package auth

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"encoding/base64"
	"encoding/pem"
	"errors"
	logger "eta/eta_mini_ht_api/common/component/log"
	"os"
)

// EncryptWithRSA 使用 RSA 公钥加密数据
func EncryptWithRSA(publicKey *rsa.PublicKey, data []byte) ([]byte, error) {
	encrypted, err := rsa.EncryptPKCS1v15(rand.Reader, publicKey, data)
	if err != nil {
		return nil, err
	}
	return encrypted, nil
}

// DecryptWithRSA 使用 RSA 私钥解密数据
func DecryptWithRSA(privateKey *rsa.PrivateKey, encrypted string) ([]byte, error) {
	encKey, _ := base64.StdEncoding.DecodeString(encrypted)
	blockSize := privateKey.Size()
	maxChunkSize := blockSize
	var plaintext []byte
	for len(encKey) > 0 {
		chunkSize := maxChunkSize
		if len(encKey) < chunkSize {
			chunkSize = len(encKey)
		}

		chunk := encKey[:chunkSize]
		encKey = encKey[chunkSize:]
		decryptedChunk, err := rsa.DecryptPKCS1v15(rand.Reader, privateKey, chunk)
		if err != nil {
			return nil, err
		}
		plaintext = append(plaintext, decryptedChunk...)
	}
	return plaintext, nil
}

// ParsePrivateKeyFromPEM 解析RSA公钥
func ParsePrivateKeyFromPEM() (privateKey *rsa.PrivateKey, err error) {
	pemBlock, err := os.ReadFile("./conf/rsa_private_key.pem")
	block, _ := pem.Decode(pemBlock)
	if block == nil {
		logger.Error("私钥解析失败")
		return nil, errors.New("私钥解析失败")
	}
	privateKey, err = x509.ParsePKCS1PrivateKey(block.Bytes)
	if err != nil {
		return nil, err
	}
	return
}

func ParsePrivateKey(configPath string) (privateKey *rsa.PrivateKey, err error) {
	pemBlock, err := os.ReadFile(configPath)
	block, _ := pem.Decode(pemBlock)
	if block == nil {
		logger.Error("私钥解析失败")
		return nil, errors.New("私钥解析失败")
	}
	privateInfo, err := x509.ParsePKCS8PrivateKey(block.Bytes)
	if err != nil {
		return nil, err
	}
	privateKey = privateInfo.(*rsa.PrivateKey)
	return
}
func ParsePublicKey(configPath string) (publicKey *rsa.PublicKey, err error) {
	pemBlock, err := os.ReadFile(configPath)
	block, _ := pem.Decode(pemBlock)
	if block == nil {
		logger.Error("公钥解析失败")
		return nil, errors.New("公钥解析失败")
	}
	key, err := x509.ParsePKIXPublicKey(block.Bytes)
	if err != nil {
		return nil, err
	}
	publicKey = key.(*rsa.PublicKey)
	return
}

// ParsePublicKeyFromPEM 解析RSA公钥
func ParsePublicKeyFromPEM() (publicKey *rsa.PublicKey, err error) {
	pemBlock, err := os.ReadFile("./conf/rsa_public_key.pem")
	block, _ := pem.Decode(pemBlock)
	if block == nil {
		logger.Error("公钥解析失败")
		return nil, errors.New("公钥解析失败")
	}
	key, err := x509.ParsePKIXPublicKey(block.Bytes)
	if err != nil {
		return nil, err
	}
	publicKey = key.(*rsa.PublicKey)
	return
}