sage/lib/assets.php

<?php

namespace Roots\Sage\Assets;

/**
 * Scripts and stylesheets
 *
 * Enqueue stylesheets in the following order:
 * 1. /theme/dist/styles/main.css
 *
 * Enqueue scripts in the following order:
 * 1. Latest jQuery via Google CDN (if enabled in config.php)
 * 2. /theme/dist/scripts/modernizr.js
 * 3. /theme/dist/scripts/main.js
 *
 * Google Analytics is loaded after enqueued scripts if:
 * - An ID has been defined in config.php
 * - You're not logged in as an administrator
 */

class JsonManifest {
  private $manifest;

  public function __construct($manifest_path) {
    if (file_exists($manifest_path)) {
      $this->manifest = json_decode(file_get_contents($manifest_path), true);
    } else {
      $this->manifest = [];
    }
  }

  public function get() {
    return $this->manifest;
  }
}

function asset_path($filename) {
  $dist_path = get_template_directory_uri() . '/dist/';
  $directory = dirname($filename) . '/';
  $file = basename($filename);
  static $manifest;

  if (empty($manifest)) {
    $manifest_path = get_template_directory() . '/dist/assets.json';
    $manifest = new JsonManifest($manifest_path);
    $manifest = $manifest->get();
  }

  if (WP_ENV !== 'development' && array_key_exists($file, $manifest)) {
    return $dist_path . $directory . $manifest[$file];
  } else {
    return $dist_path . $directory . $file;
  }
}

function bower_map_to_cdn($dependency, $fallback) {
  static $bower;

  if (empty($bower)) {
    $bower_path = get_template_directory() . '/bower.json';
    $bower = new JsonManifest($bower_path);
    $bower = $bower->get();
  }

  $templates = [
    'google' => '//ajax.googleapis.com/ajax/libs/%name%/%version%/%file%'
  ];

  $version = $bower['dependencies'][$dependency['name']];

  if (isset($version) && preg_match('/^(\d+\.){2}\d+$/', $version)) {
    $search = ['%name%', '%version%', '%file%'];
    $replace = [$dependency['name'], $version, $dependency['file']];
    return str_replace($search, $replace, $templates[$dependency['cdn']]);
  } else {
    return $fallback;
  }

}

function assets() {
  wp_enqueue_style('sage_css', asset_path('styles/main.css'), false, null);

  /**
   * Grab Google CDN's latest jQuery with a protocol relative URL; fallback to local if offline
   * jQuery & Modernizr load in the footer per HTML5 Boilerplate's recommendation: http://goo.gl/nMGR7P
   * If a plugin enqueues jQuery-dependent scripts in the head, jQuery will load in the head to meet the plugin's dependencies
   * To explicitly load jQuery in the head, change the last wp_enqueue_script parameter to false
   */
  if (!is_admin() && current_theme_supports('jquery-cdn')) {
    wp_deregister_script('jquery');

    wp_register_script('jquery', bower_map_to_cdn([
      'name' => 'jquery',
      'cdn' => 'google',
      'file' => 'jquery.min.js'
    ], asset_path('scripts/jquery.js')), [], null, true);

    add_filter('script_loader_src', __NAMESPACE__ . '\\jquery_local_fallback', 10, 2);
  }

  if (is_single() && comments_open() && get_option('thread_comments')) {
    wp_enqueue_script('comment-reply');
  }

  wp_enqueue_script('modernizr', asset_path('scripts/modernizr.js'), [], null, true);
  wp_enqueue_script('jquery');
  wp_enqueue_script('sage_js', asset_path('scripts/main.js'), [], null, true);
}
add_action('wp_enqueue_scripts', __NAMESPACE__ . '\\assets', 100);

// http://wordpress.stackexchange.com/a/12450
function jquery_local_fallback($src, $handle = null) {
  static $add_jquery_fallback = false;

  if ($add_jquery_fallback) {
    echo '<script>window.jQuery || document.write(\'<script src="' . get_template_directory_uri() . '/dist/scripts/jquery.js"><\/script>\')</script>' . "\n";
    $add_jquery_fallback = false;
  }

  if ($handle === 'jquery') {
    $add_jquery_fallback = true;
  }

  return $src;
}
add_action('wp_head', __NAMESPACE__ . '\\jquery_local_fallback');

/**
 * Google Analytics snippet from HTML5 Boilerplate
 *
 * Cookie domain is 'auto' configured. See: http://goo.gl/VUCHKM
 */
function google_analytics() {
  ?>
  <script>
    <?php if (WP_ENV === 'production' && !current_user_can('manage_options')) : ?>
      (function(b,o,i,l,e,r){b.GoogleAnalyticsObject=l;b[l]||(b[l]=
      function(){(b[l].q=b[l].q||[]).push(arguments)});b[l].l=+new Date;
      e=o.createElement(i);r=o.getElementsByTagName(i)[0];
      e.src='//www.google-analytics.com/analytics.js';
      r.parentNode.insertBefore(e,r)}(window,document,'script','ga'));
    <?php else : ?>
      function ga() {
        if (window.console) {
          console.log('Google Analytics: ' + [].slice.call(arguments));
        }
      }
    <?php endif; ?>
    ga('create','<?= GOOGLE_ANALYTICS_ID; ?>','auto');ga('send','pageview');
  </script>
  <?php
}

if (GOOGLE_ANALYTICS_ID) {
  add_action('wp_footer', __NAMESPACE__ . '\\google_analytics', 20);
}