package signutil

import (
	"strconv"
	"testing"
	"time"
)

// TestHMACSHA256HexKnownVector 用公开测试向量锁定算法，避免以后「优化」时改坏。
func TestHMACSHA256HexKnownVector(t *testing.T) {
	got := HMACSHA256Hex("key", "The quick brown fox jumps over the lazy dog")
	const want = "f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8"
	if got != want {
		t.Fatalf("HMAC-SHA256 向量不符：期望 %s，实际 %s", want, got)
	}
}

// TestHMACSHA256HexBytesMatchesStringVersion 分段写入必须与整体写入等价。
func TestHMACSHA256HexBytesMatchesStringVersion(t *testing.T) {
	whole := HMACSHA256Hex("secret", "prefix-body-suffix")
	parts := HMACSHA256HexBytes("secret", []byte("prefix-"), []byte("body"), []byte("-suffix"))
	if whole != parts {
		t.Fatalf("分段写入结果不一致：%s vs %s", whole, parts)
	}
}

func TestHMACSHA256HexBytesNoParts(t *testing.T) {
	// 空内容等价于对空串做 HMAC。
	if got, want := HMACSHA256HexBytes("secret"), HMACSHA256Hex("secret", ""); got != want {
		t.Fatalf("无分段应等价于空内容：%s vs %s", got, want)
	}
}

func TestSHA256Hex(t *testing.T) {
	if got := SHA256Hex(nil); got != EmptyBodySHA256 {
		t.Fatalf("空内容应返回空串摘要常量，实际 %s", got)
	}
	if got := SHA256Hex([]byte{}); got != EmptyBodySHA256 {
		t.Fatalf("空切片应返回空串摘要常量，实际 %s", got)
	}
	const wantAbc = "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
	if got := SHA256Hex([]byte("abc")); got != wantAbc {
		t.Fatalf("SHA256(abc) 不符：期望 %s，实际 %s", wantAbc, got)
	}
}

func TestTimestampWithinSkew(t *testing.T) {
	now := time.Now().Unix()
	cases := []struct {
		name      string
		timestamp string
		skew      time.Duration
		want      bool
	}{
		{"当前时间在窗口内", itoa(now), 300 * time.Second, true},
		{"边界上刚好等于 skew", itoa(now - 300), 300 * time.Second, true},
		{"超出 skew 一秒", itoa(now - 301), 300 * time.Second, false},
		{"未来时间同样按绝对值判断", itoa(now + 301), 300 * time.Second, false},
		{"未来时间在窗口内", itoa(now + 60), 300 * time.Second, true},
		{"非法时间戳", "not-a-number", 300 * time.Second, false},
		{"空时间戳", "", 300 * time.Second, false},
		{"不裁剪空白（保持既有行为）", " " + itoa(now) + " ", 300 * time.Second, false},
		{"skew 为 0 时只有同一秒通过", itoa(now), 0, true},
		{"skew 为 0 时上一秒不通过", itoa(now - 1), 0, false},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			if got := TimestampWithinSkew(tc.timestamp, tc.skew); got != tc.want {
				t.Fatalf("期望 %v，实际 %v", tc.want, got)
			}
		})
	}
}

func TestTimestampWithinSkewSecondsMatchesDuration(t *testing.T) {
	now := itoa(time.Now().Unix())
	if TimestampWithinSkewSeconds(now, 300) != TimestampWithinSkew(now, 300*time.Second) {
		t.Fatal("秒版本与 Duration 版本应一致")
	}
}

func TestEqualSignatures(t *testing.T) {
	if !EqualSignatures("abc123", "abc123") {
		t.Fatal("相同签名应通过")
	}
	if EqualSignatures("abc123", "abc124") {
		t.Fatal("不同签名不应通过")
	}
	if EqualSignatures("abc", "abcd") {
		t.Fatal("长度不同的签名不应通过")
	}
	// 该函数不做大小写归一化，这是刻意为之（乐玩签名带 v1= 前缀，需原样比较）。
	if EqualSignatures("ABC123", "abc123") {
		t.Fatal("未归一化的版本应区分大小写")
	}
}

func TestEqualHexSignatures(t *testing.T) {
	if !EqualHexSignatures("ABC123DEF", "abc123def") {
		t.Fatal("十六进制签名应大小写不敏感")
	}
	if EqualHexSignatures("abc123", "abc124") {
		t.Fatal("不同签名不应通过")
	}
}

func itoa(v int64) string {
	return strconv.FormatInt(v, 10)
}