{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE DeriveGeneric      #-}

module Distribution.Types.IncludeRenaming (
    IncludeRenaming(..),
    defaultIncludeRenaming,
    isDefaultIncludeRenaming,
) where

import Distribution.Compat.Prelude
import Prelude ()

import Distribution.Types.ModuleRenaming

import qualified Distribution.Compat.CharParsing as P
import           Distribution.Parsec
import           Distribution.Pretty
import           Text.PrettyPrint           (text, (<+>))
import qualified Text.PrettyPrint           as Disp

-- ---------------------------------------------------------------------------
-- Module renaming

-- | A renaming on an include: (provides renaming, requires renaming)
data IncludeRenaming
    = IncludeRenaming {
        includeProvidesRn :: ModuleRenaming,
        includeRequiresRn :: ModuleRenaming
    }
    deriving (Show, Read, Eq, Ord, Typeable, Data, Generic)

instance Binary IncludeRenaming
instance Structured IncludeRenaming

instance NFData IncludeRenaming where rnf = genericRnf

-- | The 'defaultIncludeRenaming' applied when you only @build-depends@
-- on a package.
defaultIncludeRenaming :: IncludeRenaming
defaultIncludeRenaming = IncludeRenaming defaultRenaming defaultRenaming

-- | Is an 'IncludeRenaming' the default one?
isDefaultIncludeRenaming :: IncludeRenaming -> Bool
isDefaultIncludeRenaming (IncludeRenaming p r) = isDefaultRenaming p && isDefaultRenaming r

instance Pretty IncludeRenaming where
    pretty (IncludeRenaming prov_rn req_rn) =
        pretty prov_rn
          <+> (if isDefaultRenaming req_rn
                then Disp.empty
                else text "requires" <+> pretty req_rn)

instance Parsec IncludeRenaming where
    parsec = do
        prov_rn <- parsec
        req_rn <- P.option defaultRenaming $ P.try $ do
            P.spaces
            _ <- P.string "requires"
            P.spaces
            parsec
        -- Requirements don't really care if they're mentioned
        -- or not (since you can't thin a requirement.)  But
        -- we have a little hack in Configure to combine
        -- the provisions and requirements together before passing
        -- them to GHC, and so the most neutral choice for a requirement
        -- is for the "with" field to be False, so we correctly
        -- thin provisions.
        return (IncludeRenaming prov_rn req_rn)
