import 'package:cloud_firestore/cloud_firestore.dart';
    Future<List<Map<String, dynamic>>> getMessages() async {
  try {
    QuerySnapshot<Map<String, dynamic>> querySnapshot;

    if (userType == 'donor') {
      querySnapshot = await FirebaseFirestore.instance
          .collection('messages')
          .where('sender_id', isEqualTo: localid)
          .where('receiver_id', isEqualTo: global_id)
          .orderBy('time', descending: true)
          .get();
    } else if (userType == 'taker') {
      querySnapshot = await FirebaseFirestore.instance
          .collection('messages')
          .where('receiver_id', isEqualTo: localid)
          .where('sender_id', isEqualTo: taker_id)
          .orderBy('time', descending: true)
          .get();
    } else {
      throw Exception('Invalid user type');
    }
    List<Map<String, dynamic>> messages = querySnapshot.docs
        .map((doc) => doc.data())
        .toList();

    return messages;
  } catch (e) {
    print(e.toString());
    return [];
  }
}                      

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