export async function onRequestRateLimit()

in packages/better-auth/src/api/rate-limiter/index.ts [112:206]
89 lines of code
18 McCabe index (conditional complexity)

export async function onRequestRateLimit(req: Request, ctx: AuthContext) {
	if (!ctx.rateLimit.enabled) {
		return;
	}
	const path = new URL(req.url).pathname.replace(
		ctx.options.basePath || "/api/auth",
		"",
	);
	let window = ctx.rateLimit.window;
	let max = ctx.rateLimit.max;
	const ip = getIp(req, ctx.options);
	if (!ip) {
		return;
	}
	const key = ip + path;
	const specialRules = getDefaultSpecialRules();
	const specialRule = specialRules.find((rule) => rule.pathMatcher(path));

	if (specialRule) {
		window = specialRule.window;
		max = specialRule.max;
	}

	for (const plugin of ctx.options.plugins || []) {
		if (plugin.rateLimit) {
			const matchedRule = plugin.rateLimit.find((rule) =>
				rule.pathMatcher(path),
			);
			if (matchedRule) {
				window = matchedRule.window;
				max = matchedRule.max;
				break;
			}
		}
	}

	if (ctx.rateLimit.customRules) {
		const _path = Object.keys(ctx.rateLimit.customRules).find((p) => {
			if (p.includes("*")) {
				const isMatch = wildcardMatch(p)(path);
				return isMatch;
			}
			return p === path;
		});
		if (_path) {
			const customRule = ctx.rateLimit.customRules[_path];
			const resolved =
				typeof customRule === "function" ? await customRule(req) : customRule;
			if (resolved) {
				window = resolved.window;
				max = resolved.max;
			}
		}
	}

	const storage = getRateLimitStorage(ctx);
	const data = await storage.get(key);
	const now = Date.now();

	if (!data) {
		await storage.set(key, {
			key,
			count: 1,
			lastRequest: now,
		});
	} else {
		const timeSinceLastRequest = now - data.lastRequest;

		if (shouldRateLimit(max, window, data)) {
			const retryAfter = getRetryAfter(data.lastRequest, window);
			return rateLimitResponse(retryAfter);
		} else if (timeSinceLastRequest > window * 1000) {
			// Reset the count if the window has passed since the last request
			await storage.set(
				key,
				{
					...data,
					count: 1,
					lastRequest: now,
				},
				true,
			);
		} else {
			await storage.set(
				key,
				{
					...data,
					count: data.count + 1,
					lastRequest: now,
				},
				true,
			);
		}
	}
}