import createClient from "openapi-fetch";
import createQueryClient from "openapi-react-query";

import type { paths } from "./generated/schema";

const HTTP_UNAUTHORIZED = 401;

const apiBaseUrl = import.meta.env.VITE_API_BASE_URL ?? "http://localhost:3000";

type AuthHandlers = {
	generation?: () => number;
	accessToken: () => string | null;
	refresh: () => Promise<boolean>;
	clear: () => void;
};

let auth: AuthHandlers | null = null;
let hasAuthenticatedSession = false;
const authSessionListeners = new Set<() => void>();

function setAuthenticatedSession(next: boolean) {
	if (next === hasAuthenticatedSession) return;
	hasAuthenticatedSession = next;
	for (const listener of authSessionListeners) listener();
}

function configureAuthClient(handlers: AuthHandlers | null) {
	auth = handlers;
	setAuthenticatedSession(Boolean(auth?.accessToken()));
}

function getAuthenticatedSessionSnapshot() {
	return hasAuthenticatedSession;
}

function subscribeAuthenticatedSession(listener: () => void) {
	authSessionListeners.add(listener);
	return () => authSessionListeners.delete(listener);
}

async function authenticatedFetch(request: Request): Promise<Response> {
	const isAuthRequest = new URL(request.url).pathname.startsWith(
		"/api/v1/auth/",
	);
	const session = auth;
	const generation = session?.generation?.();
	const isCurrent = () => generation === auth?.generation?.();
	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);
	if (!isAuthRequest && !isCurrent())
		throw new DOMException("Session changed", "AbortError");
	if (
		response.status !== HTTP_UNAUTHORIZED ||
		isAuthRequest ||
		!auth ||
		(
			await response
				.clone()
				.json()
				.catch(() => null)
		)?.code !== "UNAUTHORIZED"
	)
		return response;
	if (!isCurrent()) throw new DOMException("Session changed", "AbortError");
	if (!(await auth.refresh())) {
		if (isCurrent()) auth.clear();
		return response;
	}
	if (!isCurrent()) throw new DOMException("Session changed", "AbortError");
	const refreshedToken = auth.accessToken();
	if (!refreshedToken) return response;
	const retried = await fetch(withToken(retryRequest, refreshedToken));
	if (!isCurrent()) throw new DOMException("Session changed", "AbortError");
	return retried;
}

const apiClient = createClient<paths>({
	baseUrl: apiBaseUrl,
	credentials: "include",
	fetch: authenticatedFetch,
});

const apiQueryClient = createQueryClient(apiClient);

export {
	apiClient,
	apiQueryClient,
	configureAuthClient,
	getAuthenticatedSessionSnapshot,
	subscribeAuthenticatedSession,
};