Replace Azure SWA with custom server

1 files changed, 51 insertions, 0 deletions

diff --git a/src/frontend/public/sw.js b/src/frontend/public/sw.js
new file mode 100644
index 0000000..70ca169
--- /dev/null
+++ b/src/frontend/public/sw.js
@@ -0,0 +1,51 @@
+const API_CACHE_NAME = 'api-cache-v1'
+const API_URL_PATTERN = /\/api\/(GetStopList)/;
+const API_MAX_AGE = 24 * 60 * 60 * 1000; // 24 hours
+
+self.addEventListener('install', (event) => {
+    event.waitUntil(self.skipWaiting());
+});
+
+self.addEventListener('activate', (event) => {
+    event.waitUntil(self.clients.claim());
+});
+
+self.addEventListener('fetch', async (event) => {
+    const url = new URL(event.request.url);
+
+    if (event.request.method !== "GET" || !API_URL_PATTERN.test(url.pathname)) {
+        return;
+    }
+
+    event.respondWith(apiCacheFirst(event.request));
+});
+
+async function apiCacheFirst(request) {
+    const cache = await caches.open(API_CACHE_NAME);
+    const cachedResponse = await cache.match(request);
+
+    if (cachedResponse) {
+        const age = Date.now() - new Date(cachedResponse.headers.get('date')).getTime();
+        if (age < API_MAX_AGE) {
+            console.debug(`SW: Cache HIT for ${request.url}`);
+            return cachedResponse;
+        }
+
+        // Cache is too old, fetch a fresh copy
+        cache.delete(request);
+    }
+
+    try {
+        const netResponse = await fetch(request);
+
+        const responseToCache = netResponse.clone();
+
+        cache.put(request, responseToCache);
+
+        console.debug(`SW: Cache MISS for ${request.url}`);
+
+        return netResponse;
+    } catch (error) {
+        throw error;
+    }
+}
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