// save user data to database
fun saveUserDataToDatabase(user : FirebaseUser?){
val email = user?.email
val uid = user?.uid
var userDTO = UserDTO()
userDTO.email = email
userDTO.emoji = "\uD83D\uDC3C \uD83C\uDF3F \uD83D\uDDA4 "
FirebaseFirestore.getInstance().collection("users").document(uid!!).set(userDTO)
//
finish()
startActivity(Intent(this, MainActivity::class.java))
}
LoginActivity.kt