import { describe, expect, it } from "vitest";
import { clientKeyFrom, createRateLimiter } from "@/lib/rate-limit";

describe("createRateLimiter", () => {
  it("allows up to the limit within a window, then refuses", () => {
    const limiter = createRateLimiter({ limit: 3, windowMs: 1000 });
    expect(limiter.allow("a", 0)).toBe(true);
    expect(limiter.allow("a", 1)).toBe(true);
    expect(limiter.allow("a", 2)).toBe(true);
    expect(limiter.allow("a", 3)).toBe(false);
    expect(limiter.allow("a", 999)).toBe(false);
  });

  it("starts a fresh window once the previous one expires", () => {
    const limiter = createRateLimiter({ limit: 1, windowMs: 1000 });
    expect(limiter.allow("a", 0)).toBe(true);
    expect(limiter.allow("a", 500)).toBe(false);
    expect(limiter.allow("a", 1000)).toBe(true);
  });

  it("tracks keys independently", () => {
    const limiter = createRateLimiter({ limit: 1, windowMs: 1000 });
    expect(limiter.allow("a", 0)).toBe(true);
    expect(limiter.allow("a", 1)).toBe(false);
    expect(limiter.allow("b", 1)).toBe(true);
  });

  it("reset forgets a key's attempts", () => {
    const limiter = createRateLimiter({ limit: 1, windowMs: 1000 });
    expect(limiter.allow("a", 0)).toBe(true);
    expect(limiter.allow("a", 1)).toBe(false);
    limiter.reset("a");
    expect(limiter.allow("a", 2)).toBe(true);
  });

  it("sweeps expired entries instead of growing past maxKeys", () => {
    const limiter = createRateLimiter({ limit: 1, windowMs: 1000, maxKeys: 3 });
    expect(limiter.allow("a", 0)).toBe(true);
    expect(limiter.allow("b", 0)).toBe(true);
    expect(limiter.allow("c", 0)).toBe(true);
    // All three are expired at t=1000; the sweep makes room, and the new
    // key is not throttled by leftover state.
    expect(limiter.allow("d", 1000)).toBe(true);
    expect(limiter.allow("d", 1001)).toBe(false);
  });

  it("keeps live windows intact across a sweep", () => {
    const limiter = createRateLimiter({ limit: 1, windowMs: 1000, maxKeys: 2 });
    expect(limiter.allow("a", 0)).toBe(true);
    expect(limiter.allow("b", 500)).toBe(true);
    expect(limiter.allow("c", 600)).toBe(true); // sweep drops nothing live
    expect(limiter.allow("b", 700)).toBe(false); // b's window survived
  });
});

describe("clientKeyFrom", () => {
  it("uses the first hop of x-forwarded-for", () => {
    const headers = new Headers({ "x-forwarded-for": "203.0.113.7, 10.0.0.1" });
    expect(clientKeyFrom(headers)).toBe("203.0.113.7");
  });

  it("falls back to x-real-ip, then to a shared bucket", () => {
    expect(clientKeyFrom(new Headers({ "x-real-ip": "203.0.113.9" }))).toBe("203.0.113.9");
    expect(clientKeyFrom(new Headers())).toBe("unknown");
  });

  it("caps the key length so junk headers cannot bloat the store", () => {
    const headers = new Headers({ "x-forwarded-for": "x".repeat(500) });
    expect(clientKeyFrom(headers)).toHaveLength(100);
  });
});