feat: Enhance trip creation and management features with user validation, improved error handling, and Firestore integration

lib/models/trip.dart

@@ -36,17 +36,51 @@ class Trip {
       title: map['title'] ?? '',
       description: map['description'] ?? '',
       location: map['location'] ?? '',
-      startDate: DateTime.fromMillisecondsSinceEpoch(map['startDate']),
-      endDate: DateTime.fromMillisecondsSinceEpoch(map['endDate']),
+      startDate: _parseDateTime(map['startDate']),
+      endDate: _parseDateTime(map['endDate']),
       budget: map['budget']?.toDouble(),
       participants: List<String>.from(map['participants'] ?? []),
       createdBy: map['createdBy'] ?? '',
-      createdAt: DateTime.fromMillisecondsSinceEpoch(map['createdAt']),
-      updatedAt: DateTime.fromMillisecondsSinceEpoch(map['updatedAt']),
+      createdAt: _parseDateTime(map['createdAt']),
+      updatedAt: _parseDateTime(map['updatedAt']),
       status: map['status'] ?? 'draft',
     );
   }
 
+  // Méthode helper pour parser les dates depuis différents formats
+  static DateTime _parseDateTime(dynamic dateValue) {
+    if (dateValue == null) {
+      return DateTime.now();
+    }
+
+    if (dateValue is DateTime) {
+      return dateValue;
+    }
+
+    if (dateValue is String) {
+      try {
+        // Essayer de parser comme ISO 8601
+        return DateTime.parse(dateValue);
+      } catch (e) {
+        print('Erreur parsing date string: $dateValue - $e');
+        return DateTime.now();
+      }
+    }
+
+    if (dateValue is int) {
+      try {
+        // Traiter comme millisecondes
+        return DateTime.fromMillisecondsSinceEpoch(dateValue);
+      } catch (e) {
+        print('Erreur parsing date int: $dateValue - $e');
+        return DateTime.now();
+      }
+    }
+
+    print('Type de date non supporté: ${dateValue.runtimeType} - $dateValue');
+    return DateTime.now();
+  }
+
   // Constructeur pour créer un Trip depuis JSON
   factory Trip.fromJson(String jsonStr) {
     Map<String, dynamic> map = json.decode(jsonStr);