{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeFamilies #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  Haddock.Backends.Hoogle
-- Copyright   :  (c) Neil Mitchell 2006-2008
-- License     :  BSD-like
--
-- Maintainer  :  haddock@projects.haskell.org
-- Stability   :  experimental
-- Portability :  portable
--
-- Write out Hoogle compatible documentation
-- http://www.haskell.org/hoogle/
-----------------------------------------------------------------------------
module Haddock.Backends.Hoogle (
    -- * Main entry point to Hoogle output generation
    ppHoogle

    -- * Utilities for generating Hoogle output during interface creation
  , ppExportD
  ) where

import Documentation.Haddock.Markup
import Haddock.GhcUtils
import Haddock.Types hiding (Version)
import Haddock.Utils hiding (out)

import GHC
import GHC.Core.InstEnv
import GHC.Driver.Ppr
import GHC.Plugins (TopLevelFlag(..))
import GHC.Types.SourceText
import GHC.Utils.Outputable as Outputable
import GHC.Utils.Panic
import GHC.Unit.State

import Data.Char
import Data.Foldable (toList)
import Data.List (intercalate, isPrefixOf)
import Data.Maybe
import Data.Version

import System.Directory
import System.FilePath

prefix :: [String]
prefix = ["-- Hoogle documentation, generated by Haddock"
         ,"-- See Hoogle, http://www.haskell.org/hoogle/"
         ,""]


ppHoogle :: DynFlags -> UnitState -> String -> Version -> String -> Maybe (Doc RdrName) -> [Interface] -> FilePath -> IO ()
ppHoogle dflags unit_state package version synopsis prologue ifaces odir = do
    let -- Since Hoogle is line based, we want to avoid breaking long lines.
        dflags' = dflags{ pprCols = maxBound }
        filename = package ++ ".txt"
        contents = prefix ++
                   docWith dflags' (drop 2 $ dropWhile (/= ':') synopsis) prologue ++
                   ["@package " ++ package] ++
                   ["@version " ++ showVersion version
                   | not (null (versionBranch version))
                   ] ++
                   concat [ppModule dflags' unit_state i | i <- ifaces, OptHide `notElem` ifaceOptions i]
    createDirectoryIfMissing True odir
    writeUtf8File (odir </> filename) (unlines contents)

ppModule :: DynFlags -> UnitState -> Interface -> [String]
ppModule dflags unit_state iface =
  "" : ppDocumentation dflags (ifaceDoc iface) ++
  ["module " ++ moduleString (ifaceMod iface)] ++
  concatMap ppExportItem (ifaceRnExportItems $ iface) ++
  concatMap (ppInstance dflags unit_state) (ifaceInstances iface)

-- | If the export item is an 'ExportDecl', get the attached Hoogle textual
-- database entries for that export declaration.
ppExportItem :: ExportItem DocNameI -> [String]
ppExportItem (ExportDecl RnExportD { rnExpDHoogle = o }) = o
ppExportItem _                                           = []

---------------------------------------------------------------------
-- Utility functions

dropHsDocTy :: HsSigType GhcRn -> HsSigType GhcRn
dropHsDocTy = drop_sig_ty
    where
        drop_sig_ty (HsSig x a b)  = HsSig x a (drop_lty b)
        drop_sig_ty x@XHsSigType{} = x

        drop_lty (L src x) = L src (drop_ty x)

        drop_ty (HsForAllTy x a e) = HsForAllTy x a (drop_lty e)
        drop_ty (HsQualTy x a e) = HsQualTy x a (drop_lty e)
        drop_ty (HsBangTy x a b) = HsBangTy x a (drop_lty b)
        drop_ty (HsAppTy x a b) = HsAppTy x (drop_lty a) (drop_lty b)
        drop_ty (HsAppKindTy x a at b) = HsAppKindTy x (drop_lty a) at (drop_lty b)
        drop_ty (HsFunTy x w a b) = HsFunTy x w (drop_lty a) (drop_lty b)
        drop_ty (HsListTy x a) = HsListTy x (drop_lty a)
        drop_ty (HsTupleTy x a b) = HsTupleTy x a (map drop_lty b)
        drop_ty (HsOpTy x p a b c) = HsOpTy x p (drop_lty a) b (drop_lty c)
        drop_ty (HsParTy x a) = HsParTy x (drop_lty a)
        drop_ty (HsKindSig x a b) = HsKindSig x (drop_lty a) b
        drop_ty (HsDocTy _ a _) = drop_ty $ unL a
        drop_ty x = x

