{-# LANGUAGE FlexibleInstances #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
{-# OPTIONS_HADDOCK hide #-}
-----------------------------------------------------------------------------
-- |
-- Module      :  Haddock.GhcUtils
-- Copyright   :  (c) David Waern 2006-2009
-- License     :  BSD-like
--
-- Maintainer  :  haddock@projects.haskell.org
-- Stability   :  experimental
-- Portability :  portable
--
-- Utils for dealing with types from the GHC API
-----------------------------------------------------------------------------

module Haddock.GhcUtils where


import Data.Version
import qualified Data.Map as Map
import Control.Arrow
import Data.Foldable hiding (concatMap)
import Data.Traversable
import Distribution.Compat.ReadP
import Distribution.Text

import Outputable
import Name
import Packages
import Module
import RdrName (GlobalRdrEnv)
import HscTypes
import LazyUniqFM
import GHC


moduleString :: Module -> String
moduleString = moduleNameString . moduleName 


-- return the name of the package, with version info
modulePackageString :: Module -> String
modulePackageString = packageIdString . modulePackageId


-- return the (name,version) of the package
modulePackageInfo :: Module -> (String, [Char])
modulePackageInfo modu = case unpackPackageId pkg of
                          Nothing -> (packageIdString pkg, "")
                          Just x -> (display $ pkgName x, showVersion (pkgVersion x))
  where pkg = modulePackageId modu


-- This was removed from GHC 6.11
-- XXX we shouldn't be using it, probably

-- | Try and interpret a GHC 'PackageId' as a cabal 'PackageIdentifer'. Returns @Nothing@ if
-- we could not parse it as such an object.
unpackPackageId :: PackageId -> Maybe PackageIdentifier
unpackPackageId p
  = case [ pid | (pid,"") <- readP_to_S parse str ] of
        []      -> Nothing
        (pid:_) -> Just pid
  where str = packageIdString p


mkModuleNoPackage :: String -> Module
mkModuleNoPackage str = mkModule (stringToPackageId "") (mkModuleName str)


lookupLoadedHomeModuleGRE  :: GhcMonad m => ModuleName -> m (Maybe GlobalRdrEnv)
lookupLoadedHomeModuleGRE mod_name = withSession $ \hsc_env ->
  case lookupUFM (hsc_HPT hsc_env) mod_name of
    Just mod_info      -> return (mi_globals (hm_iface mod_info))
    _not_a_home_module -> return Nothing


instance (Outputable a, Outputable b) => Outputable (Map.Map a b) where
  ppr m = ppr (Map.toList m)


isNameSym :: Name -> Bool
isNameSym = isSymOcc . nameOccName


isVarSym :: OccName -> Bool
isVarSym = isLexVarSym . occNameFS


getMainDeclBinder :: HsDecl name -> Maybe name
getMainDeclBinder (TyClD d) = Just (tcdName d)
getMainDeclBinder (ValD d)
   = case collectAcc d [] of
        []       -> Nothing 
        (name:_) -> Just (unLoc name)
getMainDeclBinder (SigD d) = sigNameNoLoc d
getMainDeclBinder (ForD (ForeignImport name _ _)) = Just (unLoc name)
getMainDeclBinder (ForD (ForeignExport _ _ _)) = Nothing
getMainDeclBinder _ = Nothing


isTyClD :: HsDecl a -> Bool
isTyClD (TyClD _) = True
isTyClD _ = False


isClassD :: HsDecl a -> Bool
isClassD (TyClD d) = isClassDecl d
isClassD _ = False


isDocD :: HsDecl a -> Bool
isDocD (DocD _) = True
isDocD _ = False


isInstD :: HsDecl a -> Bool
isInstD (InstD _) = True
isInstD (TyClD d) = isFamInstDecl d
isInstD _ = False


declATs :: HsDecl a -> [a]
declATs (TyClD d) | isClassDecl d = map (tcdName . unL) $ tcdATs d
declATs _ = []


pretty :: Outputable a => a -> String
pretty x = showSDoc (ppr x)


trace_ppr :: Outputable a => a -> b -> b
trace_ppr x y = trace (pretty x) y


-------------------------------------------------------------------------------
-- Located
-------------------------------------------------------------------------------


unL :: Located a -> a
unL (L _ x) = x


reL :: a -> Located a
reL = L undefined


instance Foldable Located where
  foldMap f (L _ x) = f x


instance Traversable Located where
  mapM f (L l x) = (return . L l) =<< f x  


-------------------------------------------------------------------------------
-- NamedThing instances
-------------------------------------------------------------------------------


instance NamedThing (TyClDecl Name) where
  getName = tcdName


instance NamedThing (ConDecl Name) where
  getName = unL . con_name


-------------------------------------------------------------------------------
-- Subordinates
-------------------------------------------------------------------------------


class Parent a where
  children :: a -> [Name]


instance Parent (ConDecl Name) where
  children con =
    case con_details con of
      RecCon fields -> map (unL . cd_fld_name) fields
      _             -> []


instance Parent (TyClDecl Name) where
  children d
    | isDataDecl  d = map (unL . con_name . unL) . tcdCons $ d
    | isClassDecl d =
        map (tcdName . unL) (tcdATs d) ++
        [ unL n | L _ (TypeSig n _) <- tcdSigs d ]
    | otherwise = []


-- | A parent and its children
family :: (NamedThing a, Parent a) => a -> (Name, [Name])
family = getName &&& children


-- | A mapping from the parent (main-binder) to its children and from each
-- child to its grand-children, recursively.
families :: TyClDecl Name -> [(Name, [Name])]
families d
  | isDataDecl  d = family d : map (family . unL) (tcdCons d)
  | isClassDecl d = family d : concatMap (families . unL) (tcdATs d)
  | otherwise     = []


-- | A mapping from child to parent
parentMap :: TyClDecl Name -> [(Name, Name)]
parentMap d = [ (c, p) | (p, cs) <- families d, c <- cs ]


-- | The parents of a subordinate in a declaration
parents :: Name -> HsDecl Name -> [Name]
parents n (TyClD d) = [ p | (c, p) <- parentMap d, c == n ]
parents _ _ = []