--- /dev/null
+<?php
+
+/**
+ * @file
+ * Handles AdvAgg CSS Minify installation and upgrade tasks.
+ */
+
+use Drupal\Core\Url;
+
+/**
+ * Implements hook_requirements().
+ */
+function advagg_css_minify_requirements($phase) {
+ $config = \Drupal::config('advagg_css_minify.settings');
+ $requirements = [];
+
+ // If not at runtime, return here.
+ if ($phase !== 'runtime') {
+ return $requirements;
+ }
+
+ // Make sure a minifier is being used.
+ if ($config->get('minifier') == 0) {
+ $active = FALSE;
+ $file_settings = $config->get('file_settings');
+ if ($file_settings) {
+ $file_settings = array_column($file_settings, 'path', 'minifier');
+ unset($file_settings[0]);
+ if ($file_settings) {
+ $active = TRUE;
+ }
+ }
+
+ if (!$active) {
+ $requirements['advagg_css_minify_not_on'] = [
+ 'title' => t('AdvAgg CSS Minify'),
+ 'severity' => REQUIREMENT_WARNING,
+ 'value' => t('AdvAgg CSS Minification is disabled.'),
+ 'description' => t('Go to the <a href="@settings">AdvAgg CSS Minify settings page</a> and select a minifier, or go to the <a href="@modules">modules page</a> and disable the "AdvAgg CSS Minify" module.', [
+ '@settings' => Url::fromRoute('advagg_css_minify.settings')->toString(),
+ '@modules' => Url::fromRoute('system.modules_list', [], [
+ 'fragment' => 'edit-modules-advanced-cssjs-aggregation',
+ ])->toString(),
+ ]),
+ ];
+ }
+ }
+
+ return $requirements;
+}