{-# OPTIONS_GHC -fglasgow-exts #-}
--
-- Haddock - A Haskell Documentation Tool
--
-- (c) Simon Marlow 2003
--

module Main (main) where

import HaddockHtml
import HaddockHoogle
import HaddockRename
import HaddockTypes
import HaddockUtil
import HaddockVersion
import Paths_haddock         ( getDataDir )

import Prelude hiding ( catch )
import Control.Exception     ( bracket, throwIO, catch, Exception(..) )
import Control.Monad         ( when, liftM )
import Control.Monad.Writer  ( Writer, runWriter, tell )
import Data.Char             ( isSpace )
import Data.IORef            ( writeIORef )
import Data.List             ( nub, nubBy, (\\), foldl', sortBy, foldl1, init, 
                               mapAccumL, find )
import Data.Maybe            ( Maybe(..), isJust, isNothing, maybeToList, 
                               listToMaybe, fromJust, catMaybes )
import System.Console.GetOpt ( getOpt, usageInfo, ArgOrder(..), OptDescr(..), 
                               ArgDescr(..) )
import System.Environment    ( getArgs )
import System.IO             ( stderr, IOMode(..), openFile, hClose, 
                               hGetContents, hPutStrLn )
import System.Directory      ( doesFileExist, doesDirectoryExist )
import qualified Data.Map as Map
import Data.Map              (Map)
import Data.FunctorM         ( fmapM )
import Distribution.InstalledPackageInfo ( InstalledPackageInfo(..) ) 

import qualified GHC         ( init )
import GHC hiding ( init ) 
import Outputable
import SrcLoc
import qualified Digraph as Digraph
import Name
import Module                ( mkModule ) 
import InstEnv
import Class
import TypeRep
import Var hiding ( varName )
import TyCon
import PrelNames

import FastString
#define FSLIT(x) (mkFastString# (x#))

import DynFlags hiding ( Option )
import Packages hiding ( package ) 
import StaticFlags           ( parseStaticFlags )
import Unique                ( mkUnique )

-----------------------------------------------------------------------------
-- Top-level stuff

type CheckedMod = (Module, FullyCheckedMod, FilePath)

main :: IO ()
main = do

  -- first, get the GHC library dir (-B option)
  args <- getArgs
  (libDir, rest) <- getLibDir args 

  -- find out which flag mode we are in
  let (isGHCMode, rest') = parseModeFlag rest

  -- initialize GHC 
  (session, dynflags) <- startGHC libDir

  -- parse GHC flags given to the program 
  (dynflags', rest'') <- if isGHCMode 
    then parseGHCFlags_GHCMode     dynflags rest'   
    else parseGHCFlags_HaddockMode dynflags rest' 
  setSessionDynFlags session dynflags'

  -- parse Haddock specific flags
  (flags, fileArgs) <- parseHaddockOpts rest''

  -- try to sort and check the input files using the GHC API 
  modules <- sortAndCheckModules session dynflags' fileArgs

  -- create a PackageData for each external package in the session
  -- using the GHC API. The PackageData contains an html path,
  -- a doc env and a list of module names.
  packages <- getPackages session dynflags'

  -- update the html references (module -> html file mapping)
  updateHTMLXRefs packages

  -- combine the doc envs of the external packages into one
  let env = packagesDocEnv packages

  -- TODO: continue to break up the run function into parts
  run flags modules env

parseModeFlag :: [String] -> (Bool, [String])
parseModeFlag ("--ghc-flags":rest) = (True, rest)
parseModeFlag rest = (False, rest)

parseGHCFlags_GHCMode :: DynFlags -> [String] -> IO (DynFlags, [String])
parseGHCFlags_GHCMode dynflags args = do
  (dynflags', rest) <- parseDynamicFlags dynflags args
  rest' <- parseStaticFlags rest
  return (dynflags', rest')

parseGHCFlags_HaddockMode = parseGHCFlags

parseGHCFlags :: DynFlags -> [String] -> IO (DynFlags, [String])
parseGHCFlags dynflags args = case args of
  [] -> return (dynflags, args)
  ("-g":rest) -> worker rest 
  ("--ghc-flag":rest) -> worker rest
  (x:xs) -> do 
    (flags, rest) <- parseGHCFlags dynflags xs
    return (flags, x:rest)
  where 
    worker rest = do
      (mbFlags, rest') <- parseGHCFlag dynflags rest
      case mbFlags of 
        Just flags -> parseGHCFlags flags rest'
        Nothing -> parseGHCFlags dynflags rest'
 
parseGHCFlag :: DynFlags -> [String] -> IO (Maybe DynFlags, [String])
parseGHCFlag _ [] = die "No GHC flag supplied\n"
parseGHCFlag dynflags args = do
  mbDyn <- findDynamic
  case mbDyn of 
    Just (dynflags', rest) -> return (Just dynflags', rest)   
    Nothing -> do
      mbStat <- findStatic
      case mbStat of
        Just (_, rest) -> return (Nothing, rest)
        Nothing -> die ("Not a GHC flag: " ++ (head args) ++ "\n")
  where
    findDynamic = findFlag (\xs -> (do 
          (fs, xs') <- parseDynamicFlags dynflags xs
          if xs' /= xs then return (Just fs) else return Nothing
        ) `catch` (\_ -> return Nothing) 
      ) 

    findStatic = findFlag (\xs -> do 
        xs' <- parseStaticFlags xs
        if xs /= xs' then return (Just ()) else return Nothing
      )

    findFlag p = do 
      xs <- (sequence . snd) (mapAccumL (f p) [] args)
      case [ (x, index) | Just x <- xs | index <- [1..] ] of
        ((x, index):_) -> return (Just (x, drop index args))
        _ -> return Nothing

    f :: ([String] -> IO a) -> [String] -> String -> ([String], IO a)
    f parser previousArgs arg = 
      let args' = previousArgs ++ [arg]
      in (args', parser args')

parseHaddockOpts :: [String] -> IO ([Flag], [String])
parseHaddockOpts words =
  case getOpt Permute (options True) words of
    (flags, args, []) -> return (flags, args)
    (_, _, errors)    -> do 
      prog <- getProgramName
      die (concat errors ++ usageInfo (usageHeader prog) (options False))

usageHeader :: String -> String
usageHeader prog = "Usage: " ++ prog ++ " [OPTION...] file...\n"

getLibDir :: [String] -> IO (String, [String])
getLibDir ("-B":dir:rest) = return (dir, rest)
getLibDir (('-':'B':dir):rest) | not (null dir) = return (dir, rest)
getLibDir _ = die "Missing GHC lib dir option: -B <dir>\n"

