package android

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

	log "github.com/sirupsen/logrus"
)

func padding(src []byte, blocksize int) []byte {
	padnum := blocksize - len(src)%blocksize
	pad := bytes.Repeat([]byte{byte(padnum)}, padnum)
	return append(src, pad...)
}

func unpadding(src []byte) []byte {
	n := len(src)
	unpadnum := int(src[n-1])
	return src[:n-unpadnum]
}

func EncryptAES(src []byte, key []byte) []byte {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil
	}
	src = padding(src, block.BlockSize())
	blockSize := block.BlockSize()
	if len(key) < blockSize {
		return nil
	}
	blockmode := cipher.NewCBCEncrypter(block, key[:blockSize])
	blockmode.CryptBlocks(src, src)
	return src
}

func DecryptAES(src []byte, key []byte) []byte {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil
	}
	blockSize := block.BlockSize()
	if len(key) < blockSize {
		return nil
	}
	blockmode := cipher.NewCBCDecrypter(block, key[:blockSize])
	blockmode.CryptBlocks(src, src)
	src = unpadding(src)
	return src
}

func AESEncrypt(src []byte, key []byte) []byte {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil
	}
	src = padding(src, block.BlockSize())
	blockSize := block.BlockSize()
	if len(key) < blockSize {
		return nil
	}
	blockmode := cipher.NewCBCEncrypter(block, key[:blockSize])
	blockmode.CryptBlocks(src, src)
	return src
}

func AESDecrypt(src []byte, key []byte) []byte {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil
	}
	blockSize := block.BlockSize()
	if len(key) < blockSize {
		return nil
	}
	blockmode := cipher.NewCBCDecrypter(block, key[:blockSize])
	blockmode.CryptBlocks(src, src)
	src = unpadding(src)
	return src
}

func AesEncrypt(RequestSerialize []byte, key []byte) []byte {
	//根据key 生成密文
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil
	}

	blockSize := block.BlockSize()
	RequestSerialize = PKCS5Padding(RequestSerialize, blockSize)

	blockMode := cipher.NewCBCEncrypter(block, key[:blockSize])
	crypted := make([]byte, len(RequestSerialize))
	blockMode.CryptBlocks(crypted, RequestSerialize)

	return crypted
}

func AesDecrypt(body []byte, key []byte) []byte {
	// fmt.Printf("%x\n\n", body)
	// fmt.Printf("%x\n\n", key)
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil
	}
	blockMode := cipher.NewCBCDecrypter(block, key[:block.BlockSize()])
	origData := make([]byte, len(body))
	blockMode.CryptBlocks(origData, body)
	origData = PKCS5UnPadding(origData)
	// fmt.Printf("%x\n", origData)
	return origData
}

// =================== ECB ======================
func AesEncryptECB(origData []byte, key []byte) (encrypted []byte) {
	cipher, _ := aes.NewCipher(generateKey(key))
	length := (len(origData) + aes.BlockSize) / aes.BlockSize
	plain := make([]byte, length*aes.BlockSize)
	copy(plain, origData)
	pad := byte(len(plain) - len(origData))
	for i := len(origData); 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(origData); bs, be = bs+cipher.BlockSize(), be+cipher.BlockSize() {
		cipher.Encrypt(encrypted[bs:be], plain[bs:be])
	}

	return encrypted
}

func AesDecryptECB(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
}

func CompressAndAes(RequestSerialize []byte, aeskey []byte) []byte {
	compressed := DoZlibCompress(RequestSerialize)
	return AesEncrypt(compressed, aeskey)
}

func DecompressAndAesDecrypt(body []byte, key []byte) []byte {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil
	}

	if len(body)%aes.BlockSize != 0 {
		log.Error(fmt.Sprintf("crypto/cipher: data is not a multiple of the block size，[BodyLength：%v] [AesLength：%v]", len(body), aes.BlockSize))
		return nil
	}

	blockMode := cipher.NewCBCDecrypter(block, key[:block.BlockSize()])
	origData := make([]byte, len(body))
	blockMode.CryptBlocks(origData, body)
	origData = PKCS5UnPadding(origData)
	origData = DoZlibUnCompress(origData)
	return origData
}

func PKCS5UnPadding(origData []byte) []byte {
	length := len(origData)
	unpadding := int(origData[length-1])
	if length < unpadding {
		return nil
	}
	return origData[:(length - unpadding)]
}

func PKCS5Padding(ciphertext []byte, blockSize int) []byte {
	padding := blockSize - len(ciphertext)%blockSize
	//填充
	padtext := bytes.Repeat([]byte{byte(padding)}, padding)

	return append(ciphertext, padtext...)
}