module CabalGild.Action.GetCabalVersion where

import qualified CabalGild.Extra.Either as Either
import qualified CabalGild.Extra.FieldLine as FieldLine
import qualified CabalGild.Extra.Name as Name
import qualified CabalGild.Extra.String as String
import qualified Data.List as List
import qualified Data.Maybe as Maybe
import qualified Distribution.CabalSpecVersion as CabalSpecVersion
import qualified Distribution.FieldGrammar.Newtypes as Newtypes
import qualified Distribution.Fields as Fields
import qualified Distribution.Parsec as Parsec

fromFields :: [Fields.Field a] -> CabalSpecVersion.CabalSpecVersion
fromFields fs = Maybe.fromMaybe CabalSpecVersion.CabalSpecV1_0 $ do
  f <- List.find isCabalVersion fs
  fls <- getFieldLines f
  Newtypes.getSpecVersion <$> fromFieldLines fls

isCabalVersion :: Fields.Field a -> Bool
isCabalVersion f = case f of
  Fields.Field n _ -> Name.value n == String.toUtf8 "cabal-version"
  Fields.Section {} -> False

getFieldLines :: Fields.Field a -> Maybe [Fields.FieldLine a]
getFieldLines f = case f of
  Fields.Field _ fls -> Just fls
  Fields.Section {} -> Nothing

fromFieldLines :: [Fields.FieldLine a] -> Maybe Newtypes.SpecVersion
fromFieldLines =
  Either.hush
    . Parsec.runParsecParser Parsec.parsec ""
    . FieldLine.toFieldLineStream