Main.java

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;

public class Main {

    static class Transaction {
        String type;
        double amount;
        double balanceAfter;
        LocalDateTime timestamp;

        Transaction(String type, double amount, double balanceAfter) {
            this.type = type;
            this.amount = amount;
            this.balanceAfter = balanceAfter;
            this.timestamp = LocalDateTime.now();
        }

        @Override
        public String toString() {
            DateTimeFormatter fmt = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
            return String.format("[%s] %-8s $%-10.2f Balance after: $%.2f",
                    timestamp.format(fmt), type, amount, balanceAfter);
        }
    }

    static abstract class Account {
        String accountNumber;
        String ownerName;
        double balance;
        List<Transaction> history = new ArrayList<>();

        Account(String accountNumber, String ownerName, double balance) {
            this.accountNumber = accountNumber;
            this.ownerName = ownerName;
            this.balance = balance;
        }

        abstract String getAccountType();

        abstract double getMinimumBalance();

        void deposit(double amount) {
            balance += amount;
            history.add(new Transaction("DEPOSIT", amount, balance));
        }

        void withdraw(double amount) {
            balance -= amount;
            history.add(new Transaction("WITHDRAW", amount, balance));
        }
    }

    static class SavingsAccount extends Account {
        SavingsAccount(String accountNumber, String ownerName, double balance) {
            super(accountNumber, ownerName, balance);
        }

        @Override
        String getAccountType() {
            return "Savings";
        }

        @Override
        double getMinimumBalance() {
            return 100;
        }
    }

    static class CheckingAccount extends Account {
        CheckingAccount(String accountNumber, String ownerName, double balance) {
            super(accountNumber, ownerName, balance);
        }

        @Override
        String getAccountType() {
            return "Checking";
        }

        @Override
        double getMinimumBalance() {
            return -200;
        }
    }

    static Map<String, Account> accounts = new HashMap<>();
    static Scanner scanner = new Scanner(System.in);
    static int nextAccountNumber = 1001;

    public static void main(String[] args) {
        boolean running = true;
        while (running) {
            printMenu();
            String choice = scanner.nextLine().trim();
            switch (choice) {
                case "1":
                    createAccount();
                    break;
                case "2":
                    viewAccountDetails();
                    break;
                case "3":
                    deposit();
                    break;
                case "4":
                    withdraw();
                    break;
                case "5":
                    viewTransactionHistory();
                    break;
                case "6":
                    running = false;
                    System.out.println("Goodbye!");
                    break;
                default:
                    System.out.println("Invalid option. Please try again.");
            }
        }
        scanner.close();
    }

    static void printMenu() {
        System.out.println("\n===== Console Bank =====");
        System.out.println("1. Create account");
        System.out.println("2. View account details");
        System.out.println("3. Deposit money");
        System.out.println("4. Withdraw money");
        System.out.println("5. View transaction history");
        System.out.println("6. Exit");
        System.out.print("Choose an option: ");
    }

    static void createAccount() {
        System.out.print("Enter owner name: ");
        String name = scanner.nextLine().trim();
        if (name.isEmpty()) {
            System.out.println("Name cannot be empty.");
            return;
        }

        String type;
        while (true) {
            System.out.print("Enter account type (checking/savings): ");
            type = scanner.nextLine().trim().toLowerCase();
            if (type.equals("checking") || type.equals("savings")) {
                break;
            }
            System.out.println("Please enter 'checking' or 'savings'.");
        }

        double initialDeposit = 0;
        while (true) {
            System.out.print("Enter initial deposit amount (0 or more): ");
            try {
                initialDeposit = Double.parseDouble(scanner.nextLine().trim());
                if (initialDeposit < 0) {
                    System.out.println("Amount cannot be negative.");
                    continue;
                }
                break;
            } catch (NumberFormatException e) {
                System.out.println("Please enter a valid number.");
            }
        }

        String accountNumber = String.valueOf(nextAccountNumber++);
        Account account = type.equals("savings")
                ? new SavingsAccount(accountNumber, name, 0)
                : new CheckingAccount(accountNumber, name, 0);
        if (initialDeposit > 0) {
            account.deposit(initialDeposit);
        }
        accounts.put(accountNumber, account);

        System.out.println("Account created successfully!");
        System.out.println("Your account number is: " + accountNumber);
    }

    static Account findAccount() {
        System.out.print("Enter account number: ");
        String accountNumber = scanner.nextLine().trim();
        Account account = accounts.get(accountNumber);
        if (account == null) {
            System.out.println("Account not found.");
        }
        return account;
    }

    static void viewAccountDetails() {
        Account account = findAccount();
        if (account == null) return;

        System.out.println("\n--- Account Details ---");
        System.out.println("Account Number: " + account.accountNumber);
        System.out.println("Owner Name: " + account.ownerName);
        System.out.println("Account Type: " + account.getAccountType());
        System.out.printf("Balance: $%.2f%n", account.balance);
    }

    static void deposit() {
        Account account = findAccount();
        if (account == null) return;

        System.out.print("Enter amount to deposit: ");
        double amount;
        try {
            amount = Double.parseDouble(scanner.nextLine().trim());
        } catch (NumberFormatException e) {
            System.out.println("Please enter a valid number.");
            return;
        }

        if (amount <= 0) {
            System.out.println("Deposit amount must be positive.");
            return;
        }

        account.deposit(amount);
        System.out.printf("Deposit successful. New balance: $%.2f%n", account.balance);
    }

    static void withdraw() {
        Account account = findAccount();
        if (account == null) return;

        System.out.print("Enter amount to withdraw: ");
        double amount;
        try {
            amount = Double.parseDouble(scanner.nextLine().trim());
        } catch (NumberFormatException e) {
            System.out.println("Please enter a valid number.");
            return;
        }

        if (amount <= 0) {
            System.out.println("Withdrawal amount must be positive.");
            return;
        }

        if (account.balance - amount < account.getMinimumBalance()) {
            System.out.printf("Insufficient funds. %s accounts cannot go below $%.2f.%n",
                    account.getAccountType(), account.getMinimumBalance());
            return;
        }

        account.withdraw(amount);
        System.out.printf("Withdrawal successful. New balance: $%.2f%n", account.balance);
    }

    static void viewTransactionHistory() {
        Account account = findAccount();
        if (account == null) return;

        if (account.history.isEmpty()) {
            System.out.println("No transactions yet.");
            return;
        }

        System.out.println("\n--- Transaction History for " + account.accountNumber + " ---");
        for (Transaction t : account.history) {
            System.out.println(t);
        }
    }
}