{-# LANGUAGE CPP                  #-}
{-# LANGUAGE OverloadedStrings    #-}

{-|
Module      : GHCup.Utils.MegaParsec
Description : MegaParsec utilities
Copyright   : (c) Julian Ospald, 2020
License     : LGPL-3.0
Maintainer  : hasufell@hasufell.de
Stability   : experimental
Portability : portable
-}
module GHCup.Utils.MegaParsec where

import           GHCup.Types

import           Control.Applicative
#if !MIN_VERSION_base(4,13,0)
import           Control.Monad.Fail             ( MonadFail )
#endif
import           Data.Functor
import           Data.Maybe
import           Data.Text                      ( Text )
import           Data.Versions
import           Data.Void
import           System.FilePath

import qualified Data.List.NonEmpty            as NE
import qualified Data.Text                     as T
import qualified Text.Megaparsec               as MP


choice' :: (MonadFail f, MP.MonadParsec e s f) => [f a] -> f a
choice' []       = fail "Empty list"
choice' [x     ] = x
choice' (x : xs) = MP.try x <|> choice' xs


parseUntil :: MP.Parsec Void Text a -> MP.Parsec Void Text Text
parseUntil p = do
  (MP.try (MP.lookAhead p) $> mempty)
    <|> (do
          c  <- T.singleton <$> MP.anySingle
          c2 <- parseUntil p
          pure (c `mappend` c2)
        )

parseUntil1 :: MP.Parsec Void Text a -> MP.Parsec Void Text Text
parseUntil1 p = do
  i1 <- MP.getOffset
  t <- parseUntil p
  i2 <- MP.getOffset
  if i1 == i2 then fail "empty parse" else pure t



-- | Parses e.g.
--   * armv7-unknown-linux-gnueabihf-ghc
--   * armv7-unknown-linux-gnueabihf-ghci
ghcTargetBinP :: Text -> MP.Parsec Void Text (Maybe Text, Text)
ghcTargetBinP t =
  (,)
    <$> (   MP.try
            (Just <$> parseUntil1 (MP.chunk "-" *> MP.chunk t) <* MP.chunk "-"
            )
        <|> ((\ _ x -> x) Nothing <$> mempty)
        )
    <*> (MP.chunk t <* MP.eof)


-- | Extracts the version from @ProjectVersion="8.10.5"@.
ghcProjectVersion :: MP.Parsec Void Text Version
ghcProjectVersion = do
  _ <- MP.chunk "ProjectVersion=\""
  ver <- parseUntil1 $ MP.chunk "\""
  MP.setInput ver
  version'


-- | Extracts target triple and version from e.g.
--   * armv7-unknown-linux-gnueabihf-8.8.3
--   * armv7-unknown-linux-gnueabihf-8.8.3
ghcTargetVerP :: MP.Parsec Void Text GHCTargetVersion
ghcTargetVerP =
  (\x y -> GHCTargetVersion x y)
    <$> (MP.try (Just <$> parseUntil1 (MP.chunk "-" *> verP') <* MP.chunk "-")
        <|> ((\ _ x -> x) Nothing <$> mempty)
        )
    <*> (version' <* MP.eof)
 where
  verP' :: MP.Parsec Void Text Text
  verP' = do
    v <- version'
    let startsWithDigists =
          and
            . take 3
            . concatMap
              (map
                (\case
                  (Digits _) -> True
                  (Str    _) -> False
                ) . NE.toList)
            . NE.toList
            $ _vChunks v
    if startsWithDigists && isNothing (_vEpoch v)
      then pure $ prettyVer v
      else fail "Oh"


verP :: MP.Parsec Void Text Text -> MP.Parsec Void Text Versioning
verP suffix = do
  ver <- parseUntil suffix
  if T.null ver
    then fail "empty version"
    else do
      rest <- MP.getInput
      MP.setInput ver
      v <- versioning'
      MP.setInput rest
      pure v


pathSep :: MP.Parsec Void Text Char
pathSep = MP.oneOf pathSeparators