text: import React from 'react';
  import PropTypes from 'prop-types';
  import Document, { Head, Main, NextScript } from 'next/document';
  import flush from 'styled-jsx/server';
  import { GA_TRACKING_ID, PT_ENGINE_CODE } from '../lib/analytics'
  class MyDocument extends Document {
  
    render() {
      const { pageContext } = this.props;
      
      return (
        <html lang="en" dir="ltr">
          <Head>
            <meta charSet="utf-8" />
            {/* Use minimum-scale=1 to enable GPU rasterization */}
            <meta
              name="viewport"
              content="minimum-scale=1, initial-scale=1, width=device-width, shrink-to-fit=no"
            />
            {/* PWA primary color */}
            <meta
              name="theme-color"
              content={pageContext ? pageContext.theme.palette.primary.main : null}
            />
            <link
              rel="stylesheet"
              href="https://fonts.googleapis.com/css?family=Poppins:300,400,500"
            />
             <script
              async
              src={`https://www.googletagmanager.com/gtag/js?id=${GA_TRACKING_ID}`}
              />
              <script
                  dangerouslySetInnerHTML={{
                    __html: `
                  window.dataLayer = window.dataLayer || [];
                  function gtag(){dataLayer.push(arguments);}
                  gtag('js', new Date());
                  gtag('config', '${GA_TRACKING_ID}');
                `
                  }}
              />
              <script
                  dangerouslySetInnerHTML={{
                    __html: `
                    window._pt_lt = new Date().getTime();
                    window._pt_sp_2 = [];
                    _pt_sp_2.push('setAccount,${PT_ENGINE_CODE}');
                    var _protocol = (("https:" == document.location.protocol) ? " https://" : " http://");
                    (function() {
                        var atag = document.createElement('script'); atag.type = 'text/javascript'; atag.async = true;
                        atag.src = _protocol + 'cjs.ptengine.com/pta_en.js';
                        var s = document.getElementsByTagName('script')[0];
                        s.parentNode.insertBefore(atag, s);
                    })();
                `
                  }}
              />
          </Head>
          <body>
            <Main />
            <NextScript />
          </body>
        </html>
      );
    }
  }
  
  MyDocument.getInitialProps = ctx => {
    // Resolution order
    //
    // On the server:
    // 1. app.getInitialProps
    // 2. page.getInitialProps
    // 3. document.getInitialProps
    // 4. app.render
    // 5. page.render
    // 6. document.render
    //
    // On the server with error:
    // 1. document.getInitialProps
    // 2. app.render
    // 3. page.render
    // 4. document.render
    //
    // On the client
    // 1. app.getInitialProps
    // 2. page.getInitialProps
    // 3. app.render
    // 4. page.render
  
    // Render app and page and get the context of the page with collected side effects.
    let pageContext;
    const page = ctx.renderPage(Component => {
      const WrappedComponent = props => {
        pageContext = props.pageContext;
        return <Component {...props} />;
      };
  
      WrappedComponent.propTypes = {
        pageContext: PropTypes.object.isRequired,
      };
  
      return WrappedComponent;
    });
  
    let css;
    // It might be undefined, e.g. after an error.
    if (pageContext) {
      css = pageContext.sheetsRegistry.toString();
    }
  
    return {
      ...page,
      pageContext,
      // Styles fragment is rendered after the app and page rendering finish.
      styles: (
        <React.Fragment>
          <style
            id="jss-server-side"
            // eslint-disable-next-line react/no-danger
            dangerouslySetInnerHTML={{ __html: css }}
          />
          {flush() || null}
        </React.Fragment>
      ),
    };
  };
  
  export default MyDocument;
  