ATMSystem.java

import java.io.*;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.*;

/**
 * 🏧 ATM Sistemi
 * Kavramlar: OOP, File I/O, HashMap, Exception Handling, Enum
 */

enum TransactionType {
    DEPOSIT, WITHDRAW, TRANSFER, BALANCE_CHECK
}

class ATMTransaction {
    private TransactionType type;
    private double amount;
    private double balanceAfter;
    private LocalDateTime dateTime;

    public ATMTransaction(TransactionType type, double amount, double balanceAfter) {
        this.type = type;
        this.amount = amount;
        this.balanceAfter = balanceAfter;
        this.dateTime = LocalDateTime.now();
    }

    @Override
    public String toString() {
        DateTimeFormatter fmt = DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm:ss");
        return String.format("%s | %-15s | Miktar: %8.2f TL | Bakiye: %8.2f TL",
            dateTime.format(fmt), type, amount, balanceAfter);
    }
}

class ATMAccount {
    private String cardNumber;
    private String pin;
    private String ownerName;
    private double balance;
    private boolean isLocked;
    private int failedAttempts;
    private List<ATMTransaction> transactions;
    private static final int MAX_ATTEMPTS = 3;

    public ATMAccount(String cardNumber, String pin, String ownerName, double balance) {
        this.cardNumber = cardNumber;
        this.pin = pin;
        this.ownerName = ownerName;
        this.balance = balance;
        this.isLocked = false;
        this.failedAttempts = 0;
        this.transactions = new ArrayList<>();
    }

    public boolean validatePin(String enteredPin) {
        if (isLocked) throw new IllegalStateException("❌ Kart bloke edilmiştir! Bankanızla iletişime geçin.");

        if (this.pin.equals(enteredPin)) {
            failedAttempts = 0;
            return true;
        } else {
            failedAttempts++;
            if (failedAttempts >= MAX_ATTEMPTS) {
                isLocked = true;
                throw new IllegalStateException("❌ 3 hatalı giriş! Kartınız bloke edildi.");
            }
            throw new IllegalArgumentException("❌ Hatalı PIN! " + (MAX_ATTEMPTS - failedAttempts) + " hakkınız kaldı.");
        }
    }

    public void deposit(double amount) {
        if (amount <= 0) throw new IllegalArgumentException("❌ Geçersiz miktar!");
        if (amount > 10000) throw new IllegalArgumentException("❌ Tek seferde max 10.000 TL yatırabilirsiniz!");
        balance += amount;
        transactions.add(new ATMTransaction(TransactionType.DEPOSIT, amount, balance));
        System.out.printf("✅ %.2f TL yatırıldı. Güncel bakiye: %.2f TL%n", amount, balance);
    }

    public void withdraw(double amount) {
        if (amount <= 0) throw new IllegalArgumentException("❌ Geçersiz miktar!");
        if (amount > 5000) throw new IllegalArgumentException("❌ Günlük çekim limiti 5.000 TL!");
        if (amount > balance) throw new IllegalStateException("❌ Yetersiz bakiye!");
        balance -= amount;
        transactions.add(new ATMTransaction(TransactionType.WITHDRAW, amount, balance));
        System.out.printf("✅ %.2f TL çekildi. Güncel bakiye: %.2f TL%n", amount, balance);
    }

    public void transfer(ATMAccount target, double amount) {
        this.withdraw(amount);
        target.balance += amount;
        target.transactions.add(new ATMTransaction(TransactionType.DEPOSIT, amount, target.balance));
        System.out.printf("✅ %s hesabına %.2f TL transfer edildi.%n", target.ownerName, amount);
    }

    public void printMiniStatement() {
        System.out.println("\n======= MİNİ EKSTRE =======");
        System.out.println("Kart: **** **** **** " + cardNumber.substring(12));
        System.out.println("Sahip: " + ownerName);
        System.out.printf("Bakiye: %.2f TL%n", balance);
        System.out.println("--- Son 5 İşlem ---");
        int start = Math.max(0, transactions.size() - 5);
        transactions.subList(start, transactions.size()).forEach(System.out::println);
        System.out.println("===========================\n");
    }

