content: import classNames from 'classnames';
  import React from 'react';
  import PropTypes from 'prop-types';
  import Transition, {
    ENTERED,
    ENTERING,
  } from 'react-transition-group/Transition';
  import onEnd from 'dom-helpers/transition/end';
  import triggerBrowserReflow from './utils/triggerBrowserReflow';
  
  const propTypes = {
    /**
     * Show the component; triggers the fade in or fade out animation
     */
    in: PropTypes.bool,
  
    /**
     * Wait until the first "enter" transition to mount the component (add it to the DOM)
     */
    mountOnEnter: PropTypes.bool,
  
    /**
     * Unmount the component (remove it from the DOM) when it is faded out
     */
    unmountOnExit: PropTypes.bool,
  
    /**
     * Run the fade in animation when the component mounts, if it is initially
     * shown
     */
    appear: PropTypes.bool,
  
    /**
     * Duration of the fade animation in milliseconds, to ensure that finishing
     * callbacks are fired even if the original browser transition end events are
     * canceled
     */
    timeout: PropTypes.number,
  
    /**
     * Callback fired before the component fades in
     */
    onEnter: PropTypes.func,
    /**
     * Callback fired after the component starts to fade in
     */
    onEntering: PropTypes.func,
    /**
     * Callback fired after the has component faded in
     */
    onEntered: PropTypes.func,
    /**
     * Callback fired before the component fades out
     */
    onExit: PropTypes.func,
    /**
     * Callback fired after the component starts to fade out
     */
    onExiting: PropTypes.func,
    /**
     * Callback fired after the component has faded out
     */
    onExited: PropTypes.func,
  };
  
  const defaultProps = {
    in: false,
    timeout: 300,
    mountOnEnter: false,
    unmountOnExit: false,
    appear: false,
  };
  
  const fadeStyles = {
    [ENTERING]: 'show',
    [ENTERED]: 'show',
  };
  
  class Fade extends React.Component {
    handleEnter = node => {
      triggerBrowserReflow(node);
      if (this.props.onEnter) this.props.onEnter(node);
    };
  
    render() {
      const { className, children, ...props } = this.props;
  
      return (
        <Transition addEndListener={onEnd} {...props} onEnter={this.handleEnter}>
          {(status, innerProps) =>
            React.cloneElement(children, {
              ...innerProps,
              className: classNames(
                'fade',
                className,
                children.props.className,
                fadeStyles[status],
              ),
            })
          }
        </Transition>
      );
    }
  }
  
  Fade.propTypes = propTypes;
  Fade.defaultProps = defaultProps;
  
  export default Fade;
  