package encrypt

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"crypto/md5"
	"crypto/rand"
	"encoding/base64"
	"encoding/hex"
	"errors"
	"fmt"
	"io"

	"github.com/1Panel-dev/1Panel/backend/global"
)

func StringEncrypt(text string) (string, error) {
	if len(text) == 0 {
		return "", errors.New("it is not possible to encrypt an empty string.")
	}
	key := global.CONF.System.EncryptKey
	pass := []byte(text)
	xpass, err := aesEncryptWithSalt([]byte(key), pass)
	if err == nil {
		pass64 := base64.StdEncoding.EncodeToString(xpass)
		return pass64, err
	}
	return "", err
}

func StringDecrypt(text string) (string, error) {
	if len(text) == 0 {
		return "", errors.New("it is not possible to decrypt an empty string.")
	}
	key := global.CONF.System.EncryptKey
	bytesPass, err := base64.StdEncoding.DecodeString(text)
	if err != nil {
		return "", err
	}
	var tpass []byte
	tpass, err = aesDecryptWithSalt([]byte(key), bytesPass)
	if err == nil {
		result := string(tpass[:])
		return result, err
	}
	return "", err
}

func Md5(str string) string {
	h := md5.New()
	h.Write([]byte(str))
	return hex.EncodeToString(h.Sum(nil))
}

func padding(plaintext []byte, blockSize int) []byte {
	padding := blockSize - len(plaintext)%blockSize
	padtext := bytes.Repeat([]byte{byte(padding)}, padding)
	return append(plaintext, padtext...)
}

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

func aesEncryptWithSalt(key, plaintext []byte) ([]byte, error) {
	plaintext = padding(plaintext, aes.BlockSize)
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}
	ciphertext := make([]byte, aes.BlockSize+len(plaintext))
	iv := ciphertext[0:aes.BlockSize]
	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
		return nil, err
	}
	cbc := cipher.NewCBCEncrypter(block, iv)
	cbc.CryptBlocks(ciphertext[aes.BlockSize:], plaintext)
	return ciphertext, nil
}
func aesDecryptWithSalt(key, ciphertext []byte) ([]byte, error) {
	var block cipher.Block
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}
	if len(ciphertext) < aes.BlockSize {
		return nil, fmt.Errorf("iciphertext too short")
	}
	iv := ciphertext[:aes.BlockSize]
	ciphertext = ciphertext[aes.BlockSize:]
	cbc := cipher.NewCBCDecrypter(block, iv)
	cbc.CryptBlocks(ciphertext, ciphertext)
	ciphertext = unPadding(ciphertext)
	return ciphertext, nil
}