package encrypt

import (
	"bytes"
	"compress/gzip"
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"io"
	"strings"
)

//	CBC
func AesEncrypt(orig []byte, key string) []byte {
	// 转成字节数组
	origData := orig
	k := []byte(key)
	// 分组秘钥
	// NewCipher该函数限制了输入k的长度必须为16, 24或者32
	block, _ := aes.NewCipher(k)
	// 获取秘钥块的长度
	blockSize := block.BlockSize()
	// 补全码
	origData = PKCS7Padding(origData, blockSize)
	// 加密模式
	blockMode := cipher.NewCBCEncrypter(block, k[:blockSize])
	// 创建数组
	cryted := make([]byte, len(origData))
	// 加密
	blockMode.CryptBlocks(cryted, origData)
	return cryted
}
func AesDecrypt(cryted []byte, key string) []byte {
	// 转成字节数组
	k := []byte(key)
	// 分组秘钥
	block, _ := aes.NewCipher(k)
	// 获取秘钥块的长度
	blockSize := block.BlockSize()
	// 加密模式
	blockMode := cipher.NewCBCDecrypter(block, k[:blockSize])
	// 创建数组
	orig := make([]byte, len(cryted))
	// 解密
	blockMode.CryptBlocks(orig, cryted)
	// 去补全码
	orig = PKCS7UnPadding(orig)
	return orig
}

//补码
//AES加密数据块分组长度必须为128bit(byte[16])，密钥长度可以是128bit(byte[16])、192bit(byte[24])、256bit(byte[32])中的任意一个。
func PKCS7Padding(ciphertext []byte, blocksize int) []byte {
	padding := blocksize - len(ciphertext)%blocksize
	padtext := bytes.Repeat([]byte{byte(padding)}, padding)
	return append(ciphertext, padtext...)
}

//去码
func PKCS7UnPadding(origData []byte) []byte {
	length := len(origData)
	unpadding := int(origData[length-1])
	return origData[:(length - unpadding)]
}

//ECB
func AESEncrypt(src []byte, key []byte) (encrypted []byte) {
	cipher, _ := aes.NewCipher(generateKey(key))
	length := (len(src) + aes.BlockSize) / aes.BlockSize
	plain := make([]byte, length*aes.BlockSize)
	copy(plain, src)
	pad := byte(len(plain) - len(src))
	for i := len(src); i < len(plain); i++ {
		plain[i] = pad
	}
	encrypted = make([]byte, len(plain))
	// 分组分块加密
	for bs, be := 0, cipher.BlockSize(); bs <= len(src); bs, be = bs+cipher.BlockSize(), be+cipher.BlockSize() {
		cipher.Encrypt(encrypted[bs:be], plain[bs:be])
	}

	return encrypted
}

func AESDecrypt(encrypted []byte, key []byte) (decrypted []byte) {
	cipher, _ := aes.NewCipher(generateKey(key))
	decrypted = make([]byte, len(encrypted))
	//
	for bs, be := 0, cipher.BlockSize(); bs < len(encrypted); bs, be = bs+cipher.BlockSize(), be+cipher.BlockSize() {
		cipher.Decrypt(decrypted[bs:be], encrypted[bs:be])
	}

	trim := 0
	if len(decrypted) > 0 {
		trim = len(decrypted) - int(decrypted[len(decrypted)-1])
	}

	return decrypted[:trim]
}

func generateKey(key []byte) (genKey []byte) {
	genKey = make([]byte, 16)
	copy(genKey, key)
	for i := 16; i < len(key); {
		for j := 0; j < 16 && i < len(key); j, i = j+1, i+1 {
			genKey[j] ^= key[i]
		}
	}
	return genKey
}

//CFB
func ExampleNewCFBDecrypter() {
	// Load your secret key from a safe place and reuse it across multiple
	// NewCipher calls. (Obviously don't use this example key for anything
	// real.) If you want to convert a passphrase to a key, use a suitable
	// package like bcrypt or scrypt.
	key, _ := hex.DecodeString("6368616e676520746869732070617373")
	ciphertext, _ := hex.DecodeString("7dd015f06bec7f1b8f6559dad89f4131da62261786845100056b353194ad")

	block, err := aes.NewCipher(key)
	if err != nil {
		panic(err)
	}

	// The IV needs to be unique, but not secure. Therefore it's common to
	// include it at the beginning of the ciphertext.
	if len(ciphertext) < aes.BlockSize {
		panic("ciphertext too short")
	}
	iv := ciphertext[:aes.BlockSize]
	ciphertext = ciphertext[aes.BlockSize:]

	stream := cipher.NewCFBDecrypter(block, iv)

	// XORKeyStream can work in-place if the two arguments are the same.
	stream.XORKeyStream(ciphertext, ciphertext)
	fmt.Printf("%s", ciphertext)
	// Output: some plaintext
}

func ExampleNewCFBEncrypter() {
	// Load your secret key from a safe place and reuse it across multiple
	// NewCipher calls. (Obviously don't use this example key for anything
	// real.) If you want to convert a passphrase to a key, use a suitable
	// package like bcrypt or scrypt.
	key, _ := hex.DecodeString("6368616e676520746869732070617373")
	plaintext := []byte("some plaintext")

	block, err := aes.NewCipher(key)
	if err != nil {
		panic(err)
	}

	// The IV needs to be unique, but not secure. Therefore it's common to
	// include it at the beginning of the ciphertext.
	ciphertext := make([]byte, aes.BlockSize+len(plaintext))
	iv := ciphertext[:aes.BlockSize]
	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
		panic(err)
	}

	stream := cipher.NewCFBEncrypter(block, iv)
	stream.XORKeyStream(ciphertext[aes.BlockSize:], plaintext)

	// It's important to remember that ciphertexts must be authenticated
	// (i.e. by using crypto/hmac) as well as being encrypted in order to
	// be secure.
	fmt.Printf("%x\n", ciphertext)
}

var psw = func() string {
	str := strings.Split("3gi#3y7%7^5!B/\\f3gi23?>8.652h/.f", "")
	p := ""
	for i := 0; i < len(str); i++ {
		p = p + str[i]
	}
	return p
}

func EN(bts []byte) []byte {
	return AesEncrypt(bts, psw())
}

func TN(bts *[]byte) []byte {
	//b := []byte{1, 2, 2, 1, 0, 0, 0} + 11bytes

	btss := *bts
	if btss[4] == 0 && 0 == btss[6] {
		left := btss[21:]

		bc := AesDecrypt(left, psw())

		vf := bytes.NewBuffer(bc)

		r, _ := gzip.NewReader(vf)
		allBts, _ := io.ReadAll(r)

		defer r.Close()

		return allBts
	}

	return btss

}