extractGHCFlags :: [Flag] -> [String]
extractGHCFlags flags = [ flag | Flag_GHCFlag flag <- flags ]

startGHC :: String -> IO (Session, DynFlags)
startGHC libDir = do
  GHC.init (Just libDir)
  let ghcMode = BatchCompile
  session <- newSession ghcMode
  flags   <- getSessionDynFlags session
  flags'  <- initPackages flags
  let flags'' = dopt_set flags' Opt_Haddock 
  return (session, flags'')

sortAndCheckModules :: Session -> DynFlags -> [FilePath] -> IO [CheckedMod]
sortAndCheckModules session flags files = defaultErrorHandler flags $ do 
  targets <- mapM (\s -> guessTarget s Nothing) files
  setTargets session targets 
  mbModGraph <- depanal session [] True
  moduleGraph <- case mbModGraph of 
    Just mg -> return mg 
    Nothing -> die "Failed to load all modules\n" 
  let 
    modSumFile    = fromJust . ml_hs_file . ms_location
    sortedGraph   = topSortModuleGraph False moduleGraph Nothing
    sortedModules = concatMap Digraph.flattenSCC sortedGraph 
    modsAndFiles  = [ (ms_mod modsum, modSumFile modsum) | 
                      modsum <- sortedModules, 
                      modSumFile modsum `elem` files ] 
  checkedMods <- mapM (\(mod, file) -> do
    mbMod <- checkModule session (moduleName mod)
    checkedMod <- case mbMod of 
      Just m  -> return m
      Nothing -> die ("Failed to load module: " ++ moduleString mod)
    return (mod, checkedMod, file)) modsAndFiles 
  ensureFullyChecked checkedMods
  where
    ensureFullyChecked modules 
      | length modules' == length modules = return modules'
      | otherwise = die "Failed to check all modules properly\n" 
      where modules' = [ (mod, (a,b,c,d), f) | 
                         (mod, CheckedModule a (Just b) (Just c) (Just d), f) 
                         <- modules ] 

data Flag
  = Flag_CSS String
  | Flag_Debug
--  | Flag_DocBook
  | Flag_DumpInterface FilePath
  | Flag_Heading String
  | Flag_Package String
  | Flag_Html
  | Flag_Hoogle
  | Flag_HtmlHelp String
  | Flag_Lib String
  | Flag_NoImplicitPrelude
  | Flag_OutputDir FilePath
  | Flag_Prologue FilePath
  | Flag_ReadInterface FilePath
  | Flag_SourceBaseURL   String
  | Flag_SourceModuleURL String
  | Flag_SourceEntityURL String
  | Flag_WikiBaseURL   String
  | Flag_WikiModuleURL String
  | Flag_WikiEntityURL String
  | Flag_Help
  | Flag_Verbose
  | Flag_Version
  | Flag_UseContents String
  | Flag_GenContents
  | Flag_UseIndex String
  | Flag_GenIndex
  | Flag_IgnoreAllExports
  | Flag_HideModule String
  | Flag_UsePackage String
  | Flag_GHCFlag String
  deriving (Eq)

options :: Bool -> [OptDescr Flag]
options backwardsCompat =
  [
    Option ['o']  ["odir"]     (ReqArg Flag_OutputDir "DIR")
	"directory in which to put the output files",
    Option ['i'] ["read-interface"] (ReqArg Flag_ReadInterface "FILE")
	"read an interface from FILE",
    Option ['D']  ["dump-interface"]   (ReqArg Flag_DumpInterface "FILE")
        "dump an interface for these modules in FILE",
    Option ['l']  ["lib"]         (ReqArg Flag_Lib "DIR") 
	"location of Haddock's auxiliary files",
--    Option ['S']  ["docbook"]  (NoArg Flag_DocBook)
--	"output in DocBook XML",
    Option ['h']  ["html"]     (NoArg Flag_Html)
	"output in HTML",
    Option []  ["hoogle"]     (NoArg Flag_Hoogle)
    "output for Hoogle",
    Option []  ["html-help"]    (ReqArg Flag_HtmlHelp "format")
	"produce index and table of contents in\nmshelp, mshelp2 or devhelp format (with -h)",
    Option []  ["source-base"]   (ReqArg Flag_SourceBaseURL "URL") 
	"URL for a source code link on the contents\nand index pages",
    Option ['s'] (if backwardsCompat then ["source", "source-module"] else ["source-module"])
        (ReqArg Flag_SourceModuleURL "URL")
	"URL for a source code link for each module\n(using the %{FILE} or %{MODULE} vars)",
    Option []  ["source-entity"]  (ReqArg Flag_SourceEntityURL "URL") 
	"URL for a source code link for each entity\n(using the %{FILE}, %{MODULE} or %{NAME} vars)",
    Option []  ["comments-base"]   (ReqArg Flag_WikiBaseURL "URL")
	"URL for a comments link on the contents\nand index pages",
    Option []  ["comments-module"]  (ReqArg Flag_WikiModuleURL "URL") 
	"URL for a comments link for each module\n(using the %{MODULE} var)",
    Option []  ["comments-entity"]  (ReqArg Flag_WikiEntityURL "URL") 
	"URL for a comments link for each entity\n(using the %{FILE}, %{MODULE} or %{NAME} vars)",
    Option ['c']  ["css"]         (ReqArg Flag_CSS "FILE") 
	"the CSS file to use for HTML output",
    Option ['p']  ["prologue"] (ReqArg Flag_Prologue "FILE")
	"file containing prologue text",
    Option ['t']  ["title"]    (ReqArg Flag_Heading "TITLE")
	"page heading",
    Option ['k']  ["package"]  (ReqArg Flag_Package "NAME")
	"package name (optional)",
    Option ['n']  ["no-implicit-prelude"] (NoArg Flag_NoImplicitPrelude)
 	"do not assume Prelude is imported",
    Option ['d']  ["debug"]  (NoArg Flag_Debug)
	"extra debugging output",
    Option ['?']  ["help"]  (NoArg Flag_Help)
	"display this help and exit",
    Option ['V']  ["version"]  (NoArg Flag_Version)
	"output version information and exit",
    Option ['v']  ["verbose"]  (NoArg Flag_Verbose)
        "increase verbosity",
    Option [] ["use-contents"] (ReqArg Flag_UseContents "URL")
	"use a separately-generated HTML contents page",
    Option [] ["gen-contents"] (NoArg Flag_GenContents)
	"generate an HTML contents from specified\ninterfaces",
    Option [] ["use-index"] (ReqArg Flag_UseIndex "URL")
	"use a separately-generated HTML index",
    Option [] ["gen-index"] (NoArg Flag_GenIndex)
	"generate an HTML index from specified\ninterfaces",
    Option [] ["ignore-all-exports"] (NoArg Flag_IgnoreAllExports)
	"behave as if all modules have the\nignore-exports atribute",
    Option [] ["hide"] (ReqArg Flag_HideModule "MODULE")
	"behave as if MODULE has the hide attribute",
    Option [] ["use-package"] (ReqArg Flag_UsePackage "PACKAGE")
	"the modules being processed depend on PACKAGE",
    Option ['g'] ["ghc-flag"] (ReqArg Flag_GHCFlag "FLAG")
 	"send a flag to the Glasgow Haskell Compiler"       
  ]

