#include "screens/auth/RegisterScreen.h"

#include "auth/AuthManager.h"
#include "auth/AuthTypes.h"
#include "ui/theme/Theme.h"
#include "ui/widgets/LanguageSwitcher.h"

#include <QEvent>
#include <QFrame>
#include <QHBoxLayout>
#include <QHideEvent>
#include <QPainter>
#include <QRegularExpression>
#include <QTimer>
#include <QVBoxLayout>

namespace fincept::screens {

// ── Obsidian Styles ──────────────────────────────────────────────────────────

static QString card_style() {
    return QString("background: %1; border: 1px solid %2;").arg(ui::colors::BG_SURFACE(), ui::colors::BORDER_DIM());
}

static QString input_style() {
    return QString("QLineEdit {"
                   "  background: %1; color: %2;"
                   "  border: 1px solid %3;"
                   "  padding: 4px 8px; font-size: 14px;"
                   "  font-family: 'Consolas','Courier New',monospace;"
                   "  selection-background-color: %4; selection-color: %5;"
                   "}"
                   "QLineEdit:focus { border: 1px solid %6; }"
                   "QLineEdit::placeholder { color: %7; }")
        .arg(ui::colors::BG_SURFACE(), ui::colors::TEXT_PRIMARY(), ui::colors::BORDER_DIM(), ui::colors::AMBER(),
             ui::colors::BG_BASE(), ui::colors::BORDER_BRIGHT(), ui::colors::TEXT_DIM());
}

static QString btn_primary() {
    return QString("QPushButton {"
                   "  background: rgba(217,119,6,0.1); color: %1;"
                   "  border: 1px solid %2;"
                   "  padding: 0 16px; font-size: 13px; font-weight: 700;"
                   "  font-family: 'Consolas','Courier New',monospace;"
                   "}"
                   "QPushButton:hover { background: %1; color: %3; }"
                   "QPushButton:disabled { color: %4; background: %5; border-color: %6; }")
        .arg(ui::colors::AMBER(), ui::colors::AMBER_DIM(), ui::colors::BG_BASE(), ui::colors::TEXT_DIM(),
             ui::colors::BG_RAISED(), ui::colors::BORDER_DIM());
}

static QString link_style() {
    return QString("QPushButton {"
                   "  color: %1; background: transparent; border: none;"
                   "  font-size: 12px; font-weight: 400;"
                   "  font-family: 'Consolas','Courier New',monospace;"
                   "}"
                   "QPushButton:hover { color: %2; }")
        .arg(ui::colors::TEXT_SECONDARY(), ui::colors::TEXT_PRIMARY());
}

static QString label_style() {
    return QString("color: %1; font-size: 12px; font-weight: 700;"
                   "background: transparent; letter-spacing: 0.5px;"
                   "font-family: 'Consolas','Courier New',monospace;")
        .arg(ui::colors::TEXT_SECONDARY());
}

static QString muted_style() {
    return QString("color: %1; font-size: 12px; background: transparent;"
                   "font-family: 'Consolas','Courier New',monospace;")
        .arg(ui::colors::TEXT_TERTIARY());
}

static QString check_off() {
    return QString("color: %1; font-size: 11px; background: transparent;"
                   "font-family: 'Consolas','Courier New',monospace;")
        .arg(ui::colors::TEXT_DIM());
}

static QString check_on() {
    return QString("color: %1; font-size: 11px; background: transparent;"
                   "font-family: 'Consolas','Courier New',monospace;")
        .arg(ui::colors::POSITIVE());
}

static QFrame* make_separator() {
    auto* sep = new QFrame;
    sep->setFixedHeight(1);
    sep->setStyleSheet(QString("background: %1; border: none;").arg(ui::colors::BORDER_DIM()));
    return sep;
}

// ── Constructor ──────────────────────────────────────────────────────────────

RegisterScreen::RegisterScreen(QWidget* parent) : QWidget(parent) {
    auto* root = new QVBoxLayout(this);
    root->setContentsMargins(0, 0, 0, 0);

