/**
 * Authentication Handler for StreetRacer Web Dashboard
 * Handles login, subscription/credit-based access, and session management
 *
 * Access model:
 * - PERMANENT_VIP_EMAILS: Full access always
 * - Subscribers (standard/premium/vip): Dashboard access included, but
 *   Sessions tab (500 credits) and Route editor (1000 credits) cost extra
 * - Non-subscribers: Pay credits per month for dashboard tiers:
 *   Basic (1000cr) = Stats + Rankings
 *   Extended (1500cr) = + Sessions
 *   Full (2500cr) = All features
 *   Sessions tab (500cr) and Route editor (1000cr) cost extra on top
 *
 * Firebase structure:
 *   dashboardAccess/{uid}: { tier, activatedAt, expiresAt, creditsPaid }
 *   dashboardFeatures/{uid}/{featureId}: { unlockedAt, creditsPaid }
 */

// Admin/VIP accounts that always have full access
const PERMANENT_VIP_EMAILS = [
    'francois.reinert@me.com',
    'leonard.reinert@me.com'
];

// Dashboard access tiers for non-subscribers
const DASHBOARD_TIERS = {
    basic: { name: 'Basis', cost: 1000, tabs: ['statistics', 'rankings'] },
    extended: { name: 'Erweitert', cost: 1500, tabs: ['statistics', 'rankings', 'sessions'] },
    full: { name: 'Komplett', cost: 2500, tabs: ['statistics', 'rankings', 'sessions', 'track-editor'] },
};

// Per-feature costs (for ALL users including subscribers)
const FEATURE_COSTS = {
    sessions: { name: 'Session-Details', cost: 500 },
    'track-editor': { name: 'Streckeneditor', cost: 1000 },
    'carcache-editor': { name: 'CarCache-Editor', cost: 1000 },
};

class AuthHandler {
    constructor() {
        this.currentUser = null;
        this.userSubscription = null;
        this.dashboardAccess = null; // { tier, expiresAt } for non-subscribers
        this.unlockedFeatures = {};  // { sessions: true, 'track-editor': true }
        this.accessLevel = 'none';   // 'permanent_vip', 'subscriber', 'credit_basic', 'credit_extended', 'credit_full', 'none'
        this.setupEventListeners();
        this.checkAuthState();
    }

    setupEventListeners() {
        document.getElementById('logout-btn')?.addEventListener('click', () => this.handleLogout());
        document.getElementById('google-login-btn')?.addEventListener('click', () => this.handleGoogleLogin());
        document.getElementById('apple-login-btn')?.addEventListener('click', () => this.handleAppleLogin());
    }

    checkAuthState() {
        auth.onAuthStateChanged(async (user) => {
            if (user) {
                console.log('User logged in:', user.email);
                this.currentUser = user;

                const access = await this.checkAccess(user.uid);

                if (access.allowed) {
                    this.accessLevel = access.level;
                    this.showDashboard();
                    this.loadUserData(user.uid);
                    this.applyAccessRestrictions();
                } else {
                    // Show access purchase options
                    this.showAccessOptions(user.uid, access);
                }
            } else {
                console.log('User logged out');
                this.currentUser = null;
                this.accessLevel = 'none';
                this.showLoginScreen();
            }
        });
    }

    async handleGoogleLogin() {
        this.showError('');
        try {
            const provider = new firebase.auth.GoogleAuthProvider();
            await auth.signInWithPopup(provider);
            // onAuthStateChanged will handle the rest
        } catch (error) {
            if (error.code !== 'auth/popup-closed-by-user') {
                console.error('Google login error:', error);
                this.showError(`Google-Anmeldung fehlgeschlagen: ${error.message}`);
            }
        }
    }

    async handleAppleLogin() {
        this.showError('');
        try {
            const provider = new firebase.auth.OAuthProvider('apple.com');
            provider.addScope('email');
            provider.addScope('name');
            await auth.signInWithPopup(provider);
            // onAuthStateChanged will handle the rest
        } catch (error) {
            if (error.code !== 'auth/popup-closed-by-user') {
                console.error('Apple login error:', error);
                this.showError(`Apple-Anmeldung fehlgeschlagen: ${error.message}`);
            }
        }
    }

    async handleLogout() {
        try {
            await auth.signOut();
        } catch (error) {
            console.error('Logout error:', error);
        }
    }

    /**
     * Check user's dashboard access level
     * Returns { allowed, level, subscription, credits, dashboardAccess }
     */
    async checkAccess(uid) {
        try {
            const userEmail = this.currentUser?.email?.toLowerCase();