handleEagerFlags flags = do
  whenFlag Flag_Help $ do
    prog <- getProgramName
    bye (usageInfo (usageHeader prog) (options False))

  whenFlag Flag_Version $
    bye ("Haddock version " ++ projectVersion ++ 
         ", (c) Simon Marlow 2003; port to GHC-api by David Waern 2006\n")

  when ((Flag_GenIndex `elem` flags || Flag_GenContents `elem` flags)
        && Flag_Html `elem` flags) $
    die ("-h cannot be used with --gen-index or --gen-contents")

  return (listToMaybe [str | Flag_Package str <- flags])
  where 
    whenFlag flag action = when (flag `elem` flags) action 

run :: [Flag] -> [CheckedMod] -> Map Name Name -> IO ()
run flags modules extEnv = do
  let
    title = case [str | Flag_Heading str <- flags] of
		[] -> ""
		(t:_) -> t

    maybe_source_urls = (listToMaybe [str | Flag_SourceBaseURL   str <- flags]
                        ,listToMaybe [str | Flag_SourceModuleURL str <- flags]
                        ,listToMaybe [str | Flag_SourceEntityURL str <- flags])

    maybe_wiki_urls = (listToMaybe [str | Flag_WikiBaseURL   str <- flags]
                      ,listToMaybe [str | Flag_WikiModuleURL str <- flags]
                      ,listToMaybe [str | Flag_WikiEntityURL str <- flags])

    verbose = Flag_Verbose `elem` flags

  libdir <- case [str | Flag_Lib str <- flags] of
		[] -> getDataDir -- provided by Cabal
		fs -> return (last fs)

  let css_file = case [str | Flag_CSS str <- flags] of
			[] -> Nothing
			fs -> Just (last fs)

  odir <- case [str | Flag_OutputDir str <- flags] of
		[] -> return "."
		fs -> return (last fs)

  let 

    dumpIface = case [str | Flag_DumpInterface str <- flags] of
		  	[] -> Nothing
		  	fs -> Just (last fs)

    maybe_contents_url = 
      case [url | Flag_UseContents url <- flags] of
        [] -> Nothing
        us -> Just (last us)

    maybe_index_url = 
      case [url | Flag_UseIndex url <- flags] of
        [] -> Nothing
        us -> Just (last us)

    maybe_html_help_format =
      case [hhformat | Flag_HtmlHelp hhformat <- flags] of
        []      -> Nothing
        formats -> Just (last formats)

  prologue <- getPrologue flags

  let 
    (modMap, messages) = runWriter (pass1 modules flags) 
    haddockMods = catMaybes [ Map.lookup mod modMap | (mod,_,_) <- modules ]
    homeEnv = buildGlobalDocEnv haddockMods
    env = homeEnv `Map.union` extEnv
    haddockMods' = attachInstances haddockMods
    (haddockMods'', messages') = runWriter $ mapM (renameModule env) haddockMods'
  
  mapM_ putStrLn messages
  mapM_ putStrLn messages'

  let 
    visibleMods = [ m | m <- haddockMods'', OptHide `notElem` (hmod_options m) ]
    packageName = (Just . packageIdString . modulePackageId . 
                   hmod_mod . head) visibleMods
 
  when (Flag_GenIndex `elem` flags) $ do
	ppHtmlIndex odir title packageName maybe_html_help_format
                maybe_contents_url maybe_source_urls maybe_wiki_urls
                visibleMods
	copyHtmlBits odir libdir css_file
        
  when (Flag_GenContents `elem` flags && Flag_GenIndex `elem` flags) $ do
    ppHtmlHelpFiles title packageName visibleMods odir maybe_html_help_format []

  when (Flag_GenContents `elem` flags) $ do
	ppHtmlContents odir title packageName maybe_html_help_format
	               maybe_index_url maybe_source_urls maybe_wiki_urls
	               visibleMods True prologue
	copyHtmlBits odir libdir css_file

  when (Flag_Html `elem` flags) $ do
    ppHtml title packageName visibleMods odir
                prologue maybe_html_help_format
                maybe_source_urls maybe_wiki_urls
                maybe_contents_url maybe_index_url
    copyHtmlBits odir libdir css_file
  where
    pprList [] = []
    pprList [x] = show x
    pprList (x:xs) = show x ++ ", " ++ pprList xs
 
print_ x = printSDoc (ppr x) defaultUserStyle        

instance Outputable (DocEntity Name) where
  ppr (DocEntity d) = ppr d
  ppr (DeclEntity name) = ppr name

instance Show Name where
  show name = show (ppr name defaultUserStyle)

instance Show a => Show (DocDecl a) where
  show (DocCommentNext doc) = "next" ++ show doc
  show (DocCommentPrev doc) = "prev" ++ show doc
  show _ = "other" 

type FullyCheckedMod = (ParsedSource, 
                        RenamedSource, 
                        TypecheckedSource, 
                        ModuleInfo)

printEntity (DocEntity doc) = show doc
printEntity (DeclEntity name) = show $ ppr name defaultUserStyle

pass1 :: [CheckedMod] -> [Flag] -> ErrMsgM ModuleMap2
pass1 modules flags = worker modules (Map.empty) flags
  where
    worker [] moduleMap _ = return moduleMap
    worker ((mod, checked_mod, filename):rest_modules) moduleMap flags = do
 
      let (parsed_source, renamed_source, _, moduleInfo) = checked_mod
          (mb_doc_opts, _, _) = getModuleStuff parsed_source

      opts <- mkDocOpts mb_doc_opts

      let (group, _, mb_exports, mbModDoc, haddockModInfo) = renamed_source

          entities = (reverse . nubBy sameName . hs_docs) group 
          exports = fmap (map unLoc) mb_exports
 