    // Top-right language picker — visible without account.
    auto* top_row = new QHBoxLayout;
    top_row->setContentsMargins(20, 20, 20, 0);
    top_row->addStretch();
    top_row->addWidget(new ui::LanguageSwitcher(this));
    root->addLayout(top_row);

    auto* overlay = new QVBoxLayout;
    overlay->setAlignment(Qt::AlignCenter);
    root->addLayout(overlay, 1);

    pages_ = new QStackedWidget;
    pages_->setMinimumWidth(480);
    pages_->setMaximumWidth(620);
    pages_->setStyleSheet("background: transparent;");

    build_form_page();
    build_otp_page();

    overlay->addWidget(pages_, 0, Qt::AlignCenter);

    retranslateUi();

    auto& auth = auth::AuthManager::instance();
    connect(&auth, &auth::AuthManager::signup_succeeded, this, [this]() {
        register_btn_->setEnabled(true);
        register_btn_->setText(tr("  CREATE ACCOUNT  "));
        otp_email_->setText(email_->text().trimmed());
        otp_input_->clear();
        otp_error_->hide();
        pages_->setCurrentIndex(1);
    });
    connect(&auth, &auth::AuthManager::signup_failed, this, [this](const QString& err) {
        register_btn_->setEnabled(true);
        register_btn_->setText(tr("  CREATE ACCOUNT  "));
        error_label_->setText(err);
        error_label_->show();
    });
    connect(&auth, &auth::AuthManager::otp_verified, this, [this]() {
        verify_btn_->setEnabled(true);
        for (QLineEdit* w : {first_name_, last_name_, username_, email_, phone_, country_code_, password_,
                             confirm_pw_, otp_input_}) {
            if (w)
                w->clear();
        }
        if (password_)
            password_->setEchoMode(QLineEdit::Password);
        if (confirm_pw_)
            confirm_pw_->setEchoMode(QLineEdit::Password);
        if (error_label_)
            error_label_->hide();
        if (otp_error_)
            otp_error_->hide();
        pages_->setCurrentIndex(0);
    });
    connect(&auth, &auth::AuthManager::otp_failed, this, [this](const QString& err) {
        verify_btn_->setEnabled(true);
        verify_btn_->setText(tr("  VERIFY  "));
        otp_error_->setText(err);
        otp_error_->show();
    });
}

// ── Background ───────────────────────────────────────────────────────────────

void RegisterScreen::hideEvent(QHideEvent* event) {
    QWidget::hideEvent(event);

    // Window-manager hides (minimise / workspace switch) must not destroy a
    // half-filled form; only wipe when the user navigates away in-app.
    if (event && event->spontaneous())
        return;

    for (QLineEdit* w :
         {first_name_, last_name_, username_, email_, phone_, country_code_, password_, confirm_pw_, otp_input_}) {
        if (w)
            w->clear();
    }
    if (password_)
        password_->setEchoMode(QLineEdit::Password);
    if (confirm_pw_)
        confirm_pw_->setEchoMode(QLineEdit::Password);
    update_password_strength();
    reset_resend_cooldown(); // P3: no timers while the screen is off-stack
    if (error_label_)
        error_label_->hide();
    if (otp_error_)
        otp_error_->hide();
    if (pages_)
        pages_->setCurrentIndex(0);
}

void RegisterScreen::changeEvent(QEvent* event) {
    if (event->type() == QEvent::LanguageChange) {
        retranslateUi();
    }
    QWidget::changeEvent(event);
}

void RegisterScreen::paintEvent(QPaintEvent* /*event*/) {
    QPainter p(this);
    p.fillRect(rect(), QColor(ui::colors::BG_BASE()));

    p.setPen(QPen(QColor(ui::colors::BG_RAISED()), 1));
    const int step = 24;
    for (int x = 0; x < width(); x += step)
        p.drawLine(x, 0, x, height());
    for (int y = 0; y < height(); y += step)
        p.drawLine(0, y, width(), y);
}

// ── Form Page ────────────────────────────────────────────────────────────────

void RegisterScreen::build_form_page() {
    auto* page = new QWidget(this);
    page->setStyleSheet(card_style());

    auto* vl = new QVBoxLayout(page);
    vl->setContentsMargins(28, 18, 28, 18);
    vl->setSpacing(6);

