NanoID-3.4.0: app/Main.hs

{-# LANGUAGE CPP             #-}
{-# LANGUAGE RecordWildCards #-}

import           Control.Monad

#if !MIN_VERSION_base(4,11,0)
import           Data.Monoid           ((<>))
#endif

import qualified Data.ByteString.Char8 as C
import           Data.Either
import           Options.Applicative
import           System.Exit
import           System.Random.MWC

import           Data.NanoID
import           Options

main :: IO ()
main = do
  Options{..} <- execParser opts
  if showver
    then putStrLn showVer >> exitFailure
    else if length < 1 || length > 21
      then strFail "nanoid length"
    else if quantity < 1
      then strFail "quantity"
      else do
        let alphabet' =
              if password
                then specialPassword
                else toAlphabet alphabet
        replicateM_ quantity $
          createSystemRandom
            >>= customNanoID alphabet' (toEnum length)
            >>= putNanoID newline
        exitSuccess
  where
    strFail m = putStrLn ("Bad " <> m <> ". See help (-h).") >> exitFailure
    putNanoID nl = put nl . unNanoID
      where put nl = if nl then C.putStrLn else C.putStr