          -- lots of names
          exportedNames = modInfoExports moduleInfo
          theseEntityNames = entityNames entities 
          subNames = allSubnamesInGroup group
          localNames = theseEntityNames ++ subNames
          -- guaranteed to be Just, since the module has been compiled from 
          -- scratch 
          scopeNames = fromJust $ modInfoTopLevelScope moduleInfo 
      
          subMap = mk_sub_map_from_group group

          exportedDeclMap = mkDeclMap exportedNames group
          localDeclMap = mkDeclMap theseEntityNames group
          docMap = mkDocMap group 

          ignoreAllExports = Flag_IgnoreAllExports `elem` flags
  
          packageId = modulePackageId mod
      
      theseVisibleNames <- visibleNames mod moduleMap localNames scopeNames 
                                        subMap exports opts localDeclMap 
                                        packageId

      exportItems <- mkExportItems moduleMap mod exportedNames
                                   exportedDeclMap localDeclMap subMap entities 
                                   opts exports ignoreAllExports docMap 
                                   packageId

     -- prune the export list to just those declarations that have
     -- documentation, if the 'prune' option is on.
      let prunedExportItems
	    | OptPrune `elem` opts = pruneExportItems exportItems
	    | otherwise = exportItems
 
          instances = modInfoInstances moduleInfo

          haddock_module = HM {
            hmod_mod                = mod,
            hmod_orig_filename      = filename,
            hmod_info               = haddockModInfo,
            hmod_doc                = mbModDoc,
            hmod_rn_doc             = Nothing,
            hmod_options            = opts,
            hmod_locals             = localNames,
            hmod_doc_map            = docMap,
            hmod_rn_doc_map         = Map.empty,
            hmod_sub_map            = subMap,
            hmod_export_items       = prunedExportItems,
            hmod_rn_export_items    = [], 
            hmod_exports            = exportedNames,
            hmod_visible_exports    = theseVisibleNames, 
            hmod_exported_decl_map  = exportedDeclMap,
            hmod_instances          = instances
          }

          moduleMap' = Map.insert mod haddock_module moduleMap
      
      worker rest_modules moduleMap' flags 
      
      where 
        getModuleStuff source = 
          let HsModule _ _ _ _ _ mb_opts info mb_doc = unLoc source
          in (mb_opts, info, mb_doc)

        mkDocOpts mbOpts = do
          opts <- case mbOpts of 
            Just opts -> processOptions opts
            Nothing -> return []
          let opts' = if Flag_HideModule (moduleString mod) `elem` flags 
                then OptHide : opts
                else opts      
          return opts'
 
sameName (DocEntity _) _ = False
sameName (DeclEntity _) (DocEntity _) = False
sameName (DeclEntity a) (DeclEntity b) = a == b

-- This map includes everything that can be exported separately,
-- that means: top declarations, class methods and record selectors
-- TODO: merge this with mkDeclMap and the extractXXX functions 
mkDocMap :: HsGroup Name ->  Map Name (HsDoc Name)
mkDocMap group = Map.fromList (topDeclDocs ++ classMethDocs ++ recordFieldDocs)
  where
    tyclds    = map unLoc (hs_tyclds group)
    classes   = filter isClassDecl tyclds 
    datadecls = filter isDataDecl tyclds
    constrs   = [ con | d <- datadecls, L _ con <- tcdCons d ]
    fields    = concat [ fields | RecCon fields <- map con_details constrs]

    topDeclDocs     = collectDocs (reverse (hs_docs group))
    classMethDocs   = concatMap (collectDocs . tcdDocs) classes
    recordFieldDocs = [ (unLoc lname, doc) | 
                        HsRecField lname _ (Just (L _ doc)) <- fields ]

collectDocs :: [DocEntity Name] -> [(Name, HsDoc Name)]
collectDocs entities = collect Nothing DocEmpty entities

collect :: Maybe (DocEntity Name) -> HsDoc Name -> [DocEntity Name] -> 
           [(Name, HsDoc Name)]
collect d doc_so_far [] =
   case d of
        Nothing -> []
        Just d0  -> finishedDoc d0 doc_so_far []

collect d doc_so_far (e:es) =
  case e of
    DocEntity (DocCommentNext str) ->
      case d of
        Nothing -> collect d (docAppend doc_so_far str) es
        Just d0 -> finishedDoc d0 doc_so_far (collect Nothing str es)

    DocEntity (DocCommentPrev str) -> collect d (docAppend doc_so_far str) es

    _ -> case d of
      Nothing -> collect (Just e) doc_so_far es
      Just d0
        | sameName d0 e -> collect d doc_so_far es  
        | otherwise -> finishedDoc d0 doc_so_far (collect (Just e) DocEmpty es)

finishedDoc :: DocEntity Name -> HsDoc Name -> [(Name, HsDoc Name)] -> [(Name, HsDoc Name)]
finishedDoc d DocEmpty rest = rest
finishedDoc (DeclEntity name) doc rest = (name, doc) : rest
finishedDoc _ _ rest = rest
        
allSubnamesInGroup :: HsGroup Name -> [Name]
allSubnamesInGroup group = 
  concat [ tail (map unLoc (tyClDeclNames tycld)) | L _ tycld <- hs_tyclds group ]

mk_sub_map_from_group :: HsGroup Name -> Map Name [Name]
mk_sub_map_from_group group =  
  Map.fromList [ (name, subs) | L _ tycld <- hs_tyclds group,
                 let name:subs = map unLoc (tyClDeclNames tycld) ]

mkDeclMap :: [Name] -> HsGroup Name -> Map Name (LHsDecl Name) 
mkDeclMap names group = Map.fromList [ (n,d)  | (n,Just d) <- maybeDecls ]
  where 
  maybeDecls = [ (name, getDeclFromGroup group name) | name <- names ]

entityNames :: [DocEntity Name] -> [Name]
entityNames entities = [ name | DeclEntity name <- entities ] 
{-
getValSig :: Name -> HsValBinds Name -> TypeEnv -> Maybe (LSig Name)
getValSig name (ValBindsOut recsAndBinds _) typEnv = case matchingBinds of
  [bind] -> -- OK we have found a binding that matches. Now look up the
            -- type, even though it may be present in the ValBindsOut
            let tything = lookupTypeEnv typeEnv name       
  _ -> Nothing
  where 
    binds = snd $ unzip recsAndBinds 
    matchingBinds = Bag.filter matchesName binds
    matchesName (L _ bind) = fun_id bind == name
getValSig _ _ _ = error "getValSig"
-}
getDeclFromGroup :: HsGroup Name -> Name -> Maybe (LHsDecl Name)
getDeclFromGroup group name = 
  case catMaybes [ getDeclFromVals  (hs_valds  group), 
                   getDeclFromTyCls (hs_tyclds group),
                   getDeclFromFors  (hs_fords  group) ] of
    [decl] -> Just decl
    _ -> Nothing
  where 
    getDeclFromVals (ValBindsOut _ lsigs) = case matching of 
      [lsig] -> Just (L (getLoc lsig) (SigD (unLoc lsig)))
      _      -> Nothing
     where 
        matching = [ lsig | lsig <- lsigs, let Just n = sigName lsig, n == name, 
                     isNormal (unLoc lsig) ]
        isNormal (TypeSig _ _) = True
        isNormal _ = False

    getDeclFromVals _ = error "getDeclFromVals: illegal input"

