Critical fixes modernization

EBanking.DataAccess/DatabaseAccess.cs

@@ -1,7 +1,23 @@
+using System.Configuration;
+
 namespace EBanking.DataAccess
 {
-    public class DatabaseAccess
+    public static class DatabaseAccess
     {
-        private const string _connectionString = @"Data Source = .;Initial Catalog=eBanking;Integrated Security=True";
+        private const string ConnectionStringName = "EBankingDb";
+
+        private static readonly Lazy<string> _connectionString = new(() =>
+        {
+            var configString = ConfigurationManager.ConnectionStrings[ConnectionStringName]?.ConnectionString;
+            if (string.IsNullOrWhiteSpace(configString))
+            {
+                throw new InvalidOperationException(
+                    $"Connection string '{ConnectionStringName}' was not found in configuration. " +
+                    "Ensure App.config defines <connectionStrings><add name=\"" + ConnectionStringName + "\" ... /></connectionStrings>.");
+            }
+            return configString;
+        });
+
+        public static string ConnectionString => _connectionString.Value;
     }
 }

EBanking.DataAccess/EBanking.DataAccess.csproj

@@ -7,6 +7,8 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="BCrypt.Net-Next" Version="4.0.3" />
+    <PackageReference Include="System.Configuration.ConfigurationManager" Version="6.0.1" />
     <PackageReference Include="System.Data.SqlClient" Version="4.8.3" />
   </ItemGroup>
 

EBanking.DataAccess/Models/Account.cs

@@ -4,7 +4,7 @@ public class Account
     {
         public string AccountNumber { get; set; }
         public int UserId { get; set; }
-        public double Balance { get; set; }
+        public decimal Balance { get; set; }
         public string Type { get; set; }
         public string Currency { get; set; }
         public DateTime DateCreated { get; set; }

EBanking.DataAccess/Models/CurrencyExchange.cs

@@ -3,6 +3,6 @@ namespace EBanking.DataAccess.Models
     public class CurrencyExchange
     {
         public string Currency { get; set; }
-        public double Value { get; set; }
+        public decimal Value { get; set; }
     }
 }

EBanking.DataAccess/Models/Transaction.cs

@@ -5,8 +5,8 @@ public class Transaction
         public int TransactionId { get; set; }
         public string AccountNumber { get; set; }
         public string CardNumber { get; set; }
-        public double Amount { get; set; }
-        public double BalanceAfterTransaction { get; set; }
+        public decimal Amount { get; set; }
+        public decimal BalanceAfterTransaction { get; set; }
         public DateTime Date { get; set; }
         public string SecondaryPartyName { get; set; }
         public string SecondaryPartyAccountNumber { get; set; }

EBanking.DataAccess/Repositories/IAccountRepository.cs

@@ -6,8 +6,8 @@ public interface IAccountRepository
     {
         void CreateAccount(Account model);
         List<Account> GetAccountsByUserId(int userId);
-        Task<Account> GetAccountByAccountNumber(string accountNumber);
-        void UpdateBalance(double balance, string accountNumber);
+        Account GetAccountByAccountNumber(string accountNumber);
+        void UpdateBalance(decimal balance, string accountNumber);
         bool IsValidAccount(string accountNumber);
     }
 }

EBanking.DataAccess/Repositories/ITransactionRepository.cs

@@ -6,5 +6,19 @@ public interface ITransactionRepository
     {
         int CreateTransaction(Transaction transaction);
         List<Transaction> GetTransactionsByAccountNumber(string accountNumber);
+        void ExecuteTransfer(
+            string payerAccountNumber,
+            string recipientAccountNumber,
+            decimal amount,
+            string recipientName,
+            string payerFullName,
+            DateTime occurredAt);
+        void ExecuteExchange(
+            string sourceAccountNumber,
+            string destinationAccountNumber,
+            decimal sourceAmount,
+            decimal destinationAmount,
+            string userFullName,
+            DateTime occurredAt);
     }
 }

EBanking.DataAccess/Repositories/Implementation/AccountRepository.cs

@@ -1,15 +1,14 @@
 using EBanking.DataAccess.Models;
+using System.Data;
 using System.Data.SqlClient;
 
 namespace EBanking.DataAccess.Repositories.Implementation
 {
     public class AccountRepository : IAccountRepository
     {
-        private const string _connectionString = @"Data Source = .\SQLEXPRESS;Initial Catalog=EBankingSystem;Integrated Security=True";
-
         public void CreateAccount(Account model)
         {
-            using (SqlConnection sqlConnection = new SqlConnection(_connectionString))
+            using (SqlConnection sqlConnection = new SqlConnection(DatabaseAccess.ConnectionString))
             {
                 sqlConnection.Open();
 
@@ -19,21 +18,21 @@ public void CreateAccount(Account model)
                         "VALUES(@accountNumber, @userId, @balance, @currency, @type, @dateCreated)";
                     sqlCommand.Parameters.AddWithValue("@accountNumber", model.AccountNumber);
                     sqlCommand.Parameters.AddWithValue("@userId", model.UserId);
-                    sqlCommand.Parameters.AddWithValue("@balance", model.Balance);
+                    sqlCommand.Parameters.Add(new SqlParameter("@balance", SqlDbType.Decimal) { Precision = 18, Scale = 2, Value = model.Balance });
                     sqlCommand.Parameters.AddWithValue("@currency", model.Currency);
                     sqlCommand.Parameters.AddWithValue("@type", model.Type);
                     sqlCommand.Parameters.AddWithValue("@dateCreated", model.DateCreated);
 
