<?php
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Asset\AttachedAssetsInterface;
/**
 * @file
 * Module to associate icons with menu items
 */

use Drupal\Core\File\FileSystemInterface;
use Drupal\Core\Render\Element;
use Drupal\file\Entity\File;

define('SIMPLE_MENU_ICONS_CSS_PATH', 'public://css');

/**
 * Implements hook_theme().
 */
function simple_menu_icons_theme($existing, $type, $theme, $path) {
  return [
    'simple_menu_icons_css_item' => [
      'variables' => ['icons' => NULL],
      'template' => 'simple-menu-icons-css-item',
    ],
  ];
}

/**
 * Implements hook_form_BASE_FORM_ID_alter()
 *
 * @param $form
 * @param \Drupal\Core\Form\FormStateInterface $form_state
 * @param $form_id
 */
function simple_menu_icons_form_menu_link_content_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  $menu_link = $form_state->getFormObject()->getEntity();
  $menu_link_options = $menu_link->link->first()->options ?: [];

  $form['icon_upload'] = [
    '#type' => 'managed_file',
    '#title' => t('Icon image'),
    '#description' => t("If you'd like an image to display next to this menu item, upload it here."),
    '#upload_validators' => [
      'file_validate_extensions' => ['gif png jpg jpeg svg'],
    ],
    '#upload_location' => 'public://menu_icons/',
    '#default_value' => !empty($menu_link_options['menu_icon']['fid']) ? [$menu_link_options['menu_icon']['fid']] : FALSE,
  ];
  $form['actions']['submit']['#submit'][] = 'simple_menu_icons_menu_link_content_form_submit';
}

/**
 * Process the submitted form.
 *
 * @param $form
 * @param \Drupal\Core\Form\FormStateInterface $form_state
 */
function simple_menu_icons_menu_link_content_form_submit($form, FormStateInterface $form_state) {
  // First we just grab the file ID for the icon we uploaded, if any.
  $icon_field = $form_state->getValue('icon_upload');
  $file_id = empty($icon_field) ? FALSE : reset($icon_field);

  if (!empty($file_id)) {
    // Make this a permanent file so that cron doesn't delete it later.
    $file = File::load($file_id);
    $file->status = FILE_STATUS_PERMANENT;
    $file->save();
    $file_usage = \Drupal::service('file.usage');
    $file_usage->add($file, 'simple_menu_icons', 'default_image', $file_id);
    $fileUri = $file->getFileUri();
    $options['menu_icon']['uri'] = $fileUri;
  }

  // Now we need the Menu Item entity that is being saved.
  $menu_link = $form_state->getFormObject()->getEntity();
  $options['menu_icon']['fid'] = $file_id;
  $menu_link_options = $menu_link->link->first()->options;
  $menu_link->link->first()->options = array_merge($menu_link_options, $options);
  $menu_link->save();

  simple_menu_icons_css_generate();
  if (!empty($file_id)) {
    drupal_flush_all_caches();
  }
}

/**
 * Build CSS based on menu IDs
 */
function simple_menu_icons_css_generate() {
  $db = \Drupal::database();
  $result = $db->select('menu_link_content_data', 'm')
    ->fields('m', ['id', 'link__options'])
    ->execute();

  while ($item = $result->fetchObject()) {
    $options = unserialize($item->link__options);

    if (empty($options['menu_icon']['fid'])) {
      continue;
    }

    // Grab the image's path for referencing it as a background image.
    $file = File::load($options['menu_icon']['fid']);
    if (empty($file)) {
      continue;
    }
    $image_path = $file->getFileUri();

    // Grab the image's width so that we know how much padding to add.
    $image = Drupal::service('image.factory')->get($image_path);
    $image_width = $image->getWidth();

    $menu_icons[] = [
      'mlid' => $item->id,
      'path' => file_url_transform_relative(file_create_url($image_path)),
      'width' => $image_width,
    ];
  }

  $csspath = SIMPLE_MENU_ICONS_CSS_PATH;

  // Save or delete the CSS file, depending on if there's anything to save.
  if (!empty($menu_icons)) {
    // Build the CSS using our Twig template.
    $menu_css = [
      '#theme' => 'simple_menu_icons_css_item',
      '#icons' => $menu_icons,
    ];
    $css = \Drupal::service('renderer')->renderPlain($menu_css);

