package main
//smtp

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/md5"
	"crypto/rand"
	"encoding/hex"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"net/smtp"
	"os"
	"strings"
)
var (
	to = flag.String("to", "michael.maksimov54@yandex.ru", "User name")
	sub = flag.String("sub", "test", "Subject")//заголовок
	mes = flag.String("mes", "hello", "message")
)


func main() {
	//fmt.Println("Starting the application...")
	//ciphertext := encrypt([]byte("B38mg520"), "password")
	//fmt.Printf("Encrypted: %x\n", ciphertext)
	//plaintext := decrypt(ciphertext, "password")
	//fmt.Printf("Decrypted: %s\n", plaintext)
	flag.Parse()
	path := "C:\\Users\\Миша\\go\\src\\Lab3.1\\data.txt"
	f, _ := ioutil.ReadFile(path)
	lines := strings.Split(string(f), "\n")
	for i:=0;i<len(lines);i++{
		fmt.Println(lines[i])
	}
	//test:=encrypt([]byte("B38mg520"), "password")
    //fmt.Println(test)
	//ioutil.WriteFile("pass",test,0644) //кодируем код от почты и  записываем его в файл
	fmt.Println([]byte(lines[3]))
	fmt.Println(string (decrypt([]byte(lines[3]), "password")))
	from := lines[4]
	//to := "danila@posevin.com"
	//Обычно идентификатор(sidentity) должен быть пустой строкой, чтобы действовать как имя пользователя.
	auth := smtp.PlainAuth("",lines[2] ,string(decrypt([]byte(lines[3]), "password")), lines[0])
	message := `To: "` + *to + `"\r\nSubject: ` + *sub + `\r\n\r\n` + *mes+`\r\n`

	if err := smtp.SendMail(lines[0]+":"+lines[1], auth, from, []string{*to}, []byte(message)); err != nil {
		fmt.Println("Error SendMail: ", err)
		os.Exit(1)
	}
	fmt.Println("Email Sent!")
}


func encrypt(data []byte, passphrase string) []byte {
	block, _ := aes.NewCipher([]byte(createHash(passphrase)))
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		panic(err.Error())
	}
	nonce := make([]byte, gcm.NonceSize())
	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
		panic(err.Error())
	}
	ciphertext := gcm.Seal(nonce, nonce, data, nil)
	return ciphertext
}

func createHash(key string) string {
	hasher := md5.New()
	hasher.Write([]byte(key))
	return hex.EncodeToString(hasher.Sum(nil))
}


func decrypt(data []byte, passphrase string) []byte {
	key := []byte(createHash(passphrase))
	block, err := aes.NewCipher(key)
	if err != nil {
		panic(err.Error())
	}
	gcm, err := cipher.NewGCM(block)
	if err != nil {
		panic(err.Error())
	}
	nonceSize := gcm.NonceSize()
	nonce, ciphertext := data[:nonceSize], data[nonceSize:]
	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
	if err != nil {
		panic(err.Error())
	}
	return plaintext
}