            // 1. Permanent VIP
            if (userEmail && PERMANENT_VIP_EMAILS.includes(userEmail)) {
                console.log('Permanent VIP account:', userEmail);
                return { allowed: true, level: 'permanent_vip' };
            }

            // 2. Check subscription
            const subSnap = await database.ref(`subscriptions/${uid}`).once('value');
            const subscription = subSnap.val();
            this.userSubscription = subscription;

            if (subscription && subscription.tier && subscription.expiresAt > Date.now()) {
                console.log('Subscriber access:', subscription.tier);
                // All subscribers get dashboard access
                return { allowed: true, level: 'subscriber', subscription };
            }

            // 3. Check credit-based dashboard access
            const accessSnap = await database.ref(`dashboardAccess/${uid}`).once('value');
            const dashAccess = accessSnap.val();
            this.dashboardAccess = dashAccess;

            if (dashAccess && dashAccess.expiresAt > Date.now()) {
                console.log('Credit-based access:', dashAccess.tier);
                return { allowed: true, level: `credit_${dashAccess.tier}`, dashboardAccess: dashAccess };
            }

            // 4. Check credits balance for purchase option
            const creditsSnap = await database.ref(`credits/${uid}/balance`).once('value');
            const credits = creditsSnap.val() || 0;

            return { allowed: false, level: 'none', credits, subscription };
        } catch (error) {
            console.error('Error checking access:', error);
            return { allowed: false, level: 'none', credits: 0 };
        }
    }

    /**
     * Load unlocked features for user
     */
    async loadUnlockedFeatures(uid) {
        try {
            const snap = await database.ref(`dashboardFeatures/${uid}`).once('value');
            const features = snap.val() || {};
            this.unlockedFeatures = {};

            for (const [featureId, data] of Object.entries(features)) {
                if (data.expiresAt > Date.now()) {
                    this.unlockedFeatures[featureId] = true;
                }
            }
        } catch (error) {
            console.error('Error loading features:', error);
        }
    }

    /**
     * Apply access restrictions - hide/lock tabs based on access level
     */
    async applyAccessRestrictions() {
        const uid = this.currentUser?.uid;
        if (!uid) return;

        await this.loadUnlockedFeatures(uid);

        // Permanent VIP and subscribers with unlocked features
        const isPermanentVIP = this.accessLevel === 'permanent_vip';

        // Determine which tabs are accessible
        let accessibleTabs = ['statistics', 'rankings']; // Always accessible for any logged-in user

        if (isPermanentVIP) {
            accessibleTabs = ['statistics', 'sessions', 'track-editor', 'carcache-editor', 'rankings'];
        } else if (this.accessLevel === 'subscriber') {
            // Subscribers get stats + rankings free, sessions + track-editor + carcache-editor need credits
            accessibleTabs = ['statistics', 'rankings'];
            if (this.unlockedFeatures['sessions']) accessibleTabs.push('sessions');
            if (this.unlockedFeatures['track-editor']) accessibleTabs.push('track-editor');
            if (this.unlockedFeatures['carcache-editor']) accessibleTabs.push('carcache-editor');
        } else if (this.accessLevel.startsWith('credit_')) {
            const tier = this.accessLevel.replace('credit_', '');
            const tierConfig = DASHBOARD_TIERS[tier];
            if (tierConfig) {
                accessibleTabs = [...tierConfig.tabs];
            }
            // Also check per-feature unlocks
            if (this.unlockedFeatures['sessions'] && !accessibleTabs.includes('sessions')) {
                accessibleTabs.push('sessions');
            }
            if (this.unlockedFeatures['track-editor'] && !accessibleTabs.includes('track-editor')) {
                accessibleTabs.push('track-editor');
            }
            if (this.unlockedFeatures['carcache-editor'] && !accessibleTabs.includes('carcache-editor')) {
                accessibleTabs.push('carcache-editor');
            }
        }