    // If theme debug is enabled, there will be HTML comments showing the
    // path to the Twig template. That breaks the CSS, so we convert them
    // to CSS comment format here.
    $css = str_replace('<!--', '/*', $css);
    $css = str_replace('-->', '*/', $css);
    // Generate suffix for new css file.
    $css_suffix = time();
    // Delete old css file if exists.
    $css_old_suffix = \Drupal::state()
      ->get('simple_menu_icons_css_suffix') ?: NULL;
    if ($css_old_suffix) {
      \Drupal::service('file_system')->delete($csspath . '/menu_icons_' . $css_old_suffix . '.css');
    }
    else {
      \Drupal::service('file_system')->delete($csspath . '/menu_icons.css');
    }
    // Save suffix to db.
    \Drupal::state()->set('simple_menu_icons_css_suffix', $css_suffix);
    // Save the CSS to a file in the files directory.
    // make directory writable if it is read-only.
    \Drupal::service('file_system')->prepareDirectory($csspath, FileSystemInterface::CREATE_DIRECTORY | FileSystemInterface::MODIFY_PERMISSIONS);
    \Drupal::service('file_system')->saveData($css, $csspath . '/menu_icons_' . $css_suffix . '.css', FileSystemInterface::EXISTS_REPLACE);
  }
  else {
    $css_suffix = \Drupal::state()->get('simple_menu_icons_css_suffix') ?: NULL;
    if ($css_suffix) {
      \Drupal::service('file_system')->delete($csspath . '/menu_icons_' . $css_suffix . '.css');
    }
    else {
      \Drupal::service('file_system')->delete($csspath . '/menu_icons.css');
    }
  }

  // Either way, we should flush CSS cache so that aggregated CSS gets rebuilt.
  \Drupal::service('asset.css.collection_optimizer')->deleteAll();
  _drupal_flush_css_js();
}

/**
 * Implements hook_rebuild().
 */
function simple_menu_icons_rebuild() {
  simple_menu_icons_css_generate();
}

/**
 * Implements hook_css_alter().
 *
 * @param $css
 * @param \Drupal\Core\Asset\AttachedAssetsInterface $assets
 */
function simple_menu_icons_css_alter(&$css, AttachedAssetsInterface $assets) {
  $css_suffix = \Drupal::state()->get('simple_menu_icons_css_suffix') ?: NULL;
  if ($css_suffix) {
    $cssfile = SIMPLE_MENU_ICONS_CSS_PATH . '/menu_icons_' . $css_suffix . '.css';
  }
  else {
    $cssfile = SIMPLE_MENU_ICONS_CSS_PATH . '/menu_icons.css';
  }
  if (file_exists($cssfile) && $css) {
    $css_path = file_create_url($cssfile);
    if (!empty($css_path)) {
      $css[$css_path] = [
        'weight' => CSS_COMPONENT,
        'group' => CSS_AGGREGATE_DEFAULT,
        'type' => 'file',
        'data' => $css_path,
        'media' => 'all',
        'preprocess' => TRUE,
        'browsers' => [
          'IE' => TRUE,
          '!IE' => TRUE,
        ],
      ];
    }
  }
}

/**
 * Implements hook_preprocess_menu().
 *
 * @param $variables
 */
function simple_menu_icons_preprocess_menu(&$variables) {
  foreach ($variables['items'] as &$item) {
    _simple_menu_icons_preprocess_menu_item_recursive($item);
  }
}

/**
 * Helper function to recursively preprocess hierarchical menus.
 *
 * @param array $item
 *   Menu item array.
 */
function _simple_menu_icons_preprocess_menu_item_recursive(&$item) {
  if (empty($item['original_link'])) {
    return;
  }

  $link_plugin = $item['original_link']->getPluginDefinition();

  if (empty($link_plugin) || empty($link_plugin['metadata']['entity_id'])) {
    return;
  }

  $mlid = $link_plugin['metadata']['entity_id'];
  $item['attributes']->addClass('menu-icon');
  $item['attributes']->addClass('menu-icon-' . $mlid);

  if (!empty($item['below'])) {
    foreach ($item['below'] as $key => &$value) {
      _simple_menu_icons_preprocess_menu_item_recursive($value);
    }
  }
}