content: import React from 'react';
  import PropTypes from 'prop-types';
  
  export default class ModalRoot extends React.PureComponent {
  
    static propTypes = {
      children: PropTypes.node,
      onClose: PropTypes.func.isRequired,
    };
  
    state = {
      revealed: !!this.props.children,
    };
  
    activeElement = this.state.revealed ? document.activeElement : null;
  
    handleKeyUp = (e) => {
      if ((e.key === 'Escape' || e.key === 'Esc' || e.keyCode === 27)
           && !!this.props.children) {
        this.props.onClose();
      }
    }
  
    handleKeyDown = (e) => {
      if (e.key === 'Tab') {
        const focusable = Array.from(this.node.querySelectorAll('button:not([disabled]), [href], input:not([disabled]), select:not([disabled]), textarea:not([disabled]), [tabindex]:not([tabindex="-1"])')).filter((x) => window.getComputedStyle(x).display !== 'none');
        const index = focusable.indexOf(e.target);
  
        let element;
  
        if (e.shiftKey) {
          element = focusable[index - 1] || focusable[focusable.length - 1];
        } else {
          element = focusable[index + 1] || focusable[0];
        }
  
        if (element) {
          element.focus();
          e.stopPropagation();
          e.preventDefault();
        }
      }
    }
  
    componentDidMount () {
      window.addEventListener('keyup', this.handleKeyUp, false);
      window.addEventListener('keydown', this.handleKeyDown, false);
    }
  
    componentWillReceiveProps (nextProps) {
      if (!!nextProps.children && !this.props.children) {
        this.activeElement = document.activeElement;
  
        this.getSiblings().forEach(sibling => sibling.setAttribute('inert', true));
      } else if (!nextProps.children) {
        this.setState({ revealed: false });
      }
      if (!nextProps.children && !!this.props.children) {
        this.activeElement.focus();
        this.activeElement = null;
      }
    }
  
    componentDidUpdate (prevProps) {
      if (!this.props.children && !!prevProps.children) {
        this.getSiblings().forEach(sibling => sibling.removeAttribute('inert'));
      }
      if (this.props.children) {
        requestAnimationFrame(() => {
          this.setState({ revealed: true });
        });
      }
    }
  
    componentWillUnmount () {
      window.removeEventListener('keyup', this.handleKeyUp);
      window.removeEventListener('keydown', this.handleKeyDown);
    }
  
    getSiblings = () => {
      return Array(...this.node.parentElement.childNodes).filter(node => node !== this.node);
    }
  
    setRef = ref => {
      this.node = ref;
    }
  
    render () {
      const { children, onClose } = this.props;
      const { revealed } = this.state;
      const visible = !!children;
  
      if (!visible) {
        return (
          <div className='modal-root' ref={this.setRef} style={{ opacity: 0 }} />
        );
      }
  
      return (
        <div className='modal-root' ref={this.setRef} style={{ opacity: revealed ? 1 : 0 }}>
          <div style={{ pointerEvents: visible ? 'auto' : 'none' }}>
            <div role='presentation' className='modal-root__overlay' onClick={onClose} />
            <div role='dialog' className='modal-root__container'>{children}</div>
          </div>
        </div>
      );
    }
  
  }
  