    // Header bar
    auto* header = new QWidget(this);
    header->setFixedHeight(38);
    header->setStyleSheet(QString("background: %1; border: none;").arg(ui::colors::BG_RAISED()));
    auto* hl = new QHBoxLayout(header);
    hl->setContentsMargins(14, 0, 14, 0);

    auto* back = new QPushButton(QStringLiteral("<"));
    back->setFixedSize(24, 24);
    back->setStyleSheet(QString("QPushButton { color: %1; background: transparent; border: none;"
                                "  font-size: 16px; font-family: 'Consolas','Courier New',monospace; }"
                                "QPushButton:hover { color: %2; }")
                            .arg(ui::colors::TEXT_SECONDARY(), ui::colors::TEXT_PRIMARY()));
    connect(back, &QPushButton::clicked, this, &RegisterScreen::navigate_login);
    hl->addWidget(back);

    form_title_ = new QLabel;
    form_title_->setStyleSheet(QString("color: %1; font-size: 14px; font-weight: 700;"
                                       "background: transparent; letter-spacing: 1px;"
                                       "font-family: 'Consolas','Courier New',monospace;")
                                   .arg(ui::colors::AMBER()));
    hl->addWidget(form_title_);
    hl->addStretch();
    vl->addWidget(header);

    vl->addWidget(make_separator());

    // Helper that creates a label + line edit; stores both pointers via output params.
    auto add_field = [&](QLabel*& label_out, QLineEdit*& field_out, QLayout* parent) {
        label_out = new QLabel;
        label_out->setStyleSheet(label_style());
        static_cast<QBoxLayout*>(parent)->addWidget(label_out);
        field_out = new QLineEdit;
        field_out->setFixedHeight(30);
        field_out->setStyleSheet(input_style());
        static_cast<QBoxLayout*>(parent)->addWidget(field_out);
    };

    // Name row — side by side
    auto* name_row = new QWidget(this);
    name_row->setStyleSheet("background: transparent;");
    auto* nrl = new QHBoxLayout(name_row);
    nrl->setContentsMargins(0, 0, 0, 0);
    nrl->setSpacing(8);

    auto* fn_col = new QVBoxLayout;
    fn_col->setSpacing(2);
    add_field(first_name_lbl_, first_name_, fn_col);
    nrl->addLayout(fn_col);

    auto* ln_col = new QVBoxLayout;
    ln_col->setSpacing(2);
    add_field(last_name_lbl_, last_name_, ln_col);
    nrl->addLayout(ln_col);
    vl->addWidget(name_row);

    // Username is required by POST /user/register; do not invent it from the
    // name fields (that hid the control and caused silent collisions — #318).
    add_field(username_lbl_, username_, vl);

    add_field(email_lbl_, email_, vl);

    // Phone + country code side by side
    auto* ph_row = new QWidget(this);
    ph_row->setStyleSheet("background: transparent;");
    auto* phl = new QHBoxLayout(ph_row);
    phl->setContentsMargins(0, 0, 0, 0);
    phl->setSpacing(8);

    auto* cc_col = new QVBoxLayout;
    cc_col->setSpacing(2);
    add_field(code_lbl_, country_code_, cc_col);
    country_code_->setFixedWidth(72);
    phl->addLayout(cc_col);

    auto* ph_col = new QVBoxLayout;
    ph_col->setSpacing(2);
    add_field(phone_lbl_, phone_, ph_col);
    phl->addLayout(ph_col);

    vl->addWidget(ph_row);

    add_field(password_lbl_, password_, vl);
    password_->setEchoMode(QLineEdit::Password);

    // Password strength — compact single row hints. The labels are symbolic
    // ("8+", "A-Z", etc.) — left untranslated.
    auto* pw_checks = new QWidget(this);
    pw_checks->setStyleSheet("background: transparent;");
    auto* pcl = new QHBoxLayout(pw_checks);
    pcl->setContentsMargins(0, 0, 0, 0);
    pcl->setSpacing(8);

    auto make_check = [&](QLabel*& lbl, const char* text) {
        lbl = new QLabel(QString::fromUtf8(text));
        lbl->setStyleSheet(check_off());
        pcl->addWidget(lbl);
    };
    make_check(pw_len_, "8+");
    make_check(pw_up_, "A-Z");
    make_check(pw_low_, "a-z");
    make_check(pw_num_, "0-9");
    make_check(pw_spec_, "!@#");
    pcl->addStretch();
    vl->addWidget(pw_checks);

    connect(password_, &QLineEdit::textChanged, this, &RegisterScreen::update_password_strength);

    add_field(confirm_pw_lbl_, confirm_pw_, vl);
    confirm_pw_->setEchoMode(QLineEdit::Password);

