You're Offline
Please check your internet connection and try again.
`, {
status: 200,
headers: { 'Content-Type': 'text/html' }
});
})
);
return;
}
// Handle API requests
if (url.pathname.startsWith('/api/')) {
event.respondWith(
fetch(request)
.catch(() => {
// API offline - return a meaningful response
return new Response(
JSON.stringify({
error: 'Offline',
message: 'API request queued for when connection is restored'
}),
{
status: 503,
headers: { 'Content-Type': 'application/json' }
}
);
})
);
return;
}
// Handle static assets
event.respondWith(
caches.match(request)
.then(response => {
if (response) {
return response;
}
return fetch(request)
.then(response => {
// Don't cache non-successful responses
if (!response || response.status !== 200 || response.type !== 'basic') {
return response;
}
// Clone the response for caching
const responseToCache = response.clone();
caches.open(CACHE_NAME)
.then(cache => {
cache.put(request, responseToCache);
})
.catch(error => {
console.warn('Failed to cache resource:', error);
});
return response;
})
.catch(error => {
console.warn('Failed to fetch resource:', request.url, error);
// Return a basic 404 response for failed requests
return new Response('Not found', { status: 404 });
});
})
);
});
// Background Sync for scan queue
self.addEventListener('sync', (event) => {
console.log('Background sync triggered:', event.tag);
if (event.tag === 'sync-scans') {
event.waitUntil(syncPendingScans());
}
});
// Sync pending scans from IndexedDB
async function syncPendingScans() {
try {
console.log('Syncing pending scans...');
// This would normally interface with IndexedDB
// For now, we'll just log the sync attempt
// In a real implementation:
// 1. Open IndexedDB connection
// 2. Get all pending scans
// 3. Send each to the verify API
// 4. Update scan records with results
// 5. Handle conflicts and errors
console.log('Scan sync completed');
// Notify clients of sync completion
const clients = await self.clients.matchAll();
clients.forEach(client => {
client.postMessage({
type: 'SYNC_COMPLETE',
timestamp: Date.now()
});
});
} catch (error) {
console.error('Background sync failed:', error);
// Schedule retry with exponential backoff
setTimeout(() => {
self.registration.sync.register('sync-scans');
}, getBackoffDelay());
}
}
// Exponential backoff for failed syncs
let syncRetryCount = 0;
function getBackoffDelay() {
const delays = [1000, 2000, 5000, 10000, 30000]; // 1s, 2s, 5s, 10s, 30s
const delay = delays[Math.min(syncRetryCount, delays.length - 1)];
syncRetryCount++;
return delay;
}
// Reset retry count on successful sync
self.addEventListener('message', (event) => {
if (event.data && event.data.type === 'SYNC_SUCCESS') {
syncRetryCount = 0;
}
});
// Handle push notifications (for future use)
self.addEventListener('push', (event) => {
console.log('Push message received:', event);
const options = {
body: event.data ? event.data.text() : 'Scanner notification',
icon: '/icon-192x192.png',
badge: '/badge-72x72.png',
vibrate: [100, 50, 100],
data: {
dateOfArrival: Date.now(),
primaryKey: 1
},
actions: [
{
action: 'open-scanner',
title: 'Open Scanner',
icon: '/action-icon.png'
}
]
};
event.waitUntil(
self.registration.showNotification('BCT Scanner', options)
);
});
// Handle notification clicks
self.addEventListener('notificationclick', (event) => {
console.log('Notification clicked:', event);
event.notification.close();
event.waitUntil(
self.clients.matchAll().then(clients => {
// Check if scanner is already open
const scannerClient = clients.find(client =>
client.url.includes('/scan')
);
if (scannerClient) {
// Focus existing scanner
return scannerClient.focus();
} else {
// Open new scanner window
return self.clients.openWindow('/scan');
}
})
);
});
console.log('Service Worker script loaded');