File: bundles/fontawesome_bundle/fontawesome_bundle.module

<?php

/**
 * @file
 * Contains fontawesome_bundle.module
 */

use Drupal\Component\Utility\UrlHelper;

/**
 * Implements hook_page_attachments()
 */
function fontawesome_bundle_page_attachments(array &$page) {
  // Load the configuration settings
  $config_settings = \Drupal::config('fontawesome_bundle.settings');

  $libraries = \Drupal::service('library.discovery')->getLibrariesByExtension('fontawesome_bundle');

  $config_defaults = '';

  if (!$config_settings) {
    $config_defaults = _fontawesome_bundle_defaults();
  }
  else {
    $fa_defaults = _fontawesome_bundle_defaults();
    $config_defaults = [
      'method' => $config_settings->get('method') ? $config_settings->get('method') : $fa_defaults['method'],
      'use_cdn' => $config_settings->get('use_cdn') ? $config_settings->get('use_cdn') : $fa_defaults['use_cdn'],
      'external_location' => $config_settings->get('external_location') ? $config_settings->get('external_location') : $fa_defaults['external_location'],
      'use_solid' => $config_settings->get('use_solid') ? $config_settings->get('use_solid') : $fa_defaults['use_solid'],
      'use_regular' => $config_settings->get('use_regular') ? $config_settings->get('use_regular') : $fa_defaults['use_regular'],
      'use_light' => $config_settings->get('use_light') ? $config_settings->get('use_light') : $fa_defaults['use_light'],
      'use_brand' => $config_settings->get('use_brand') ? $config_settings->get('use_brand') : $fa_defaults['use_brand'],
    ];
  }

  if ($config_defaults['use_solid'] && $config_defaults['use_light'] && $config_defaults['use_light'] && $config_defaults['use_brand']) {

    // Attach all.js/all.cs library
    $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_defaults['method'];
  }
  else {

    if ($libraries['fontawesome_bundle.' . $config_defaults['method'] . '.base']) {
      $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_defaults['method'] . '.base';
    }
    // If enabled then attach solid.js/solid.css
    if ($config_defaults['use_solid']) {
      $file_path = _fontawesome_bundle_get_file_path($libraries, $config_defaults['method'], 'solid');
      if(!$config_defaults['use_cdn'] && !file_exists($file_path)) {
        \Drupal::messenger()->addError('File solid.css does not exists.');
      }
      $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_defaults['method'] . '.solid';
    }

    // If enabled then attach regular.js/regular.css
    if ($config_defaults['use_regular']) {
      $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_defaults['method'] . '.regular';
    }

    // If enabled then attach light.js/light.css
    if ($config_defaults['use_light']) {
      $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_defaults['method'] . '.light';
    }

    // If enabled then attach brands.js/brands.css
    if ($config_defaults['use_brand']) {
      $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_defaults['method'] . '.brands';
    }
  }

  /*

  if ($config_settings->get('use_solid') && $config_settings->get('use_light') && $config_settings->get('use_light') && $config_settings->get('use_brand')) {

    // Attach all.js/all.cs library
    $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_settings->get('method');
  }
  else {

    if ($libraries['fontawesome_bundle.' . $config_settings->get('method') . '.base']) {
      $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_settings->get('method') . '.base';
    }
    // If enabled then attach solid.js/solid.css
    if ($config_settings->get('use_solid')) {
      $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_settings->get('method') . '.solid';
    }

    // If enabled then attach regular.js/regular.css
    if ($config_settings->get('use_regular')) {
      $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_settings->get('method') . '.regular';
    }

    // If enabled then attach light.js/light.css
    if ($config_settings->get('use_light')) {
      $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_settings->get('method') . '.light';
    }

    // If enabled then attach brands.js/brands.css
    if ($config_settings->get('use_brand')) {
      $page['#attached']['library'][] = 'fontawesome_bundle/fontawesome_bundle.' . $config_settings->get('method') . '.brands';
    }
  }*/
}

