interface RateLimitResult {
  allowed: boolean;
  retryAfter: number;
}

export async function checkRateLimit(
  identifier: string,
  route: string,
  limit: number,
): Promise<RateLimitResult> {
  const cache = typeof caches !== "undefined" ? (caches as any).default as Cache | undefined : undefined;
  if (!cache) return { allowed: true, retryAfter: 0 };

  const minute = Math.floor(Date.now() / 60000);
  const cacheKey = new Request(`https://rate-limit.internal/${identifier}:${route}:${minute}`);

  let count = 0;
  const match = await cache.match(cacheKey);
  if (match) {
    count = parseInt(await match.text(), 10) || 0;
  }

  count++;

  await cache.put(
    cacheKey,
    new Response(String(count), {
      headers: { "Cache-Control": "public, max-age=60" },
    }),
  );

  if (count > limit) {
    const retryAfter = Math.ceil(((minute + 1) * 60000 - Date.now()) / 1000);
    return { allowed: false, retryAfter };
  }

  return { allowed: true, retryAfter: 0 };
}

export async function hashToken(token: string): Promise<string> {
  const buf = await crypto.subtle.digest("SHA-256", new TextEncoder().encode(token));
  return Array.from(new Uint8Array(buf))
    .map((b) => b.toString(16).padStart(2, "0"))
    .join("");
}

export function getRouteLimit(method: string, pathname: string): { route: string; limit: number } {
  if (method === "POST" && pathname === "/api/trade") return { route: "trade", limit: 30 };
  if (method === "POST" && /^\/api\/comments\/[^/]+\/vote$/.test(pathname)) return { route: "vote", limit: 20 };
  if (method === "POST" && pathname === "/api/comments") return { route: "comments", limit: 10 };
  if (method === "GET" && pathname === "/api/search") return { route: "search", limit: 30 };
  return { route: "api", limit: 60 };
}