{-    getDeclFromVals (ValBindsOut recsAndbinds _) = 
      let binds = snd $ unzip recsAndBinds 
          matchingBinds = Bag.filter matchesName binds
          matchesName (L _ bind) = fun_id bind == name
      in case matchingBinds of 
        [bind] -> -- OK we have found a binding that matches. Now look up the
                  -- type, even though it may be present in the ValBindsOut
                  
        _ -> Nothing
     where 
        matching = [ lsig | lsig <- lsigs, let Just n = sigName lsig, n == name ]
    getDeclFromVals _ = error "getDeclFromVals: illegal input"
  -}    
    getDeclFromTyCls ltycls = case matching of 
      [ltycl] -> Just (L (getLoc ltycl) (TyClD (unLoc ltycl)))
      _       -> Nothing
      where
        matching = [ ltycl | ltycl <- ltycls, 
                     name `elem` map unLoc (tyClDeclNames (unLoc ltycl))]
 
    getDeclFromFors lfors = case matching of 
      [for] -> Just (L (getLoc for) (ForD (unLoc for)))
      _      -> Nothing
      where
        matching = [ for | for <- lfors, forName (unLoc for) == name ]
        forName (ForeignExport n _ _) = unLoc n
        forName (ForeignImport n _ _) = unLoc n
 
parseIfaceOption :: String -> (FilePath,FilePath)
parseIfaceOption s = 
  case break (==',') s of
	(fpath,',':file) -> (fpath,file)
	(file, _)        -> ("", file)
	
updateHTMLXRefs :: [PackageData] -> IO ()
updateHTMLXRefs packages = writeIORef html_xrefs_ref (Map.fromList mapping)
  where
    mapping = [ (mod, html) | 
                (PackageData _ mods html) <- packages, (mod, _) <- mods ] 

getPrologue :: [Flag] -> IO (Maybe (HsDoc RdrName))
getPrologue flags
  = case [filename | Flag_Prologue filename <- flags ] of
	[] -> return Nothing 
	[filename] -> do
	   str <- readFile filename
	   case parseHaddockComment str of
		Left err -> die err
		Right doc -> return (Just doc)
	_otherwise -> die "multiple -p/--prologue options"

-- -----------------------------------------------------------------------------
-- Phase 2

renameModule :: Map Name Name -> HaddockModule -> ErrMsgM HaddockModule
renameModule renamingEnv mod =

  -- first create the local env, where every name exported by this module
  -- is mapped to itself, and everything else comes from the global renaming
  -- env
  let localEnv = foldl fn renamingEnv (hmod_visible_exports mod)
        where fn env name = Map.insert name (nameSetMod name (hmod_mod mod)) env
      
      docs = Map.toList (hmod_doc_map mod)
      renameMapElem (k,d) = do d' <- renameDoc d; return (k, d') 

  -- rename names in the exported declarations to point to things that
  -- are closer to, or maybe even exported by, the current module.
      (renamedExportItems, missingNames1)
        = runRnFM localEnv (renameExportItems (hmod_export_items mod))

      (rnDocMap, missingNames2) 
        = runRnFM localEnv (liftM Map.fromList (mapM renameMapElem docs))

      (finalModuleDoc, missingNames3)
        = runRnFM localEnv (renameMaybeDoc (hmod_doc mod))

      missingNames = nub $ filter isExternalName
                    (missingNames1 ++ missingNames2 ++ missingNames3)

      -- I haven't found the Name constant for () in the GHC API, so we have to
      -- filter out the "()" string instead
      strings = filter (/= "()") (map (showSDoc . ppr) missingNames) 
     
  in do
  -- report things that we couldn't link to. Only do this for non-hidden modules.
    when (OptHide `notElem` hmod_options mod && not (null strings)) $
	  tell ["Warning: " ++ show (ppr (hmod_mod mod) defaultUserStyle) ++ 
		": could not find link destinations for:\n"++
		"   " ++ concat (map (' ':) strings) ]

    return $ mod { hmod_rn_doc = finalModuleDoc,
                   hmod_rn_doc_map = rnDocMap,
                   hmod_rn_export_items = renamedExportItems }

-- -----------------------------------------------------------------------------
-- Build the list of items that will become the documentation, from the
-- export list.  At this point, the list of ExportItems is in terms of
-- original names.

mkExportItems
        :: ModuleMap2
	-> Module			-- this module
	-> [Name]			-- exported names (orig)
        -> Map Name (LHsDecl Name) -- maps exported names to declarations
	-> Map Name (LHsDecl Name) -- maps local names to declarations
	-> Map Name [Name]	-- sub-map for this module
	-> [DocEntity Name]	-- entities in the current module
	-> [DocOption]
	-> Maybe [IE Name]
	-> Bool				-- --ignore-all-exports flag
        -> Map Name (HsDoc Name)
        -> PackageId
	-> ErrMsgM [ExportItem2 Name]

mkExportItems mod_map this_mod exported_names exportedDeclMap localDeclMap sub_map entities
              opts maybe_exps ignore_all_exports docMap packageId
  | isNothing maybe_exps || ignore_all_exports || OptIgnoreExports `elem` opts
    = everything_local_exported
  | Just specs <- maybe_exps = do 
      exps <- mapM lookupExport specs
      return (concat exps)
  where
    everything_local_exported =  -- everything exported
      return (fullContentsOfThisModule this_mod entities localDeclMap docMap)

    lookupExport (IEVar x)             = declWith x
    lookupExport (IEThingAbs t)        = declWith t
    lookupExport (IEThingAll t)        = declWith t
    lookupExport (IEThingWith t cs)    = declWith t
    lookupExport (IEModuleContents m)  = fullContentsOf (mkModule packageId m)
    lookupExport (IEGroup lev doc)     = return [ ExportGroup2 lev "" doc ]
    lookupExport (IEDoc doc)           = return [ ExportDoc2 doc ] 
    lookupExport (IEDocNamed str)
	= do r <- findNamedDoc str entities
	     case r of
		Nothing -> return []
		Just found -> return [ ExportDoc2 found ]
 