    public void saveTransactionsToFile() throws IOException {
        String filename = cardNumber.substring(12) + "_transactions.txt";
        try (BufferedWriter w = new BufferedWriter(new FileWriter(filename, true))) {
            for (ATMTransaction t : transactions) {
                w.write(t.toString());
                w.newLine();
            }
        }
        System.out.println("✅ İşlemler " + filename + " dosyasına kaydedildi.");
    }

    public String getCardNumber() { return cardNumber; }
    public String getOwnerName()  { return ownerName; }
    public double getBalance()    { return balance; }
    public boolean isLocked()     { return isLocked; }
}

class ATM {
    private Map<String, ATMAccount> accounts = new HashMap<>();
    private ATMAccount currentSession = null;

    public void addAccount(ATMAccount account) {
        accounts.put(account.getCardNumber(), account);
    }

    public boolean insertCard(String cardNumber) {
        ATMAccount account = accounts.get(cardNumber);
        if (account == null) { System.out.println("❌ Kart bulunamadı!"); return false; }
        if (account.isLocked()) { System.out.println("❌ Bu kart bloke edilmiştir!"); return false; }
        currentSession = account;
        System.out.println("✅ Kart takıldı. Hoş geldiniz, " + account.getOwnerName() + "!");
        return true;
    }

    public boolean enterPin(String pin) {
        if (currentSession == null) { System.out.println("❌ Önce kart takın!"); return false; }
        try {
            return currentSession.validatePin(pin);
        } catch (Exception e) {
            System.out.println(e.getMessage());
            return false;
        }
    }

    public void performDeposit(double amount) {
        try { currentSession.deposit(amount); }
        catch (Exception e) { System.out.println(e.getMessage()); }
    }

    public void performWithdraw(double amount) {
        try { currentSession.withdraw(amount); }
        catch (Exception e) { System.out.println(e.getMessage()); }
    }

    public void performTransfer(String targetCard, double amount) {
        ATMAccount target = accounts.get(targetCard);
        if (target == null) { System.out.println("❌ Hedef hesap bulunamadı!"); return; }
        try { currentSession.transfer(target, amount); }
        catch (Exception e) { System.out.println(e.getMessage()); }
    }

    public void ejectCard() {
        if (currentSession != null) {
            try { currentSession.saveTransactionsToFile(); }
            catch (IOException e) { System.out.println("Log hatası: " + e.getMessage()); }
            System.out.println("👋 Kartınızı alınız. Güle güle, " + currentSession.getOwnerName() + "!");
            currentSession = null;
        }
    }

    public ATMAccount getCurrentSession() { return currentSession; }
}

public class ATMSystem {
    public static void main(String[] args) {
        ATM atm = new ATM();

        atm.addAccount(new ATMAccount("1234567890123456", "1234", "Bengü Gedik", 5000.0));
        atm.addAccount(new ATMAccount("9876543210987654", "5678", "Ahmet Yılmaz", 2000.0));

        System.out.println("=== ATM SİMÜLASYONU ===\n");

        // Senaryo 1: Normal işlem
        atm.insertCard("1234567890123456");
        atm.enterPin("0000"); // hatalı
        atm.enterPin("1234"); // doğru
        atm.performDeposit(1000);
        atm.performWithdraw(500);
        atm.performTransfer("9876543210987654", 200);
        atm.getCurrentSession().printMiniStatement();
        atm.ejectCard();

        System.out.println("\n--- Senaryo 2: Kart Bloke ---");
        atm.insertCard("9876543210987654");
        atm.enterPin("0000");
        atm.enterPin("1111");
        atm.enterPin("2222"); // 3. hatalı → bloke
        atm.insertCard("9876543210987654"); // bloke kontrolü
    }
}