    // Error
    error_label_ = new QLabel;
    error_label_->setWordWrap(true);
    error_label_->setStyleSheet(QString("color: %1; font-size: 12px;"
                                        "background: rgba(220,38,38,0.08);"
                                        "border: 1px solid #7f1d1d; padding: 4px 8px;"
                                        "font-family: 'Consolas','Courier New',monospace;")
                                    .arg(ui::colors::NEGATIVE()));
    error_label_->hide();
    vl->addWidget(error_label_);

    vl->addSpacing(2);

    register_btn_ = new QPushButton;
    register_btn_->setFixedHeight(32);
    register_btn_->setStyleSheet(btn_primary());
    connect(register_btn_, &QPushButton::clicked, this, &RegisterScreen::on_register);
    vl->addWidget(register_btn_);

    vl->addWidget(make_separator());

    // Login link
    auto* login_row = new QWidget(this);
    login_row->setStyleSheet("background: transparent;");
    auto* lrl = new QHBoxLayout(login_row);
    lrl->setAlignment(Qt::AlignCenter);
    lrl->setContentsMargins(0, 0, 0, 0);

    have_account_lbl_ = new QLabel;
    have_account_lbl_->setStyleSheet(muted_style());
    lrl->addWidget(have_account_lbl_);

    signin_btn_ = new QPushButton;
    signin_btn_->setStyleSheet(QString("QPushButton { color: %1; background: transparent; border: none;"
                                       "  font-size: 12px; font-weight: 700;"
                                       "  font-family: 'Consolas','Courier New',monospace; }"
                                       "QPushButton:hover { color: %2; }")
                                   .arg(ui::colors::AMBER(), ui::colors::TEXT_PRIMARY()));
    connect(signin_btn_, &QPushButton::clicked, this, &RegisterScreen::navigate_login);
    lrl->addWidget(signin_btn_);
    vl->addWidget(login_row);

    // ── Input limits ─────────────────────────────────────────────────────────
    // Client-side caps mirroring the register endpoint's constraints, so an
    // over-long value is stopped at the keyboard instead of on a round trip.
    first_name_->setMaxLength(100);
    last_name_->setMaxLength(100);
    username_->setMaxLength(50);
    email_->setMaxLength(254); // RFC 5321 maximum
    country_code_->setMaxLength(5);
    phone_->setMaxLength(20);
    password_->setMaxLength(128);
    confirm_pw_->setMaxLength(128);

    // ── Accessibility + keyboard order ───────────────────────────────────────
    // The form is built from nested column layouts (name row, phone row), so
    // the natural focus chain jumps sideways. Pin it to reading order.
    first_name_->setAccessibleName(tr("First name"));
    last_name_->setAccessibleName(tr("Last name"));
    username_->setAccessibleName(tr("Username"));
    email_->setAccessibleName(tr("Email address"));
    country_code_->setAccessibleName(tr("Country calling code"));
    phone_->setAccessibleName(tr("Phone number"));
    password_->setAccessibleName(tr("Password"));
    confirm_pw_->setAccessibleName(tr("Confirm password"));
    register_btn_->setAccessibleName(tr("Create account"));
    signin_btn_->setAccessibleName(tr("Go to sign in"));
    error_label_->setAccessibleName(tr("Registration error"));

    setTabOrder(first_name_, last_name_);
    setTabOrder(last_name_, username_);
    setTabOrder(username_, email_);
    setTabOrder(email_, country_code_);
    setTabOrder(country_code_, phone_);
    setTabOrder(phone_, password_);
    setTabOrder(password_, confirm_pw_);
    setTabOrder(confirm_pw_, register_btn_);
    setTabOrder(register_btn_, signin_btn_);