-                    sqlCommand.ExecuteScalar();
+                    sqlCommand.ExecuteNonQuery();
                 }
             }
         }
 
-        public async Task<Account> GetAccountByAccountNumber(string accountNumber)
+        public Account GetAccountByAccountNumber(string accountNumber)
         {
             Account account = new Account();
 
-            using (SqlConnection sqlConnection = new SqlConnection(_connectionString))
+            using (SqlConnection sqlConnection = new SqlConnection(DatabaseAccess.ConnectionString))
             {
                 sqlConnection.Open();
 
@@ -48,7 +47,7 @@ public async Task<Account> GetAccountByAccountNumber(string accountNumber)
                         {
                             account.UserId = (int)reader["userId"];
                             account.AccountNumber = reader["accountNumber"] as string;
-                            account.Balance = decimal.ToDouble((decimal)reader["balance"]);
+                            account.Balance = (decimal)reader["balance"];
                             account.DateCreated = (DateTime)reader["dateCreated"];
                             account.Type = reader["type"] as string;
                             account.Currency = reader["currency"] as string;
@@ -64,7 +63,7 @@ public List<Account> GetAccountsByUserId(int userId)
         {
             List<Account> accounts = new List<Account>();
 
-            using (SqlConnection sqlConnection = new SqlConnection(_connectionString))
+            using (SqlConnection sqlConnection = new SqlConnection(DatabaseAccess.ConnectionString))
             {
                 sqlConnection.Open();
 
@@ -81,7 +80,7 @@ public List<Account> GetAccountsByUserId(int userId)
                             {
                                 UserId = (int)reader["userId"],
                                 AccountNumber = reader["accountNumber"] as string,
-                                Balance = decimal.ToDouble((decimal)reader["balance"]),
+                                Balance = (decimal)reader["balance"],
                                 DateCreated = (DateTime)reader["dateCreated"],
                                 Type = reader["type"] as string,
                                 Currency = reader["currency"] as string,
@@ -103,37 +102,33 @@ public List<Account> GetAccountsByUserId(int userId)
 
         public bool IsValidAccount(string accountNumber)
         {
-            object accountId;
-
-            using (SqlConnection sqlConnection = new SqlConnection(_connectionString))
+            using (SqlConnection sqlConnection = new SqlConnection(DatabaseAccess.ConnectionString))
             {
                 sqlConnection.Open();
 
                 using (SqlCommand sqlCommand = sqlConnection.CreateCommand())
                 {
-                    sqlCommand.CommandText = "SELECT * FROM Account WHERE accountNumber = @accountNumber";
+                    sqlCommand.CommandText = "SELECT 1 FROM Account WHERE accountNumber = @accountNumber";
                     sqlCommand.Parameters.AddWithValue("@accountNumber", accountNumber);
 
-                    accountId = sqlCommand.ExecuteScalar();
+                    return sqlCommand.ExecuteScalar() is not null;
                 }
             }
-
-            return accountId as string is not null;
         }
 
-        public void UpdateBalance(double balance, string accountNumber)
+        public void UpdateBalance(decimal balance, string accountNumber)
         {
-            using (SqlConnection sqlConnection = new SqlConnection(_connectionString))
+            using (SqlConnection sqlConnection = new SqlConnection(DatabaseAccess.ConnectionString))
             {
                 sqlConnection.Open();
 
                 using (SqlCommand sqlCommand = sqlConnection.CreateCommand())
                 {
                     sqlCommand.CommandText = "UPDATE Account SET balance = @balance WHERE accountNumber = @accountNumber";
-                    sqlCommand.Parameters.AddWithValue("@balance", balance);
+                    sqlCommand.Parameters.Add(new SqlParameter("@balance", SqlDbType.Decimal) { Precision = 18, Scale = 2, Value = balance });
                     sqlCommand.Parameters.AddWithValue("@accountNumber", accountNumber);
 
-                    sqlCommand.ExecuteScalar();
+                    sqlCommand.ExecuteNonQuery();
                 }
             }
         }

EBanking.DataAccess/Repositories/Implementation/CurrencyExchangeRepository.cs

@@ -5,13 +5,11 @@ namespace EBanking.DataAccess.Repositories.Implementation
 {
     public class CurrencyExchangeRepository : ICurrencyExchangeRepository
     {
-        private const string _connectionString = @"Data Source = .\SQLEXPRESS;Initial Catalog=EBankingSystem;Integrated Security=True";
-
         public List<CurrencyExchange> GetExchangeRatesByCurrency(string currency)
         {
             List<CurrencyExchange> exchangeRates = new List<CurrencyExchange>();
 
-            using (SqlConnection sqlConnection = new SqlConnection(_connectionString))
+            using (SqlConnection sqlConnection = new SqlConnection(DatabaseAccess.ConnectionString))
             {
                 sqlConnection.Open();
 
@@ -26,7 +24,7 @@ public List<CurrencyExchange> GetExchangeRatesByCurrency(string currency)
                             exchangeRates.Add(new CurrencyExchange
                             {
                                 Currency = reader["currency"] as string,
-                                Value = decimal.ToDouble((decimal)reader["value"]),
+                                Value = (decimal)reader["value"],
                             });
                         }
                     }