outHsSigType :: DynFlags -> HsSigType GhcRn -> String
outHsSigType dflags = out dflags . reparenSigType . dropHsDocTy

dropComment :: String -> String
dropComment (' ':'-':'-':' ':_) = []
dropComment (x:xs) = x : dropComment xs
dropComment [] = []

outWith :: Outputable a => (SDoc -> String) -> a -> [Char]
outWith p =
      f
    . unwords
    . map (dropWhile isSpace)
    . lines
    . p
    . ppr
  where
      f xs | " <document comment>" `isPrefixOf` xs = f $ drop 19 xs
      f (x:xs) = x : f xs
      f [] = []

out :: Outputable a => DynFlags -> a -> String
out dflags = outWith $ showSDoc dflags

operator :: String -> String
operator (x:xs) | not (isAlphaNum x) && x `notElem` "_' ([{" = '(' : x:xs ++ ")"
operator x = x

commaSeparate :: Outputable a => DynFlags -> [a] -> String
commaSeparate dflags = showSDoc dflags . interpp'SP

---------------------------------------------------------------------
-- How to print each export

ppExportD :: DynFlags -> ExportD GhcRn -> [String]
ppExportD dflags
    ExportD
      { expDDecl     = L _ decl
      , expDPats     = bundledPats
      , expDMbDoc    = mbDoc
      , expDSubDocs  = subdocs
      , expDFixities = fixities
      }
  = concat
      [ ppDocumentation dflags' dc ++ f d
      | (d, (dc, _)) <- (decl, mbDoc) : bundledPats
      ] ++ ppFixities
  where
    -- Since Hoogle is line based, we want to avoid breaking long lines.
    dflags' :: DynFlags
    dflags' = dflags{ pprCols = maxBound }

    f :: HsDecl GhcRn -> [String]
    f (TyClD _ d@DataDecl{})  = ppData dflags' d subdocs
    f (TyClD _ d@SynDecl{})   = ppSynonym dflags' d
    f (TyClD _ d@ClassDecl{}) = ppClass dflags' d subdocs
    f (TyClD _ (FamDecl _ d)) = ppFam dflags' d
    f (ForD _ (ForeignImport _ name typ _)) = [pp_sig dflags' [name] typ]
    f (ForD _ (ForeignExport _ name typ _)) = [pp_sig dflags' [name] typ]
    f (SigD _ sig) = ppSig dflags' sig
    f _ = []

    ppFixities :: [String]
    ppFixities = concatMap (ppFixity dflags') fixities


ppSigWithDoc :: DynFlags -> Sig GhcRn -> [(Name, DocForDecl Name)] -> [String]
ppSigWithDoc dflags sig subdocs = case sig of
    TypeSig _ names t -> concatMap (mkDocSig "" (dropWildCards t)) names
    PatSynSig _ names t -> concatMap (mkDocSig "pattern " t) names
    _ -> []
  where
    mkDocSig leader typ n = mkSubdocN dflags n subdocs
                                      [leader ++ pp_sig dflags [n] typ]

ppSig :: DynFlags -> Sig GhcRn -> [String]
ppSig dflags x  = ppSigWithDoc dflags x []

pp_sig :: DynFlags -> [LocatedN Name] -> LHsSigType GhcRn -> String
pp_sig dflags names (L _ typ)  =
    operator prettyNames ++ " :: " ++ outHsSigType dflags typ
    where
      prettyNames = intercalate ", " $ map (out dflags) names