/**
 * Get the file path from the libraries
 */
function _fontawesome_bundle_get_file_path($libraries, $method, $style) {
  $path = drupal_get_path('module', 'fontawesome_bundle') . '/';

  if ($method == 'svg') {
    $path .= $libraries['fontawesome_bundle.' . $method . '.' . $style]['js'][0]['data'];
  }
  else if ($method == 'webfonts') {
    $path .= $libraries['fontawesome_bundle.' . $method . '.' . $style]['css'][0]['data'];
  }

  return $path;
}

/**
 * Default values for the configuration
 */
function _fontawesome_bundle_defaults() {
  return [
    'method' => 'svg',
    'use_cdn' => TRUE,
    'external_location' => 'https://use.fontawesome.com/releases/v5.8.2/js/all.js',
    'use_solid' => TRUE,
    'use_regular' => FALSE,
    'use_light' => FALSE,
    'use_brand' => FALSE,
  ];
}

/**
 * Implements hook_library_info_alter()
 */
function fontawesome_bundle_library_info_alter(&$libraries, $extension) {
  // Alter the library info only for the fontawesome_bundle
  if ($extension == 'fontawesome_bundle') {
    // Load the configuration settings
    $config_settings = \Drupal::config('fontawesome_bundle.settings');

    // Fetch the enabled styles
    $styles = _fontawesome_bundle_get_enabled_styles();

    $config_defaults = '';
    if (!$config_settings) {
      $config_defaults = _fontawesome_bundle_defaults();
    }
    else {
      $fa_defaults = _fontawesome_bundle_defaults();
      $config_defaults = [
        'method' => $config_settings->get('method') ? $config_settings->get('method') : $fa_defaults['method'],
        'use_cdn' => $config_settings->get('use_cdn') ? $config_settings->get('use_cdn') : $fa_defaults['use_cdn'],
        'external_location' => $config_settings->get('external_location') ? $config_settings->get('external_location') : $fa_defaults['external_location'],
        'use_solid' => $config_settings->get('use_solid') ? $config_settings->get('use_solid') : $fa_defaults['use_solid'],
        'use_regular' => $config_settings->get('use_regular') ? $config_settings->get('use_regular') : $fa_defaults['use_regular'],
        'use_light' => $config_settings->get('use_light') ? $config_settings->get('use_light') : $fa_defaults['use_light'],
        'use_brand' => $config_settings->get('use_brand') ? $config_settings->get('use_brand') : $fa_defaults['use_brand'],
        /*
        'method' => $config_settings->get('method'),
        'use_cdn' => $config_settings->get('use_cdn'),
        'external_location' => $config_settings->get('external_location'),
        'use_solid' => $config_settings->get('use_solid'),
        'use_regular' => $config_settings->get('use_regular'),
        'use_light' => $config_settings->get('use_light'),
        'use_brand' => $config_settings->get('use_brand'),*/
      ];
    }

    // Check if CDN is enabled and the External File location is set
    if ($config_defaults['use_cdn'] && $config_defaults['external_location']) {
      // Check if all the styles are enabled
      if (count($styles) == 4) {
        _fontawesome_bundle_modify_library($libraries, $config_defaults['method'], NULL, $config_defaults['external_location']);
      }
      else {
        if ($config_defaults['use_solid']) {
          _fontawesome_bundle_modify_library($libraries, $config_defaults['method'], 'solid', $config_defaults['external_location']);
        }

        $cdnComponents = parse_url($config_defaults['external_location']);
        $cdnComponents['path'] = explode('/', $cdnComponents['path']);
        unset($cdnComponents['path'][count($cdnComponents['path']) - 1]);
        unset($cdnComponents['path'][count($cdnComponents['path']) - 1]);
        $cdnComponents['path'] = implode('/', $cdnComponents['path']) . '/';

