style: 优化表单样式并提升表单性能

plugins/itstudio-recruitment/includes/email-otp.php

@@ -57,6 +57,36 @@ function itstudio_join_otp_random_code() {
     return (string) wp_rand(100000, 999999);
 }
 
+function itstudio_join_otp_email_exists_in_form($form_id, $field_id, $email) {
+    global $wpdb;
+
+    $form_id = absint($form_id);
+    $field_id = absint($field_id);
+    $email = itstudio_join_otp_normalize_email($email);
+    if ($form_id <= 0 || $field_id <= 0 || $email === '') {
+        return false;
+    }
+
+    $items_table = $wpdb->prefix . 'frm_items';
+    $metas_table = $wpdb->prefix . 'frm_item_metas';
+    $count = $wpdb->get_var(
+        $wpdb->prepare(
+            "SELECT COUNT(1)
+             FROM {$metas_table} AS meta
+             INNER JOIN {$items_table} AS item ON item.id = meta.item_id
+             WHERE item.form_id = %d
+               AND item.is_draft = 0
+               AND meta.field_id = %d
+               AND LOWER(TRIM(meta.meta_value)) = %s",
+            $form_id,
+            $field_id,
+            $email
+        )
+    );
+
+    return (int) $count > 0;
+}
+
 function itstudio_join_otp_json_error($message_cn, $message_en, $status = 400, $extra = array()) {
     wp_send_json_error(
         array_merge(
@@ -85,6 +115,10 @@ function itstudio_join_otp_send_ajax() {
         itstudio_join_otp_json_error('请输入有效的邮箱地址。', 'Please enter a valid email address.', 400);
     }
 
+    if (itstudio_join_otp_email_exists_in_form($config['form_id'], $config['email_field_id'], $email)) {
+        itstudio_join_otp_json_error('该邮箱已经报名，无需重复提交。', 'This email has already been used to apply.', 409);
+    }
+
     $ip = itstudio_join_otp_get_client_ip();
     $otp_key = itstudio_join_otp_key($email, $config['form_id']);
     $existing = get_transient($otp_key);