From 59430445098daab1c6d17507f0272ba84bac84dc Mon Sep 17 00:00:00 2001
From: m5r <mokht@rmi.al>
Date: Sat, 4 Jun 2022 23:34:33 +0200
Subject: [PATCH] cache loader data and document, network-first approach

---
 app/service-worker/cache-utils.ts | 130 +++++++++++++++++++++++-------
 app/service-worker/fetch.ts       |  23 ++++--
 2 files changed, 120 insertions(+), 33 deletions(-)

diff --git a/app/service-worker/cache-utils.ts b/app/service-worker/cache-utils.ts
index b31c2be..372665c 100644
--- a/app/service-worker/cache-utils.ts
+++ b/app/service-worker/cache-utils.ts
@@ -1,32 +1,106 @@
-import type { FetchEventWithPreloadResponse } from "./fetch";
+import { json } from "@remix-run/server-runtime";
 
 export const ASSET_CACHE = "asset-cache";
+export const DATA_CACHE = "data-cache";
+export const DOCUMENT_CACHE = "document-cache";
 
-export async function cacheAsset(event: FetchEventWithPreloadResponse) {
-	const url = new URL(event.request.url);
-	const cachedResponse = await caches.match(event.request, {
-		cacheName: ASSET_CACHE,
-		ignoreVary: true,
-		ignoreSearch: true,
-	});
-
-	console.debug(`Serving asset from ${cachedResponse ? "cache" : " network"}`, url.pathname);
-
-	const fetchPromise = (async () => {
-		const cache = await caches.open(ASSET_CACHE);
-		const preloadedResponse = await event.preloadResponse;
-		const response = preloadedResponse || (await fetch(event.request));
-		switch (response.status) {
-			case 200:
-				cache.put(event.request, response.clone());
-				break;
-			case 404:
-				cache.delete(event.request);
-				break;
-		}
-
-		return response;
-	})();
-
-	return cachedResponse || fetchPromise;
+export function isAssetRequest(request: Request) {
+	return ["font", "image", "script", "style"].includes(request.destination);
+}
+
+export function isLoaderRequest(request: Request) {
+	const url = new URL(request.url);
+	return request.method.toLowerCase() === "get" && url.searchParams.get("_data");
+}
+
+export function isDocumentGetRequest(request: Request) {
+	return request.method.toLowerCase() === "get" && request.mode === "navigate";
+}
+
+export function cacheAsset(event: FetchEvent) {
+	// stale-while-revalidate
+	const url = new URL(event.request.url);
+	return caches
+		.match(event.request, {
+			cacheName: ASSET_CACHE,
+			ignoreVary: true,
+			ignoreSearch: true,
+		})
+		.then((cachedResponse) => {
+			console.debug(`Serving asset from ${cachedResponse ? "cache" : " network"}`, url.pathname);
+
+			const fetchPromise = event.preloadResponse
+				.then((preloadedResponse?: Response) => preloadedResponse || fetch(event.request.clone()))
+				.then((response) =>
+					caches.open(ASSET_CACHE).then((cache) => {
+						switch (response.status) {
+							case 200:
+								cache.put(event.request, response.clone());
+								break;
+							case 404:
+								cache.delete(event.request);
+								break;
+						}
+
+						return response;
+					}),
+				);
+
+			return cachedResponse || fetchPromise;
+		});
+}
+
+export function cacheLoaderData(event: FetchEvent) {
+	// network-first
+	const url = new URL(event.request.url);
+	console.debug("Serving data from network", url.pathname + url.search);
+
+	return event.preloadResponse
+		.then((preloadedResponse?: Response) => preloadedResponse || fetch(event.request.clone()))
+		.then((response) =>
+			caches
+				.open(DATA_CACHE)
+				.then((cache) => cache.put(event.request, response.clone()))
+				.then(() => response),
+		)
+		.catch(() => {
+			console.debug("Serving data from network failed, falling back to cache", url.pathname + url.search);
+			return caches.match(event.request).then((response) => {
+				if (!response) {
+					return json(
+						{ message: "Network Error" },
+						{
+							status: 500,
+							headers: { "X-Remix-Catch": "yes", "X-Remix-Worker": "yes" },
+						},
+					);
+				}
+
+				response.headers.set("X-Remix-Worker", "yes");
+				return response;
+			});
+		});
+}
+
+export function cacheDocument(event: FetchEvent): Promise<Response> {
+	// network-first
+	const url = new URL(event.request.url);
+	console.debug("Serving document from network", url.pathname);
+	return caches.open(DOCUMENT_CACHE).then((cache) =>
+		fetch(event.request.clone())
+			.then((response) => {
+				cache.put(event.request, response.clone());
+				return response;
+			})
+			.catch((error) => {
+				console.debug("Serving document from network failed, falling back to cache", url.pathname);
+				return caches.match(event.request).then((response) => {
+					if (!response) {
+						throw error;
+					}
+
+					return response;
+				});
+			}),
+	);
 }
diff --git a/app/service-worker/fetch.ts b/app/service-worker/fetch.ts
index b49fbfc..bedd28a 100644
--- a/app/service-worker/fetch.ts
+++ b/app/service-worker/fetch.ts
@@ -1,13 +1,26 @@
-import { ASSET_CACHE, cacheAsset } from "~/service-worker/cache-utils";
+import {
+	cacheAsset,
+	cacheDocument,
+	cacheLoaderData,
+	isAssetRequest,
+	isDocumentGetRequest,
+	isLoaderRequest,
+} from "~/service-worker/cache-utils";
 
 declare let self: ServiceWorkerGlobalScope;
 
-export type FetchEventWithPreloadResponse = FetchEvent & { preloadResponse?: Promise<Response | undefined> };
-
-export default async function handleFetch(event: FetchEventWithPreloadResponse) {
-	if (["font", "image", "script", "style"].includes(event.request.destination)) {
+export default async function handleFetch(event: FetchEvent) {
+	if (isAssetRequest(event.request)) {
 		return cacheAsset(event);
 	}
 
+	if (isLoaderRequest(event.request)) {
+		return cacheLoaderData(event);
+	}
+
+	if (isDocumentGetRequest(event.request)) {
+		return cacheDocument(event);
+	}
+
 	return fetch(event.request);
 }