-- note: does not yet output documentation for class methods
ppClass :: DynFlags -> TyClDecl GhcRn -> [(Name, DocForDecl Name)] -> [String]
ppClass dflags decl@(ClassDecl {}) subdocs =
    (ppDecl ++ ppTyFams) : ppMethods
  where
    ppDecl :: String
    ppDecl =
      out dflags
        decl
          { tcdSigs = []
          , tcdATs = []
          , tcdATDefs = []
          , tcdMeths = emptyLHsBinds
          }

    ppMethods :: [String]
    ppMethods = concat . map (ppSig' . unLoc . add_ctxt) $ tcdSigs decl

    ppSig' = flip (ppSigWithDoc dflags) subdocs

    add_ctxt = addClassContext (tcdName decl) (tyClDeclTyVars decl)

    ppTyFams :: String
    ppTyFams
        | null $ tcdATs decl = ""
        | otherwise = (" " ++) . showSDoc dflags . whereWrapper $ concat
            [ map pprTyFam (tcdATs decl)
            , map (pprTyFamInstDecl NotTopLevel . unLoc) (tcdATDefs decl)
            ]

    pprTyFam :: LFamilyDecl GhcRn -> SDoc
    pprTyFam (L _ at) = vcat' $ map text $
        mkSubdocN dflags
          (fdLName at)
          subdocs
          -- Associated type families should not be printed as top-level
          -- (avoid printing the `family` keyword)
          (ppFam dflags at{fdTopLevel = NotTopLevel})

    whereWrapper elems = vcat'
        [ text "where" <+> lbrace
        , nest 4 . vcat . map (Outputable.<> semi) $ elems
        , rbrace
        ]
ppClass _ _non_cls_decl _ = []

ppFam :: DynFlags -> FamilyDecl GhcRn -> [String]
ppFam dflags decl@(FamilyDecl { fdInfo = info })
  = [out dflags decl']
  where
    decl' = case info of
              -- We don't need to print out a closed type family's equations
              -- for Hoogle, so pretend it doesn't have any.
              ClosedTypeFamily{} -> decl { fdInfo = OpenTypeFamily }
              _                  -> decl

ppInstance :: DynFlags -> UnitState -> ClsInst -> [String]
ppInstance dflags unit_state x =
  [dropComment $ outWith (showSDocForUser dflags unit_state alwaysQualify) cls]
  where
    -- As per #168, we don't want safety information about the class
    -- in Hoogle output. The easiest way to achieve this is to set the
    -- safety information to a state where the Outputable instance
    -- produces no output which means no overlap and unsafe (or [safe]
    -- is generated).
    cls = x { is_flag = OverlapFlag { overlapMode = NoOverlap NoSourceText
                                    , isSafeOverlap = False } }

ppSynonym :: DynFlags -> TyClDecl GhcRn -> [String]
ppSynonym dflags x = [out dflags x]

ppData :: DynFlags -> TyClDecl GhcRn -> [(Name, DocForDecl Name)] -> [String]
ppData dflags decl@DataDecl { tcdLName = name, tcdTyVars = tvs, tcdFixity = fixity, tcdDataDefn = defn } subdocs
    = out dflags (ppDataDefnHeader (pp_vanilla_decl_head name tvs fixity) defn) :
      concatMap (ppCtor dflags decl subdocs . unLoc) (dd_cons defn)
ppData _ _ _ = panic "ppData"

-- | for constructors, and named-fields...
lookupCon :: DynFlags -> [(Name, DocForDecl Name)] -> LocatedN Name -> [String]
lookupCon dflags subdocs (L _ name) = case lookup name subdocs of
  Just (d, _) -> ppDocumentation dflags d
  _ -> []

ppCtor :: DynFlags -> TyClDecl GhcRn -> [(Name, DocForDecl Name)] -> ConDecl GhcRn -> [String]
ppCtor dflags dat subdocs con@ConDeclH98 { con_args = con_args' }
  -- AZ:TODO get rid of the concatMap
   = concatMap (lookupCon dflags subdocs) [con_name con] ++ f con_args'
    where
        f (PrefixCon _ args) = [typeSig name $ (map hsScaledThing args) ++ [resType]]
        f (InfixCon a1 a2) = f $ PrefixCon [] [a1,a2]
        f (RecCon (L _ recs)) = f (PrefixCon [] $ map (hsLinear . cd_fld_type . unLoc) recs) ++ concat
                          [(concatMap (lookupCon dflags subdocs . noLocA . foExt . unLoc) (cd_fld_names r)) ++
                           [out dflags (map (foExt . unLoc) $ cd_fld_names r) `typeSig` [resType, cd_fld_type r]]
                          | r <- map unLoc recs]

        funs = foldr1 (\x y -> reL $ HsFunTy noAnn (HsUnrestrictedArrow noHsUniTok) x y)
        apps = foldl1 (\x y -> reL $ HsAppTy noExtField x y)

        typeSig nm flds = operator nm ++ " :: " ++
                          outHsSigType dflags (unL $ mkEmptySigType $ funs flds)

