/**
 * Simplified Authentication Helper
 * 
 * This provides a streamlined authentication solution that works with
 * the simplified server-side authentication approach.
 */
class SimpleAuth {
    /**
     * Initialize the authentication helper
     */
    constructor() {
        this.token = localStorage.getItem('token');
        this.user = JSON.parse(localStorage.getItem('user') || 'null');
    }
    
    /**
     * Parse a JWT token to extract its payload
     * @param {string} token - The JWT token to parse
     * @returns {object|null} The decoded payload or null if invalid
     */
    parseJwt(token) {
        try {
            const base64Url = token.split('.')[1];
            const base64 = base64Url.replace(/-/g, '+').replace(/_/g, '/');
            const jsonPayload = decodeURIComponent(atob(base64).split('').map(function(c) {
                return '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2);
            }).join(''));
            
            return JSON.parse(jsonPayload);
        } catch (e) {
            console.error('Error parsing JWT token:', e);
            return null;
        }
    }
    
    /**
     * Login a user
     * @param {object} credentials - The user credentials (username, password)
     * @returns {Promise<object>} The login result
     */
    async login(credentials) {
        try {
            const response = await fetch('/api/login', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json'
                },
                body: JSON.stringify(credentials)
            });
            
            const data = await response.json();
            
            if (!response.ok) {
                throw new Error(data.error || 'Login failed');
            }
            
            // Store token and user data
            this.token = data.token;
            localStorage.setItem('token', data.token);
            
            // Parse user data from token
            const payload = this.parseJwt(data.token);
            this.user = {
                id: payload.uid,
                username: payload.username,
                accessLevel: payload.accessLevel
            };
            localStorage.setItem('user', JSON.stringify(this.user));
            
            return {
                success: true,
                user: this.user
            };
        } catch (error) {
            console.error('Login error:', error);
            return {
                success: false,
                error: error.message
            };
        }
    }
    
    /**
     * Logout the current user
     */
    logout() {
        this.token = null;
        this.user = null;
        localStorage.removeItem('token');
        localStorage.removeItem('user');
        
        // Redirect to home page
        window.location.href = '/';
    }
    
    /**
     * Check if the user is authenticated
     * @returns {boolean} True if authenticated, false otherwise
     */
    isAuthenticated() {
        return !!this.token && !!this.user;
    }
    
    /**
     * Check if the user is an admin
     * @returns {boolean} True if admin, false otherwise
     */
    isAdmin() {
        return this.isAuthenticated() && this.user.accessLevel === 1;
    }
    
    /**
     * Get the current user
     * @returns {object|null} The current user or null if not authenticated
     */
    getUser() {
        return this.user;
    }
    
    /**
     * Get the authentication token
     * @returns {string|null} The token or null if not authenticated
     */
    getToken() {
        return this.token;
    }
    
    /**
     * Make an authenticated API request
     * @param {string} url - The URL to fetch
     * @param {object} options - Fetch options
     * @returns {Promise<Response>} The fetch response
     */
    async fetchAuth(url, options = {}) {
        if (!this.token) {
            throw new Error('Not authenticated');
        }
        
        const headers = {
            ...options.headers,
            'Authorization': `Bearer ${this.token}`
        };
        
        return fetch(url, {
            ...options,
            headers
        });
    }
}

// Create a global instance
const auth = new SimpleAuth();