package token

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/base64"
	"fmt"
	"io"
	pb "schain/proto"

	"golang.org/x/net/context"
)

// 用于注册grpc服务
type RequestServer struct {
	pb.UnimplementedPingServer
}

var key string = "0123456789abcdef"

func (s *RequestServer) Login(ctx context.Context, in *pb.LoginRequest) (*pb.LoginReply, error) {
	//实现aes解密
	// 解密字符串
	de_name, err := decrypt(in.Username, key)
	if err != nil {
		panic("Decryption error")
	}
	de_password, err := decrypt(in.Password, key)
	if err != nil {
		panic("Decryption error")
	}
	fmt.Println("Loginrequest: ", de_name)
	if de_name == "Wuxinyu" && de_password == "123456" {
		tokenString := CreateToken(in.Username)
		return &pb.LoginReply{Status: "200", Token: tokenString}, nil

	} else {
		return &pb.LoginReply{Status: "403", Token: ""}, nil
	}

}

// SayHello 生成对 Ping 请求的响应
func (s *RequestServer) SayHello(ctx context.Context, in *pb.PingMessage) (*pb.PingMessage, error) {
	//生成响应消息
	msg := "bar"
	// 从上下文中检查用户认证信息
	userName := CheckAuth(ctx)
	//将用户名添加到消息中
	msg += " " + userName
	return &pb.PingMessage{Greeting: msg}, nil
}

func encrypt(plainText string, key string) (string, error) {
	keyBytes := []byte(key)

	block, err := aes.NewCipher(keyBytes)
	if err != nil {
		return "", err
	}

	// 创建一个加密器
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

	// 创建一个随机的 nonce，长度必须与加密块大小相同
	nonce := make([]byte, gcm.NonceSize())
	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
		return "", err
	}

	// 使用 nonce 加密数据
	ciphertext := gcm.Seal(nonce, nonce, []byte(plainText), nil)
	return base64.StdEncoding.EncodeToString(ciphertext), nil
}

func decrypt(ciphertext string, key string) (string, error) {
	decodedCiphertext, err := base64.StdEncoding.DecodeString(ciphertext)
	if err != nil {
		return "", err
	}

	block, err := aes.NewCipher([]byte(key))
	if err != nil {
		return "", err
	}

	// 创建一个解密器
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

	// 从密文中提取 nonce
	nonceSize := gcm.NonceSize()
	if len(decodedCiphertext) < nonceSize {
		return "", fmt.Errorf("ciphertext too short")
	}
	nonce := decodedCiphertext[:nonceSize]
	ciphertextBytes := decodedCiphertext[nonceSize:]

	// 解密数据
	plaintext, err := gcm.Open(nil, nonce, ciphertextBytes, nil)
	if err != nil {
		return "", err
	}

	return string(plaintext), nil
}