        // Update nav buttons
        document.querySelectorAll('.nav-btn').forEach(btn => {
            const tab = btn.dataset.tab;
            const isAccessible = accessibleTabs.includes(tab);
            const featureCost = FEATURE_COSTS[tab];

            if (!isAccessible && featureCost && !isPermanentVIP) {
                // Show as locked with cost
                btn.classList.add('locked');
                btn.setAttribute('data-cost', featureCost.cost);
                // Add lock icon if not already there
                if (!btn.querySelector('.lock-icon')) {
                    const lockSpan = document.createElement('span');
                    lockSpan.className = 'material-icons lock-icon';
                    lockSpan.textContent = 'lock';
                    lockSpan.style.cssText = 'font-size: 14px; margin-left: 4px; color: #ff9800;';
                    btn.appendChild(lockSpan);

                    const costSpan = document.createElement('span');
                    costSpan.className = 'cost-label';
                    costSpan.textContent = `${featureCost.cost}`;
                    costSpan.style.cssText = 'font-size: 10px; color: #ff9800; margin-left: 2px;';
                    btn.appendChild(costSpan);
                }

                // Override click to show purchase dialog
                btn.onclick = (e) => {
                    e.preventDefault();
                    e.stopPropagation();
                    this.showFeaturePurchaseDialog(tab, featureCost);
                };
            } else {
                btn.classList.remove('locked');
                btn.querySelector('.lock-icon')?.remove();
                btn.querySelector('.cost-label')?.remove();
                btn.onclick = null; // restore default
            }
        });

        // Update VIP label to show actual tier
        const vipLabel = document.querySelector('.vip-label');
        if (vipLabel) {
            if (isPermanentVIP) {
                vipLabel.textContent = 'ADMIN';
                vipLabel.style.background = 'linear-gradient(135deg, #ff0000, #ff4444)';
            } else if (this.accessLevel === 'subscriber') {
                const tierName = this.userSubscription?.tier?.toUpperCase() || 'ABO';
                vipLabel.textContent = tierName;
                if (this.userSubscription?.tier === 'vip') {
                    vipLabel.style.background = 'linear-gradient(135deg, #FFD700, #FFA500)';
                } else if (this.userSubscription?.tier === 'premium') {
                    vipLabel.style.background = 'linear-gradient(135deg, #9C27B0, #E040FB)';
                } else {
                    vipLabel.style.background = 'linear-gradient(135deg, #2196F3, #64B5F6)';
                }
            } else {
                const tier = this.accessLevel.replace('credit_', '');
                const tierConfig = DASHBOARD_TIERS[tier];
                vipLabel.textContent = tierConfig?.name?.toUpperCase() || 'GAST';
                vipLabel.style.background = 'linear-gradient(135deg, #607D8B, #90A4AE)';
            }
        }
    }

    /**
     * Show dialog for purchasing a locked feature
     */
    showFeaturePurchaseDialog(featureId, featureInfo) {
        const existing = document.getElementById('feature-purchase-modal');
        if (existing) existing.remove();

        const modal = document.createElement('div');
        modal.id = 'feature-purchase-modal';
        modal.style.cssText = 'position:fixed;top:0;left:0;right:0;bottom:0;background:rgba(0,0,0,0.8);display:flex;align-items:center;justify-content:center;z-index:10000;';
        modal.innerHTML = `
            <div style="background:#1a1a2e;border-radius:16px;padding:32px;max-width:400px;width:90%;text-align:center;border:1px solid rgba(255,255,255,0.1);">
                <span class="material-icons" style="font-size:48px;color:#ff9800;margin-bottom:16px;">lock_open</span>
                <h3 style="color:#fff;margin:0 0 8px;">${featureInfo.name} freischalten</h3>
                <p style="color:#aaa;margin:0 0 24px;">Schalte dieses Feature für den aktuellen Monat frei.</p>
                <div style="background:rgba(255,152,0,0.1);border:1px solid rgba(255,152,0,0.3);border-radius:8px;padding:16px;margin-bottom:24px;">
                    <span style="font-size:32px;font-weight:bold;color:#ff9800;">${featureInfo.cost.toLocaleString('de-DE')}</span>
                    <span style="color:#aaa;display:block;font-size:13px;">Credits / Monat</span>
                </div>
                <div style="display:flex;gap:12px;justify-content:center;">
                    <button onclick="this.closest('#feature-purchase-modal').remove()" style="padding:10px 24px;border-radius:8px;border:1px solid rgba(255,255,255,0.2);background:transparent;color:#fff;cursor:pointer;">Abbrechen</button>
                    <button id="confirm-feature-purchase" style="padding:10px 24px;border-radius:8px;border:none;background:linear-gradient(135deg,#ff9800,#ff5722);color:#fff;cursor:pointer;font-weight:bold;">Freischalten</button>
                </div>
            </div>
        `;
        document.body.appendChild(modal);

        modal.addEventListener('click', (e) => { if (e.target === modal) modal.remove(); });

        document.getElementById('confirm-feature-purchase').addEventListener('click', async () => {
            await this.purchaseFeature(featureId, featureInfo.cost);
            modal.remove();
        });
    }

