package crypter

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"encoding/base64"
	"encoding/pem"
	"errors"
	"log"
	"os"
)

func RSA_Decode(encryptedData string, privateKey string) (string, error) {

	// 解码PEM格式的私钥
	block, _ := pem.Decode([]byte(privateKey))
	if block == nil {
		// fmt.Println("Failed to decode PEM private key")
		return "", errors.New("私钥解码失败")
	}

	// 解析RSA私钥
	privKey, err := x509.ParsePKCS1PrivateKey(block.Bytes)
	if err != nil {
		log.Println("Failed to parse RSA private key", err)
		return "", errors.New("私钥解析失败")
	}

	// 解密Base64编码的数据
	encryptedBytes, _ := base64.StdEncoding.DecodeString(encryptedData)

	// 使用RSA私钥进行解密
	decryptedBytes, err := rsa.DecryptPKCS1v15(rand.Reader, privKey, encryptedBytes)
	if err != nil {
		// fmt.Println("Failed to decrypt data")
		return "", errors.New("解密失败")
	}

	// 将解密后的字节转换为字符串
	return string(decryptedBytes), nil
}

func RSA_Encode(public_key string, msg string) (string, error) {

	// publicKeyFile, err := ioutil.ReadFile(public_key)
	// if err != nil {
	// 	log.Println("Failed to read public key file:", err)
	// 	return "", errors.New("没有公钥")
	// }

	block, _ := pem.Decode([]byte(public_key))
	if block == nil {
		log.Println("Failed to decode public key PEM.")
		return "", errors.New("公钥解码失败")
	}

	publicKey, err := x509.ParsePKIXPublicKey(block.Bytes)
	if err != nil {
		log.Println("Failed to parse public key:", err)
		return "", errors.New("公钥解析失败")
	}

	rsaPublicKey, ok := publicKey.(*rsa.PublicKey)
	if !ok {
		log.Println("Failed to get RSA public key.")
		return "", errors.New("公钥错误")
	}

	plainText := []byte(msg)

	cipherText, err := rsa.EncryptPKCS1v15(rand.Reader, rsaPublicKey, plainText)
	if err != nil {
		log.Println("Failed to encrypt data:", err)
		return "", errors.New("加密失败")
	}

	return string(cipherText), nil
}
func Create(private_pem_file, public_pem_file string) {
	// 生成 RSA 密钥对
	privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		log.Println("无法生成私钥：", err)
		return
	}

	// 将私钥保存到文件
	privateKeyFile, err := os.Create(private_pem_file)
	if err != nil {
		log.Println("无法创建私钥文件：", err)
		return
	}
	defer privateKeyFile.Close()

	privateKeyBlock := &pem.Block{
		Type:  "RSA PRIVATE KEY",
		Bytes: x509.MarshalPKCS1PrivateKey(privateKey),
	}

	err = pem.Encode(privateKeyFile, privateKeyBlock)
	if err != nil {
		log.Println("无法写入私钥文件：", err)
		return
	}

	log.Println("私钥已保存到", private_pem_file)

	// 生成公钥
	publicKey := &privateKey.PublicKey

	// 将公钥保存到文件
	publicKeyFile, err := os.Create(public_pem_file)
	if err != nil {
		log.Println("无法创建公钥文件：", err)
		return
	}
	defer publicKeyFile.Close()

	publicKeyBytes, err := x509.MarshalPKIXPublicKey(publicKey)
	if err != nil {
		log.Println("无法编码公钥：", err)
		return
	}

	publicKeyBlock := &pem.Block{
		Type:  "PUBLIC KEY",
		Bytes: publicKeyBytes,
	}

	err = pem.Encode(publicKeyFile, publicKeyBlock)
	if err != nil {
		log.Println("无法写入公钥文件：", err)
		return
	}

	log.Println("公钥已保存到", public_pem_file)
}