Banking system

CT1/banking.cpp

@@ -0,0 +1,275 @@
+#include <stdexcept>
+#include <cstdint>
+#include <map>
+#include <iostream>
+#include <limits>
+#include <sstream>
+
+#define RESET       "\033[0m"
+#define RED         "❌ \033[31m"
+#define GREEN       "✅ \033[32m"
+#define BOLDWHITE   "\033[1m\033[37m"
+
+using money_t   = int64_t;
+using account_n = std::string;
+constexpr size_t ACCOUNT_LEN = 4;
+
+class Bank;
+class Account;
+
+enum class MenuState {
+    MENU,
+    VIEW = 1,
+    ADD_ACCOUNT = 2,
+    TRANSFER = 3,
+    DEPOSIT = 4,
+    WITHDRAW = 5,
+    EXIT = 6,
+};
+
+//######################################################
+
+class BankingException : public std::exception {
+public: const char* what() const noexcept override {
+        return "Internal exception!";
+    }
+};
+class InsufficientFundsException : public BankingException {
+    const char* what() const noexcept override {
+        return "Insufficient funds!";
+    }
+};
+class InvalidAmountException : public BankingException {
+    const char* what() const noexcept override {
+        return "Invalid amount!";
+    }
+};
+class InvalidAccountException : public BankingException {
+    const char* what() const noexcept override {
+        return "Invalid account number!";
+    }
+};
+class InvalidArgument : public BankingException {
+    const char* what() const noexcept override {
+        return "Invalid argument!";
+    }
+};
+
+//######################################################
+
+std::istream& operator>>(std::istream& is, MenuState& state) {
+    int a;
+    if (!(is >> a)) {
+        is.clear();
+        is.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
+        throw InvalidArgument();
+    }
+
+    state = static_cast<MenuState>(a);
+
+    return is;
+}
+
+template <class T>
+T getInput(std::istream& is) {
+    T n;
+    if (!(is >> n) || n < 0) {
+        is.clear();
+        is.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
+        throw InvalidAmountException();
+    }
+
+    return n;
+}
+
+template <>
+account_n getInput<account_n>(std::istream& is) {
+    std::string s;
+    int64_t n;
+
+    if (!(is >> s)) {
+        is.clear();
+        is.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
+        throw InvalidAmountException();
+    }
+
+    std::istringstream iss(s);
+    if (!(iss >> n) || n < 0 || s.size() != ACCOUNT_LEN) {
+        is.clear();
+        is.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
+        throw InvalidAmountException();
+    }
+
+    return s;
+}
+
+constexpr const char* MENU_MSG = "=== Bank Account Management System ===\n1. View balance\n2. Create account\n3. Transfer funds\n4. Deposit funds\n5. Withdraw funds\n6. Exit\n";
+
+//######################################################
+
+class Account{
+    private:
+        money_t m_balance;
+    public:
+        Account(money_t m = 0) : m_balance(m) {}
+        ~Account() = default;
+
+        money_t getBalance() {
+            return m_balance;
+        }
+
+        bool deposit(money_t m) {
+            if (m < 1) throw InvalidAmountException();
+            if (m + m_balance < m_balance) throw std::overflow_error("Account overflow");
+            m_balance += m;
+            return true;
+        }
+
+        bool withdraw(money_t m) {
+            if (m > m_balance) throw InsufficientFundsException();
+            m_balance -= m;
+            return true;
+        } 
+
+        void setBalance(money_t m) {
+            m_balance = m;
+        }
+};
+
+//######################################################
+
+class Bank
+{
+private:
+    std::map<account_n, Account> db;
+public:
+    Bank()  = default;
+    ~Bank() = default;
+
+    account_n addAccount(account_n n = 0, money_t b = 0) {
+        if (n == "0000") n = db.size(); // generate account number
+        auto it = db.emplace(n, Account(b));
+        if( !it.second ) throw InvalidAccountException();
+        return it.first->first;
+    }
+
+    bool transfer(account_n from, account_n to, money_t amount) {
+        auto itFrom = db.find(from);
+        auto itTo = db.find(to);
+        money_t fromState;
+
+        if (itFrom == db.end() || itTo == db.end() || itFrom == itTo) throw InvalidAccountException();
+
+        fromState = itFrom->second.getBalance();
+        itFrom->second.withdraw(amount);
+        
+        try {
+            itTo->second.deposit(amount);
+        } catch(std::exception& e) {
+            itFrom->second.setBalance(fromState);
+            throw;
+        }
+
+        return true;
+    }
+
+    bool deposit(account_n a, money_t m) {
+        auto it = db.find(a);
+        if (it == db.end()) throw InvalidAccountException();
+        return it->second.deposit(m);
+    }
+
+    bool withdraw(account_n a, money_t m) {
+        auto it = db.find(a);
+        if (it == db.end()) throw InvalidAccountException();
+        return it->second.withdraw(m);
+    }
+
+    money_t getBalance(account_n a) {
+        auto it = db.find(a);
+        if (it == db.end()) throw InvalidAccountException();
+        return it->second.getBalance();
+    }
+};
+
+//######################################################
+
+int main(int ragc, char* argv[]) {
+    std::ostream& os = std::cout;
+    std::istream& is = std::cin;
+
+    MenuState state = MenuState::MENU;
+
+    Bank b;
+    for (;;) {
+        try {
+            account_n from = "0000";
+            account_n to   = "0000";
+            money_t amount = 0;
+
+            os << BOLDWHITE << MENU_MSG << RESET;
+            is >> state;
+
+            switch (state) {
+            case MenuState::VIEW :
+                os << "Account number: ";
+                from = getInput<account_n>(is);
+                amount = b.getBalance(from);
+                os << GREEN << "Balance: " << "$" << amount << "\n" << RESET;
+                break;
+
+            case MenuState::TRANSFER :
+                os << "From account: ";
+                from = getInput<account_n>(is);
+                os << "To account: ";
+                to = getInput<account_n>(is);
+                os << "Amount: $";
+                amount = getInput<money_t>(is);
+                b.transfer(from, to, amount);
+                os << GREEN << "$" << amount << " transfered from " << from << " to " << to << "\n" << RESET;
+                break;
+
+            case MenuState::ADD_ACCOUNT :
+                os << "New account number (0 for auto): ";
+                from = getInput<account_n>(is);
+                os << "Starting balance: $";
+                amount = getInput<money_t>(is);
+                from = b.addAccount(from, amount);
+                os << GREEN << "Account " << from << " created with $" << amount << RESET;
+                break;
+
+            case MenuState::DEPOSIT :
+                os << "To account: ";
+                to = getInput<account_n>(is);
+                os << "Amount: $";
+                amount = getInput<money_t>(is);
+                b.deposit(to, amount);
+                os << GREEN << "$" << amount << " deposited\n" << RESET;
+                break;
+
+            case MenuState::WITHDRAW :
+                os << "From account: ";
+                from = getInput<account_n>(is);
+                os << "Amount: $";
+                amount = getInput<money_t>(is);
+                b.withdraw(from, amount);
+                os << GREEN << "$" << amount << " withdrawed\n" << RESET;
+                break;
+
+            case MenuState::EXIT :
+                os << "Exiting...\n";
+                return EXIT_SUCCESS;
+                break;
+
+            case MenuState::MENU :
+            default:
+                throw InvalidArgument();
+            }
+        } catch (BankingException& e) {
+            os << RED << e.what() << RESET;
+            // return EXIT_FAILURE;
+        }
+        state = MenuState::MENU;
+        os << "\n\n";
+    }
+}