    /**
     * Purchase a feature with credits
     */
    async purchaseFeature(featureId, cost) {
        const uid = this.currentUser?.uid;
        if (!uid) return;

        try {
            // Check balance
            const creditsSnap = await database.ref(`credits/${uid}/balance`).once('value');
            const balance = creditsSnap.val() || 0;

            if (balance < cost) {
                this.showToast(`Nicht genug Credits (${balance.toLocaleString('de-DE')} / ${cost.toLocaleString('de-DE')} benötigt)`, true);
                return;
            }

            // Deduct credits
            const now = Date.now();
            const d = new Date();
            const nextMonth = new Date(d.getFullYear(), d.getMonth() + 1, 1);

            const updates = {};
            updates[`credits/${uid}/balance`] = balance - cost;
            updates[`credits/${uid}/totalSpent`] = firebase.database.ServerValue.increment(cost);
            updates[`credits/${uid}/lastUpdated`] = now;
            updates[`credits/${uid}/transactions/${now}`] = {
                type: 'dashboard_feature',
                amount: -cost,
                description: `Dashboard: ${FEATURE_COSTS[featureId]?.name || featureId}`,
                timestamp: now,
            };
            updates[`dashboardFeatures/${uid}/${featureId}`] = {
                unlockedAt: now,
                expiresAt: nextMonth.getTime(),
                creditsPaid: cost,
            };

            await database.ref().update(updates);

            this.showToast(`${FEATURE_COSTS[featureId]?.name || featureId} freigeschaltet!`);
            this.unlockedFeatures[featureId] = true;
            this.applyAccessRestrictions();

            // Switch to the unlocked tab
            if (window.dashboard) {
                window.dashboard.switchTab(featureId);
            }
        } catch (error) {
            console.error('Error purchasing feature:', error);
            this.showToast('Fehler beim Freischalten', true);
        }
    }

    /**
     * Show access tier purchase options for non-subscribers
     */
    showAccessOptions(uid, accessInfo) {
        const loginScreen = document.getElementById('login-screen');
        const loginContainer = loginScreen.querySelector('.login-container');

        // Check if user has any subscription at all
        const hasExpiredSub = accessInfo.subscription && accessInfo.subscription.expiresAt <= Date.now();
        const credits = accessInfo.credits || 0;

        loginContainer.innerHTML = `
            <div class="logo">
                <h1>STREET<span class="accent">RACER</span></h1>
                <p class="tagline">Web Dashboard</p>
            </div>
            <div class="login-form" style="max-width:500px;">
                <p style="color:#aaa;text-align:center;margin-bottom:8px;">Angemeldet als <strong style="color:#fff;">${this.currentUser?.email}</strong></p>
                <p style="color:#aaa;text-align:center;margin-bottom:4px;">Dein Guthaben: <strong style="color:#ff9800;">${credits.toLocaleString('de-DE')} Credits</strong></p>
                ${hasExpiredSub ? '<p style="color:#ff5252;text-align:center;margin-bottom:16px;">Dein Abonnement ist abgelaufen</p>' : ''}

                <div style="border-top:1px solid rgba(255,255,255,0.1);padding-top:20px;margin-top:12px;">
                    <h3 style="color:#fff;text-align:center;margin:0 0 4px;">Dashboard-Zugang per Credits</h3>
                    <p style="color:#888;text-align:center;font-size:13px;margin:0 0 16px;">Oder abonniere in der App für dauerhaften Zugang</p>

                    <div style="display:flex;flex-direction:column;gap:12px;">
                        ${this._renderAccessTier('basic', credits)}
                        ${this._renderAccessTier('extended', credits)}
                        ${this._renderAccessTier('full', credits)}
                    </div>
                </div>

                <button onclick="authHandler.handleLogout()" style="margin-top:20px;padding:10px;width:100%;border-radius:8px;border:1px solid rgba(255,255,255,0.2);background:transparent;color:#aaa;cursor:pointer;">Abmelden</button>
            </div>
        `;
    }

