package response

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"encoding/base64"
	"lone-services/pkg/utils"
)

var (
	isDebug    bool
	encryptKey string
)

// Init 初始化响应加密相关配置（对应旧项目 base.is_debug / encrypt.encrypt_key）
func Init(debug bool, key string) {
	isDebug = debug
	encryptKey = key
}

type Crypto struct{}

// EncryptKey 加密
func (c Crypto) EncryptKey(data []byte, key string) (map[string]string, Error) {
	info, err := c.aesCBCEncryptKey(data, key)
	if err != nil {
		return nil, err
	}

	return info, nil
}

func (c Crypto) aesCBCEncryptKey(data []byte, key string) (map[string]string, Error) {
	k := []byte(key)
	iv := utils.GetRandString(NumberSixteen)

	// 分组密钥
	block, err := aes.NewCipher(k)
	if err != nil {
		return nil, ErrorEncryptAesKeyError
	}
	// 获取密钥块的长度
	blockSize := block.BlockSize()
	// 补充码
	data = c.pKCS7Padding(data, blockSize)
	// 加密模式
	blockMode := cipher.NewCBCEncrypter(block, []byte(iv))
	// 创建数组
	crypted := make([]byte, len(data))

	// 加密
	blockMode.CryptBlocks(crypted, data)
	return map[string]string{
		"data": base64.StdEncoding.EncodeToString(crypted),
		"iv":   iv,
	}, nil
}

func (c Crypto) pKCS7Padding(ciphertext []byte, blockSize int) []byte {
	// 判断缺少几位长度，最少为 1，最多为 blockSize
	padding := blockSize - len(ciphertext)%blockSize
	// 补足位数，把切片 []byte{byte(padding)} 复制 padding 个
	padtext := bytes.Repeat([]byte{byte(padding)}, padding)
	return append(ciphertext, padtext...)
}