content: import React from 'react';
  import ReactSwipeableViews from 'react-swipeable-views';
  import ImmutablePropTypes from 'react-immutable-proptypes';
  import PropTypes from 'prop-types';
  import Video from 'mastodon/features/video';
  import classNames from 'classnames';
  import { defineMessages, injectIntl, FormattedMessage } from 'react-intl';
  import IconButton from 'mastodon/components/icon_button';
  import ImmutablePureComponent from 'react-immutable-pure-component';
  import ImageLoader from './image_loader';
  import Icon from 'mastodon/components/icon';
  import GIFV from 'mastodon/components/gifv';
  
  const messages = defineMessages({
    close: { id: 'lightbox.close', defaultMessage: 'Close' },
    previous: { id: 'lightbox.previous', defaultMessage: 'Previous' },
    next: { id: 'lightbox.next', defaultMessage: 'Next' },
  });
  
  export const previewState = 'previewMediaModal';
  
  export default @injectIntl
  class MediaModal extends ImmutablePureComponent {
  
    static propTypes = {
      media: ImmutablePropTypes.list.isRequired,
      status: ImmutablePropTypes.map,
      index: PropTypes.number.isRequired,
      onClose: PropTypes.func.isRequired,
      intl: PropTypes.object.isRequired,
    };
  
    static contextTypes = {
      router: PropTypes.object,
    };
  
    state = {
      index: null,
      navigationHidden: false,
    };
  
    handleSwipe = (index) => {
      this.setState({ index: index % this.props.media.size });
    }
  
    handleNextClick = () => {
      this.setState({ index: (this.getIndex() + 1) % this.props.media.size });
    }
  
    handlePrevClick = () => {
      this.setState({ index: (this.props.media.size + this.getIndex() - 1) % this.props.media.size });
    }
  
    handleChangeIndex = (e) => {
      const index = Number(e.currentTarget.getAttribute('data-index'));
      this.setState({ index: index % this.props.media.size });
    }
  
    handleKeyDown = (e) => {
      switch(e.key) {
      case 'ArrowLeft':
        this.handlePrevClick();
        e.preventDefault();
        e.stopPropagation();
        break;
      case 'ArrowRight':
        this.handleNextClick();
        e.preventDefault();
        e.stopPropagation();
        break;
      }
    }
  
    componentDidMount () {
      window.addEventListener('keydown', this.handleKeyDown, false);
  
      if (this.context.router) {
        const history = this.context.router.history;
  
        history.push(history.location.pathname, previewState);
  
        this.unlistenHistory = history.listen(() => {
          this.props.onClose();
        });
      }
    }
  
    componentWillUnmount () {
      window.removeEventListener('keydown', this.handleKeyDown);
  
      if (this.context.router) {
        this.unlistenHistory();
  
        if (this.context.router.history.location.state === previewState) {
          this.context.router.history.goBack();
        }
      }
    }
  
    getIndex () {
      return this.state.index !== null ? this.state.index : this.props.index;
    }
  
    toggleNavigation = () => {
      this.setState(prevState => ({
        navigationHidden: !prevState.navigationHidden,
      }));
    };
  
    handleStatusClick = e => {
      if (e.button === 0 && !(e.ctrlKey || e.metaKey)) {
        e.preventDefault();
        this.context.router.history.push(`/statuses/${this.props.status.get('id')}`);
      }
    }
  
    render () {
      const { media, status, intl, onClose } = this.props;
      const { navigationHidden } = this.state;
  
      const index = this.getIndex();
      let pagination = [];
  
      const leftNav  = media.size > 1 && <button tabIndex='0' className='media-modal__nav media-modal__nav--left' onClick={this.handlePrevClick} aria-label={intl.formatMessage(messages.previous)}><Icon id='chevron-left' fixedWidth /></button>;
      const rightNav = media.size > 1 && <button tabIndex='0' className='media-modal__nav  media-modal__nav--right' onClick={this.handleNextClick} aria-label={intl.formatMessage(messages.next)}><Icon id='chevron-right' fixedWidth /></button>;
  
      if (media.size > 1) {
        pagination = media.map((item, i) => {
          const classes = ['media-modal__button'];
          if (i === index) {
            classes.push('media-modal__button--active');
          }
          return (<li className='media-modal__page-dot' key={i}><button tabIndex='0' className={classes.join(' ')} onClick={this.handleChangeIndex} data-index={i}>{i + 1}</button></li>);
        });
      }
  
      const content = media.map((image) => {
        const width  = image.getIn(['meta', 'original', 'width']) || null;
        const height = image.getIn(['meta', 'original', 'height']) || null;
  
        if (image.get('type') === 'image') {
          return (
            <ImageLoader
              previewSrc={image.get('preview_url')}
              src={image.get('url')}
              width={width}
              height={height}
              alt={image.get('description')}
              key={image.get('url')}
              onClick={this.toggleNavigation}
            />
          );
        } else if (image.get('type') === 'video') {
          const { time } = this.props;
  
          return (
            <Video
              preview={image.get('preview_url')}
              blurhash={image.get('blurhash')}
              src={image.get('url')}
              width={image.get('width')}
              height={image.get('height')}
              startTime={time || 0}
              onCloseVideo={onClose}
              detailed
              alt={image.get('description')}
              key={image.get('url')}
            />
          );
        } else if (image.get('type') === 'gifv') {
          return (
            <GIFV
              src={image.get('url')}
              width={width}
              height={height}
              key={image.get('preview_url')}
              alt={image.get('description')}
              onClick={this.toggleNavigation}
            />
          );
        }
  
        return null;
      }).toArray();
  
      // you can't use 100vh, because the viewport height is taller
      // than the visible part of the document in some mobile
      // browsers when it's address bar is visible.
      // https://developers.google.com/web/updates/2016/12/url-bar-resizing
      const swipeableViewsStyle = {
        width: '100%',
        height: '100%',
      };
  
      const containerStyle = {
        alignItems: 'center', // center vertically
      };
  
      const navigationClassName = classNames('media-modal__navigation', {
        'media-modal__navigation--hidden': navigationHidden,
      });
  
      return (
        <div className='modal-root__modal media-modal'>
          <div
            className='media-modal__closer'
            role='presentation'
            onClick={onClose}
          >
            <ReactSwipeableViews
              style={swipeableViewsStyle}
              containerStyle={containerStyle}
              onChangeIndex={this.handleSwipe}
              onSwitching={this.handleSwitching}
              index={index}
            >
              {content}
            </ReactSwipeableViews>
          </div>
  
          <div className={navigationClassName}>
            <IconButton className='media-modal__close' title={intl.formatMessage(messages.close)} icon='times' onClick={onClose} size={40} />
  
            {leftNav}
            {rightNav}
  
            {status && (
              <div className={classNames('media-modal__meta', { 'media-modal__meta--shifted': media.size > 1 })}>
                <a href={status.get('url')} onClick={this.handleStatusClick}><Icon id='comments' /> <FormattedMessage id='lightbox.view_context' defaultMessage='View context' /></a>
              </div>
            )}
  
            <ul className='media-modal__pagination'>
              {pagination}
            </ul>
          </div>
        </div>
      );
    }
  
  }
  