swruntime: implement fetch event

src/client/swruntime.ts

@@ -1,21 +1,121 @@
+import { ScramjetClient } from "./client";
 import { encodeUrl } from "./shared";
 
-class ScramjetServiceWorkerRuntime {
-	constructor() {
-		addEventListener("message", (event) => {
-			if ("scramjet$type" in event.data) {
-				event.stopImmediatePropagation();
+export class ScramjetServiceWorkerRuntime {
+	constructor(public client: ScramjetClient) {
+		addEventListener("connect", (cevent: MessageEvent) => {
+			const port = cevent.ports[0];
 
-				return;
-			}
+			port.addEventListener("message", (event) => {
+				if ("scramjet$type" in event.data) {
+					handleMessage(client, event.data, port);
+				}
+			});
+
+			port.start();
 		});
 	}
+
+	hook() {}
 }
 
-declare global {
-	interface Window {
-		ScramjetServiceWorkerRuntime: typeof ScramjetServiceWorkerRuntime;
+function handleMessage(
+	client: ScramjetClient,
+	data: MessageW2R,
+	port: MessagePort
+) {
+	const type = data.scramjet$type;
+	const token = data.scramjet$token;
+
+	if (type === "fetch") {
+		const fetchhandlers = client.eventcallbacks.get("fetch");
+		if (!fetchhandlers) return;
+
+		for (const handler of fetchhandlers) {
+			const request = data.scramjet$request;
+			const fakeRequest = new Request(request.url, {
+				body: request.body,
+				headers: new Headers(request.headers),
+				method: request.method,
+				mode: request.mode,
+			});
+
+			Object.defineProperty(fakeRequest, "destination", {
+				value: request.destinitation,
+			});
+
+			const fakeFetchEvent = new FetchEvent("fetch", {
+				request: fakeRequest,
+			});
+
+			fakeFetchEvent.respondWith = async (
+				response: Response | Promise<Response>
+			) => {
+				response = await response;
+
+				response.body;
+				port.postMessage({
+					scramjet$type: "fetch",
+					scramjet$token: token,
+					scramjet$response: {
+						body: response.body,
+						headers: Array.from(response.headers.entries()),
+						status: response.status,
+						statusText: response.statusText,
+					},
+				} as MessageR2W);
+			};
+
+			handler.proxiedCallback(trustEvent(fakeFetchEvent));
+		}
 	}
 }
 
-self.ScramjetServiceWorkerRuntime = ScramjetServiceWorkerRuntime;
+function trustEvent(event: Event): Event {
+	return new Proxy(event, {
+		get(target, prop, reciever) {
+			if (prop === "isTrusted") return true;
+
+			return Reflect.get(target, prop, reciever);
+		},
+	});
+}
+
+export type TransferrableResponse = {
+	body: ReadableStream;
+	headers: [string, string][];
+	status: number;
+	statusText: string;
+};
+
+export type TransferrableRequest = {
+	body: ReadableStream;
+	headers: [string, string][];
+	destinitation: RequestDestination;
+	method: Request["method"];
+	mode: Request["mode"];
+	url: string;
+};
+
+type FetchResponseMessage = {
+	scramjet$type: "fetch";
+	scramjet$response: TransferrableResponse;
+};
+
+type FetchRequestMessage = {
+	scramjet$type: "fetch";
+	scramjet$request: TransferrableRequest;
+};
+
+// r2w = runtime to (service) worker
+
+type MessageTypeR2W = FetchResponseMessage;
+type MessageTypeW2R = FetchRequestMessage;
+
+type MessageCommon = {
+	scramjet$type: string;
+	scramjet$token: number;
+};
+
+export type MessageR2W = MessageCommon & MessageTypeR2W;
+export type MessageW2R = MessageCommon & MessageTypeW2R;