    _renderAccessTier(tierKey, userCredits) {
        const tier = DASHBOARD_TIERS[tierKey];
        const canAfford = userCredits >= tier.cost;
        const tabLabels = {
            'statistics': 'Statistiken',
            'rankings': 'Ranglisten',
            'sessions': 'Sessions',
            'track-editor': 'Streckeneditor',
        };
        const included = tier.tabs.map(t => tabLabels[t] || t).join(', ');

        return `
            <div style="background:rgba(255,255,255,0.05);border:1px solid rgba(255,255,255,0.1);border-radius:12px;padding:16px;display:flex;align-items:center;justify-content:space-between;">
                <div>
                    <strong style="color:#fff;">${tier.name}</strong>
                    <span style="color:#ff9800;font-weight:bold;margin-left:8px;">${tier.cost.toLocaleString('de-DE')} Credits/Monat</span>
                    <div style="color:#888;font-size:12px;margin-top:4px;">${included}</div>
                </div>
                <button onclick="authHandler.purchaseDashboardAccess('${tierKey}')"
                    style="padding:8px 16px;border-radius:8px;border:none;color:#fff;cursor:pointer;font-weight:bold;white-space:nowrap;${canAfford ? 'background:linear-gradient(135deg,#ff9800,#ff5722);' : 'background:#555;opacity:0.6;cursor:not-allowed;'}"
                    ${canAfford ? '' : 'disabled'}>
                    Freischalten
                </button>
            </div>
        `;
    }

    /**
     * Purchase dashboard access tier with credits
     */
    async purchaseDashboardAccess(tierKey) {
        const uid = this.currentUser?.uid;
        if (!uid) return;

        const tier = DASHBOARD_TIERS[tierKey];
        if (!tier) return;

        try {
            const creditsSnap = await database.ref(`credits/${uid}/balance`).once('value');
            const balance = creditsSnap.val() || 0;

            if (balance < tier.cost) {
                this.showToast('Nicht genug Credits', true);
                return;
            }

            const now = Date.now();
            const d = new Date();
            const nextMonth = new Date(d.getFullYear(), d.getMonth() + 1, 1);

            const updates = {};
            updates[`credits/${uid}/balance`] = balance - tier.cost;
            updates[`credits/${uid}/totalSpent`] = firebase.database.ServerValue.increment(tier.cost);
            updates[`credits/${uid}/lastUpdated`] = now;
            updates[`credits/${uid}/transactions/${now}`] = {
                type: 'dashboard_access',
                amount: -tier.cost,
                description: `Dashboard ${tier.name}-Zugang (1 Monat)`,
                timestamp: now,
            };
            updates[`dashboardAccess/${uid}`] = {
                tier: tierKey,
                activatedAt: now,
                expiresAt: nextMonth.getTime(),
                creditsPaid: tier.cost,
            };

            await database.ref().update(updates);

            this.dashboardAccess = { tier: tierKey, expiresAt: nextMonth.getTime() };
            this.accessLevel = `credit_${tierKey}`;

            this.showToast(`Dashboard ${tier.name}-Zugang freigeschaltet!`);
            this.showDashboard();
            this.loadUserData(uid);
            this.applyAccessRestrictions();
        } catch (error) {
            console.error('Error purchasing dashboard access:', error);
            this.showToast('Fehler beim Freischalten', true);
        }
    }

    async loadUserData(uid) {
        try {
            const userRef = database.ref(`users/${uid}`);
            const userSnapshot = await userRef.once('value');
            const userData = userSnapshot.val();

            if (userData?.nickname) {
                document.getElementById('user-nickname').textContent = userData.nickname;
            } else {
                const carRef = database.ref(`cars/${uid}`);
                const carSnapshot = await carRef.once('value');
                const carData = carSnapshot.val();
                if (carData?.nickname) {
                    document.getElementById('user-nickname').textContent = carData.nickname;
                }
            }
        } catch (error) {
            console.error('Error loading user data:', error);
        }
    }

    showError(message) {
        const errorEl = document.getElementById('login-error');
        if (errorEl) errorEl.textContent = message;
    }

    showToast(message, isError = false) {
        const toast = document.createElement('div');
        toast.style.cssText = `position:fixed;top:20px;right:20px;padding:12px 24px;border-radius:8px;color:#fff;font-weight:500;z-index:99999;transition:opacity 0.3s;${isError ? 'background:#f44336;' : 'background:#4CAF50;'}`;
        toast.textContent = message;
        document.body.appendChild(toast);
        setTimeout(() => { toast.style.opacity = '0'; setTimeout(() => toast.remove(), 300); }, 3000);
    }

    showLoginScreen() {
        document.getElementById('login-screen').classList.remove('hidden');
        document.getElementById('dashboard').classList.add('hidden');

