package crypto

import (
	"crypto/hmac"
	"crypto/sha256"
	"fmt"
)

// HMACSigner HMAC签名器
type HMACSigner struct {
	key []byte
}

// NewHMACSigner 创建HMAC签名器
func NewHMACSigner(key string) *HMACSigner {
	return &HMACSigner{key: []byte(key)}
}

func (s *HMACSigner) Sign(data []byte) ([]byte, error) {
	h := hmac.New(sha256.New, s.key)
	h.Write(data)
	return h.Sum(nil), nil
}

func (s *HMACSigner) Verify(data, signature []byte) error {
	expected, err := s.Sign(data)
	if err != nil {
		return err
	}

	if !hmac.Equal(expected, signature) {
		return fmt.Errorf("签名验证失败")
	}

	return nil
}