package utils

import (
	"cmii-uav-watchdog-common/models"
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"encoding/json"
	"errors"
	"io"
)

// Encrypt 加密字符串
func Encrypt(plaintext string, key string) (string, error) {
	// 创建hash
	hasher := sha256.New()
	hasher.Write([]byte(key))
	keyBytes := hasher.Sum(nil)
	
	// 创建cipher
	block, err := aes.NewCipher(keyBytes)
	if err != nil {
		return "", err
	}
	
	// 创建gcm
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}
	
	// 创建nonce
	nonce := make([]byte, gcm.NonceSize())
	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
		return "", err
	}
	
	// 加密
	ciphertext := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
	
	// 编码为base64
	return base64.StdEncoding.EncodeToString(ciphertext), nil
}

// Decrypt 解密字符串
func Decrypt(encrypted string, key string) (string, error) {
	// 解码base64
	ciphertext, err := base64.StdEncoding.DecodeString(encrypted)
	if err != nil {
		return "", err
	}
	
	// 创建hash
	hasher := sha256.New()
	hasher.Write([]byte(key))
	keyBytes := hasher.Sum(nil)
	
	// 创建cipher
	block, err := aes.NewCipher(keyBytes)
	if err != nil {
		return "", err
	}
	
	// 创建gcm
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}
	
	// 检查长度
	if len(ciphertext) < gcm.NonceSize() {
		return "", errors.New("密文太短")
	}
	
	// 分离nonce和密文
	nonce, ciphertext := ciphertext[:gcm.NonceSize()], ciphertext[gcm.NonceSize():]
	
	// 解密
	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
	if err != nil {
		return "", err
	}
	
	return string(plaintext), nil
}

// EncryptHostInfo 加密主机信息
func EncryptHostInfo(hostInfo models.HostInfo) (string, error) {
	// 序列化主机信息
	data, err := json.Marshal(hostInfo)
	if err != nil {
		return "", err
	}
	
	// 计算SHA256作为统一标识
	hasher := sha256.New()
	hasher.Write(data)
	hash := base64.StdEncoding.EncodeToString(hasher.Sum(nil))
	
	return hash, nil
}

// GenerateHostKey 生成主机唯一标识
func GenerateHostKey(hostInfo models.HostInfo) string {
	// 序列化主机信息
	key := hostInfo.UUID
	if key == "" {
		key = hostInfo.MAC
	}
	return key
}