refactor: enforce frontend view model boundaries

src/shared/api/client.ts

@@ -8,13 +8,16 @@ import { ApiErrorCode, apiErrorCode, isApiErrorCode } from "./problem-details";
 const HTTP_UNAUTHORIZED = 401;
 
 const configuredBaseUrl: unknown = import.meta.env.VITE_API_BASE_URL;
+
 const apiBaseUrl
 	= typeof configuredBaseUrl === "string"
 		? configuredBaseUrl
 		: "http://localhost:3000";
 
 type AuthHandlers = {
-	accessToken: () => null | string | undefined;
+	accessToken: () => null
+		| string
+		| undefined;
 	clear: () => void;
 	generation?: () => number;
 	refresh: () => Promise<boolean>;
@@ -22,12 +25,16 @@ type AuthHandlers = {
 
 const inFlight = new Set<{ invalidated: boolean; pathname: string }>();
 const latestReads = new Map<string, { pending: number; sequence: number }>();
+
 function invalidateApiRequests(isMatches: (pathname: string) => boolean) {
 	for (const request of inFlight)
 		if (isMatches(request.pathname)) request.invalidated = true;
 }
 
-const sessionState: { handlers?: AuthHandlers; hasSession: boolean } = { hasSession: false };
+const sessionState: { handlers?: AuthHandlers; hasSession: boolean } = {
+	hasSession: false,
+};
+
 const authSessionListeners = new Set<() => void>();
 
 async function authenticatedFetch(request: Request): Promise<Response> {
@@ -36,17 +43,21 @@ async function authenticatedFetch(request: Request): Promise<Response> {
 	url.searchParams.sort();
 	const key = `${request.method} ${url}`;
 	const ticket = { invalidated: false, pathname: url.pathname };
+
 	const read
 		= request.method === "GET"
 			? (latestReads.get(key) ?? { pending: 0, sequence: 0 })
 			: undefined;
+
 	if (read) {
 		read.sequence += 1;
 		read.pending += 1;
 		latestReads.set(key, read);
 	}
+
 	const sequence = read?.sequence;
 	inFlight.add(ticket);
+
 	try {
 		return await fetchCurrent(
 			request,
@@ -72,47 +83,65 @@ async function fetchCurrent(
 	const isAuthRequest = new URL(request.url).pathname.startsWith(
 		"/api/v1/auth/",
 	);
+
 	const session = sessionState.handlers;
 	const generation = session?.generation?.();
+
 	const isCurrent = () =>
 		(session?.generation
 			? generation === session.generation()
 			&& generation === sessionState.handlers?.generation?.()
 			: session === sessionState.handlers) && isLatest();
+
 	const token = session?.accessToken();
+
 	const withToken = (source: Request, value: string) => {
 		const headers = new Headers(source.headers);
 		headers.set("Authorization", `Bearer ${value}`);
+
 		return new Request(source, { headers });
 	};
+
 	const authorized
 		= token && !isAuthRequest ? withToken(request, token) : request;
+
 	const retryRequest = authorized.clone();
 	const response = await fetch(authorized);
 	await response.clone().arrayBuffer();
 	if (!isAuthRequest && !isCurrent())
 		throw new DOMException("Session changed", "AbortError");
-	if (isAuthRequest || !sessionState.handlers || response.status !== HTTP_UNAUTHORIZED)
+	if (
+		isAuthRequest
+		|| !sessionState.handlers
+		|| response.status !== HTTP_UNAUTHORIZED
+	)
 		return response;
 	let problem: unknown;
+
 	try {
 		problem = await response.clone().json();
 	}
 	catch {
 		return response;
 	}
-	if (!isApiErrorCode(apiErrorCode(problem), ApiErrorCode.Unauthorized)) return response;
+
+	if (!isApiErrorCode(apiErrorCode(problem), ApiErrorCode.Unauthorized))
+		return response;
 	if (!isCurrent()) throw new DOMException("Session changed", "AbortError");
+
 	if (!(await sessionState.handlers.refresh())) {
 		if (isCurrent()) sessionState.handlers.clear();
+
 		return response;
 	}
+
 	if (!isCurrent()) throw new DOMException("Session changed", "AbortError");
 	const refreshedToken = sessionState.handlers.accessToken();
 	if (!refreshedToken) return response;
 	const retried = await fetch(withToken(retryRequest, refreshedToken));
 	await retried.clone().arrayBuffer();
 	if (!isCurrent()) throw new DOMException("Session changed", "AbortError");
+
 	return retried;
 }
 
@@ -128,6 +157,7 @@ function setAuthenticatedSession(hasSession: boolean) {
 
 function subscribeAuthenticatedSession(listener: () => void) {
 	authSessionListeners.add(listener);
+
 	return () => authSessionListeners.delete(listener);
 }