        -- We print the constructors as comma-separated list. See GHC
        -- docs for con_names on why it is a list to begin with.
        name = commaSeparate dflags . toList $ unL <$> getConNames con

        tyVarArg (UserTyVar _ _ n) = HsTyVar noAnn NotPromoted n
        tyVarArg (KindedTyVar _ _ n lty) = HsKindSig noAnn (reL (HsTyVar noAnn NotPromoted n)) lty
        tyVarArg _ = panic "ppCtor"

        resType = apps $ map reL $
                        (HsTyVar noAnn NotPromoted (reL (tcdName dat))) :
                        map (tyVarArg . unLoc) (hsQTvExplicit $ tyClDeclTyVars dat)

ppCtor dflags _dat subdocs (ConDeclGADT { con_names = names
                                        , con_bndrs = L _ outer_bndrs
                                        , con_mb_cxt = mcxt
                                        , con_g_args = args
                                        , con_res_ty = res_ty })
   = concatMap (lookupCon dflags subdocs) names ++ [typeSig]
    where
        typeSig = operator name ++ " :: " ++ outHsSigType dflags con_sig_ty
        name = out dflags $ unL <$> names
        con_sig_ty = HsSig noExtField outer_bndrs theta_ty where
          theta_ty = case mcxt of
            Just theta -> noLocA (HsQualTy { hst_xqual = noExtField, hst_ctxt = theta, hst_body = tau_ty })
            Nothing -> tau_ty
          tau_ty = foldr mkFunTy res_ty $
            case args of PrefixConGADT pos_args -> map hsScaledThing pos_args
                         RecConGADT (L _ flds) _ -> map (cd_fld_type . unL) flds
          mkFunTy a b = noLocA (HsFunTy noAnn (HsUnrestrictedArrow noHsUniTok) a b)

ppFixity :: DynFlags -> (Name, Fixity) -> [String]
ppFixity dflags (name, fixity) = [out dflags ((FixitySig noExtField [noLocA name] fixity) :: FixitySig GhcRn)]


---------------------------------------------------------------------
-- DOCUMENTATION

ppDocumentation :: Outputable o => DynFlags -> Documentation o -> [String]
ppDocumentation dflags (Documentation d w) = mdoc dflags d ++ doc dflags w


doc :: Outputable o => DynFlags -> Maybe (Doc o) -> [String]
doc dflags = docWith dflags ""

mdoc :: Outputable o => DynFlags -> Maybe (MDoc o) -> [String]
mdoc dflags = docWith dflags "" . fmap _doc

docWith :: Outputable o => DynFlags -> String -> Maybe (Doc o) -> [String]
docWith _ [] Nothing = []
docWith dflags header d
  = ("":) $ zipWith (++) ("-- | " : repeat "--   ") $
    lines header ++ ["" | header /= "" && isJust d] ++
    maybe [] (showTags . markup (markupTag dflags)) d

mkSubdocN :: DynFlags -> LocatedN Name -> [(Name, DocForDecl Name)] -> [String] -> [String]
mkSubdocN dflags n subdocs s = mkSubdoc dflags (n2l n) subdocs s

mkSubdoc :: DynFlags -> LocatedA Name -> [(Name, DocForDecl Name)] -> [String] -> [String]
mkSubdoc dflags n subdocs s = concatMap (ppDocumentation dflags) getDoc ++ s
 where
   getDoc = maybe [] (return . fst) (lookup (unLoc n) subdocs)

data Tag = TagL Char [Tags] | TagP Tags | TagPre Tags | TagInline String Tags | Str String
           deriving Show

type Tags = [Tag]

box :: (a -> b) -> a -> [b]
box f x = [f x]

str :: String -> [Tag]
str a = [Str a]