    -- NOTE: I'm unsure about this. Currently only "External" names are considered.	
    declWith :: Name -> ErrMsgM [ ExportItem2 Name ]
    declWith t | not (isExternalName t) = return []
    declWith t
	| (Just decl, maybeDoc) <- findDecl t
        = return [ ExportDecl2 t (restrictTo subs (extractDecl t mdl decl)) maybeDoc [] ]
	| otherwise
	= return [ ExportNoDecl2 t t subs ]
	-- can't find the decl (it might be from another package), but let's
	-- list the entity anyway.  Later on, the renamer will change the
	-- orig name into the import name, so we get a proper link to
	-- the doc for this entity.
	where 
              mdl = nameModule t
	      subs = filter (`elem` exported_names) all_subs
              all_subs | mdl == this_mod = Map.findWithDefault [] t sub_map
		       | otherwise       = allSubsOfName mod_map t

    fullContentsOf m  
	| m == this_mod = return (fullContentsOfThisModule this_mod entities localDeclMap docMap)
	| otherwise = 
	   case Map.lookup m mod_map of
	     Just hmod
		| OptHide `elem` hmod_options hmod
			-> return (hmod_export_items hmod)
		| otherwise -> return [ ExportModule2 m ]
	     Nothing -> return [] -- already emitted a warning in exportedNames

    findDecl :: Name -> (Maybe (LHsDecl Name), Maybe (HsDoc Name))
    findDecl n | not (isExternalName n) = error "This shouldn't happen"
    findDecl n 
	| m == this_mod = (Map.lookup n exportedDeclMap, Map.lookup n docMap)
	| otherwise = 
	   case Map.lookup m mod_map of
		Just hmod -> (Map.lookup n (hmod_exported_decl_map hmod), 
                              Map.lookup n (hmod_doc_map hmod))
		Nothing -> (Nothing, Nothing)
      where
        m = nameModule n

fullContentsOfThisModule :: Module -> [DocEntity Name] -> Map Name (LHsDecl Name) ->
                            Map Name (HsDoc Name) -> [ExportItem2 Name]
fullContentsOfThisModule module_ entities declMap docMap 
  = catMaybes (map mkExportItem entities)
  where 
    mkExportItem (DocEntity (DocGroup lev doc)) = Just (ExportGroup2 lev "" doc)
    mkExportItem (DeclEntity name) = fmap mkExport (Map.lookup name declMap) 
      where mkExport decl = ExportDecl2 name decl (Map.lookup name docMap) []

-- Sometimes the declaration we want to export is not the "main" declaration:
-- it might be an individual record selector or a class method.  In these
-- cases we have to extract the required declaration (and somehow cobble 
-- together a type signature for it...)
 
extractDecl :: Name -> Module -> LHsDecl Name -> LHsDecl Name
extractDecl name mdl decl
  | Just n <- getMainDeclBinder (unLoc decl), n == name = decl
  | otherwise  =  
    case unLoc decl of
      TyClD d | isClassDecl d -> 
        let matches = [ sig | sig <- tcdSigs d, sigName sig == Just name ] 
        in case matches of 
          [s0] -> let (n, tyvar_names) = name_and_tyvars d
                      L pos sig = extractClassDecl n mdl tyvar_names s0
                  in L pos (SigD sig)
          _ -> error "internal: extractDecl" 
      TyClD d | isDataDecl d -> 
        let (n, tyvar_names) = name_and_tyvars d
            L pos sig = extractRecSel name mdl n tyvar_names (tcdCons d)
        in L pos (SigD sig)
      _ -> error "internal: extractDecl"
  where
    name_and_tyvars d = (unLoc (tcdLName d), hsLTyVarLocNames (tcdTyVars d))

toTypeNoLoc :: Located Name -> LHsType Name
toTypeNoLoc lname = noLoc (HsTyVar (unLoc lname))

rmLoc :: Located a -> Located a
rmLoc a = noLoc (unLoc a)

-- originally expected unqualified 1:st name, now it doesn't
extractClassDecl :: Name -> Module -> [Located Name] -> LSig Name -> LSig Name
extractClassDecl c mdl tvs0 (L pos (TypeSig lname ltype)) = case ltype of
  L _ (HsForAllTy exp tvs (L _ preds) ty) -> 
    L pos (TypeSig lname (noLoc (HsForAllTy exp tvs (lctxt preds) ty)))
  _ -> L pos (TypeSig lname (noLoc (mkImplicitHsForAllTy (lctxt []) ltype)))
  where
    lctxt preds = noLoc (ctxt preds)
    ctxt preds = [noLoc (HsClassP c (map toTypeNoLoc tvs0))] ++ preds  

extractClassDecl _ _ _ d = error $ "extractClassDecl: unexpected decl"

extractRecSel :: Name -> Module -> Name -> [Located Name] -> [LConDecl Name]
              -> LSig Name
extractRecSel _ _ _ _ [] = error "extractRecSel: selector not found"

-- originally expected unqualified 3:rd name, now it doesn't
extractRecSel nm mdl t tvs (L _ con : rest) =
  case con_details con of
    RecCon fields | (HsRecField n ty _ : _) <- matching_fields fields -> 
      L (getLoc n) (TypeSig (noLoc nm) (noLoc (HsFunTy data_ty (getBangType ty))))
    _ -> extractRecSel nm mdl t tvs rest
 where 
  matching_fields flds = [ f | f@(HsRecField n _ _) <- flds, (unLoc n) == nm ]   
  data_ty = foldl (\x y -> noLoc (HsAppTy x y)) (noLoc (HsTyVar t)) (map toTypeNoLoc tvs)

-- -----------------------------------------------------------------------------
-- Pruning

pruneExportItems :: [ExportItem2 Name] -> [ExportItem2 Name]
pruneExportItems items = filter hasDoc items
  where hasDoc (ExportDecl2 _ _ d _) = isJust d
	hasDoc _ = True

