// static/js/shared/api-client.js
/**
 * API Client for Multi-Tenant Ecommerce Platform
 *
 * Provides utilities for:
 * - Making authenticated API calls
 * - Token management
 * - Error handling
 * - Request/response interceptors
 */

const API_BASE_URL = '/api/v1';

/**
 * API Client Class
 */
class APIClient {
    constructor(baseURL = API_BASE_URL) {
        this.baseURL = baseURL;
    }

    /**
     * Get stored authentication token
     */
    getToken() {
        return localStorage.getItem('admin_token') || localStorage.getItem('vendor_token');
    }

    /**
     * Get default headers with authentication
     */
    getHeaders(additionalHeaders = {}) {
        const headers = {
            'Content-Type': 'application/json',
            ...additionalHeaders
        };

        const token = this.getToken();
        if (token) {
            headers['Authorization'] = `Bearer ${token}`;
        }

        return headers;
    }

    /**
     * Make API request
     */
    async request(endpoint, options = {}) {
        const url = `${this.baseURL}${endpoint}`;

        const config = {
            ...options,
            headers: this.getHeaders(options.headers)
        };

        try {
            const response = await fetch(url, config);

            // Handle 401 Unauthorized
            if (response.status === 401) {
                this.handleUnauthorized();
                throw new Error('Unauthorized - please login again');
            }

            // Parse response
            const data = await response.json();

            // Handle non-OK responses
            if (!response.ok) {
                throw new Error(data.detail || data.message || 'Request failed');
            }

            return data;

        } catch (error) {
            console.error('API request failed:', error);
            throw error;
        }
    }

    /**
     * GET request
     */
    async get(endpoint, params = {}) {
        const queryString = new URLSearchParams(params).toString();
        const url = queryString ? `${endpoint}?${queryString}` : endpoint;

        return this.request(url, {
            method: 'GET'
        });
    }

    /**
     * POST request
     */
    async post(endpoint, data = {}) {
        return this.request(endpoint, {
            method: 'POST',
            body: JSON.stringify(data)
        });
    }

    /**
     * PUT request
     */
    async put(endpoint, data = {}) {
        return this.request(endpoint, {
            method: 'PUT',
            body: JSON.stringify(data)
        });
    }

    /**
     * DELETE request
     */
    async delete(endpoint) {
        return this.request(endpoint, {
            method: 'DELETE'
        });
    }

    /**
     * Handle unauthorized access
     */
    handleUnauthorized() {
        localStorage.removeItem('admin_token');
        localStorage.removeItem('admin_user');
        localStorage.removeItem('vendor_token');
        localStorage.removeItem('vendor_user');

        // Redirect to appropriate login page
        if (window.location.pathname.includes('/admin/')) {
            window.location.href = '/static/admin/login.html';
        } else if (window.location.pathname.includes('/vendor/')) {
            window.location.href = '/static/vendor/login.html';
        }
    }
}

// Create global API client instance
const apiClient = new APIClient();

/**
 * Authentication helpers
 */
const Auth = {
    /**
     * Check if user is authenticated
     */
    isAuthenticated() {
        const token = localStorage.getItem('admin_token') || localStorage.getItem('vendor_token');
        return !!token;
    },

    /**
     * Get current user
     */
    getCurrentUser() {
        const userStr = localStorage.getItem('admin_user') || localStorage.getItem('vendor_user');
        if (!userStr) return null;

        try {
            return JSON.parse(userStr);
        } catch (e) {
            return null;
        }
    },

    /**
     * Check if user is admin
     */
    isAdmin() {
        const user = this.getCurrentUser();
        return user && user.role === 'admin';
    },

    /**
     * Login
     */
    async login(username, password) {
        const response = await apiClient.post('/auth/login', {
            username,
            password
        });

        // Store token and user
        if (response.user.role === 'admin') {
            localStorage.setItem('admin_token', response.access_token);
            localStorage.setItem('admin_user', JSON.stringify(response.user));
        } else {
            localStorage.setItem('vendor_token', response.access_token);
            localStorage.setItem('vendor_user', JSON.stringify(response.user));
        }

        return response;
    },

    /**
     * Logout
     */
    logout() {
        localStorage.removeItem('admin_token');
        localStorage.removeItem('admin_user');
        localStorage.removeItem('vendor_token');
        localStorage.removeItem('vendor_user');
    }
};

/**
 * Utility functions
 */
const Utils = {
    /**
     * Format date
     */
    formatDate(dateString) {
        if (!dateString) return '-';
        const date = new Date(dateString);
        return date.toLocaleDateString('en-GB', {
            day: '2-digit',
            month: 'short',
            year: 'numeric'
        });
    },

    /**
     * Format datetime
     */
    formatDateTime(dateString) {
        if (!dateString) return '-';
        const date = new Date(dateString);
        return date.toLocaleString('en-GB', {
            day: '2-digit',
            month: 'short',
            year: 'numeric',
            hour: '2-digit',
            minute: '2-digit'
        });
    },

    /**
     * Format currency
     */
    formatCurrency(amount, currency = 'EUR') {
        if (amount === null || amount === undefined) return '-';
        return new Intl.NumberFormat('en-GB', {
            style: 'currency',
            currency: currency
        }).format(amount);
    },

    /**
     * Debounce function
     */
    debounce(func, wait) {
        let timeout;
        return function executedFunction(...args) {
            const later = () => {
                clearTimeout(timeout);
                func(...args);
            };
            clearTimeout(timeout);
            timeout = setTimeout(later, wait);
        };
    },

    /**
     * Show toast notification
     */
    showToast(message, type = 'info', duration = 3000) {
        // Create toast element
        const toast = document.createElement('div');
        toast.className = `toast toast-${type}`;
        toast.textContent = message;

        // Style
        toast.style.cssText = `
            position: fixed;
            top: 20px;
            right: 20px;
            padding: 16px 24px;
            background: ${type === 'success' ? '#4caf50' : type === 'error' ? '#f44336' : '#2196f3'};
            color: white;
            border-radius: 8px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.15);
            z-index: 10000;
            animation: slideIn 0.3s ease;
            max-width: 400px;
        `;

        // Add to page
        document.body.appendChild(toast);

        // Remove after duration
        setTimeout(() => {
            toast.style.animation = 'slideOut 0.3s ease';
            setTimeout(() => toast.remove(), 300);
        }, duration);
    },

    /**
     * Confirm dialog
     */
    async confirm(message, title = 'Confirm') {
        return window.confirm(`${title}\n\n${message}`);
    }
};

// Add animation styles
const style = document.createElement('style');
style.textContent = `
    @keyframes slideIn {
        from {
            transform: translateX(400px);
            opacity: 0;
        }
        to {
            transform: translateX(0);
            opacity: 1;
        }
    }

    @keyframes slideOut {
        from {
            transform: translateX(0);
            opacity: 1;
        }
        to {
            transform: translateX(400px);
            opacity: 0;
        }
    }
`;
document.head.appendChild(style);

// Export for use in other scripts
if (typeof module !== 'undefined' && module.exports) {
    module.exports = { APIClient, apiClient, Auth, Utils };
}