u1735\u2215\u29f8\u1d23a\u4e3f';
const dot_confusables = '.\u002e\u0660\u06f0\u0701\u0702\u2024\ua4f8\ua60e\u10a50\u1d16d';

const linkRegex = new RegExp(`^\\s*(([${h_confusables}][${t_confusables}][${t_confusables}][${p_confusables}][${s_confusables}]?[${column_confusables}][${slash_confusables}][${slash_confusables}]))?[^:/\\n ]+([${dot_confusables}][^:/\\n ]+)+`);

const isLinkMisleading = (link) => {
  let linkTextParts = [];

  // Reconstruct visible text, as we do not have much control over how links
  // from remote software look, and we can't rely on `innerText` because the
  // `invisible` class does not set `display` to `none`.

  const walk = (node) => {
    switch (node.nodeType) {
    case Node.TEXT_NODE:
      linkTextParts.push(node.textContent);
      break;
    case Node.ELEMENT_NODE:
      if (node.classList.contains('invisible')) return;
      const children = node.childNodes;
      for (let i = 0; i < children.length; i++) {
        walk(children[i]);
      }
      break;
    }
  };

  walk(link);

  const linkText = linkTextParts.join('');
  const targetURL = new URL(link.href);

  // The following may not work with international domain names
  if (linkText === targetURL.origin || linkText === targetURL.host || 'www.' + linkText === targetURL.host || linkText.startsWith(targetURL.origin + '/') || linkText.startsWith(targetURL.host + '/')) {
    return false;
  }

  // The link hasn't been recognized, maybe it features an international domain name
  const hostname = decodeIDNA(targetURL.hostname);
  const host = targetURL.host.replace(targetURL.hostname, hostname);
  const origin = targetURL.origin.replace(targetURL.host, host);
  if (linkText === origin || linkText === host || linkText.startsWith(origin + '/') || linkText.startsWith(host + '/')) {
    return false;
  }

  // If the link text looks like an URL or auto-generated link, it is misleading
  return linkRegex.test(linkText);
};

export default class StatusContent extends React.PureComponent {

  static contextTypes = {
    router: PropTypes.object,
  };

  static propTypes = {
    status: ImmutablePropTypes.map.isRequired,
    expanded: PropTypes.bool,
    onExpandedToggle: PropTypes.func,
    onClick: PropTypes.func,
    collapsable: PropTypes.bool,
  };

  state = {
    hidden: true,
    collapsed: null, //  `collapsed: null` indicates that an element doesn't need collapsing, while `true` or `false` indicates that it does (and is/isn't).
  };

  _updateStatusLinks () {
    const node = this.node;

    if (!node) {
      return;
    }

    const links = node.querySelectorAll('a');

    for (var i = 0; i < links.length; ++i) {
      let link = links[i];
      if (link.classList.contains('status-link')) {
        continue;
      }
      link.classList.add('status-link');

      let mention = this.props.status.get('mentions').find(item => link.href === item.get('url'));

      if (mention) {
        link.addEventListener('click', this.onMentionClick.bind(this, mention), false);
        link.setAttribute('title', mention.get('acct'));
      } else if (link.textContent[0] === '#' || (link.previousSibling && link.previousSibling.textContent && link.previousSibling.textContent[link.previousSibling.textContent.length - 1] === '#')) {
        link.addEventListener('click', this.onHashtagClick.bind(this, link.text), false);
      } else {
        link.setAttribute('title', link.href);
        link.classList.add('unhandled-link');

        if (isLinkMisleading(link)) {
          while (link.firstChild) {
            link.removeChild(link.firstChild);
          }

          const prefix = (link.href.match(/https?:\/\/(www\.)?/) || [''])[0];
          const text   = link.href.substr(prefix.length, 30);
          const suffix = link.href.substr(prefix.length + 30);
          const cutoff = !!suffix;

          const prefixTag = document.createElement('span');
          prefixTag.classList.add('invisible');
          prefixTag.textContent = prefix;
          link.appendChild(prefixTag);

          const textTag = document.createElement('span');
          if (cutoff) {
            textTag.classList.add('ellipsis');
          }
          textTag.textContent = text;
          link.appendChild(textTag);

          const suffixTag = document.createElement('span');
          suffixTag.classList.add('invisible');
          suffixTag.textContent = suffix;
          link.appendChild(suffixTag);
        }
      }

      link.setAttribute('target', '_blank');
      link.setAttribute('rel', 'noopener');
    }

    if (
      this.props.collapsable
      && this.props.onClick
      && this.state.collapsed === null
      && node.clientHeight > MAX_HEIGHT
      && this.props.status.get('spoiler_text').length === 0
    ) {
      this.setState({ collapsed: true });
    }
  }

