package crypter

import (
	"encoding/base64"
	"errors"

	"crypto/des"
	"encoding/hex"
)

// ECB模式加密，返回16进制结果
func TripleECBEncryptForHex(key, plaintext string) (string, error) {

	keyBytes, err := base64.StdEncoding.DecodeString(key)

	if err != nil {
		return "", err
	}

	data := []byte(plaintext)
	ciphertext, err := TripleECBEncrypt(keyBytes, data)
	if err != nil {
		return "", err
	}
	return hex.EncodeToString(ciphertext), nil
}

// ECB模式解密16进制密文
func TripleECBDecryptFromHex(key, plaintext string) (string, error) {

	keyBytes, err := base64.StdEncoding.DecodeString(key)

	if err != nil {
		return "", err
	}

	data, err := hex.DecodeString(plaintext)
	if err != nil {
		return "", err
	}

	ciphertext, err := TripleECBDecrypt(keyBytes, data)
	if err != nil {
		return "", err
	}
	return string(ciphertext), nil
}

// ECB模式加密，返回byte
func TripleECBEncrypt(key, plaintext []byte) ([]byte, error) {

	// 创建Triple DES的块加密器
	block, err := des.NewTripleDESCipher(key)
	if err != nil {
		return []byte(""), err
	}

	// 创建切片来存储加密后的密文
	ciphertext := make([]byte, len(plaintext))

	// 复制明文到切片中
	copy(ciphertext, plaintext)

	// 应用PKCS#7填充
	ciphertext = PKCS5Padding(ciphertext, block.BlockSize())

	// 使用ECB模式加密填充后的数据
	for i := 0; i < len(ciphertext); i += block.BlockSize() {
		block.Encrypt(ciphertext[i:i+block.BlockSize()], ciphertext[i:i+block.BlockSize()])
	}

	return ciphertext, nil

}

// ECB模式解密，返回byte
func TripleECBDecrypt(key, ciphertext []byte) ([]byte, error) {
	// 创建Triple DES的块加密器（解密时也需要这个）
	block, err := des.NewTripleDESCipher(key)
	if err != nil {
		return []byte(""), err
	}

	// 检查密文长度是否是8字节的倍数
	if len(ciphertext)%des.BlockSize != 0 {
		return []byte(""), errors.New("ciphertext is not a multiple of the block size")
	}

	// 创建一个buffer来存储解密后的明文
	plaintext := make([]byte, len(ciphertext))

	// 使用ECB模式解密
	for i := 0; i < len(ciphertext); i += block.BlockSize() {
		block.Decrypt(plaintext[i:i+block.BlockSize()], ciphertext[i:i+block.BlockSize()])
	}
	plaintext = PKCS5UnPadding(plaintext)

	// 打印解密后的明文

	return plaintext, nil
}