/**
 * UrbanFlow — auth.js
 * Client-side Google Identity Services integration.
 *
 * Session is persisted in localStorage so it survives page reloads
 * and HF Space container restarts. The backend verifies the JWT on
 * every sign-in and returns the canonical user record.
 */

const UF_AUTH_KEYS = {
    email:    'uf_user_email',
    name:     'uf_user_name',
    picture:  'uf_user_picture',
    username: 'uf_user_username',
};

// ---- Session helpers ----

function getAuthSession() {
    const email = localStorage.getItem(UF_AUTH_KEYS.email);
    if (!email) return null;
    return {
        email:    email,
        name:     localStorage.getItem(UF_AUTH_KEYS.name) || '',
        picture:  localStorage.getItem(UF_AUTH_KEYS.picture) || '',
        username: localStorage.getItem(UF_AUTH_KEYS.username) || '',
    };
}

function isAuthenticated() {
    return !!localStorage.getItem(UF_AUTH_KEYS.email);
}

function saveAuthSession(user) {
    localStorage.setItem(UF_AUTH_KEYS.email,    user.email    || '');
    localStorage.setItem(UF_AUTH_KEYS.name,     user.name     || '');
    localStorage.setItem(UF_AUTH_KEYS.picture,  user.picture  || '');
    localStorage.setItem(UF_AUTH_KEYS.username, user.username || '');
}

function clearAuthSession() {
    Object.values(UF_AUTH_KEYS).forEach(k => localStorage.removeItem(k));
}

// ---- Google Identity Services ----

let _gsiInitialized = false;

/**
 * Load GIS script and initialize. Returns a Promise that resolves
 * once `google.accounts.id` is ready.
 */
function initGoogleAuth() {
    return new Promise((resolve, reject) => {
        if (_gsiInitialized) { resolve(); return; }

        fetch('api/auth/client-id')
            .then(r => r.json())
            .then(data => {
                if (data.error) { reject(data.error); return; }

                const script = document.createElement('script');
                script.src = 'https://accounts.google.com/gsi/client';
                script.async = true;
                script.defer = true;
                script.onload = () => {
                    google.accounts.id.initialize({
                        client_id: data.client_id,
                        callback: _handleCredentialResponse,
                        auto_select: false,
                        cancel_on_tap_outside: false,
                    });
                    _gsiInitialized = true;
                    resolve();
                };
                script.onerror = () => reject('Failed to load Google Identity Services');
                document.head.appendChild(script);
            })
            .catch(reject);
    });
}

/**
 * Click the hidden real Google button — this is the only reliable way
 * to open the account chooser popup from a user gesture.
 */
function _triggerGoogleSignInPopup() {
    const realBtn = document.querySelector('#gsi-hidden-btn [role="button"]');
    if (realBtn) {
        realBtn.click();
    } else {
        // Fallback: re-render and click once rendered
        _renderHiddenGoogleBtn(function() {
            const btn = document.querySelector('#gsi-hidden-btn [role="button"]');
            if (btn) btn.click();
        });
    }
}

/**
 * Render Google's real button into a hidden offscreen container,
 * then call `cb` once the iframe/button is ready.
 */
function _renderHiddenGoogleBtn(cb) {
    let container = document.getElementById('gsi-hidden-btn');
    if (!container) {
        container = document.createElement('div');
        container.id = 'gsi-hidden-btn';
        container.style.cssText = 'position:fixed;top:-9999px;left:-9999px;opacity:0;pointer-events:none;';
        document.body.appendChild(container);
    }
    container.innerHTML = '';
    google.accounts.id.renderButton(container, {
        type: 'standard',
        theme: 'filled_black',
        size: 'large',
        text: 'signin_with',
        shape: 'pill',
        width: 240,
    });
    // Give the iframe a tick to mount
    setTimeout(function() {
        container.style.pointerEvents = 'auto';
        if (cb) cb();
    }, 100);
}

// Internal: will be overridden by the page that triggers sign-in
let _onAuthSuccess = null;

function _handleCredentialResponse(response) {
    fetch('api/auth/verify', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ credential: response.credential }),
    })
        .then(r => {
            if (!r.ok) throw new Error('Verification failed');
            return r.json();
        })
        .then(user => {
            saveAuthSession(user);

            const handleSuccess = (u) => {
                _hideAuthOverlay();
                if (_onAuthSuccess) _onAuthSuccess(u);
                else {
                    if (typeof populateProfileUI === 'function') populateProfileUI();
                }
            };

            if (user.new_user) {
                _showOnboardingForm(user, function(u) {
                    // After onboarding, check consent
                    _checkConsentThenProceed(u, handleSuccess);
                });
            } else {
                // Existing user — check consent
                _checkConsentThenProceed(user, handleSuccess);
            }
        })
        .catch(err => {
            console.error('[AUTH]', err);
            const overlay = document.getElementById('auth-overlay');
            const errEl = overlay ? overlay.querySelector('.auth-error') : null;
            if (errEl) {
                errEl.textContent = 'Sign-in failed. Please try again.';
                errEl.classList.remove('hidden');
            }
        });
}

/**
 * Show the auth overlay, render the custom button that delegates
 * to the real Google button click for a reliable account chooser.
 */
function promptGoogleSignIn(onSuccess) {
    _onAuthSuccess = (user) => {
        if (user.new_user) {
            _showOnboardingForm(user, onSuccess);
        } else {
            _hideAuthOverlay();
            onSuccess(user);
        }
    };

    _showAuthOverlay();

    initGoogleAuth().then(() => {
        const btnContainer = document.getElementById('auth-google-btn');
        if (!btnContainer) return;

