package token

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"fmt"
	"io"
	"syscall"
	"os"

	"golang.org/x/term"
)

func Must[T any](v T, err error) T {
	if err != nil {
		panic(err)
	}
	return v
}

func Token() string {
	hash := sha256.Sum256(Password())
	v, err := Decrypt(string(Must(io.ReadAll(Must(os.Open("encrypted"))))), hash[:])
	if err != nil {
		panic(err)
	}
	return v
}

func Password() []byte {
	print("Password: ")
	p, err := term.ReadPassword(int(syscall.Stdin))
	if err != nil {
		panic(err)
	}
	return p
}

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

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

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

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

func Decrypt(cipherText string, key []byte) (string, error) {
	ciphertext, err := base64.StdEncoding.DecodeString(cipherText)
	if err != nil {
		return "", err
	}

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

	gcm, err := cipher.NewGCM(block)
	if err != nil {
		return "", err
	}

	nonceSize := gcm.NonceSize()
	if len(ciphertext) < nonceSize {
		return "", fmt.Errorf("ciphertext too short")
	}

	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
	plainText, err := gcm.Open(nil, nonce, ciphertext, nil)
	if err != nil {
		return "", err
	}

	return string(plainText), nil
}