From 2e94226b1c76231220c054b9a69abf1b5ba2fd18 Mon Sep 17 00:00:00 2001
From: ayoayco <ayo@ayco.io>
Date: Mon, 19 Aug 2024 13:52:51 +0200
Subject: [PATCH] feat: new experimental `strategies` option

---
 packages/index.js                             |   1 -
 .../CacheRevalidatePreloadFallback.js         | 150 ++++++++++++++++++
 2 files changed, 150 insertions(+), 1 deletion(-)
 create mode 100644 packages/strategies/CacheRevalidatePreloadFallback.js

diff --git a/packages/index.js b/packages/index.js
index 9e8c7d2..8bd043b 100644
--- a/packages/index.js
+++ b/packages/index.js
@@ -1,4 +1,3 @@
-// @ts-check
 /**
  * @license MIT <https://opensource.org/licenses/MIT>
  * @author Ayo Ayco <https://ayo.ayco.io>
diff --git a/packages/strategies/CacheRevalidatePreloadFallback.js b/packages/strategies/CacheRevalidatePreloadFallback.js
new file mode 100644
index 0000000..43e630f
--- /dev/null
+++ b/packages/strategies/CacheRevalidatePreloadFallback.js
@@ -0,0 +1,150 @@
+/**
+ * Note: @ayco/astro-sw integration injects variables `__prefix`, `__version`, & `__assets`
+ * -- find usage in `astro.config.mjs` integrations
+ * @see https://ayco.io/n/@ayco/astro-sw
+ */
+const cacheName = `${__prefix ?? 'app'}-v${__version ?? '000'}`
+
+/**
+ * TODO: respect a log config property for logInfo
+ */
+
+const cleanOldCaches = async () => {
+    const allowCacheNames = ['cozy-reader', cacheName];
+    const allCaches = await caches.keys();
+    allCaches.forEach(key => {
+        if (!allowCacheNames.includes(key)) {
+            // logInfo('Deleting old cache', {force: !!forceLogging, data: key, context: 'cozy-sw'});
+            caches.delete(key);
+        }
+    });
+}
+
+const addResourcesToCache = async (resources) => {
+    const cache = await caches.open(cacheName);
+    // logInfo('adding resources to cache...', { force: !!forceLogging, context: 'cozy-sw', data: resources })
+    await cache.addAll(resources);
+};
+
+const putInCache = async (request, response) => {
+    const cache = await caches.open(cacheName);
+    // logInfo('adding one response to cache...', { force: forceLogging, context: 'cozy-sw', data: request.url })
+    // if exists, replace
+
+    const keys = await cache.keys();
+    if (keys.includes(request)) {
+        cache.delete(request);
+    }
+
+    await cache.put(request, response);
+};
+
+
+const cacheAndRevalidate = async ({ request, preloadResponsePromise, fallbackUrl }) => {
+
+    const cache = await caches.open(cacheName);
+
+    // Try get the resource from the cache
+    const responseFromCache = await cache.match(request);
+    if (responseFromCache) {
+        // logInfo('using cached response...', { force: forceLogging, context: 'cozy-sw', data: responseFromCache.url })
+        // get network response for revalidation of cached assets
+        fetch(request.clone()).then((responseFromNetwork) => {
+            if (responseFromNetwork) {
+                // logInfo('fetched updated resource...', { force: forceLogging, context: 'cozy-sw', data: responseFromNetwork.url })
+                putInCache(request, responseFromNetwork.clone());
+            }
+        }).catch((error) => {
+            logError('failed to fetch updated resource', { force: forceLogging, context: 'cozy-sw', data: error })
+        });
+
+        return responseFromCache;
+    }
+
+
+
+    // Try to use the preloaded response, if it's there
+    // NOTE: Chrome throws errors regarding preloadResponse, see:
+    // https://bugs.chromium.org/p/chromium/issues/detail?id=1420515
+    // https://github.com/mdn/dom-examples/issues/145
+    // To avoid those errors, remove or comment out this block of preloadResponse
+    // code along with enableNavigationPreload() and the "activate" listener.
+    const preloadResponse = await preloadResponsePromise;
+    if (preloadResponse) {
+        putInCache(request, preloadResponse.clone());
+        // logInfo('using preload response', { force: forceLogging, context: 'cozy-sw', data: preloadResponse.url })
+        return preloadResponse;
+    }
+
+    try {
+        // Try to get the resource from the network for 5 seconds
+        const responseFromNetwork = await fetch(request.clone());
+        // response may be used only once
+        // we need to save clone to put one copy in cache
+        // and serve second one
+        putInCache(request, responseFromNetwork.clone());
+        // logInfo('using network response', { force: forceLogging, context: 'cozy-sw', data: responseFromNetwork.url })
+        return responseFromNetwork;
+
+    } catch (error) {
+
+        // Try the fallback
+        const fallbackResponse = await cache.match(fallbackUrl);
+        if (fallbackResponse) {
+            // logInfo('using fallback cached response...', { force: forceLogging, context: 'cozy-sw', data: fallbackResponse.url })
+            return fallbackResponse;
+        }
+
+        // when even the fallback response is not available,
+        // there is nothing we can do, but we must always
+        // return a Response object
+        return new Response('Network error happened', {
+            status: 408,
+            headers: { 'Content-Type': 'text/plain' },
+        });
+    }
+};
+
+const enableNavigationPreload = async () => {
+    if (self.registration.navigationPreload) {
+        // Enable navigation preloads!
+        await self.registration.navigationPreload.enable();
+    }
+};
+
+const activateFn = (event) => {
+    // logInfo('activating service worker...', { force: forceLogging, context: 'cozy-sw' })
+    cleanOldCaches();
+    event.waitUntil(enableNavigationPreload());
+};
+
+const installFn = (event) => {
+
+    // logInfo('installing service worker...', { force: forceLogging, context: 'cozy-sw' })
+    self.skipWaiting(); // go straight to activate
+
+    event.waitUntil(
+        addResourcesToCache(__assets ?? [])
+    );
+};
+
+const fetchFn = (event) => {
+    // logInfo('fetch happened', {data: event});
+    
+    event.respondWith(
+        cacheAndRevalidate({
+            request: event.request,
+            preloadResponsePromise: event.preloadResponse,
+            fallbackUrl: './',
+        })
+    );
+};
+
+const waitFn = (event) => {}
+
+export default {
+    fetchFn,
+    installFn,
+    activateFn,
+    waitFn
+}
\ No newline at end of file