        // Render the hidden real Google button first so it's ready
        _renderHiddenGoogleBtn(null);

        // Show our styled button that delegates to it
        btnContainer.innerHTML = TEMPLATES.authGoogleBtn;
    });
}

// ---- Auth Overlay (injected into DOM) ----

function _showAuthOverlay() {
    let overlay = document.getElementById('auth-overlay');
    if (!overlay) {
        overlay = document.createElement('div');
        overlay.id = 'auth-overlay';
        overlay.className = 'auth-overlay';
        overlay.innerHTML = TEMPLATES.authOverlay;
        document.body.appendChild(overlay);
        overlay.addEventListener('click', function(e) {
            if (e.target === overlay) _hideAuthOverlay();
        });
    }
    overlay.style.display = 'flex';
    document.body.style.overflow = 'hidden';
}

function _hideAuthOverlay() {
    const overlay = document.getElementById('auth-overlay');
    if (overlay) {
        overlay.style.display = 'none';
        document.body.style.overflow = '';
    }
}

// ---- Onboarding Form (username) ----

function _showOnboardingForm(user, onSuccess) {
    const overlay = document.getElementById('auth-overlay');
    if (!overlay) return;

    const card = overlay.querySelector('.auth-card');
    card.innerHTML = getOnboardFormTemplate(user);
    overlay._onboardUser = user;
    overlay._onboardCallback = onSuccess;
}

function _submitOnboarding() {
    const overlay = document.getElementById('auth-overlay');
    const input = document.getElementById('auth-username-input');
    const errEl = document.getElementById('auth-onboard-error');
    const username = (input ? input.value : '').trim();

    if (!username || username.length < 2) {
        if (errEl) { errEl.textContent = 'Please enter at least 2 characters.'; errEl.classList.remove('hidden'); }
        return;
    }

    const user = overlay._onboardUser;
    const btn = document.getElementById('auth-onboard-submit');
    if (btn) { btn.disabled = true; btn.textContent = 'Saving...'; }

    fetch('api/auth/onboard', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ email: user.email, username: username }),
    })
        .then(r => {
            if (!r.ok) throw new Error('Onboarding failed');
            return r.json();
        })
        .then(() => {
            user.username = username;
            saveAuthSession(user);
            _hideAuthOverlay();
            if (overlay._onboardCallback) overlay._onboardCallback(user);
        })
        .catch(() => {
            if (errEl) { errEl.textContent = 'Something went wrong. Please try again.'; errEl.classList.remove('hidden'); }
            if (btn) { btn.disabled = false; btn.textContent = 'Continue'; }
        });
}

// ---- Logout ----

function showLogoutConfirm() {
    let modal = document.getElementById('logout-confirm-modal');
    if (!modal) {
        modal = document.createElement('div');
        modal.id = 'logout-confirm-modal';
        modal.className = 'auth-overlay';
        modal.onclick = (e) => { if (e.target === modal) hideLogoutConfirm(); };
        modal.innerHTML = TEMPLATES.logoutModal;
        document.body.appendChild(modal);
    }
    modal.style.display = 'flex';
    document.body.style.overflow = 'hidden';
}

function hideLogoutConfirm() {
    const modal = document.getElementById('logout-confirm-modal');
    if (modal) { modal.style.display = 'none'; document.body.style.overflow = ''; }
}

function executeLogout() {
    clearAuthSession();
    sessionStorage.clear();
    hideLogoutConfirm();
    if (typeof showOnboardingPhase === 'function') {
        showOnboardingPhase();
        if (typeof initApp === 'function') {
            const sp = document.getElementById('sidebar-profile');
            if (sp) sp.style.display = 'none';
        }
    } else {
        window.location.replace('/');
    }
}

// ---- Consent Modal ----

let _consentCallback = null;
let _consentUser = null;

function _checkConsentThenProceed(user, callback) {
    if (localStorage.getItem('uf_terms_accepted')) {
        callback(user);
        return;
    }
    // Show consent modal
    _consentCallback = callback;
    _consentUser = user;
    _showConsentModal();
}

function _showConsentModal() {
    let overlay = document.getElementById('consent-overlay');
    if (!overlay) {
        overlay = document.createElement('div');
        overlay.id = 'consent-overlay';
        overlay.className = 'auth-overlay';
        overlay.innerHTML = TEMPLATES.consentModal;
        document.body.appendChild(overlay);
        // No click-to-close — user must agree
    }
    overlay.style.display = 'flex';
    document.body.style.overflow = 'hidden';
}

function onConsentCheckboxChange() {
    const cb = document.getElementById('consent-checkbox');
    const btn = document.getElementById('consent-accept-btn');
    const label = document.getElementById('consent-label');
    if (!cb || !btn) return;
    if (cb.checked) {
        btn.disabled = false;
        btn.style.background = '#0a0a0a';
        btn.style.border = '1px solid var(--cocoa)';
        btn.style.color = 'var(--cocoa-l)';
        btn.style.cursor = 'pointer';
        if (label) label.style.borderColor = 'var(--cocoa)';
    } else {
        btn.disabled = true;
        btn.style.background = '#1a1a1a';
        btn.style.border = '1px solid #222';
        btn.style.color = '#555';
        btn.style.cursor = 'not-allowed';
        if (label) label.style.borderColor = '#222';
    }
}

function acceptConsent() {
    localStorage.setItem('uf_terms_accepted', 'true');
    const overlay = document.getElementById('consent-overlay');
    if (overlay) {
        overlay.style.display = 'none';
        document.body.style.overflow = '';
    }
    if (_consentCallback && _consentUser) {
        _consentCallback(_consentUser);
    }
    _consentCallback = null;
    _consentUser = null;
}