let authMode = 'login'; // 'login' или 'register'

function showAuthModal() {
    document.getElementById('auth-modal').classList.remove('hidden');
}

function hideAuthModal() {
    document.getElementById('auth-modal').classList.add('hidden');
}

function setAuthMode(mode) {
    authMode = mode;
    const titleEl = document.getElementById('auth-title');
    const submitBtnText = document.getElementById('auth-submit-text');
    const toggleBtn = document.getElementById('auth-toggle-btn');
    const errorEl = document.getElementById('auth-error');

    errorEl.classList.add('hidden');

    if (mode === 'register') {
        titleEl.innerText = "Регистрация нового пользователя";
        submitBtnText.innerText = "Зарегистрироваться";
        toggleBtn.innerText = "Уже есть аккаунт? Войти";
    } else {
        titleEl.innerText = "Авторизация в системе";
        submitBtnText.innerText = "Войти в систему";
        toggleBtn.innerText = "Создать новый аккаунт";
    }
}

function toggleAuthMode() {
    setAuthMode(authMode === 'login' ? 'register' : 'login');
}

async function handleLogin(e) {
    e.preventDefault();
    const usernameInput = document.getElementById('auth-username-input');
    const passwordInput = document.getElementById('auth-password-input');
    const errorEl = document.getElementById('auth-error');

    const username = usernameInput.value.trim();
    const password = passwordInput.value;

    if (!username || !password) return;

    errorEl.classList.add('hidden');
    const endpoint = authMode === 'register' ? '/api/v1/auth/register' : '/api/v1/auth/login';

    try {
        const res = await fetch(endpoint, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ username, password })
        });

        const data = await res.json();

        if (res.status === 200) {
            API_TOKEN = data.token;
            CURRENT_USERNAME = data.username;
            IS_GUEST = false;

            localStorage.setItem(AUTH_TOKEN_KEY, data.token);
            localStorage.setItem('scud_username', data.username);
            localStorage.removeItem('scud_is_guest');

            hideAuthModal();
            updateUIState();
            loadTasks();
        } else {
            errorEl.innerText = data.detail || "Ошибка авторизации";
            errorEl.classList.remove('hidden');
        }
    } catch (err) {
        errorEl.innerText = "Ошибка соединения с сервером";
        errorEl.classList.remove('hidden');
    }
}

function enableGuestMode() {
    IS_GUEST = true;
    API_TOKEN = "";
    CURRENT_USERNAME = "Гость";
    localStorage.setItem('scud_is_guest', 'true');
    hideAuthModal();
    updateUIState();
}

function logout() {
    localStorage.removeItem(AUTH_TOKEN_KEY);
    localStorage.removeItem('scud_username');
    localStorage.removeItem('scud_is_guest');
    API_TOKEN = "";
    CURRENT_USERNAME = "";
    IS_GUEST = false;
    showAuthModal();
}

function updateUIState() {
    const tasksBtn = document.getElementById('tasks-drawer-btn');
    const guestBadge = document.getElementById('guest-badge');
    const usernameBadge = document.getElementById('username-badge');

    if (IS_GUEST) {
        if (tasksBtn) tasksBtn.classList.add('hidden');
        if (guestBadge) guestBadge.classList.remove('hidden');
        if (usernameBadge) usernameBadge.classList.add('hidden');
    } else {
        if (tasksBtn) tasksBtn.classList.remove('hidden');
        if (guestBadge) guestBadge.classList.add('hidden');
        if (usernameBadge) {
            usernameBadge.innerText = CURRENT_USERNAME || 'User';
            usernameBadge.classList.remove('hidden');
        }
    }
}