{-# LANGUAGE LambdaCase #-}

module Main where

import Options.Applicative
import SortImports (sortImports)
import System.Environment (getArgs)
import System.IO (hReady, stdin)
import SortImports.Types (Qualified(..))

versionNumber :: String
versionNumber = "v1.2.0"

version :: Parser Mode
version = flag' Version $ mconcat
  [ long "version"
  , short 'v'
  , help "Version number"
  ]

data Mode
  = Version
  | FileInput FilePath
  | StdInput

data Options = Options
  { _options_mode :: Mode
  , _options_convert :: Maybe Qualified
  }

fileInput :: Parser Mode
fileInput = FileInput <$> strOption (mconcat
  [ long "file"
  , short 'f'
  , metavar "FILENAME"
  , help "Input file"
  ])

stdInput :: Parser Mode
stdInput = flag' StdInput $ mconcat
  [ long "stdin"
  , help "Read input from stdin"
  ]

convertToQualifiedPost :: Parser Bool
convertToQualifiedPost = switch (long "convert-to-qualified-post" <> help "Whether to convert all qualified imports to use ImportQualifiedPost")

convertToQualifiedPre :: Parser Bool
convertToQualifiedPre = switch (long "convert-to-qualified-pre" <> help "Whether to convert all ImportQualifiedPost imports to use older \"import qualified\" syntax")

options :: Parser Options
options = Options
  <$> (version <|> fileInput <|> stdInput)
  <*> (post <|> pre)
  where
    post = ((\x -> if x then Just Qualified_Post else Nothing) <$> convertToQualifiedPost)
    pre = ((\x -> if x then Just Qualified_Pre else Nothing) <$> convertToQualifiedPre)

run :: Options -> IO ()
run opts = case _options_mode opts of
  Version        -> putStrLn versionNumber
  FileInput path -> readFile path >>= putStr . (sortImports convert)
  StdInput       -> interact (sortImports convert)
  where
    convert = _options_convert opts

main :: IO ()
main = do
  noArgs   <- null <$> getArgs
  anyStdin <- hReady stdin
  if noArgs && anyStdin
    then run (Options StdInput Nothing)
    else execParser opts >>= run
  where opts = info (options <**> helper) $ mconcat
          [ briefDesc
          , header "sort-imports - Sort Haskell import statements"
          , footer "Input is read from stdin by default if no arguments are provided."
          ]