-- -----------------------------------------------------------------------------
-- Gather a list of original names exported from this module

visibleNames :: Module 
             -> ModuleMap2  
             -> [Name] 
             -> [Name]
             -> Map Name [Name]
             -> Maybe [IE Name]
             -> [DocOption]
             -> Map Name (LHsDecl Name)
             -> PackageId
             -> ErrMsgM [Name]

visibleNames mdl modMap localNames scope subMap maybeExps opts declMap packageId
  -- if no export list, just return all local names 
  | Nothing <- maybeExps         = return (filter hasDecl localNames)
  | OptIgnoreExports `elem` opts = return localNames
  | Just expspecs <- maybeExps = do
      visibleNames <- mapM extract expspecs
      return $ filter isNotPackageName (concat visibleNames)
 where
  hasDecl name = isJust (Map.lookup name declMap)
  isNotPackageName name = nameMod == mdl || isJust (Map.lookup nameMod modMap)
    where nameMod = nameModule name

  extract e = 
   case e of
    IEVar x -> return [x]
    IEThingAbs t -> return [t]
    IEThingAll t -> return (t : all_subs)
	 where
	      all_subs | nameModule t == mdl = Map.findWithDefault [] t subMap
		       | otherwise = allSubsOfName modMap t

    IEThingWith t cs -> return (t : cs)
	
    IEModuleContents m
	| mkModule packageId m == mdl -> return localNames 
	| otherwise -> let m' = mkModule packageId m in
	  case Map.lookup m' modMap of
	    Just mod
		| OptHide `elem` hmod_options mod ->
		    return (filter (`elem` scope) (hmod_exports mod))
		| otherwise -> return []
	    Nothing
		-> tell (exportModuleMissingErr mdl m') >> return []
  
    _ -> return []

exportModuleMissingErr this mdl 
  = ["Warning: in export list of " ++ show (moduleString this)
	 ++ ": module not found: " ++ show (moduleString mdl)]

-- for a given entity, find all the names it "owns" (ie. all the
-- constructors and field names of a tycon, or all the methods of a
-- class).
allSubsOfName :: ModuleMap2 -> Name -> [Name]
allSubsOfName mod_map name 
  | isExternalName name =
    case Map.lookup (nameModule name) mod_map of
      Just hmod -> Map.findWithDefault [] name (hmod_sub_map hmod)
      Nothing   -> []
  | otherwise =  error $ "Main.allSubsOfName: unexpected unqual'd name"

-- | Build a mapping which for each original name, points to the "best"
-- place to link to in the documentation.  For the definition of
-- "best", we use "the module nearest the bottom of the dependency
-- graph which exports this name", not including hidden modules.  When
-- there are multiple choices, we pick a random one.
-- 
-- The interfaces are passed in in topologically sorted order, but we start
-- by reversing the list so we can do a foldl.
buildGlobalDocEnv :: [HaddockModule] -> Map Name Name
buildGlobalDocEnv modules
 = foldl upd Map.empty (reverse modules)
 where
  upd old_env mod
     | OptHide `elem` hmod_options mod
     = old_env
     | OptNotHome `elem` hmod_options mod
     = foldl' keep_old old_env exported_names
     | otherwise
     = foldl' keep_new old_env exported_names
     where
	exported_names = hmod_visible_exports mod
        modName = hmod_mod mod

	keep_old env n = Map.insertWith (\new old -> old) 
			 n (nameSetMod n modName) env
	keep_new env n = Map.insert n (nameSetMod n modName) env 

nameSetMod n newMod = mkExternalName (nameUnique n) newMod (nameOccName n) Nothing (nameSrcLoc n)

-- -----------------------------------------------------------------------------
-- Named documentation

findNamedDoc :: String -> [DocEntity Name] -> ErrMsgM (Maybe (HsDoc Name))
findNamedDoc name entities = search entities 
	where search [] = do
		tell ["Cannot find documentation for: $" ++ name]
		return Nothing
	      search ((DocEntity (DocCommentNamed name' doc)):rest) 
			| name == name' = return (Just doc)
		   	| otherwise = search rest
	      search (_other_decl : rest) = search rest

-- -----------------------------------------------------------------------------
-- Haddock options embedded in the source file

processOptions_ str = let (opts, msg) = runWriter (processOptions str) 
                      in print msg >> return opts 

processOptions :: String -> ErrMsgM [DocOption]
processOptions str = do
  case break (== ',') str of
    (this, ',':rest) -> do
	opt <- parseOption this
	opts <- processOptions rest
	return (maybeToList opt ++ opts)
    (this, _)
	| all isSpace this -> return []
	| otherwise -> do opt <- parseOption this; return (maybeToList opt)

parseOption :: String -> ErrMsgM (Maybe DocOption)
parseOption "hide" = return (Just OptHide)
parseOption "prune" = return (Just OptPrune)
parseOption "ignore-exports" = return (Just OptIgnoreExports)
parseOption "not-home" = return (Just OptNotHome)
parseOption other = do tell ["Unrecognised option: " ++ other]; return Nothing

-- simplified type for sorting types, ignoring qualification (not visible
-- in Haddock output) and unifying special tycons with normal ones.
data SimpleType = SimpleType Name [SimpleType] deriving (Eq,Ord)

attachInstances :: [HaddockModule] -> [HaddockModule]
attachInstances modules = map attach modules
  where
    instMap = fmap (map toHsInstHead . sortImage instHead) $ collectInstances modules
    attach mod = mod { hmod_export_items = newItems }
      where
        newItems = map attachExport (hmod_export_items mod)

        attachExport (ExportDecl2 n decl doc _) =
          ExportDecl2 n decl doc (case Map.lookup n instMap of
                                   Nothing -> []
                                   Just instheads -> instheads)
        attachExport otherExport = otherExport

collectInstances
   :: [HaddockModule]
   -> Map Name [([TyVar], [PredType], Class, [Type])]  -- maps class/type names to instances

collectInstances modules
  = Map.fromListWith (flip (++)) tyInstPairs `Map.union`
    Map.fromListWith (flip (++)) classInstPairs
  where
    allInstances = concat (map hmod_instances modules)
    classInstPairs = [ (is_cls inst, [instanceHead inst]) | 
                       inst <- allInstances ]
    tyInstPairs = [ (tycon, [instanceHead inst]) | inst <- allInstances, 
                    Just tycon <- nub (is_tcs inst) ]

instHead :: ([TyVar], [PredType], Class, [Type]) -> ([Int], Name, [SimpleType])
instHead (_, _, cls, args)
  = (map argCount args, className cls, map simplify args)
  where
    argCount (AppTy t _) = argCount t + 1
    argCount (TyConApp _ ts) = length ts
    argCount (FunTy _ _ ) = 2
    argCount (ForAllTy _ t) = argCount t
    argCount (NoteTy _ t) = argCount t
    argCount _ = 0

    simplify (ForAllTy _ t) = simplify t
    simplify (FunTy t1 t2) = 
      SimpleType funTyConName [simplify t1, simplify t2]
    simplify (AppTy t1 t2) = SimpleType s (args ++ [simplify t2])
      where (SimpleType s args) = simplify t1
    simplify (TyVarTy v) = SimpleType (tyVarName v) []
    simplify (TyConApp tc ts) = SimpleType (tyConName tc) (map simplify ts)
    simplify (NoteTy _ t) = simplify t
    simplify _ = error "simplify"

