import { describe, expect, it } from "vitest";
import { SoftwareSigner, buildSigner, buildVerifier } from "./signer.js";

// The signer is half of the anti-fraud chain (the other half is event-log's hashing).
// These tests pin: a sign/verify round-trip, rejection of any tamper, constant-time
// length handling, and the keyId rotation contract that lets one chain span keys.

describe("SoftwareSigner", () => {
  it("verifies its own signature (round-trip)", () => {
    const s = new SoftwareSigner("a-test-secret-key");
    const sig = s.sign("hello world");
    expect(s.verify("hello world", sig)).toBe(true);
  });

  it("rejects a signature over different content (tamper-evidence)", () => {
    const s = new SoftwareSigner("a-test-secret-key");
    const sig = s.sign("amount=100");
    // Flip the signed content — the whole point of signing the payload.
    expect(s.verify("amount=9999", sig)).toBe(false);
  });

  it("rejects a signature made under a different key (forgery)", () => {
    const real = new SoftwareSigner("the-real-host-key");
    const forger = new SoftwareSigner("an-attacker-guess");
    const forged = forger.sign("amount=100");
    expect(real.verify("amount=100", forged)).toBe(false);
  });

  it("rejects a malformed / wrong-length signature without throwing", () => {
    const s = new SoftwareSigner("a-test-secret-key");
    // timingSafeEqual throws on length mismatch; verify() must guard it.
    expect(() => s.verify("x", "deadbeef")).not.toThrow();
    expect(s.verify("x", "deadbeef")).toBe(false);
    expect(s.verify("x", "")).toBe(false);
  });

  it("is deterministic — same key + payload yields the same signature", () => {
    const a = new SoftwareSigner("k").sign("p");
    const b = new SoftwareSigner("k").sign("p");
    expect(a).toBe(b);
  });

  it("defaults to the v2 keyId", () => {
    expect(new SoftwareSigner("k").keyId).toBe("sw-hmac-v2");
  });
});

describe("buildSigner", () => {
  // vitest.config.ts sets EVENT_SIGNING_KEY + JWT_SECRET for the whole run.
  it("prefers EVENT_SIGNING_KEY (keyId sw-hmac-v2)", () => {
    const s = buildSigner();
    expect(s.keyId).toBe("sw-hmac-v2");
    const sig = s.sign("x");
    expect(s.verify("x", sig)).toBe(true);
  });
});

describe("buildVerifier (key rotation)", () => {
  it("returns a working verifier for the configured v2 key", () => {
    const v = buildVerifier("sw-hmac-v2");
    expect(v).toBeDefined();
    const signer = new SoftwareSigner(process.env.EVENT_SIGNING_KEY!, "sw-hmac-v2");
    expect(v!.verify("x", signer.sign("x"))).toBe(true);
  });

  it("resolves the jwtfallback key when present", () => {
    const v = buildVerifier("sw-hmac-jwtfallback");
    expect(v).toBeDefined();
    const signer = new SoftwareSigner(process.env.JWT_SECRET!, "sw-hmac-jwtfallback");
    expect(v!.verify("x", signer.sign("x"))).toBe(true);
  });

  it("returns undefined for an unknown keyId (key gone, not a false tamper)", () => {
    expect(buildVerifier("atecc608-slot0")).toBeUndefined();
    expect(buildVerifier("nonsense")).toBeUndefined();
  });
});