content: import React from 'react';
  import PropTypes from 'prop-types';
  import classNames from 'classnames';
  import { componentPropType } from '@material-ui/utils';
  import warning from 'warning';
  import withStyles from '../styles/withStyles';
  
  export const styles = theme => ({
    /* Styles applied to the root element. */
    root: {
      display: 'flex',
      justifyContent: 'center',
      height: 56,
      backgroundColor: theme.palette.background.paper,
    },
  });
  
  function BottomNavigation(props) {
    const {
      children: childrenProp,
      classes,
      className: classNameProp,
      component: Component,
      onChange,
      showLabels,
      value,
      ...other
    } = props;
  
    const className = classNames(classes.root, classNameProp);
  
    const children = React.Children.map(childrenProp, (child, childIndex) => {
      if (!React.isValidElement(child)) {
        return null;
      }
  
      warning(
        child.type !== React.Fragment,
        [
          "Material-UI: the BottomNavigation component doesn't accept a Fragment as a child.",
          'Consider providing an array instead.',
        ].join('\n'),
      );
  
      const childValue = child.props.value === undefined ? childIndex : child.props.value;
      return React.cloneElement(child, {
        selected: childValue === value,
        showLabel: child.props.showLabel !== undefined ? child.props.showLabel : showLabels,
        value: childValue,
        onChange,
      });
    });
  
    return (
      <Component className={className} {...other}>
        {children}
      </Component>
    );
  }
  
  BottomNavigation.propTypes = {
    /**
     * The content of the component.
     */
    children: PropTypes.node.isRequired,
    /**
     * Override or extend the styles applied to the component.
     * See [CSS API](#css-api) below for more details.
     */
    classes: PropTypes.object.isRequired,
    /**
     * @ignore
     */
    className: PropTypes.string,
    /**
     * The component used for the root node.
     * Either a string to use a DOM element or a component.
     */
    component: componentPropType,
    /**
     * Callback fired when the value changes.
     *
     * @param {object} event The event source of the callback
     * @param {any} value We default to the index of the child
     */
    onChange: PropTypes.func,
    /**
     * If `true`, all `BottomNavigationAction`s will show their labels.
     * By default, only the selected `BottomNavigationAction` will show its label.
     */
    showLabels: PropTypes.bool,
    /**
     * The value of the currently selected `BottomNavigationAction`.
     */
    value: PropTypes.any,
  };
  
  BottomNavigation.defaultProps = {
    component: 'div',
    showLabels: false,
  };
  
  export default withStyles(styles, { name: 'MuiBottomNavigation' })(BottomNavigation);
  