private static final Set<Character> SIMILAR = new HashSet<>(Arrays.asList(
        '0','O','o','1','l','I','|','5','S','2','Z','8','B'
));


private static final SecureRandom RNG = new SecureRandom();

// UI components
private JTextField outputField;
private JSlider lengthSlider;
private JCheckBox lowerBox, upperBox, digitBox, symbolBox, excludeSimilarBox, requireEachBox;
private JLabel entropyLabel, strengthLabel;

public PasswordGeneratorGUI() {
    super("🔐 Générateur de mots de passe");

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(500, 300);
    setLayout(new BorderLayout(10,10));

    // Top output
    JPanel top = new JPanel(new BorderLayout(5,5));
    outputField = new JTextField();
    outputField.setFont(new Font("Monospaced", Font.PLAIN, 16));
    top.add(outputField, BorderLayout.CENTER);

    JButton copyBtn = new JButton("Copier");
    copyBtn.addActionListener(e -> copyToClipboard());
    top.add(copyBtn, BorderLayout.EAST);

    add(top, BorderLayout.NORTH);

    // Center controls
    JPanel center = new JPanel();

    center.setLayout(new GridLayout(0,2));

    lowerBox = new JCheckBox("Minuscules (a-z)", true);
    upperBox = new JCheckBox("Majuscules (A-Z)", true);
    digitBox = new JCheckBox("Chiffres (0-9)", true);
    symbolBox = new JCheckBox("Symboles (!@#…)", true);
    excludeSimilarBox = new JCheckBox("Exclure caractères ambigus (0,O,1,l...)", true);
    requireEachBox = new JCheckBox("Exiger ≥1 caractère de chaque catégorie", true);

    center.add(lowerBox);
    center.add(upperBox);
    center.add(digitBox);
    center.add(symbolBox);
    center.add(excludeSimilarBox);
    center.add(requireEachBox);

    add(center, BorderLayout.CENTER);

    // Bottom panel
    JPanel bottom = new JPanel(new BorderLayout(5,5));

    lengthSlider = new JSlider(8, 64, 16);
    lengthSlider.setMajorTickSpacing(14);
    lengthSlider.setMinorTickSpacing(2);
    lengthSlider.setPaintTicks(true);
    lengthSlider.setPaintLabels(true);

    bottom.add(new JLabel("Longueur :"), BorderLayout.WEST);
    bottom.add(lengthSlider, BorderLayout.CENTER);

    JButton genBtn = new JButton("Générer");
    genBtn.addActionListener(e -> generatePassword());
    bottom.add(genBtn, BorderLayout.EAST);

    add(bottom, BorderLayout.SOUTH);

    // Status panel
    JPanel status = new JPanel(new GridLayout(2,1));
    entropyLabel = new JLabel("Entropie : -- bits");
    strengthLabel = new JLabel("Robustesse : --");
    status.add(entropyLabel);
    status.add(strengthLabel);
    add(status, BorderLayout.WEST);

    setLocationRelativeTo(null); // center window
    setVisible(true);
}

private void copyToClipboard() {
    String text = outputField.getText();
    if (text.isEmpty()) return;
    Toolkit.getDefaultToolkit()
            .getSystemClipboard()
            .setContents(new StringSelection(text), null);
    JOptionPane.showMessageDialog(this, "Mot de passe copié !");
}

private void generatePassword() {
    int length = lengthSlider.getValue();

    java.util.List<String> sets = new ArrayList<>();
    if (lowerBox.isSelected()) sets.add(LOWER);
    if (upperBox.isSelected()) sets.add(UPPER);
    if (digitBox.isSelected()) sets.add(DIGIT);
    if (symbolBox.isSelected()) sets.add(SYMBOL);

    String pool = combineAndFilter(sets, excludeSimilarBox.isSelected());

    if (pool.isEmpty()) {
        JOptionPane.showMessageDialog(this, "Aucun jeu de caractères disponible !");
        return;
    }

    String pwd = requireEachBox.isSelected()
            ? generateWithRequirement(length, sets, pool, excludeSimilarBox.isSelected())
            : randomFromPool(pool, length);

    outputField.setText(pwd);

    // update entropy
    int uniqueChars = (int) pool.chars().distinct().count();
    double entropyBits = length * (Math.log(uniqueChars)/Math.log(2));
    String strength = strengthLabel(entropyBits);

    entropyLabel.setText(String.format("Entropie : ~%.0f bits", entropyBits));
    strengthLabel.setText("Robustesse : " + strength);
}

private String combineAndFilter(java.util.List<String> sets, boolean excludeSimilar) {
    StringBuilder sb = new StringBuilder();
    for (String s : sets) sb.append(s);

    StringBuilder out = new StringBuilder();
    for (char c : sb.toString().toCharArray()) {
        if (excludeSimilar && SIMILAR.contains(c)) continue;
        out.append(c);
    }
    return out.toString();
}

private String generateWithRequirement(int length, java.util.List<String> sets, String pool, boolean excludeSimilar) {
    java.util.List<Character> chars = new ArrayList<>();

    for (String s : sets) {
        String filtered = combineAndFilter(Collections.singletonList(s), excludeSimilar);
        if (!filtered.isEmpty()) {
            chars.add(filtered.charAt(RNG.nextInt(filtered.length())));
        }
    }

    for (int i = chars.size(); i < length; i++) {
        chars.add(pool.charAt(RNG.nextInt(pool.length())));
    }

    // shuffle
    Collections.shuffle(chars, RNG);
    StringBuilder sb = new StringBuilder();
    for (char c : chars) sb.append(c);
    return sb.toString();
}

private String randomFromPool(String pool, int length) {
    StringBuilder sb = new StringBuilder(length);
    for (int i = 0; i < length; i++) {
        sb.append(pool.charAt(RNG.nextInt(pool.length())));
    }
    return sb.toString();
}

private String strengthLabel(double bits) {
    if (bits < 28) return "Très faible";
    if (bits < 36) return "Faible";
    if (bits < 60) return "Correct";
    if (bits < 128) return "Fort";
    return "Très fort";
}

public static void main(String[] args) {
    SwingUtilities.invokeLater(PasswordGeneratorGUI::new);
}