    // Enter anywhere in the form submits, matching the login screen.
    for (QLineEdit* w : {first_name_, last_name_, username_, email_, country_code_, phone_, password_, confirm_pw_})
        connect(w, &QLineEdit::returnPressed, this, &RegisterScreen::on_register);

    pages_->addWidget(page);
}

// ── OTP Page ─────────────────────────────────────────────────────────────────

void RegisterScreen::build_otp_page() {
    auto* page = new QWidget(this);
    page->setStyleSheet(card_style());

    auto* vl = new QVBoxLayout(page);
    vl->setContentsMargins(28, 22, 28, 22);
    vl->setSpacing(10);

    // Header
    auto* header = new QWidget(this);
    header->setFixedHeight(38);
    header->setStyleSheet(QString("background: %1; border: none;").arg(ui::colors::BG_RAISED()));
    auto* hl = new QHBoxLayout(header);
    hl->setContentsMargins(14, 0, 14, 0);

    otp_title_ = new QLabel;
    otp_title_->setStyleSheet(QString("color: %1; font-size: 14px; font-weight: 700;"
                                      "background: transparent; letter-spacing: 1px;"
                                      "font-family: 'Consolas','Courier New',monospace;")
                                  .arg(ui::colors::AMBER()));
    hl->addWidget(otp_title_);
    hl->addStretch();
    vl->addWidget(header);

    otp_email_ = new QLabel;
    otp_email_->setWordWrap(true);
    otp_email_->setStyleSheet(muted_style());
    vl->addWidget(otp_email_);

    vl->addWidget(make_separator());

    otp_code_lbl_ = new QLabel;
    otp_code_lbl_->setStyleSheet(label_style());
    vl->addWidget(otp_code_lbl_);

    otp_input_ = new QLineEdit;
    otp_input_->setFixedHeight(34);
    otp_input_->setStyleSheet(QString("QLineEdit {"
                                      "  background: %1; color: %2;"
                                      "  border: 1px solid %3;"
                                      "  padding: 6px 10px; font-size: 15px;"
                                      "  font-family: 'Consolas','Courier New',monospace;"
                                      "  selection-background-color: %4; selection-color: %5;"
                                      "}"
                                      "QLineEdit:focus { border: 1px solid %6; }")
                                  .arg(ui::colors::BG_SURFACE(), ui::colors::TEXT_PRIMARY(), ui::colors::BORDER_DIM(),
                                       ui::colors::AMBER(), ui::colors::BG_BASE(), ui::colors::BORDER_BRIGHT()));
    vl->addWidget(otp_input_);

    otp_error_ = new QLabel;
    otp_error_->setWordWrap(true);
    otp_error_->setStyleSheet(QString("color: %1; font-size: 12px;"
                                      "background: rgba(220,38,38,0.08);"
                                      "border: 1px solid #7f1d1d; padding: 4px 8px;"
                                      "font-family: 'Consolas','Courier New',monospace;")
                                  .arg(ui::colors::NEGATIVE()));
    otp_error_->hide();
    vl->addWidget(otp_error_);

    verify_btn_ = new QPushButton;
    verify_btn_->setFixedHeight(32);
    verify_btn_->setStyleSheet(btn_primary());
    connect(verify_btn_, &QPushButton::clicked, this, &RegisterScreen::on_verify_otp);
    vl->addWidget(verify_btn_);

    resend_btn_ = new QPushButton;
    resend_btn_->setStyleSheet(link_style());
    connect(resend_btn_, &QPushButton::clicked, this, &RegisterScreen::on_resend_otp);
    vl->addWidget(resend_btn_, 0, Qt::AlignCenter);

    back_to_form_btn_ = new QPushButton;
    back_to_form_btn_->setStyleSheet(link_style());
    connect(back_to_form_btn_, &QPushButton::clicked, this, [this]() { pages_->setCurrentIndex(0); });
    vl->addWidget(back_to_form_btn_, 0, Qt::AlignCenter);

    vl->addStretch();
    connect(otp_input_, &QLineEdit::returnPressed, this, &RegisterScreen::on_verify_otp);

    otp_input_->setMaxLength(12);
    otp_input_->setAccessibleName(tr("Email verification code"));
    otp_error_->setAccessibleName(tr("Verification error"));
    verify_btn_->setAccessibleName(tr("Verify email"));
    resend_btn_->setAccessibleName(tr("Resend verification code"));
    back_to_form_btn_->setAccessibleName(tr("Back to the registration form"));
    setTabOrder(otp_input_, verify_btn_);
    setTabOrder(verify_btn_, resend_btn_);
    setTabOrder(resend_btn_, back_to_form_btn_);