        foreach (['base', 'solid', 'regular', 'light', 'brands'] as $style) {
          if (isset($libraries['fontawesome_bundle.' . $config_defaults['method'] . '.' . $style])) {
            $cdnBase = $cdnComponents['path'];
            $cdnBase = (strlen($cdnComponents['scheme']) > 0 ? $cdnComponents['scheme'] . '://' : '') . $cdnComponents['host'] . $cdnComponents['path'];
            $cdnBase = $cdnBase . ($config_defaults['method'] == 'svg' ? 'js/' : 'css/');
            $cdnBase .= ($style == 'base' ? 'fontawesome' : $style) . '.' . ($config_defaults['method'] == 'svg' ? 'js' : 'css');
            _fontawesome_bundle_modify_library($libraries, $config_defaults['method'], $style, $cdnBase);
          }
        }
      }
    }else{
    }
    /*
    // Check if CDN is enabled and the External File location is set
    if ($config_settings->get('use_cdn') && $config_settings->get('external_location')) {
      // Check if all the styles are enabled
      if (count($styles) == 4) {
        _fontawesome_bundle_modify_library($libraries, $config_settings->get('method'), NULL, $config_settings->get('external_location'));
      }
      else {
        if ($config_settings->get('use_solid')) {
          _fontawesome_bundle_modify_library($libraries, $config_settings->get('method'), 'solid', $config_settings->get('external_location'));
        }

        $cdnComponents = parse_url($config_settings->get('external_location'));
        $cdnComponents['path'] = explode('/', $cdnComponents['path']);
        unset($cdnComponents['path'][count($cdnComponents['path']) - 1]);
        unset($cdnComponents['path'][count($cdnComponents['path']) - 1]);
        $cdnComponents['path'] = implode('/', $cdnComponents['path']) . '/';

        foreach (['base', 'solid', 'regular', 'light', 'brands'] as $style) {
          if (isset($libraries['fontawesome_bundle.' . $config_settings->get('method') . '.' . $style])) {
            $cdnBase = $cdnComponents['path'];
            $cdnBase = (strlen($cdnComponents['scheme']) > 0 ? $cdnComponents['scheme'] . '://' : '') . $cdnComponents['host'] . $cdnComponents['path'];
            $cdnBase = $cdnBase . ($config_settings->get('method') == 'svg' ? 'js/' : 'css/');
            $cdnBase .= ($style == 'base' ? 'fontawesome' : $style) . '.' . ($config_settings->get('method') == 'svg' ? 'js' : 'css');
            _fontawesome_bundle_modify_library($libraries, $config_settings->get('method'), $style, $cdnBase);
          }
        }
      }
    }*/
  }
}

/**
 * Validates the url of the external icon url
 *
 * @param string $url
 *  The url to validate
 *
 * @return boolean
 *  Whether the url is valid
 */
function _fontawesome_bundle_validate_url($url) {
  if (!empty($url) && UrlHelper::isValid($url)) {
    return TRUE;
  }
  return FALSE;
}

/**
 * Returns currently enabled icon styles
 */
function _fontawesome_bundle_get_enabled_styles() {
  $config_settings = \Drupal::config('fontawesome_bundle.settings');

  $config_defaults = '';
  if (!$config_settings) {
    $config_defaults = _fontawesome_bundle_defaults();
  }
  else {
    $config_defaults = [
      'use_solid' => $config_settings->get('use_solid'),
      'use_regular' => $config_settings->get('use_regular'),
      'use_light' => $config_settings->get('use_light'),
      'use_brand' => $config_settings->get('use_brand'),
    ];
  }

  $styles = [];

  if ($config_defaults['use_solid']) {
    $styles[] = 'solid';
  }

  if ($config_defaults['use_regular']) {
    $styles[] = 'regular';
  }

  if ($config_defaults['use_light']) {
    $styles[] = 'light';
  }

  if($config_defaults['use_brand']) {
    $styles[] = 'brands';
  }

  return $styles;
}

/**
 * Alter the library info
 */
function _fontawesome_bundle_modify_library(&$libraries, $type, $librarySuffix, $cdnLocation) {
  $libraryName = 'fontawesome_bundle.' . $type;
  if (!empty($librarySuffix)) {
    $libraryName .= '.' . $librarySuffix;
  }

  // Alter library for 'svg' method
  if ($type == 'svg') {
    $libSettings = $libraries[$libraryName]['js'];
    $libraries[$libraryName]['js'] = [
      $cdnLocation => $libSettings,
    ];
  }

  // Alter library for 'webfonts' method
  if ($type == 'webfonts') {
    $libSettings = $libraries[$libraryName]['css']['theme'];
    $libraries[$libraryName]['css']['theme'] = [
      $cdnLocation => $libSettings,
    ];
  }
}