package auth

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"encoding/base64"
	"errors"
	"fmt"
	"github.com/cloudwego/hertz/pkg/common/json"
	"github.com/spf13/viper"
)

type H struct {
	User_id string
	Time    int64
	Role_id string
}

var mKey = ""

// pkcs7Padding 填充
func pkcs7Padding(data []byte, blockSize int) []byte {
	//判断缺少几位长度。最少1，最多 blockSize
	padding := blockSize - len(data)%blockSize
	//补足位数。把切片[]byte{byte(padding)}复制padding个
	padText := bytes.Repeat([]byte{byte(padding)}, padding)
	return append(data, padText...)
}

func pkcs7UnPadding(data []byte) ([]byte, error) {
	length := len(data)
	if length == 0 {
		return nil, errors.New("error！")
	}

	unPadding := int(data[length-1])
	if unPadding >= length {
		return nil, errors.New("error！")
	}
	return data[:(length - unPadding)], nil
}

func aesEncrypt(data []byte, key []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, errors.New("key error")
	}

	blockSize := block.BlockSize()
	encryptBytes := pkcs7Padding(data, blockSize)
	crypted := make([]byte, len(encryptBytes))
	blockMode := cipher.NewCBCEncrypter(block, key[:blockSize])
	blockMode.CryptBlocks(crypted, encryptBytes)
	return crypted, nil
}

func aesDecrypt(data []byte, key []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}
	blockSize := block.BlockSize()
	blockMode := cipher.NewCBCDecrypter(block, key[:blockSize])
	crypted := make([]byte, len(data))
	blockMode.CryptBlocks(crypted, data)
	crypted, err = pkcs7UnPadding(crypted)
	if err != nil {
		return nil, err
	}
	return crypted, nil
}

func EncryptByAes(data H) (string, error) {
	sdat, err := json.Marshal(data)

	if err != nil {
		return "", err
	}

	res, err := aesEncrypt(sdat, []byte(mKey))
	if err != nil {
		return "", err
	}

	return base64.StdEncoding.EncodeToString(res), nil
}

func DecryptByAes(data string) (*H, error) {
	dataByte, err := base64.StdEncoding.DecodeString(data)
	if err != nil {
		return nil, err
	}
	dat, err := aesDecrypt(dataByte, []byte(mKey))
	if err != nil {
		return nil, err
	}
	var ret = new(H)
	err = json.Unmarshal(dat, ret)
	if err != nil {
		return nil, err
	}
	return ret, nil
}

func init() {
	viper.SetConfigFile("./config.json")
	err := viper.ReadInConfig()
	if err != nil {
		fmt.Println(err)
		return
	}
	mKey = viper.GetString("authKey")
}