{-# LANGUAGE OverloadedStrings #-}
import Data.Char (isLower, isNumber)
import Data.Text.Lazy (unpack, Text)
import Data.Monoid (mappend)
import Data.Text.Lazy (lines, Text, all, unpack, splitOn)
import Prelude hiding(lines, all)
import Shelly

(<>) = mappend

data NewUser = NewUser {
                 login :: Text
               , lastName :: Text
               , firstName :: Text
               }

usersFromCSV :: Text -> [NewUser]
usersFromCSV csv = map userFromLine (lines csv) where
  userFromLine line = toUser (line `splitOn` ",") where

    toUser (l:lname:fname:[]) | checkLogin l = NewUser {login = l, lastName = lname, firstName = fname}
    toUser _ = error $ unpack $ "expected \"login,lastname,firstname\" but got: " <> line

    checkLogin = all (\char -> isLower char || isNumber char)