    pages_->addWidget(page);
}

// ── Re-translation ───────────────────────────────────────────────────────────

void RegisterScreen::retranslateUi() {
    if (form_title_)
        form_title_->setText(tr("CREATE ACCOUNT"));
    if (first_name_lbl_)
        first_name_lbl_->setText(tr("FIRST NAME"));
    if (last_name_lbl_)
        last_name_lbl_->setText(tr("LAST NAME"));
    if (username_lbl_)
        username_lbl_->setText(tr("USERNAME"));
    if (email_lbl_)
        email_lbl_->setText(tr("EMAIL"));
    if (code_lbl_)
        code_lbl_->setText(tr("CODE"));
    if (phone_lbl_)
        phone_lbl_->setText(tr("PHONE"));
    if (password_lbl_)
        password_lbl_->setText(tr("PASSWORD"));
    if (confirm_pw_lbl_)
        confirm_pw_lbl_->setText(tr("CONFIRM PASSWORD"));

    if (first_name_)
        first_name_->setPlaceholderText(tr("First"));
    if (last_name_)
        last_name_->setPlaceholderText(tr("Last"));
    if (username_)
        username_->setPlaceholderText(tr("3-50 chars, letters/numbers/_"));
    if (email_)
        email_->setPlaceholderText(tr("user@domain.com"));
    if (country_code_)
        country_code_->setPlaceholderText(tr("+1"));
    if (phone_)
        phone_->setPlaceholderText(tr("234 567 8900"));
    if (password_)
        password_->setPlaceholderText(tr("min 8 characters"));
    if (confirm_pw_)
        confirm_pw_->setPlaceholderText(tr("re-enter password"));

    if (register_btn_)
        register_btn_->setText(tr("  CREATE ACCOUNT  "));
    if (have_account_lbl_)
        have_account_lbl_->setText(tr("Already have an account?"));
    if (signin_btn_)
        signin_btn_->setText(tr("SIGN IN"));

    if (otp_title_)
        otp_title_->setText(tr("VERIFY EMAIL"));
    if (otp_code_lbl_)
        otp_code_lbl_->setText(tr("VERIFICATION CODE"));
    if (otp_input_)
        otp_input_->setPlaceholderText(tr("enter code from email"));
    if (verify_btn_)
        verify_btn_->setText(tr("  VERIFY  "));
    // Don't clobber a live cooldown countdown with the idle label.
    if (resend_btn_ && resend_cooldown_left_ <= 0)
        resend_btn_->setText(tr("DIDN'T RECEIVE? RESEND"));
    else if (resend_btn_)
        resend_btn_->setText(tr("RESEND IN %1s").arg(resend_cooldown_left_));
    if (back_to_form_btn_)
        back_to_form_btn_->setText(tr("BACK TO FORM"));
}

// ── Password Strength ────────────────────────────────────────────────────────

void RegisterScreen::update_password_strength() {
    if (!password_)
        return;
    auto s = auth::validate_password(password_->text());

    // This runs on every keystroke. setStyleSheet is a full CSS reparse plus a
    // repaint of the label, so only touch a hint whose state actually flipped —
    // the steady state (user typing past the threshold) becomes a no-op.
    auto set_hint = [](QLabel* lbl, bool ok) {
        if (!lbl)
            return;
        const QVariant prev = lbl->property("hintOk");
        if (prev.isValid() && prev.toBool() == ok)
            return;
        lbl->setProperty("hintOk", ok);
        lbl->setStyleSheet(ok ? check_on() : check_off());
    };

    set_hint(pw_len_, s.min_length);
    set_hint(pw_up_, s.has_upper);
    set_hint(pw_low_, s.has_lower);
    set_hint(pw_num_, s.has_number);
    set_hint(pw_spec_, s.has_special);
}

// ── Actions ──────────────────────────────────────────────────────────────────

void RegisterScreen::on_register() {
    error_label_->hide();

