package spiderutil

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

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

//aes ecb解密
func AesECBDecrypter(data, key []byte) []byte {
	cipher, _ := aes.NewCipher(generateKey(key))
	decrypted := make([]byte, len(data))
	for bs, be := 0, cipher.BlockSize(); bs < len(data); bs, be = bs+cipher.BlockSize(), be+cipher.BlockSize() {
		cipher.Decrypt(decrypted[bs:be], data[bs:be])
	}
	trim := 0
	if len(decrypted) > 0 {
		trim = len(decrypted) - int(decrypted[len(decrypted)-1])
	}

	return decrypted[:trim]
}

//aes cbc加密
func AesCBCEncrypt(data, key, iv []byte) []byte {
	// 创建一个AES块，使用提供的密钥
	block, _ := aes.NewCipher(key)
	// 使用CBC模式创建一个加密器
	mode := cipher.NewCBCEncrypter(block, iv)
	// 对数据进行填充
	padding := aes.BlockSize - len(data)%aes.BlockSize
	padtext := append(data, bytes.Repeat([]byte{byte(padding)}, padding)...)
	// 加密数据
	encrypted := make([]byte, len(padtext))
	mode.CryptBlocks(encrypted, padtext)
	return encrypted
}

//aes cbc解密
func AesCBCDecrypter(data, key, iv []byte) []byte {
	block, _ := aes.NewCipher(key)
	decrypter := cipher.NewCBCDecrypter(block, iv)
	// 解密数据
	decrypted := make([]byte, len(data))
	decrypter.CryptBlocks(decrypted, data)
	// 去除填充
	unpadding := int(decrypted[len(decrypted)-1])
	return decrypted[:len(decrypted)-unpadding]
}

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
}