/**
 * Service Worker for Text Corruptor PWA
 * Enables offline functionality and caching
 */

const CACHE_NAME = 'text-corruptor-v1';
const urlsToCache = ['/', '/index.html', '/styles.css', '/zalgo.js', '/app.js', '/manifest.json'];

// Install event - cache essential files
self.addEventListener('install', event => {
    event.waitUntil(
        caches
            .open(CACHE_NAME)
            .then(cache => {
                console.log('Opened cache');
                return cache.addAll(urlsToCache);
            })
            .then(() => {
                // Force the service worker to become active immediately
                return self.skipWaiting();
            })
    );
});

// Fetch event - serve from cache when offline
self.addEventListener('fetch', event => {
    event.respondWith(
        caches.match(event.request).then(response => {
            // Cache hit - return response
            if (response) {
                return response;
            }

            // Clone the request because it's a stream
            const fetchRequest = event.request.clone();

            return fetch(fetchRequest)
                .then(response => {
                    // Check if we received a valid response
                    if (!response || response.status !== 200 || response.type !== 'basic') {
                        return response;
                    }

                    // Clone the response because it's a stream
                    const responseToCache = response.clone();

                    caches.open(CACHE_NAME).then(cache => {
                        cache.put(event.request, responseToCache);
                    });

                    return response;
                })
                .catch(() => {
                    // Network request failed, serve offline fallback if available
                    return caches.match('/index.html');
                });
        })
    );
});

// Activate event - clean up old caches
self.addEventListener('activate', event => {
    const cacheWhitelist = [CACHE_NAME];

    event.waitUntil(
        caches
            .keys()
            .then(cacheNames => {
                return Promise.all(
                    cacheNames.map(cacheName => {
                        if (cacheWhitelist.indexOf(cacheName) === -1) {
                            console.log('Deleting old cache:', cacheName);
                            return caches.delete(cacheName);
                        }
                    })
                );
            })
            .then(() => {
                // Ensure the service worker takes control immediately
                return self.clients.claim();
            })
    );
});

// Handle messages from the client
self.addEventListener('message', event => {
    if (event.data && event.data.type === 'SKIP_WAITING') {
        self.skipWaiting();
    }
});