Exercise5.hs

{-# LANGUAGE DataKinds             #-}
{-# LANGUAGE PartialTypeSignatures #-}
{-# OPTIONS_GHC -fno-warn-partial-type-signatures #-}

module Test.Tutorial.Exercise5 where

import qualified Data.ByteString.Char8     as BS8
import           Data.Registry
import           Data.Text.Encoding        (decodeUtf8)
import           Protolude
import           System.Directory          (doesFileExist)
import           Test.Tutorial.Application

newCheckedSecretReader :: SecretReaderConfig -> Logger IO -> IO (SecretReader IO)
newCheckedSecretReader (SecretReaderConfig path) logger = do
  exists <- doesFileExist (toS path)
  if not exists then fileDoesNotExist else pure ()
  pure SecretReader {
    readSecret = do
      if exists then Just . decodeUtf8 <$> BS8.readFile (toS path)
      else fileDoesNotExist $> Nothing
    }

  where
    fileDoesNotExist = error logger ("file does not exist at " <> path)


registryIO :: Registry _ _
registryIO =
     funTo @IO App
  +: funTo @IO newLogger
  +: funTo @IO newConsole
  +: funTo @IO newUserInput
  +: funTo @IO newRng
  +: funAs @IO newCheckedSecretReader
  +: valTo @IO (SecretReaderConfig "txe/tests/Test/Tutorial/secret.txt")
  +: end

newAppIO :: IO App
newAppIO = make @(IO App) registryIO