  _updateStatusEmojis () {
    const node = this.node;

    if (!node || autoPlayGif) {
      return;
    }

    const emojis = node.querySelectorAll('.custom-emoji');

    for (var i = 0; i < emojis.length; i++) {
      let emoji = emojis[i];
      if (emoji.classList.contains('status-emoji')) {
        continue;
      }
      emoji.classList.add('status-emoji');

      emoji.addEventListener('mouseenter', this.handleEmojiMouseEnter, false);
      emoji.addEventListener('mouseleave', this.handleEmojiMouseLeave, false);
    }
  }

  componentDidMount () {
    this._updateStatusLinks();
    this._updateStatusEmojis();
  }

  componentDidUpdate () {
    this._updateStatusLinks();
    this._updateStatusEmojis();
  }

  onMentionClick = (mention, e) => {
    if (this.context.router && e.button === 0 && !(e.ctrlKey || e.metaKey)) {
      e.preventDefault();
      this.context.router.history.push(`/accounts/${mention.get('id')}`);
    }
  }

  onHashtagClick = (hashtag, e) => {
    hashtag = hashtag.replace(/^#/, '').toLowerCase();

    if (this.context.router && e.button === 0 && !(e.ctrlKey || e.metaKey)) {
      e.preventDefault();
      this.context.router.history.push(`/timelines/tag/${hashtag}`);
    }
  }

  handleEmojiMouseEnter = ({ target }) => {
    target.src = target.getAttribute('data-original');
  }

  handleEmojiMouseLeave = ({ target }) => {
    target.src = target.getAttribute('data-static');
  }

  handleMouseDown = (e) => {
    this.startXY = [e.clientX, e.clientY];
  }

  handleMouseUp = (e) => {
    if (!this.startXY) {
      return;
    }

    const [ startX, startY ] = this.startXY;
    const [ deltaX, deltaY ] = [Math.abs(e.clientX - startX), Math.abs(e.clientY - startY)];

    let element = e.target;
    while (element) {
      if (element.localName === 'button' || element.localName === 'a' || element.localName === 'label') {
        return;
      }
      element = element.parentNode;
    }

    if (deltaX + deltaY < 5 && e.button === 0 && this.props.onClick) {
      this.props.onClick();
    }

    this.startXY = null;
  }

  handleSpoilerClick = (e) => {
    e.preventDefault();

    if (this.props.onExpandedToggle) {
      // The parent manages the state
      this.props.onExpandedToggle();
    } else {
      this.setState({ hidden: !this.state.hidden });
    }
  }

  handleCollapsedClick = (e) => {
    e.preventDefault();
    this.setState({ collapsed: !this.state.collapsed });
  }

  setRef = (c) => {
    this.node = c;
  }

  render () {
    const { status } = this.props;

    if (status.get('content').length === 0) {
      return null;
    }

    const hidden = this.props.onExpandedToggle ? !this.props.expanded : this.state.hidden;

    const content = { __html: status.get('contentHtml') };
    const spoilerContent = { __html: status.get('spoilerHtml') };
    const directionStyle = { direction: 'ltr' };
    const classNames = classnames('status__content', {
      'status__content--with-action': this.props.onClick && this.context.router,
      'status__content--with-spoiler': status.get('spoiler_text').length > 0,
      'status__content--collapsed': this.state.collapsed === true,
    });

    if (isRtl(status.get('search_index'))) {
      directionStyle.direction = 'rtl';
    }

    const readMoreButton = (
      <button className='status__content__read-more-button' onClick={this.props.onClick} key='read-more'>
        <FormattedMessage id='status.read_more' defaultMessage='Read more' /><Icon id='angle-right' fixedWidth />
      </button>
    );

    if (status.get('spoiler_text').length > 0) {
      let mentionsPlaceholder = '';

      const mentionLinks = status.get('mentions').map(item => (
        <Permalink to={`/accounts/${item.get('id')}`} href={item.get('url')} key={item.get('id')} className='mention'>
          @<span>{item.get('username')}</span>
        </Permalink>
      )).reduce((aggregate, item) => [...aggregate, item, ' '], []);

      const toggleText = hidden ? <FormattedMessage id='status.show_more' defaultMessage='Show more' /> : <FormattedMessage id='status.show_less' defaultMessage='Show less' />;

      if (hidden) {
        mentionsPlaceholder = <div>{mentionLinks}</div>;
      }

      return (
        <div className={classNames} ref={this.setRef} tabIndex='0' style={directionStyle} onMouseDown={this.handleMouseDown} onMouseUp={this.handleMouseUp}>
          <p style={{ marginBottom: hidden && status.get('mentions').isEmpty() ? '0px' : null }}>
            <span dangerouslySetInnerHTML={spoilerContent} lang={status.get('language')} />
            {' '}
            <button tabIndex='0' className={`status__content__spoiler-link ${hidden ? 'status__content__spoiler-link--show-more' : 'status__content__spoiler-link--show-less'}`} onClick={this.handleSpoilerClick}>{toggleText}</button>
          </p>

          {mentionsPlaceholder}

          <div tabIndex={!hidden ? 0 : null} className={`status__content__text ${!hidden ? 'status__content__text--visible' : ''}`} style={directionStyle} dangerouslySetInnerHTML={content} lang={status.get('language')} />

          {!hidden && !!status.get('poll') && <PollContainer pollId={status.get('poll')} />}
        </div>
      );
    } else if (this.props.onClick) {
      return (
        <div className={classNames} ref={this.setRef} tabIndex='0' style={directionStyle} onMouseDown={this.handleMouseDown} onMouseUp={this.handleMouseUp}>
          <div className='status__content__text status__content__text--visible' style={directionStyle} dangerouslySetInnerHTML={content} lang={status.get('language')} />

          {!!this.state.collapsed && readMoreButton}

          {!!status.get('poll') && <PollContainer pollId={status.get('poll')} />}
        </div>
      );
    } else {
      return (
        <div className={classNames} ref={this.setRef} tabIndex='0' style={directionStyle}>
          <div className='status__content__text status__content__text--visible' style={directionStyle} dangerouslySetInnerHTML={content} lang={status.get('language')} />

          {!!status.get('poll') && <PollContainer pollId={status.get('poll')} />}
        </div>
      );
    }
  }

}