package utils

import (
	"crypto"
	"crypto/md5"
	"crypto/rand"
	"crypto/rsa"
	"crypto/sha1"
	"crypto/x509"
	"encoding/base64"
	"encoding/hex"
	"encoding/pem"
	"errors"
	"fmt"
	"golang.org/x/crypto/bcrypt"
	"net/url"
	"os"
)

func Md5(str string) string {
	hash := md5.New()
	hash.Write([]byte(str))
	bytes := hash.Sum(nil)
	md5Str := hex.EncodeToString(bytes)
	return md5Str
}

func Sign(params url.Values, signKey string) string {
	fmt.Println(params.Encode() + "&signkey=" + signKey)
	return Md5(params.Encode() + "&signkey=" + signKey)
}

func PasswordHash(password string) (string, error) {
	bytes, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	return string(bytes), err
}

func PasswordVerify(password, hash string) bool {
	err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
	return err == nil
}

func RSASign(data []byte, filename string) (string, error) {
	// 1、选择hash算法，对需要签名的数据进行hash运算
	myHash := crypto.SHA1
	hashInstance := myHash.New()
	hashInstance.Write(data)
	hashed := hashInstance.Sum(nil)

	// 2、读取私钥文件，解析出私钥对象
	privateKey, err := ReadParsePrivateKey(filename)
	fmt.Println("signErr1", err)
	if err != nil {
		return "", err
	}
	// 3、RSA数字签名（参数是随机数、私钥对象、哈希类型、签名文件的哈希串，生成bash64编码）
	bytes, err := rsa.SignPKCS1v15(rand.Reader, privateKey, myHash, hashed)
	fmt.Println("signErr2", err)
	if err != nil {
		return "", err
	}
	return base64.StdEncoding.EncodeToString(bytes), nil
}

func RSAVerify(data []byte, base64Sig, filename string) error {
	// 1、对base64编码的签名内容进行解码，返回签名字节
	bytes, err := base64.StdEncoding.DecodeString(base64Sig)
	if err != nil {
		return err
	}
	// 2、选择hash算法，对需要签名的数据进行hash运算
	myHash := crypto.SHA1
	hashInstance := myHash.New()
	hashInstance.Write(data)
	hashed := hashInstance.Sum(nil)
	// 3、读取公钥文件，解析出公钥对象
	publicKey, err := ReadParsePublicKey(filename)
	if err != nil {
		return err
	}
	// 4、RSA验证数字签名（参数是公钥对象、哈希类型、签名文件的哈希串、签名后的字节）
	return rsa.VerifyPKCS1v15(publicKey, myHash, hashed, bytes)
}

// ReadParsePublicKey 读取公钥文件，解析公钥对象
func ReadParsePublicKey(filename string) (*rsa.PublicKey, error) {
	// 1、读取公钥文件，获取公钥字节
	publicKeyBytes, err := os.ReadFile(filename)
	if err != nil {
		return nil, err
	}
	// 2、解码公钥字节，生成加密对象
	block, _ := pem.Decode(publicKeyBytes)
	if block == nil {
		return nil, errors.New("公钥信息错误！")
	}
	// 3、解析DER编码的公钥，生成公钥接口
	publicKeyInterface, err := x509.ParsePKIXPublicKey(block.Bytes)
	if err != nil {
		return nil, err
	}
	// 4、公钥接口转型成公钥对象
	publicKey := publicKeyInterface.(*rsa.PublicKey)
	return publicKey, nil
}

// ReadParsePrivateKey 读取私钥文件，解析出私钥对象
func ReadParsePrivateKey(filename string) (*rsa.PrivateKey, error) {
	// 1、读取私钥文件，获取私钥字节
	privateKeyBytes, err := os.ReadFile(filename)
	fmt.Println(string(privateKeyBytes))

	if err != nil {
		return nil, err
	}
	// 2、解码私钥字节，生成加密对象
	block, _ := pem.Decode(privateKeyBytes)

	if block == nil {
		return nil, errors.New("私钥信息错误！")
	}
	fmt.Println("blockType", block.Type)
	// 3、解析DER编码的私钥，生成私钥对象
	if block.Type == "RSA PRIVATE KEY" {
		return x509.ParsePKCS1PrivateKey(block.Bytes)
	}

	privateKey, err := x509.ParsePKCS8PrivateKey(block.Bytes)
	rsaKey, ok := privateKey.(*rsa.PrivateKey)

	if ok {
		return rsaKey, nil
	} else {
		return nil, errors.New("私钥错误")
	}
}

func Sha1(data string) string {
	h := sha1.New()
	h.Write([]byte(data))
	return hex.EncodeToString(h.Sum(nil))
}