package utils

import (
	"crypto/aes"
	"crypto/cipher"
	"encoding/base64"
	"net/http"

	"github.com/julienschmidt/httprouter"
)

func AdaptHandler(h func(http.ResponseWriter, *http.Request)) httprouter.Handle {
	return func(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
		h(w, r)
	}
}

func AesDecrypt(encryptedData, sessionKey, iv string) ([]byte, error) {
	//Base64解码
	keyBytes, err := base64.StdEncoding.DecodeString(sessionKey)
	if err != nil {
		return nil, err
	}
	ivBytes, err := base64.StdEncoding.DecodeString(iv)
	if err != nil {
		return nil, err
	}
	cryptData, err := base64.StdEncoding.DecodeString(encryptedData)
	if err != nil {
		return nil, err
	}
	origData := make([]byte, len(cryptData))
	//AES
	block, err := aes.NewCipher(keyBytes)
	if err != nil {
		return nil, err
	}
	//CBC
	mode := cipher.NewCBCDecrypter(block, ivBytes)
	//解密
	mode.CryptBlocks(origData, cryptData)
	//去除填充位
	origData = PKCS7UnPadding(origData)
	return origData, nil
}

func PKCS7UnPadding(plantText []byte) []byte {
	length := len(plantText)
	if length > 0 {
		unPadding := int(plantText[length-1])
		return plantText[:(length - unPadding)]
	}
	return plantText
}