Envelope/mobile/lib/models/messages.dart

import 'dart:convert';
import 'dart:typed_data';
import 'package:Envelope/models/conversation_users.dart';
import 'package:Envelope/models/conversations.dart';
import 'package:pointycastle/export.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '/utils/encryption/crypto_utils.dart';
import '/utils/encryption/aes_helper.dart';
import '/utils/storage/database.dart';
import '/utils/strings.dart';
import '/models/friends.dart';

const messageTypeSender = 'sender';
const messageTypeReceiver = 'receiver';

class Message {
  String id;
  String symmetricKey;
  String userSymmetricKey;
  String data;
  String senderId;
  String senderUsername;
  String associationKey;
  String createdAt;
  bool failedToSend;
  Message({
    required this.id,
    required this.symmetricKey,
    required this.userSymmetricKey,
    required this.data,
    required this.senderId,
    required this.senderUsername,
    required this.associationKey,
    required this.createdAt,
    required this.failedToSend,
  });


  factory Message.fromJson(Map<String, dynamic> json, RSAPrivateKey privKey) {
    var userSymmetricKey = CryptoUtils.rsaDecrypt(
        base64.decode(json['symmetric_key']),
        privKey,
    );

    var symmetricKey = AesHelper.aesDecrypt(
        userSymmetricKey,
        base64.decode(json['message_data']['symmetric_key']),
    );

    var senderId = AesHelper.aesDecrypt(
        base64.decode(symmetricKey),
        base64.decode(json['message_data']['sender_id']),
    );

    var data = AesHelper.aesDecrypt(
        base64.decode(symmetricKey),
        base64.decode(json['message_data']['data']),
    );

    return Message(
        id: json['id'],
        symmetricKey: symmetricKey,
        userSymmetricKey: base64.encode(userSymmetricKey),
        data: data,
        senderId: senderId,
        senderUsername: 'Unknown',
        associationKey: json['association_key'],
        createdAt: json['created_at'],
        failedToSend: false,
    );
  }

  Future<String> toJson(Conversation conversation, String messageDataId) async {
      final preferences = await SharedPreferences.getInstance();
      RSAPublicKey publicKey = CryptoUtils.rsaPublicKeyFromPem(preferences.getString('asymmetricPublicKey')!);

      final userSymmetricKey = AesHelper.deriveKey(generateRandomString(32));
      final symmetricKey = AesHelper.deriveKey(generateRandomString(32));

      List<Map<String, String>> messages = [];

      String id = '';

      List<ConversationUser> conversationUsers = await getConversationUsers(conversation);

      for (var i = 0; i < conversationUsers.length; i++) {
          ConversationUser user = conversationUsers[i];
          if (preferences.getString('username') == user.username) {
            id = user.id;

            messages.add({
              'message_data_id': messageDataId,
              'symmetric_key': base64.encode(CryptoUtils.rsaEncrypt(
                  userSymmetricKey,
                  publicKey,
              )),
              'association_key': user.associationKey,
            });

            continue;
          }

          Friend friend = await getFriendByFriendId(user.id);
          RSAPublicKey friendPublicKey = CryptoUtils.rsaPublicKeyFromPem(friend.asymmetricPublicKey);

          messages.add({
              'message_data_id': messageDataId,
              'symmetric_key': base64.encode(CryptoUtils.rsaEncrypt(
                  userSymmetricKey,
                  friendPublicKey,
              )),
              'association_key': user.associationKey,
          });
      }

      Map<String, String> messageData = {
        'id': messageDataId,
        'data': AesHelper.aesEncrypt(symmetricKey, Uint8List.fromList(data.codeUnits)),
        'sender_id': AesHelper.aesEncrypt(symmetricKey, Uint8List.fromList(id.codeUnits)),
        'symmetric_key': AesHelper.aesEncrypt(
            userSymmetricKey,
            Uint8List.fromList(base64.encode(symmetricKey).codeUnits),
        ),
      };

      return jsonEncode(<String, dynamic>{
        'message_data': messageData,
        'message': messages,
      });
  }

  @override
  String toString() {
    return '''


        id: $id
        data: $data
        senderId: $senderId
        senderUsername: $senderUsername
        associationKey: $associationKey
        createdAt: $createdAt
''';
  }

  Map<String, dynamic> toMap() {
    return {
      'id': id,
      'symmetric_key': symmetricKey,
      'user_symmetric_key': userSymmetricKey,
      'data': data,
      'sender_id': senderId,
      'sender_username': senderUsername,
      'association_key': associationKey,
      'created_at': createdAt,
      'failed_to_send': failedToSend ? 1 : 0,
    };
  }

}

Future<List<Message>> getMessagesForThread(Conversation conversation) async {
  final db = await getDatabaseConnection();

  final List<Map<String, dynamic>> maps = await db.rawQuery(
      '''
        SELECT * FROM messages WHERE association_key IN (
          SELECT association_key FROM conversation_users WHERE conversation_id = ?
        )
        ORDER BY created_at DESC;
      ''',
      [conversation.id]
  );

  return List.generate(maps.length, (i) {
    return Message(
        id: maps[i]['id'],
        symmetricKey: maps[i]['symmetric_key'],
        userSymmetricKey: maps[i]['user_symmetric_key'],
        data: maps[i]['data'],
        senderId: maps[i]['sender_id'],
        senderUsername: maps[i]['sender_username'],
        associationKey: maps[i]['association_key'],
        createdAt: maps[i]['created_at'],
        failedToSend: maps[i]['failed_to_send'] == 1,
    );
  });

}