function load_assets( $attr, $content ) {

  if ( is_admin() ) {
    return;
  }
  $url = Jetpack_Gutenberg::validate_block_embed_url(
    get_attribute( $attr, 'url' ),
    array( 'calendly.com' )
  );
  if ( empty( $url ) ) {
    return;
  }

  /*
	 * Enqueue necessary scripts and styles.
	 */
  Jetpack_Gutenberg::load_assets_as_required( FEATURE_NAME );

  $style                   = get_attribute( $attr, 'style' );
  $hide_event_type_details = get_attribute( $attr, 'hideEventTypeDetails' );
  $background_color        = get_attribute( $attr, 'backgroundColor' );
  $text_color              = get_attribute( $attr, 'textColor' );
  $primary_color           = get_attribute( $attr, 'primaryColor' );
  $classes                 = Blocks::classes( FEATURE_NAME, $attr, array( 'calendly-style-' . $style ) );
  $block_id                = wp_unique_id( 'calendly-block-' );
  $is_amp_request          = Blocks::is_amp_request();

  if ( ! wp_script_is( 'jetpack-calendly-external-js' ) && ! $is_amp_request ) {
    enqueue_calendly_js();
  }

  $base_url = $url;
  $url      = add_query_arg(
    array(
      'hide_event_type_details' => (int) $hide_event_type_details,
      'background_color'        => sanitize_hex_color_no_hash( $background_color ),
      'text_color'              => sanitize_hex_color_no_hash( $text_color ),
      'primary_color'           => sanitize_hex_color_no_hash( $primary_color ),
    ),
    $url
  );

  if ( 'link' === $style ) {
    if ( ! wp_style_is( 'jetpack-calendly-external-css' ) ) {
      wp_enqueue_style( 'jetpack-calendly-external-css', 'https://assets.calendly.com/assets/external/widget.css', null, JETPACK__VERSION );
    }

    // Render deprecated version of Calendly block if needed. New markup block button class before rendering here.
    if ( false === strpos( $content, 'wp-block-jetpack-button' ) ) {
      $content = deprecated_render_button_v1( $attr, $block_id, $classes, $url );
    } else {
      $content = str_replace( 'calendly-widget-id', esc_attr( $block_id ), $content );
      $content = str_replace( $base_url, $url, $content );
    }

    if ( ! $is_amp_request ) {
      wp_add_inline_script(
        'jetpack-calendly-external-js',
        sprintf( "calendly_attach_link_events( '%s' )", esc_js( $block_id ) )
      );
    }
  } else { // Inline style.
    if ( $is_amp_request ) {
      $content = sprintf(
        '<div class="%1$s" id="%2$s"><a href="%3$s" role="button" target="_blank">%4$s</a></div>',
        esc_attr( Blocks::classes( FEATURE_NAME, $attr ) ),
        esc_attr( $block_id ),
        esc_js( $url ),
        wp_kses_post( get_attribute( $attr, 'submitButtonText' ) )
      );
    } else {
      $content = sprintf(
        '<div class="%1$s" id="%2$s"></div>',
        esc_attr( $classes ),
        esc_attr( $block_id )
      );
      $script  = <<<JS_END
jetpackInitCalendly( '%s', '%s' );
JS_END;
      wp_add_inline_script( 'jetpack-calendly-external-js', sprintf( $script, esc_url( $url ), esc_js( $block_id ) ) );
    }
  }

  return $content;
}