package hash

import (
	"crypto/md5"
	"crypto/rand"
	"encoding/hex"
)

// GenerateSalt 生成随机盐（16字节 hex = 32字符）
func GenerateSalt() string {
	b := make([]byte, 16)
	rand.Read(b)
	return hex.EncodeToString(b)
}

// Password 用盐+MD5加密密码，返回 salt 和 hash
func Password(pwd string) (salt string, hash string) {
	salt = GenerateSalt()
	hash = MD5Salt(pwd, salt)
	return
}

// MD5Salt 用指定盐计算 MD5：md5(salt + password)
func MD5Salt(pwd, salt string) string {
	h := md5.New()
	h.Write([]byte(salt + pwd))
	return hex.EncodeToString(h.Sum(nil))
}

// Verify 验证密码：用存储的盐重新计算 MD5 比对
func Verify(storedHash, salt, pwd string) bool {
	if salt == "" || storedHash == "" {
		return false
	}
	return MD5Salt(pwd, salt) == storedHash
}