feat(SHS-5954): Allow mailto links for social media block

docroot/modules/humsci/hs_blocks/src/Plugin/Block/SocialMediaBlock.php

@@ -126,10 +126,13 @@ public function blockForm($form, FormStateInterface $form_state): array {
       $form['links'][$key] = [
         '#type' => 'container',
         'link_url' => [
-          '#type' => 'url',
+          '#type' => 'textfield',
           '#title' => $this->t('URL'),
           '#description' => $this->t('Social Media Profile URL.'),
           '#default_value' => $link['link_url'],
+          '#element_validate' => [
+            [get_class($this), 'validateUrl'],
+          ],
         ],
         'link_title' => [
           '#type' => 'textfield',
@@ -162,6 +165,31 @@ public function blockForm($form, FormStateInterface $form_state): array {
     return $form;
   }
 
+  /**
+   * Custom validation for the link_url field.
+   */
+  public static function validateUrl(array &$element, FormStateInterface $form_state, array &$complete_form) {
+    $value = $element['#value'];
+
+    if (empty($value)) {
+      return;
+    }
+
+    $mailto_regex = '/^mailto:[\w.%+-]+@[A-Za-z0-9-]+\.[A-Za-z]{2,}(?:\?[^\s]*)?$/i';
+
+    if (str_starts_with($value, 'mailto')) {
+      if (!preg_match($mailto_regex, $value)) {
+        $form_state->setError($element, t('The mailto link must include a valid email address (e.g., mailto:[email protected]).'));
+        return;
+      }
+    }
+    else {
+      if (!filter_var($value, FILTER_VALIDATE_URL)) {
+        $form_state->setError($element, t('The URL must be a valid web address (e.g., https://www.stanford.edu) or a valid email address (e.g., mailto:[email protected]).'));
+      }
+    }
+  }
+
   /**
    * {@inheritdoc}
    */