        // Restore original login form if it was replaced by access options
        const loginContainer = document.querySelector('#login-screen .login-container');
        if (loginContainer && !loginContainer.querySelector('#google-login-btn')) {
            loginContainer.innerHTML = `
                <div class="logo">
                    <h1>STREET<span class="accent">RACER</span></h1>
                    <p class="tagline">Web Dashboard</p>
                </div>
                <div class="login-form">
                    <div class="vip-badge">
                        <span class="material-icons">star</span>
                        <span>Dashboard Feature</span>
                    </div>
                    <p class="login-info">Melde dich mit deinem Account an</p>
                    <button id="google-login-btn" class="btn-social btn-google">
                        <svg width="18" height="18" viewBox="0 0 48 48"><path fill="#EA4335" d="M24 9.5c3.54 0 6.71 1.22 9.21 3.6l6.85-6.85C35.9 2.38 30.47 0 24 0 14.62 0 6.51 5.38 2.56 13.22l7.98 6.19C12.43 13.72 17.74 9.5 24 9.5z"/><path fill="#4285F4" d="M46.98 24.55c0-1.57-.15-3.09-.38-4.55H24v9.02h12.94c-.58 2.96-2.26 5.48-4.78 7.18l7.73 6c4.51-4.18 7.09-10.36 7.09-17.65z"/><path fill="#34A853" d="M10.53 28.59c-.48-1.45-.76-2.99-.76-4.59s.27-3.14.76-4.59l-7.98-6.19C.92 16.46 0 20.12 0 24c0 3.88.92 7.54 2.56 10.78l7.97-6.19z"/><path fill="#FBBC05" d="M24 48c6.48 0 11.93-2.13 15.89-5.81l-7.73-6c-2.15 1.45-4.92 2.3-8.16 2.3-6.26 0-11.57-4.22-13.47-9.91l-7.98 6.19C6.51 42.62 14.62 48 24 48z"/></svg>
                        Weiter mit Google
                    </button>
                    <button id="apple-login-btn" class="btn-social btn-apple">
                        <svg width="18" height="18" viewBox="0 0 24 24" fill="#fff"><path d="M17.05 20.28c-.98.95-2.05.88-3.08.4-1.09-.5-2.08-.48-3.24 0-1.44.62-2.2.44-3.06-.4C2.79 15.25 3.51 7.59 9.05 7.31c1.35.07 2.29.74 3.08.8 1.18-.24 2.31-.93 3.57-.84 1.51.12 2.65.72 3.4 1.8-3.12 1.87-2.38 5.98.48 7.13-.57 1.5-1.31 2.99-2.54 4.09zM12.03 7.25c-.15-2.23 1.66-4.07 3.74-4.25.29 2.58-2.34 4.5-3.74 4.25z"/></svg>
                        Weiter mit Apple
                    </button>
                    <div id="login-error" class="error-message"></div>
                    <div class="login-legal">
                        <a href="/impressum">Impressum</a>
                        <span class="login-legal-sep">|</span>
                        <a href="/privacy">Datenschutz</a>
                        <span class="login-legal-sep">|</span>
                        <a href="/agb">AGB</a>
                    </div>
                </div>
            `;
            // Re-attach event listeners
            document.getElementById('google-login-btn')?.addEventListener('click', () => this.handleGoogleLogin());
            document.getElementById('apple-login-btn')?.addEventListener('click', () => this.handleAppleLogin());
        }
    }

    showDashboard() {
        document.getElementById('login-screen').classList.add('hidden');
        document.getElementById('dashboard').classList.remove('hidden');

        if (window.dashboard) {
            window.dashboard.initialize();
        }
    }

    getCurrentUser() {
        return this.currentUser;
    }

    /**
     * Check if a specific tab is accessible for current user
     */
    canAccessTab(tabName) {
        if (this.accessLevel === 'permanent_vip') return true;
        if (['statistics', 'rankings'].includes(tabName)) return true;

        if (this.accessLevel === 'subscriber') {
            return this.unlockedFeatures[tabName] === true;
        }

        if (this.accessLevel.startsWith('credit_')) {
            const tier = this.accessLevel.replace('credit_', '');
            const tierConfig = DASHBOARD_TIERS[tier];
            if (tierConfig?.tabs.includes(tabName)) return true;
            return this.unlockedFeatures[tabName] === true;
        }

        return false;
    }
}

// Initialize auth handler
const authHandler = new AuthHandler();
window.authHandler = authHandler;