fix: resolve Invalid Date issue in email templates

- Fix date parsing for YYYY-MM-DD format to use local timezone
- Handle date strings properly to avoid timezone conversion issues
- Add validation to ensure dates are valid before formatting
- Update expiration date calculation to use consistent parsing

This fixes the "Invalid Date" display in gallery creation emails.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/src/routes/adminEvents.js

@@ -89,7 +89,14 @@ router.post('/', adminAuth, [
     const password_hash = await bcrypt.hash(password, getBcryptRounds());
     
     // Calculate expiration date (days after event date)
-    const expires_at = new Date(event_date);
+    // Parse YYYY-MM-DD format as local date to avoid timezone issues
+    let expires_at;
+    if (event_date.match(/^\d{4}-\d{2}-\d{2}$/)) {
+      const [year, month, day] = event_date.split('-').map(num => parseInt(num, 10));
+      expires_at = new Date(year, month - 1, day);
+    } else {
+      expires_at = new Date(event_date);
+    }
     expires_at.setDate(expires_at.getDate() + parseInt(expiration_days, 10));
     
     // Create folder structure

backend/src/utils/dateFormatter.js

@@ -27,7 +27,28 @@ async function formatDate(date, language = 'en') {
       }
     }
     
-    const dateObj = date instanceof Date ? date : new Date(date);
+    // Ensure proper date parsing
+    let dateObj;
+    if (date instanceof Date) {
+      dateObj = date;
+    } else if (typeof date === 'string') {
+      // For date strings like "2025-07-16", parse as local date to avoid timezone issues
+      if (date.match(/^\d{4}-\d{2}-\d{2}$/)) {
+        // Parse YYYY-MM-DD format as local date
+        const [year, month, day] = date.split('-').map(num => parseInt(num, 10));
+        dateObj = new Date(year, month - 1, day);
+      } else {
+        dateObj = new Date(date);
+      }
+    } else {
+      dateObj = new Date(date);
+    }
+    
+    // Check if date is valid
+    if (isNaN(dateObj.getTime())) {
+      console.error('Invalid date provided to formatDate:', date);
+      throw new Error('Invalid date');
+    }
     
     // Use appropriate locale based on language
     let locale = dateConfig.locale || 'en-GB';
@@ -39,33 +60,33 @@ async function formatDate(date, language = 'en') {
     
     // Format based on the configured format
     switch (dateConfig.format) {
-      case 'MM/DD/YYYY':
-        return dateObj.toLocaleDateString(locale, {
-          month: '2-digit',
-          day: '2-digit',
-          year: 'numeric'
-        });
-      case 'DD/MM/YYYY':
-        return dateObj.toLocaleDateString(locale, {
-          day: '2-digit',
-          month: '2-digit',
-          year: 'numeric'
-        });
-      case 'YYYY-MM-DD':
-        return dateObj.toISOString().split('T')[0];
-      case 'DD.MM.YYYY':
-        return dateObj.toLocaleDateString('de-DE', {
-          day: '2-digit',
-          month: '2-digit',
-          year: 'numeric'
-        });
-      default:
-        // Use long format as fallback
-        return dateObj.toLocaleDateString(locale, {
-          year: 'numeric',
-          month: 'long',
-          day: 'numeric'
-        });
+    case 'MM/DD/YYYY':
+      return dateObj.toLocaleDateString(locale, {
+        month: '2-digit',
+        day: '2-digit',
+        year: 'numeric'
+      });
+    case 'DD/MM/YYYY':
+      return dateObj.toLocaleDateString(locale, {
+        day: '2-digit',
+        month: '2-digit',
+        year: 'numeric'
+      });
+    case 'YYYY-MM-DD':
+      return dateObj.toISOString().split('T')[0];
+    case 'DD.MM.YYYY':
+      return dateObj.toLocaleDateString('de-DE', {
+        day: '2-digit',
+        month: '2-digit',
+        year: 'numeric'
+      });
+    default:
+      // Use long format as fallback
+      return dateObj.toLocaleDateString(locale, {
+        year: 'numeric',
+        month: 'long',
+        day: 'numeric'
+      });
     }
   } catch (error) {
     console.error('Error formatting date:', error);