{-# LANGUAGE TupleSections, FlexibleInstances, Rank2Types #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}

module Language.Haskell.GhcMod.SrcUtils where

import Control.Applicative ((<$>))
import CoreUtils (exprType)
import Data.Generics
import Data.Maybe (fromMaybe)
import Data.Ord as O
import GHC (LHsExpr, LPat, Id, DynFlags, SrcSpan, Type, Located, ParsedSource, RenamedSource, TypecheckedSource, GenLocated(L))
import qualified GHC as G
import GHC.SYB.Utils (Stage(..), everythingStaged)
import GhcMonad
import qualified Language.Haskell.Exts.Annotated as HE
import Language.Haskell.GhcMod.Doc
import Language.Haskell.GhcMod.Gap
import qualified Language.Haskell.GhcMod.Gap as Gap
import OccName (OccName)
import Outputable (PprStyle)
import TcHsSyn (hsPatType)

----------------------------------------------------------------

instance HasType (LHsExpr Id) where
    getType tcm e = do
        hs_env <- G.getSession
        mbe <- liftIO $ Gap.deSugar tcm e hs_env
        return $ (G.getLoc e, ) <$> CoreUtils.exprType <$> mbe

instance HasType (LPat Id) where
    getType _ (G.L spn pat) = return $ Just (spn, hsPatType pat)

----------------------------------------------------------------

listifySpans :: Typeable a => TypecheckedSource -> (Int, Int) -> [Located a]
listifySpans tcs lc = listifyStaged TypeChecker p tcs
  where
    p (L spn _) = G.isGoodSrcSpan spn && spn `G.spans` lc

listifyParsedSpans :: Typeable a => ParsedSource -> (Int, Int) -> [Located a]
listifyParsedSpans pcs lc = listifyStaged Parser p pcs
  where
    p (L spn _) = G.isGoodSrcSpan spn && spn `G.spans` lc

listifyRenamedSpans :: Typeable a => RenamedSource -> (Int, Int) -> [Located a]
listifyRenamedSpans pcs lc = listifyStaged Renamer p pcs
  where
    p (L spn _) = G.isGoodSrcSpan spn && spn `G.spans` lc

listifyStaged :: Typeable r => Stage -> (r -> Bool) -> GenericQ [r]
listifyStaged s p = everythingStaged s (++) [] ([] `mkQ` (\x -> [x | p x]))

cmp :: SrcSpan -> SrcSpan -> Ordering
cmp a b
  | a `G.isSubspanOf` b = O.LT
  | b `G.isSubspanOf` a = O.GT
  | otherwise           = O.EQ

toTup :: DynFlags -> PprStyle -> (SrcSpan, Type) -> ((Int,Int,Int,Int),String)
toTup dflag style (spn, typ) = (fourInts spn, pretty dflag style typ)

fourInts :: SrcSpan -> (Int,Int,Int,Int)
fourInts = fromMaybe (0,0,0,0) . Gap.getSrcSpan

fourIntsHE :: HE.SrcSpan -> (Int,Int,Int,Int)
fourIntsHE loc = ( HE.srcSpanStartLine loc, HE.srcSpanStartColumn loc
                 , HE.srcSpanEndLine loc, HE.srcSpanEndColumn loc)

-- Check whether (line,col) is inside a given SrcSpanInfo
typeSigInRangeHE :: Int -> Int -> HE.Decl HE.SrcSpanInfo -> Bool
typeSigInRangeHE lineNo colNo (HE.TypeSig (HE.SrcSpanInfo s _) _ _) =
  HE.srcSpanStart s <= (lineNo, colNo) && HE.srcSpanEnd s >= (lineNo, colNo)
typeSigInRangeHE lineNo colNo (HE.TypeFamDecl (HE.SrcSpanInfo s _) _ _) =
  HE.srcSpanStart s <= (lineNo, colNo) && HE.srcSpanEnd s >= (lineNo, colNo)
typeSigInRangeHE lineNo colNo (HE.DataFamDecl (HE.SrcSpanInfo s _) _ _ _) =
  HE.srcSpanStart s <= (lineNo, colNo) && HE.srcSpanEnd s >= (lineNo, colNo)
typeSigInRangeHE _  _ _= False

pretty :: DynFlags -> PprStyle -> Type -> String
pretty dflag style = showOneLine dflag style . Gap.typeForUser

showName :: DynFlags -> PprStyle -> G.Name -> String
showName dflag style name = showOneLine dflag style $ Gap.nameForUser name

showOccName :: DynFlags -> PprStyle -> OccName -> String
showOccName dflag style name = showOneLine dflag style $ Gap.occNameForUser name