package utils

import (
	"crypto/md5"
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"math/big"
)

// MD5Hash 计算MD5哈希
func MD5Hash(text string) string {
	hash := md5.Sum([]byte(text))
	return hex.EncodeToString(hash[:])
}

// SHA256Hash 计算SHA256哈希
func SHA256Hash(text string) string {
	hash := sha256.Sum256([]byte(text))
	return hex.EncodeToString(hash[:])
}

// GenerateRandomString 生成指定长度的随机字符串
func GenerateRandomString(length int) (string, error) {
	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	b := make([]byte, length)
	for i := range b {
		num, err := rand.Int(rand.Reader, big.NewInt(int64(len(charset))))
		if err != nil {
			return "", err
		}
		b[i] = charset[num.Int64()]
	}
	return string(b), nil
}

// GenerateSalt 生成盐值
func GenerateSalt() (string, error) {
	return GenerateRandomString(16)
}

// HashPassword 使用盐值哈希密码
func HashPassword(password, salt string) string {
	return SHA256Hash(password + salt)
}

// VerifyPassword 验证密码
func VerifyPassword(password, salt, hash string) bool {
	return HashPassword(password, salt) == hash
}

// GenerateToken 生成随机token
func GenerateToken() (string, error) {
	return GenerateRandomString(32)
}