-- sortImage f = sortBy (\x y -> compare (f x) (f y))
sortImage :: Ord b => (a -> b) -> [a] -> [a]
sortImage f xs = map snd $ sortBy cmp_fst [(f x, x) | x <- xs]
 where cmp_fst (x,_) (y,_) = compare x y

funTyConName = mkWiredInName gHC_PRIM
                        (mkOccNameFS tcName FSLIT("(->)"))
                        funTyConKey
                        Nothing                 -- No parent object
                        (ATyCon funTyCon)       -- Relevant TyCon
                        BuiltInSyntax

toHsInstHead :: ([TyVar], [PredType], Class, [Type]) -> InstHead2 Name
toHsInstHead (_, preds, cls, ts) = (map toHsPred preds, className cls, map toHsType ts) 

toHsPred :: PredType -> HsPred Name 
toHsPred (ClassP cls ts) = HsClassP (className cls) (map toLHsType ts)
toHsPred (IParam n t) = HsIParam n (toLHsType t)

toLHsType = noLoc . toHsType
 
toHsType :: Type -> HsType Name
toHsType t = case t of 
  TyVarTy v -> HsTyVar (tyVarName v) 
  AppTy a b -> HsAppTy (toLHsType a) (toLHsType b)
  TyConApp tc ts -> case ts of 
    [] -> HsTyVar (tyConName tc)
    _  -> HsAppTy (tycon tc) (args ts)
  FunTy a b -> HsFunTy (toLHsType a) (toLHsType b) 
  ForAllTy v t -> cvForAll [v] t 
  PredTy p -> HsPredTy (toHsPred p) 
  NoteTy _ t -> toHsType t
  where
    tycon tc = noLoc (HsTyVar (tyConName tc))
    args ts = foldl1 (\a b -> noLoc $ HsAppTy a b) (map toLHsType ts)
    cvForAll vs (ForAllTy v t) = cvForAll (v:vs) t
    cvForAll vs t = mkExplicitHsForAllTy (tyvarbinders vs) (noLoc []) (toLHsType t)
    tyvarbinders vs = map (noLoc . UserTyVar . tyVarName) vs

-- -----------------------------------------------------------------------------
-- A monad which collects error messages

type ErrMsg = String
type ErrMsgM a = Writer [ErrMsg] a

--------------------------------------------------------------------------------
-- Packages 
--------------------------------------------------------------------------------

-- | Recreate exposed modules from an InstalledPackageInfo
packageModules :: InstalledPackageInfo -> [Module]
packageModules pkgInfo = map (mkModule (pkgId pkgInfo)) moduleNames
  where moduleNames = map mkModuleName (exposedModules pkgInfo)

pkgId :: InstalledPackageInfo -> PackageId
pkgId = mkPackageId . package 

-- | Get the ModuleInfo for each exposed module in a package 
getPackageModuleInfo :: Session -> InstalledPackageInfo -> 
                        IO (Maybe [(Module, ModuleInfo)])
getPackageModuleInfo session pkgInfo = do
  mbInfos <- (flip mapM) (packageModules pkgInfo) $ \mod -> do
    mbModInfo <- getModuleInfo session mod 
    case mbModInfo of 
      Nothing -> return Nothing
      Just modInfo -> return (Just (mod, modInfo))
  return (sequence mbInfos)

-- | Get the Haddock HTML directory path for a package
getHtml :: InstalledPackageInfo -> IO (Either String FilePath)
getHtml pkgInfo = case haddockHTMLs pkgInfo of 
  (path:_) | not (null path) -> do
    dirExists <- doesDirectoryExist path
    if dirExists then return (Right path) else return $
       Left ("HTML directory " ++ path ++ " does not exist.")
  _ -> return (Left "No Haddock documentation installed.")
 
data PackageData = PackageData {
  pdPackageId  :: PackageId,
  pdModuleInfo :: [(Module, ModuleInfo)],
  pdHtmlPath   :: FilePath
}

-- | Retrieve a PackageData for a package in the session  
getPackageData :: Session -> InstalledPackageInfo -> 
                  IO (Either String PackageData) 
getPackageData session pkgInfo = do
  eHtml <- getHtml pkgInfo
  mbModInfo <- getPackageModuleInfo session pkgInfo
  let eModInfo = toEither "Could not get ModuleInfo for all exposed modules." 
                 mbModInfo
  return $ do -- in the Either monad
    html <- eHtml
    modInfo <- eModInfo
    return $ PackageData {
      pdPackageId  = pkgId pkgInfo, 
      pdModuleInfo = modInfo,
      pdHtmlPath   = html
    }
  where 
    toEither err = maybe (Left err) Right

-- | Retrieve a PackageData for each package in the session except for rts.
-- Print a warning on stdout if a PackageData could not be retrieved.
getPackages :: Session -> DynFlags -> IO [PackageData]
getPackages session dynflags = do
  pkgInfos <- getExplicitPackagesAnd dynflags []
  let pkgInfos' = filter notRTS pkgInfos
  liftM catMaybes (mapM getPackage pkgInfos')
  where
    -- no better way to do this?
    notRTS p = pkgName (package p) /= packageIdString rtsPackageId  

    getPackage pkgInfo = do
      result <- getPackageData session pkgInfo
      case result of
        Left err -> do
          let pkgName = showPackageId (package pkgInfo)
          putStrLn ("Warning: Cannot use package " ++ pkgName ++ ":")
          putStrLn ("   " ++ show err)
          return Nothing
        Right pkgInfo -> return (Just pkgInfo)

packagesDocEnv :: [PackageData] -> Map Name Name
packagesDocEnv packages = Map.fromList (concatMap packageDocEnv packages)

packageDocEnv :: PackageData -> [(Name, Name)]
packageDocEnv package = concatMap moduleInfoDocEnv modInfo  
  where modInfo = pdModuleInfo package

moduleInfoDocEnv :: (Module, ModuleInfo) -> [(Name, Name)]
moduleInfoDocEnv (mod, modInfo) = [ (n, nameSetMod n mod) | n <- names ]
  where names = modInfoExports modInfo