package utils

import (
	"crypto/aes"
	"crypto/cipher"
	"encoding/base64"
	"fmt"
)

func AesDecode(data string, key []byte) (string, error) {
	decoded, err := base64.StdEncoding.DecodeString(data)
	if err != nil {
		return "", fmt.Errorf("base64 decode error: %v", err)
	}
	block, err := aes.NewCipher(key)
	if err != nil {
		return "", fmt.Errorf("aes new cipher error: %v", err)
	}

	if len(decoded) < aes.BlockSize {
		return "", fmt.Errorf("ciphertext too short")
	}

	decrypted := make([]byte, len(decoded))
	mode := cipher.NewCBCDecrypter(block, make([]byte, aes.BlockSize))
	mode.CryptBlocks(decrypted, decoded)

	padding := decrypted[len(decrypted)-1]
	decrypted = decrypted[:len(decrypted)-int(padding)]

	return string(decrypted), nil
}