add_action('wp_head', 'nagi_g_font');
function nagi_g_font() {
  $font_family = get_theme_mod('font_radio', 'Quicksand');
  $font_url = generate_font_url($font_family);
  echo '<link href="' . esc_url($font_url) . '" rel="preload" as="style">'."\n";
  echo '<link href="' . esc_url($font_url) . '" rel="stylesheet" media="print" onload="this.media=\'all\'">'."\n";
}

function generate_font_url($font_family) {
  $font_families = array(
    '"Fugaz One"' => 'Fugaz+One&display=swap',
    '"Saira"'     => 'Saira:ital,wght@0,100..900;1,100..900&display=swap',
    '"Alice"'     => 'Alice&display=swap',
    '"Comfortaa"' => 'Comfortaa:[email protected]&display=swap',
    '"Quicksand"' => 'Quicksand:[email protected]&display=swap',
    '"Roboto"'    => 'Roboto:wght@300;400;700&display=swap',
    'none'      	=> '',
  );

  if (isset($font_families[$font_family]) && $font_family !== 'none') {
    return 'https://fonts.googleapis.com/css2?family=' . $font_families[$font_family];
  }
  return '';
}