-- | Contains common options reused in several commands.
module CommonOptions
  ( module CommonOptions,
    module Juvix.Prelude,
    module Options.Applicative,
  )
where

import Control.Exception qualified as GHC
import Juvix.Prelude
import Options.Applicative
import System.Process
import Prelude (show)

-- | Paths that are input are used to detect the root of the project.
data Path = Path
  { _pathPath :: FilePath,
    _pathIsInput :: Bool
  }
  deriving stock (Data)

makeLenses ''Path

instance Show Path where
  show = (^. pathPath)

parseInputJuvixFile :: Parser Path
parseInputJuvixFile = do
  _pathPath <-
    argument
      str
      ( metavar "JUVIX_FILE"
          <> help "Path to a .juvix file"
          <> completer juvixCompleter
      )
  pure Path {_pathIsInput = True, ..}

parseGenericOutputFile :: Parser Path
parseGenericOutputFile = do
  _pathPath <-
    option
      str
      ( long "output"
          <> short 'o'
          <> metavar "OUTPUT_FILE"
          <> help "Path to output file"
          <> action "file"
      )
  pure Path {_pathIsInput = False, ..}

parseGenericOutputDir :: Mod OptionFields FilePath -> Parser Path
parseGenericOutputDir m = do
  _pathPath <-
    option
      str
      ( long "output-dir"
          <> metavar "OUTPUT_DIR"
          <> help "Path to output directory"
          <> action "directory"
          <> m
      )
  pure Path {_pathIsInput = False, ..}

juvixCompleter :: Completer
juvixCompleter = mkCompleter $ \word -> do
  let cmd = unwords ["compgen", "-o", "plusdirs", "-f", "-X", "!*.juvix", "--", requote word]
  result <- GHC.try @GHC.SomeException $ readProcess "bash" ["-c", cmd] ""
  return . lines . fromRight [] $ result

requote :: String -> String
requote s =
  let -- Bash doesn't appear to allow "mixed" escaping
      -- in bash completions. So we don't have to really
      -- worry about people swapping between strong and
      -- weak quotes.
      unescaped =
        case s of
          -- It's already strongly quoted, so we
          -- can use it mostly as is, but we must
          -- ensure it's closed off at the end and
          -- there's no single quotes in the
          -- middle which might confuse bash.
          ('\'' : rs) -> unescapeN rs
          -- We're weakly quoted.
          ('"' : rs) -> unescapeD rs
          -- We're not quoted at all.
          -- We need to unescape some characters like
          -- spaces and quotation marks.
          elsewise -> unescapeU elsewise
   in strong unescaped
  where
    strong :: String -> String
    strong ss = '\'' : foldr go "'" ss
      where
        -- If there's a single quote inside the
        -- command: exit from the strong quote and
        -- emit it the quote escaped, then resume.
        go '\'' t = "'\\''" ++ t
        go h t = h : t

    -- Unescape a strongly quoted string
    -- We have two recursive functions, as we
    -- can enter and exit the strong escaping.
    unescapeN = goX
      where
        goX ('\'' : xs) = goN xs
        goX (x : xs) = x : goX xs
        goX [] = []

        goN ('\\' : '\'' : xs) = '\'' : goN xs
        goN ('\'' : xs) = goX xs
        goN (x : xs) = x : goN xs
        goN [] = []

    -- Unescape an unquoted string
    unescapeU = goX
      where
        goX [] = []
        goX ('\\' : x : xs) = x : goX xs
        goX (x : xs) = x : goX xs

    -- Unescape a weakly quoted string
    unescapeD = goX
      where
        -- Reached an escape character
        goX ('\\' : x : xs)
          -- If it's true escapable, strip the
          -- slashes, as we're going to strong
          -- escape instead.
          | x `elem` ("$`\"\\\n" :: String) = x : goX xs
          | otherwise = '\\' : x : goX xs
        -- We've ended quoted section, so we
        -- don't recurse on goX, it's done.
        goX ('"' : xs) =
          xs
        -- Not done, but not a special character
        -- just continue the fold.
        goX (x : xs) =
          x : goX xs
        goX [] =
          []

class HasPaths a where
  paths :: Traversal' a FilePath

optDeBruijn :: Parser Bool
optDeBruijn =
  switch
    ( long "show-de-bruijn"
        <> help "Show variable de Bruijn indices"
    )