// Progressive Web App functionality
// Handles service worker registration and PWA features

class PWAManager {
    constructor() {
        this.swRegistration = null;
        this.init();
    }

    async init() {
        console.log('PWA: Initializing PWA Manager...');
        
        if ('serviceWorker' in navigator) {
            try {
                this.swRegistration = await navigator.serviceWorker.register('/sw.js');
                console.log('SW: Service Worker registered successfully');
                
                // Listen for updates
                this.swRegistration.addEventListener('updatefound', () => {
                    console.log('SW: New version available');
                    this.showUpdateNotification();
                });
                
            } catch (error) {
                console.log('SW: Service Worker registration failed:', error);
            }
        }

        // Setup PWA install prompt
        this.setupInstallPrompt();
        
        // Setup notifications (if enabled)
        this.setupNotifications();
        
        // Show manual install option after 3 seconds if no prompt appeared
        setTimeout(() => {
            if (!document.getElementById('pwa-install-btn')) {
                this.showManualInstallButton();
            }
        }, 3000);
    }

    setupInstallPrompt() {
        let deferredPrompt;

        window.addEventListener('beforeinstallprompt', (e) => {
            console.log('PWA: beforeinstallprompt event fired');
            // Prevent Chrome 67 and earlier from automatically showing the prompt
            e.preventDefault();
            deferredPrompt = e;
            
            // Show custom install button
            this.showInstallButton(deferredPrompt);
        });

        window.addEventListener('appinstalled', () => {
            console.log('PWA: App was installed');
            this.hideInstallButton();
        });
        
        // Debug: Check if app is already installed
        if (this.isInstalled()) {
            console.log('PWA: App is already installed (standalone mode)');
        } else {
            console.log('PWA: App is not installed, waiting for install prompt...');
        }
    }

    showInstallButton(deferredPrompt) {
        // Create install button
        const installBtn = document.createElement('button');
        installBtn.id = 'pwa-install-btn';
        installBtn.className = 'btn btn-primary btn-sm';
        installBtn.innerHTML = '<i class="fas fa-download"></i> Install App';
        installBtn.style.cssText = `
            position: fixed;
            bottom: 20px;
            right: 20px;
            z-index: 1000;
            box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
        `;

        installBtn.addEventListener('click', async () => {
            if (deferredPrompt) {
                deferredPrompt.prompt();
                const { outcome } = await deferredPrompt.userChoice;
                console.log('PWA: User response to install prompt:', outcome);
                deferredPrompt = null;
                this.hideInstallButton();
            }
        });

        document.body.appendChild(installBtn);
    }

    hideInstallButton() {
        const installBtn = document.getElementById('pwa-install-btn');
        if (installBtn) {
            installBtn.remove();
        }
    }

    showUpdateNotification() {
        // Show update available notification
        const notification = document.createElement('div');
        notification.className = 'alert alert-info alert-dismissible';
        notification.style.cssText = `
            position: fixed;
            top: 20px;
            right: 20px;
            z-index: 1050;
            max-width: 300px;
        `;
        
        notification.innerHTML = `
            <strong>Update Available!</strong><br>
            A new version of the app is ready.
            <button type="button" class="btn btn-sm btn-outline-info ms-2" id="update-btn">
                Update Now
            </button>
            <button type="button" class="btn-close" data-bs-dismiss="alert"></button>
        `;

        document.body.appendChild(notification);

        // Handle update
        document.getElementById('update-btn').addEventListener('click', () => {
            if (this.swRegistration && this.swRegistration.waiting) {
                this.swRegistration.waiting.postMessage({ type: 'SKIP_WAITING' });
                window.location.reload();
            }
        });
    }

    async setupNotifications() {
        // Check if notifications are supported and get permission
        if ('Notification' in window) {
            const permission = await this.requestNotificationPermission();
            console.log('Notifications permission:', permission);
        }
    }

    async requestNotificationPermission() {
        if (Notification.permission === 'default') {
            // Only request permission when user interacts with a relevant feature
            // For now, just return the current status
            return Notification.permission;
        }
        return Notification.permission;
    }

    // Show notification (if permission granted)
    showNotification(title, options = {}) {
        if (Notification.permission === 'granted') {
            const notification = new Notification(title, {
                icon: '/icons/icon-192x192.png',
                badge: '/icons/icon-72x72.png',
                tag: 'littleshop-admin',
                ...options
            });

            // Auto-close after 5 seconds
            setTimeout(() => {
                notification.close();
            }, 5000);

            return notification;
        }
    }

    // Show manual install button for browsers that don't auto-prompt
    showManualInstallButton() {
        console.log('PWA: Showing manual install button');
        const installBtn = document.createElement('button');
        installBtn.id = 'pwa-install-btn';
        installBtn.className = 'btn btn-primary btn-sm';
        installBtn.innerHTML = '<i class="fas fa-mobile-alt"></i> Install as App';
        installBtn.style.cssText = `
            position: fixed;
            bottom: 20px;
            right: 20px;
            z-index: 1000;
            box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
        `;

        installBtn.addEventListener('click', () => {
            alert('To install this app:\\n\\n1. Click the browser menu (⋮)\\n2. Select "Install LittleShop Admin"\\n\\nOr look for the install icon in the address bar!');
        });

        document.body.appendChild(installBtn);
    }

    // Check if app is installed
    isInstalled() {
        return window.matchMedia('(display-mode: standalone)').matches ||
               window.navigator.standalone === true;
    }
}

// Initialize PWA Manager
const pwaManager = new PWAManager();
window.pwaManager = pwaManager;

// Expose notification function globally
window.showNotification = (title, options) => pwaManager.showNotification(title, options);