package utils

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/base64"
	"errors"
	"io"
)

// AESKey 从环境变量或配置中获取，这里使用默认密钥（生产环境应该从配置读取）
var defaultAESKey = []byte("your-32-byte-secret-key-here!!") // 32 bytes for AES-256

// GetAESKey 获取AES密钥（应该从配置文件或环境变量读取）
func GetAESKey() []byte {
	// TODO: 从配置文件或环境变量读取密钥
	// key := os.Getenv("AES_ENCRYPTION_KEY")
	// if key == "" {
	//     return defaultAESKey
	// }
	// return []byte(key)
	return defaultAESKey
}

// EncryptAES 使用AES-256-GCM加密数据
func EncryptAES(plaintext string) (string, error) {
	key := GetAESKey()

	// Create cipher block
	block, err := aes.NewCipher(key)
	if err != nil {
		return "", err
	}

	// Create GCM
	aesGCM, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

	// Create nonce
	nonce := make([]byte, aesGCM.NonceSize())
	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
		return "", err
	}

	// Encrypt
	ciphertext := aesGCM.Seal(nonce, nonce, []byte(plaintext), nil)

	// Encode to base64
	return base64.StdEncoding.EncodeToString(ciphertext), nil
}

// DecryptAES 使用AES-256-GCM解密数据
func DecryptAES(encrypted string) (string, error) {
	key := GetAESKey()

	// Decode from base64
	ciphertext, err := base64.StdEncoding.DecodeString(encrypted)
	if err != nil {
		return "", err
	}

	// Create cipher block
	block, err := aes.NewCipher(key)
	if err != nil {
		return "", err
	}

	// Create GCM
	aesGCM, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

	// Extract nonce
	nonceSize := aesGCM.NonceSize()
	if len(ciphertext) < nonceSize {
		return "", errors.New("ciphertext too short")
	}

	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]

	// Decrypt
	plaintext, err := aesGCM.Open(nil, nonce, ciphertext, nil)
	if err != nil {
		return "", err
	}

	return string(plaintext), nil
}
