// authentication related functions and event handling

function showAuthScreen() {
    authScreen.style.display = 'flex';
    chatScreen.style.display = 'none';
}

function showChatScreen() {
    authScreen.style.display = 'none';
    chatScreen.style.display = 'flex';
    currentUserDisplay.textContent = `👤 ${username}`;
    
    loadServers();
    loadFriends();
    loadFriendRequests();
    loadUsers();
    // fetch profile to populate avatar and pronouns if needed
    if (typeof loadProfile === 'function') loadProfile();
    startAutoRefresh();
    
    // Request browser notification permission
    requestNotificationPermission().then(granted => {
        if (granted) {
            console.log('Notification permission granted');
        }
    });
    
    // Connect to SocketIO for real-time updates
    connectSocketIO();
}

async function register() {
    const user = usernameInput.value.trim();
    const pass = passwordInput.value.trim();

    if (!user || !pass) {
        authMessage.textContent = 'Please fill in all fields';
        authMessage.className = 'auth-message error';
        return;
    }

    const code = window.prompt('Enter the one-time code (e.g. ABC-DEF-GHI):');
    if (code === null || code.trim() === '') {
        return;
    }

    try {
        const res = await fetch(`${API_URL}/register`, {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ username: user, password: pass, invite_code: code.trim() })
        });

        const text = await res.text();
        
        if (!text || text.trim() === '') {
            console.error('Empty response from server');
            authMessage.textContent = 'Server error: Empty response';
            authMessage.className = 'auth-message error';
            return;
        }
        
        let data;
        try {
            data = JSON.parse(text);
        } catch (parseError) {
            console.error('Invalid JSON response:', text);
            authMessage.textContent = 'Server error: Invalid response format';
            authMessage.className = 'auth-message error';
            return;
        }
        
        if (res.ok) {
            token = data.token;
            userId = data.user_id;
            username = data.username;
            localStorage.setItem('token', token);
            localStorage.setItem('userId', userId);
            localStorage.setItem('username', username);
            authMessage.textContent = 'Registration successful!';
            authMessage.className = 'auth-message success';
            setTimeout(showChatScreen, 500);
        } else {
            authMessage.textContent = data.error || 'Registration failed';
            authMessage.className = 'auth-message error';
        }
    } catch (error) {
        authMessage.textContent = 'Error: ' + error.message;
        authMessage.className = 'auth-message error';
    }
}

async function login() {
    const user = usernameInput.value.trim();
    const pass = passwordInput.value.trim();

    if (!user || !pass) {
        authMessage.textContent = 'Please fill in all fields';
        authMessage.className = 'auth-message error';
        return;
    }

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

        // Get response text first to check if it's valid JSON
        const text = await res.text();
        
        // Check for empty response
        if (!text || text.trim() === '') {
            console.error('Empty response from server');
            authMessage.textContent = 'Server error: Empty response';
            authMessage.className = 'auth-message error';
            return;
        }
        
        // Try to parse as JSON
        let data;
        try {
            data = JSON.parse(text);
        } catch (parseError) {
            console.error('Invalid JSON response:', text);
            authMessage.textContent = 'Server error: Invalid response format';
            authMessage.className = 'auth-message error';
            return;
        }
        
        if (res.ok) {
            token = data.token;
            userId = data.user_id;
            username = data.username;
            localStorage.setItem('token', token);
            localStorage.setItem('userId', userId);
            localStorage.setItem('username', username);
            authMessage.textContent = 'Login successful!';
            authMessage.className = 'auth-message success';
            setTimeout(showChatScreen, 500);
        } else {
            authMessage.textContent = data.error || 'Login failed';
            authMessage.className = 'auth-message error';
        }
    } catch (error) {
        authMessage.textContent = 'Error: ' + error.message;
        authMessage.className = 'auth-message error';
    }
}

function logout() {
    localStorage.removeItem('token');
    localStorage.removeItem('userId');
    localStorage.removeItem('username');
    token = null;
    userId = null;
    username = null;
    currentDMUserId = null;
    messageInput.value = '';
    
    // Disconnect SocketIO and stop auto-refresh to prevent memory leaks
    disconnectSocketIO();
    stopAutoRefresh();
    
    showAuthScreen();
}

// attach auth event listeners (called after vars are bound)
function initAuthListeners() {
    loginBtn.addEventListener('click', login);
    registerBtn.addEventListener('click', register);
    logoutBtn.addEventListener('click', logout);
}

// check token on load
function authInitCheck() {
    if (token) {
        showChatScreen();
    } else {
        showAuthScreen();
    }
}