-- | Description : mostly reversible conversion between ipynb and lhs 
module IHaskell.Convert (convert) where
import Control.Monad.Identity (Identity(Identity), unless, when)
import IHaskell.Convert.Args (ConvertSpec(ConvertSpec, convertInput, convertLhsStyle, convertOutput, convertOverwriteFiles, convertToIpynb), fromJustConvertSpec, toConvertSpec)
import IHaskell.Convert.IpynbToLhs (ipynbToLhs)
import IHaskell.Convert.LhsToIpynb (lhsToIpynb)
import IHaskell.Flags (Argument)
import System.Directory (doesFileExist)
import Text.Printf (printf)

-- | used by @IHaskell convert@
convert :: [Argument] -> IO ()
convert args = case fromJustConvertSpec (toConvertSpec args) of
  ConvertSpec { convertToIpynb = Identity toIpynb,
                convertInput = Identity inputFile,
                convertOutput = Identity outputFile,
                convertLhsStyle = Identity lhsStyle,
                convertOverwriteFiles = force }
      | toIpynb -> do
        unless force (failIfExists outputFile)
        lhsToIpynb lhsStyle inputFile outputFile
      | otherwise -> do
        unless force (failIfExists outputFile)
        ipynbToLhs lhsStyle inputFile outputFile

-- | Call fail when the named file already exists.
failIfExists :: FilePath -> IO ()
failIfExists file = do
  exists <- doesFileExist file
  when exists $ fail $
    printf "File %s already exists. To force supply --force." file