    QString fn = first_name_->text().trimmed();
    QString ln = last_name_->text().trimmed();
    QString username = auth::sanitize_input(username_->text()).toLower();
    QString em = email_->text().trimmed();
    QString ph = phone_->text().trimmed();
    QString cc = country_code_->text().trimmed();
    QString pw = password_->text();
    QString cpw = confirm_pw_->text();

    if (fn.isEmpty() || ln.isEmpty() || username.isEmpty() || em.isEmpty() || ph.isEmpty() || pw.isEmpty() ||
        cpw.isEmpty()) {
        error_label_->setText(tr("All fields are required"));
        error_label_->show();
        return;
    }
    if (username.length() < 3 || username.length() > 50) {
        error_label_->setText(tr("Username must be 3-50 characters"));
        error_label_->show();
        return;
    }
    // Keep usernames URL/API-safe; spaces from names were a common failure mode.
    if (!QRegularExpression(QStringLiteral("^[a-z0-9_]+$")).match(username).hasMatch()) {
        error_label_->setText(tr("Username may only contain letters, numbers, and underscores"));
        error_label_->show();
        return;
    }
    if (cc.isEmpty()) {
        error_label_->setText(tr("Country code is required (e.g. +1, +91)"));
        error_label_->show();
        return;
    }
    // Ensure country code starts with +
    if (!cc.startsWith('+')) {
        cc = '+' + cc;
        country_code_->setText(cc);
    }
    auto ev = auth::validate_email(em);
    if (!ev.valid) {
        error_label_->setText(ev.error);
        error_label_->show();
        return;
    }
    if (pw != cpw) {
        error_label_->setText(tr("Passwords do not match"));
        error_label_->show();
        return;
    }
    if (pw.length() < 8) {
        error_label_->setText(tr("Password must be at least 8 characters"));
        error_label_->show();
        return;
    }

    register_btn_->setEnabled(false);
    register_btn_->setText(tr("  CREATING...  "));
    auth::AuthManager::instance().signup(username, em, pw, ph, {}, cc);
}

void RegisterScreen::on_verify_otp() {
    otp_error_->hide();
    QString code = otp_input_->text().trimmed();
    if (code.isEmpty()) {
        otp_error_->setText(tr("Enter the verification code"));
        otp_error_->show();
        return;
    }
    verify_btn_->setEnabled(false);
    verify_btn_->setText(tr("  VERIFYING...  "));
    auth::AuthManager::instance().verify_otp(email_->text().trimmed(), code);
}

void RegisterScreen::on_resend_otp() {
    // Guard against double-submits: the endpoint re-runs the whole signup, and
    // hammering it is the fastest way to trip a server-side rate limit with no
    // way for the user to tell why.
    if (resend_btn_ && !resend_btn_->isEnabled())
        return;

    QString username = auth::sanitize_input(username_->text()).toLower();
    QString cc = country_code_->text().trimmed();
    if (!cc.isEmpty() && !cc.startsWith('+'))
        cc = '+' + cc;
    auth::AuthManager::instance().signup(username, email_->text().trimmed(), password_->text(),
                                         phone_->text().trimmed(), {}, cc);
    start_resend_cooldown();
}

void RegisterScreen::start_resend_cooldown() {
    if (!resend_btn_)
        return;
    resend_cooldown_left_ = 30;
    if (!resend_timer_) {
        resend_timer_ = new QTimer(this);
        resend_timer_->setInterval(1000);
        connect(resend_timer_, &QTimer::timeout, this, [this]() {
            if (--resend_cooldown_left_ <= 0) {
                reset_resend_cooldown();
                return;
            }
            resend_btn_->setText(tr("RESEND IN %1s").arg(resend_cooldown_left_));
        });
    }
    resend_btn_->setEnabled(false);
    resend_btn_->setText(tr("RESEND IN %1s").arg(resend_cooldown_left_));
    resend_timer_->start();
}

void RegisterScreen::reset_resend_cooldown() {
    resend_cooldown_left_ = 0;
    if (resend_timer_)
        resend_timer_->stop();
    if (resend_btn_) {
        resend_btn_->setEnabled(true);
        resend_btn_->setText(tr("DIDN'T RECEIVE? RESEND"));
    }
}

} // namespace fincept::screens