package hmac

import (
	"testing"
	"time"
)

func TestSignVerifyRoundTrip(t *testing.T) {
	secret := "topsecret"
	body := `{"brand_uid":"001DESke","source_url":"https://vogue.com/x"}`
	ts := tsNow()
	nonce := "abc123nonce"

	sig := Sign(secret, ts, nonce, body)
	if !Verify(secret, body, sig, ts, nonce, DefaultTTL) {
		t.Fatal("valid signature should verify")
	}
	// 篡改 body → 失败
	if Verify(secret, body+"x", sig, ts, nonce, DefaultTTL) {
		t.Fatal("tampered body should fail")
	}
	// 错误密钥 → 失败
	if Verify("wrong", body, sig, ts, nonce, DefaultTTL) {
		t.Fatal("wrong secret should fail")
	}
	// 缺头 → 失败
	if Verify(secret, body, "", ts, nonce, DefaultTTL) {
		t.Fatal("missing header should fail")
	}
}

func TestVerifyRejectsStaleTimestamp(t *testing.T) {
	secret := "s"
	body := "{}"
	// 早于窗口
	old := timeNowMinus(600)
	nonce := "n1"
	sig := Sign(secret, old, nonce, body)
	if Verify(secret, body, sig, old, nonce, DefaultTTL) {
		t.Fatal("stale timestamp should be rejected")
	}
	// 晚于窗口（未来太多）
	future := timeNowPlus(600)
	sig2 := Sign(secret, future, nonce, body)
	if Verify(secret, body, sig2, future, nonce, DefaultTTL) {
		t.Fatal("future timestamp beyond window should be rejected")
	}
}

// 简易时间助手（避免直接依赖 time.Now 的不可控）
func tsNow() string { return itoa(int64(time.Now().Unix())) }
func timeNowMinus(sec int) string {
	return itoa(int64(time.Now().Unix()) - int64(sec))
}
func timeNowPlus(sec int) string {
	return itoa(int64(time.Now().Unix()) + int64(sec))
}
func itoa(v int64) string {
	if v == 0 {
		return "0"
	}
	neg := v < 0
	if neg {
		v = -v
	}
	buf := [20]byte{}
	i := len(buf)
	for v > 0 {
		i--
		buf[i] = byte('0' + v%10)
		v /= 10
	}
	if neg {
		i--
		buf[i] = '-'
	}
	return string(buf[i:])
}