-- want things like paragraph, pre etc to be handled by blank lines in the source document
-- and things like \n and \t converted away
-- much like blogger in HTML mode
-- everything else wants to be included as tags, neatly nested for some (ul,li,ol)
-- or inlne for others (a,i,tt)
-- entities (&,>,<) should always be appropriately escaped

markupTag :: Outputable o => DynFlags -> DocMarkup o [Tag]
markupTag dflags = Markup {
  markupParagraph            = box TagP,
  markupEmpty                = str "",
  markupString               = str,
  markupAppend               = (++),
  markupIdentifier           = box (TagInline "a") . str . out dflags,
  markupIdentifierUnchecked  = box (TagInline "a") . str . showWrapped (out dflags . snd),
  markupModule               = \(ModLink m label) -> box (TagInline "a") (fromMaybe (str m) label),
  markupWarning              = box (TagInline "i"),
  markupEmphasis             = box (TagInline "i"),
  markupBold                 = box (TagInline "b"),
  markupMonospaced           = box (TagInline "tt"),
  markupPic                  = const $ str " ",
  markupMathInline           = const $ str "<math>",
  markupMathDisplay          = const $ str "<math>",
  markupUnorderedList        = box (TagL 'u'),
  markupOrderedList          = box (TagL 'o') . map snd,
  markupDefList              = box (TagL 'u') . map (\(a,b) -> TagInline "i" a : Str " " : b),
  markupCodeBlock            = box TagPre,
  markupHyperlink            = \(Hyperlink url mLabel) -> box (TagInline "a") (fromMaybe (str url) mLabel),
  markupAName                = const $ str "",
  markupProperty             = box TagPre . str,
  markupExample              = box TagPre . str . unlines . map exampleToString,
  markupHeader               = \(Header l h) -> box (TagInline $ "h" ++ show l) h,
  markupTable                = \(Table _ _) -> str "TODO: table"
  }


showTags :: [Tag] -> [String]
showTags = intercalate [""] . map showBlock


showBlock :: Tag -> [String]
showBlock (TagP xs) = showInline xs
showBlock (TagL t xs) = ['<':t:"l>"] ++ mid ++ ['<':'/':t:"l>"]
    where mid = concatMap (showInline . box (TagInline "li")) xs
showBlock (TagPre xs) = ["<pre>"] ++ showPre xs ++ ["</pre>"]
showBlock x = showInline [x]


asInline :: Tag -> Tags
asInline (TagP xs) = xs
asInline (TagPre xs) = [TagInline "pre" xs]
asInline (TagL t xs) = [TagInline (t:"l") $ map (TagInline "li") xs]
asInline x = [x]


showInline :: [Tag] -> [String]
showInline = unwordsWrap 70 . words . concatMap f
    where
        fs = concatMap f
        f (Str x) = escape x
        f (TagInline s xs) = "<"++s++">" ++ (if s == "li" then trim else id) (fs xs) ++ "</"++s++">"
        f x = fs $ asInline x

        trim = dropWhile isSpace . reverse . dropWhile isSpace . reverse


showPre :: [Tag] -> [String]
showPre = trimFront . trimLines . lines . concatMap f
    where
        trimLines = dropWhile null . reverse . dropWhile null . reverse
        trimFront xs = map (drop i) xs
            where
                ns = [length a | x <- xs, let (a,b) = span isSpace x, b /= ""]
                i = if null ns then 0 else minimum ns

        fs = concatMap f
        f (Str x) = escape x
        f (TagInline s xs) = "<"++s++">" ++ fs xs ++ "</"++s++">"
        f x = fs $ asInline x


unwordsWrap :: Int -> [String] -> [String]
unwordsWrap n = f n []
    where
        f _ s [] = [g s | s /= []]
        f i s (x:xs) | nx > i = g s : f (n - nx - 1) [x] xs
                     | otherwise = f (i - nx - 1) (x:s) xs
            where nx = length x

        g = unwords . reverse


escape :: String -> String
escape = concatMap f
    where
        f '<' = "&lt;"
        f '>' = "&gt;"
        f '&' = "&amp;"
        f x = [x]


-- | Just like 'vcat' but uses '($+$)' instead of '($$)'.
vcat' :: [SDoc] -> SDoc
vcat' = foldr ($+$) empty
