text: import React from 'react';
  import PropTypes from 'prop-types';
  import Helmet from 'react-helmet';
  import { useStaticQuery, graphql } from 'gatsby';
  
  function SEO({
    description, lang, meta, keywords, title,
  }) {
    const { site } = useStaticQuery(
      graphql`
        query {
          site {
            siteMetadata {
              title
              description
              author
            }
          }
        }
      `,
    );
  
    const metaDescription = description || site.siteMetadata.description;
  
    return (
      <Helmet
        htmlAttributes={{
          lang,
        }}
        title={title}
        titleTemplate={`%s | ${site.siteMetadata.title}`}
        meta={[
          {
            name: 'description',
            content: metaDescription,
          },
          {
            property: 'og:title',
            content: title,
          },
          {
            property: 'og:description',
            content: metaDescription,
          },
          {
            property: 'og:type',
            content: 'website',
          },
          {
            name: 'twitter:card',
            content: 'summary',
          },
          {
            name: 'twitter:creator',
            content: site.siteMetadata.author,
          },
          {
            name: 'twitter:title',
            content: title,
          },
          {
            name: 'twitter:description',
            content: metaDescription,
          },
        ]
          .concat(
            keywords.length > 0
              ? {
                name: 'keywords',
                content: keywords.join(', '),
              }
              : [],
          )
          .concat(meta)}
      />
    );
  }
  
  SEO.defaultProps = {
    lang: 'en',
    meta: [],
    keywords: [],
    description: '',
  };
  
  SEO.propTypes = {
    description: PropTypes.string,
    lang: PropTypes.string,
    meta: PropTypes.arrayOf(PropTypes.object),
    keywords: PropTypes.arrayOf(PropTypes.string),
    title: PropTypes.string.isRequired,
  };
  
  export default SEO;
  