package server

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
)

//AES ECB模式加密
func AesECBEncrypt(plainText, key []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}

	ecb := NewECBEncrypter(block)
	plainText = PKCS5Padding(plainText, block.BlockSize())
	crypted := make([]byte, len(plainText))
	ecb.CryptBlocks(crypted, plainText)
	return crypted, err
}

//AES ECB模式解密
func AESECBDecrypt(cipherText, key []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}
	blockMode := NewECBDecrypter(block)
	plainText := make([]byte, len(cipherText))
	blockMode.CryptBlocks(plainText, cipherText)
	plainText = PKCS5UnPadding(plainText)
	return plainText, err
}

//AES CBC模式加密
func AESCBCEncrypt(plainText, key []byte) {

}

func PKCS5Padding(plainText []byte, blockSize int) []byte {
	padding := blockSize - (len(plainText) % blockSize)
	padText := bytes.Repeat([]byte{byte(padding)}, padding)
	newText := append(plainText, padText...)
	return newText
}

func PKCS5UnPadding(plainText []byte) []byte {
	length := len(plainText)
	number := int(plainText[length-1])
	return plainText[:length-number]
}

type ecb struct {
	b         cipher.Block
	blockSize int
}

func newECB(b cipher.Block) *ecb {
	return &ecb{
		b:         b,
		blockSize: b.BlockSize(),
	}
}

type ecbEncrypter ecb

func NewECBEncrypter(block cipher.Block) cipher.BlockMode {
	return (*ecbEncrypter)(newECB(block))
}

func (x *ecbEncrypter) BlockSize() int { return x.blockSize }
func (x *ecbEncrypter) CryptBlocks(dst, src []byte) {
	if len(src)%x.blockSize != 0 {
		panic("crypto/cipher: input not full blocks")
	}
	if len(dst) < len(src) {
		panic("crypto/cipher: output smaller than input")
	}
	for len(src) > 0 {
		x.b.Encrypt(dst, src[:x.blockSize])
		src = src[x.blockSize:]
		dst = dst[x.blockSize:]
	}
}

type ecbDecrypter ecb

// NewECBDecrypter returns a BlockMode which decrypts in electronic code book
// mode, using the given Block.
func NewECBDecrypter(b cipher.Block) cipher.BlockMode {
	return (*ecbDecrypter)(newECB(b))
}
func (x *ecbDecrypter) BlockSize() int { return x.blockSize }
func (x *ecbDecrypter) CryptBlocks(dst, src []byte) {
	if len(src)%x.blockSize != 0 {
		panic("crypto/cipher: input not full blocks")
	}
	if len(dst) < len(src) {
		panic("crypto/cipher: output smaller than input")
	}
	for len(src) > 0 {
		x.b.Decrypt(dst, src[:x.blockSize])
		src = src[x.blockSize:]
		dst = dst[x.blockSize:]
	}
}