src/Main.java

@@ -1,5 +1,19 @@
+import me.teridax.jcash.gui.login.LoginView;
+
+import javax.swing.*;
+
 public class Main {
+
     public static void main(String[] args) {
-        System.out.println("Hello world!");
+        SwingUtilities.invokeLater(() -> {
+          //  Loader.load();
+
+            var window = new JFrame();
+            window.setTitle("Bankautomat");
+            window.setLocationByPlatform(true);
+            window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+            window.add(new LoginView());
+            window.setVisible(true);
+        });
     }
 }

src/me/teridax/jcash/banking/Bank.java

@@ -56,4 +56,15 @@ public final class Bank {
 
         return blz;
     }
+
+    public Optional<Account> getAccount(int iban) {
+        for (var owner : this.accounts.entrySet()) {
+            for (var account : owner.getValue()) {
+                if (account.getIban() == iban) {
+                    return Optional.of(account);
+                }
+            }
+        }
+        return Optional.empty();
+    }
 }

src/me/teridax/jcash/banking/BankingManagementSystem.java

@@ -54,4 +54,8 @@ public final class BankingManagementSystem {
             throw new IllegalArgumentException("Could not parse file " + file, e);
         }
     }
+
+    public Optional<Bank> getBank(String blz) {
+        return this.banks.stream().filter(b -> b.getBlz().equals(blz)).findFirst();
+    }
 }

src/me/teridax/jcash/gui/Loader.java

@@ -0,0 +1,30 @@
+package me.teridax.jcash.gui;
+
+import me.teridax.jcash.banking.BankingManagementSystem;
+
+import javax.swing.*;
+import javax.swing.filechooser.FileNameExtensionFilter;
+
+public class Loader {
+
+    private static final FileNameExtensionFilter FILE_FILTER = new FileNameExtensionFilter("Comma separated value spreadsheet", "csv", "CSV");
+
+    public static BankingManagementSystem load() throws IllegalStateException {
+        var fileChooser = new JFileChooser();
+        fileChooser.setMultiSelectionEnabled(false);
+        fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
+        fileChooser.setFileFilter(FILE_FILTER);
+        fileChooser.setDialogType(JFileChooser.OPEN_DIALOG);
+        fileChooser.setAcceptAllFileFilterUsed(false);
+
+        if (fileChooser.showDialog(null, "Load database") == JFileChooser.APPROVE_OPTION) {
+            try {
+                return BankingManagementSystem.loadFromCsv(fileChooser.getSelectedFile().toPath());
+            } catch (Exception e) {
+                throw new IllegalStateException("Unable to load database", e);
+            }
+        }
+
+        throw new IllegalStateException("No file selected");
+    }
+}

src/me/teridax/jcash/gui/login/LoginController.java

@@ -0,0 +1,58 @@
+package me.teridax.jcash.gui.login;
+
+import me.teridax.jcash.banking.Account;
+import me.teridax.jcash.banking.BankingManagementSystem;
+
+import java.awt.event.ActionEvent;
+import java.util.Optional;
+
+public class LoginController {
+
+    private LoginView view;
+    private LoginData data;
+
+    private Optional<Account> account;
+
+    public LoginController(BankingManagementSystem bms) {
+        this.view = new LoginView();
+        this.data = new LoginData(bms);
+        this.account = Optional.empty();
+
+        addActionListeners();
+    }
+
+    private void addActionListeners() {
+        this.view.getLogin().addActionListener(this::login);
+    }
+
+    private Optional<Integer> getIban() {
+        try {
+            var iban = this.view.getIban().getText();
+            return Optional.of(Integer.parseUnsignedInt(iban));
+        } catch (NumberFormatException e) {
+            return Optional.empty();
+        }
+    }
+    private Optional<Integer> getPin() {
+        try {
+            var iban = this.view.getPin().getPassword();
+            return Optional.of(Integer.parseUnsignedInt(new String(iban)));
+        } catch (NumberFormatException e) {
+            return Optional.empty();
+        }
+    }
+
+    private void login(ActionEvent ignored) {
+        var blz = this.view.getBlz().getText();
+        var iban = this.getIban();
+        if (iban.isEmpty()) {
+            return;
+        }
+        var pin = this.getPin();
+        if (pin.isEmpty()) {
+            return;
+        }
+
+        this.account = this.data.authenticateAccount(blz, iban.get(), pin.get());
+    }
+}

src/me/teridax/jcash/gui/login/LoginData.java

@@ -0,0 +1,24 @@
+package me.teridax.jcash.gui.login;
+
+import me.teridax.jcash.banking.Account;
+import me.teridax.jcash.banking.BankingManagementSystem;
+
+import java.util.Optional;
+
+public class LoginData {
+
+    private final BankingManagementSystem bms;
+
+    public LoginData(BankingManagementSystem bms) {
+        this.bms = bms;
+    }
+
+    public Optional<Account> authenticateAccount(String blz, int iban, int pin) {
+        var optionalBank = bms.getBank(blz);
+        if (optionalBank.isEmpty())
+            return Optional.empty();
+
+        var account = optionalBank.get().getAccount(iban);
+        return account.filter(value -> value.getPin() == pin);
+    }
+}

src/me/teridax/jcash/gui/login/LoginView.java

@@ -0,0 +1,75 @@
+package me.teridax.jcash.gui.login;
+
+import javax.swing.*;
+import java.awt.*;
+
+public class LoginView extends JPanel {
+
+    private final JTextField blz;
+    private final JTextField iban;
+    private final JPasswordField pin;
+    private final JButton login;
+
+    public LoginView() {
+        this.blz = new JTextField();
+        this.iban = new JTextField();
+        this.pin = new JPasswordField();
+        this.login = new JButton("Login");
+
+        setLayout(new BorderLayout(16, 16));
+        var content = new JPanel();
+        this.setBorder(BorderFactory.createEmptyBorder(8,8,8,8));
+        add(new JScrollPane(content), BorderLayout.CENTER);
+        add(new JLabel("Bankautomat"), BorderLayout.NORTH);
+
+        var layout = new GridBagLayout();
+        var constraints = new GridBagConstraints();
+        content.setLayout(layout);
+
+        constraints.gridwidth = 4;
+
+        constraints.insets = new Insets(12,12,12,12);
+
+        addInputRow(constraints, content, blz, 1, "BLZ");
+        addInputRow(constraints, content, iban, 2, "Kontonummer");
+        addInputRow(constraints, content, pin, 3, "Passwort");
+
+        constraints.gridy = 4;
+        constraints.anchor = GridBagConstraints.PAGE_END;
+        constraints.weightx = 0;
+        constraints.fill = GridBagConstraints.NONE;
+        constraints.insets = new Insets(12,12,12,12);
+        content.add(login, constraints);
+    }
+
+    private void addInputRow(GridBagConstraints constraints, JComponent target, JComponent comp, int row, String name) {
+        constraints.gridwidth = 1;
+        constraints.gridx = 1;
+        constraints.gridy = row;
+        constraints.weightx = 0;
+        constraints.fill = GridBagConstraints.HORIZONTAL;
+        target.add(new JLabel(name, SwingConstants.RIGHT), constraints);
+
+        constraints.gridx = 2;
+        constraints.gridy = row;
+        constraints.weightx = 1;
+        constraints.fill = GridBagConstraints.HORIZONTAL;
+        target.add(comp, constraints);
+    }
+
+    public JTextField getBlz() {
+        return blz;
+    }
+
+    public JTextField getIban() {
+        return iban;
+    }
+
+    public JPasswordField getPin() {
+        return pin;
+    }
+
+    public JButton getLogin() {
+        return login;
+    }
+}