module Rules.Compile (compilePackage) where

import Hadrian.BuildPath
import Hadrian.Oracles.TextFile

import Base
import Context
import Expression
import Rules.Generate
import Settings
import Settings.Default
import Target
import Utilities

import qualified Text.Parsec as Parsec

-- * Rules for building objects and Haskell interface files

compilePackage :: [(Resource, Int)] -> Rules ()
compilePackage rs = do
    root <- buildRootRules

    -- We match all file paths that look like:
    --   <root>/...stuffs.../build/...stuffs.../<something>.<suffix>
    --
    -- where:
    --   - the '...stuffs...' bits can be one or more path components,
    --   - the '<suffix>' part is a way prefix (e.g thr_p_, or nothing if
    --     vanilla) followed by an object file extension, without the dot
    --     (o, o-boot, hi, hi-boot),
    --
    -- and parse the information we need (stage, package path, ...) from
    -- the path and figure out the suitable way to produce that object file.
    objectFilesUnder root |%> \path -> do
      obj <- parsePath (parseBuildObject root) "<object file path parser>" path
      compileObject rs path obj

  where
    objectFilesUnder r = [ r -/- ("**/build/**/*" ++ pat)
                         | pat <- extensionPats
                         ]

    exts = [ "o", "hi", "o-boot", "hi-boot" ]
    patternsFor e = [ "." ++ e, ".*_" ++ e ]
    extensionPats = concatMap patternsFor exts

-- * Object file paths types and parsers

{- We are using a non uniform representation that separates
   object files produced from Haskell code and from other
   languages, because the two "groups" have to be parsed
   differently enough that this would complicated the parser
   significantly.

   Indeed, non-Haskell files can only produce .o (or .thr_o, ...)
   files while Haskell modules can produce those as well as
   interface files, both in -boot or non-boot variants.

   Moreover, non-Haskell object files live under:
     <root>/stage<N>/<path/to/pkg>/build/{c,cmm,s}/

   while Haskell object/interface files live under:
     <root>/stage<N>/<path/to/pkg>/build/

   So the kind of object is partially determined by
   whether we're in c/, cmm/ or s/ but also by the
   object file's extension, in the case of a Haskell file.
   This could have been addressed with some knot-tying but
   Parsec's monad doesn't give us a MonadFix instance.

   We therefore stick to treating those two type of object
   files non uniformly.
-}

-- | Non Haskell source languages that we compile to get object files.
data SourceLang = Asm | C | Cmm
  deriving (Eq, Show)

parseSourceLang :: Parsec.Parsec String () SourceLang
parseSourceLang = Parsec.choice
  [ Parsec.char 'c' *> Parsec.choice
      [ Parsec.string "mm" *> pure Cmm
      , pure C
      ]
  , Parsec.char 's' *> pure Asm
  ]

type Basename = String

parseBasename :: Parsec.Parsec String () Basename
parseBasename = Parsec.manyTill Parsec.anyChar (Parsec.try $ Parsec.char '.')

-- | > <c|cmm|s>/<file>.<way prefix>_o
data NonHsObject = NonHsObject SourceLang Basename Way
  deriving (Eq, Show)

parseNonHsObject :: Parsec.Parsec String () NonHsObject
parseNonHsObject = do
  lang <- parseSourceLang
  _ <- Parsec.char '/'
  file <- parseBasename
  way <- parseWayPrefix vanilla
  _ <- Parsec.char 'o'
  return (NonHsObject lang file way)

-- | > <o|hi|o-boot|hi-boot>
data SuffixType = O | Hi | OBoot | HiBoot
  deriving (Eq, Show)

parseSuffixType :: Parsec.Parsec String () SuffixType
parseSuffixType = Parsec.choice
  [ Parsec.char 'o' *> Parsec.choice
      [ Parsec.string "-boot" *> pure OBoot
      , pure O
      ]
  , Parsec.string "hi" *> Parsec.choice
      [ Parsec.string "-boot" *> pure HiBoot
      , pure Hi
      ]
  ]

-- | > <way prefix>_<o|hi|o-boot|hi-boot>
data Extension = Extension Way SuffixType
  deriving (Eq, Show)

parseExtension :: Parsec.Parsec String () Extension
parseExtension =
  Extension <$> parseWayPrefix vanilla <*> parseSuffixType

-- | > <file>.<way prefix>_<o|hi|o-boot|hi-boot>
data HsObject = HsObject Basename Extension
  deriving (Eq, Show)

parseHsObject :: Parsec.Parsec String () HsObject
parseHsObject = do
  file <- parseBasename
  ext <- parseExtension
  return (HsObject file ext)

data Object = Hs HsObject | NonHs NonHsObject
  deriving (Eq, Show)

parseObject :: Parsec.Parsec String () Object
parseObject = Parsec.choice
  [ NonHs <$> parseNonHsObject
  , Hs    <$> parseHsObject
  ]

-- * Toplevel parsers

parseBuildObject :: FilePath -> Parsec.Parsec String () (BuildPath Object)
parseBuildObject root = parseBuildPath root parseObject

-- * Getting contexts from objects

objectContext :: BuildPath Object -> Action Context
objectContext (BuildPath _ stage pkgpath obj) = do
  pkg <- getPackageFromPath pkgpath
  return (Context stage pkg way)

  where way = case obj of
          NonHs (NonHsObject _lang _file w)      -> w
          Hs (HsObject _file (Extension w _suf)) -> w

        getPackageFromPath path = do
          pkgs <- getPackages
          case filter (\p -> pkgPath p == path) pkgs of
            (p:_) -> return p
            _     -> error $ "couldn't find a package with path: " ++ path

        getPackages = do
          pkgs <- stagePackages stage
          testPkgs <- testsuitePackages
          return $ pkgs ++ if stage == Stage1 then testPkgs else []

-- * Building an object

compileHsObject
  :: [(Resource, Int)] -> FilePath -> BuildPath Object -> HsObject -> Action ()
compileHsObject rs objpath b@(BuildPath _root stage _path _o) hsobj =
  case hsobj of
    HsObject _basename (Extension _way Hi)     ->
      need [ change "hi" "o" objpath ]
    HsObject _basename (Extension _way HiBoot) ->
      need [ change "hi-boot" "o-boot" objpath ]
    HsObject _basename (Extension _way _suf)   -> do
      ctx <- objectContext b
      ctxPath <- contextPath ctx
      (src, deps) <- lookupDependencies (ctxPath -/- ".dependencies") objpath
      need (src:deps)
      needLibrary =<< contextDependencies ctx
      buildWithResources rs $ target ctx (Ghc CompileHs stage) [src] [objpath]

  where change oldSuffix newSuffix str
          | not (oldSuffix `isSuffixOf` str) = error $
              "compileHsObject.change: " ++ oldSuffix ++
              " not a suffix of " ++ str
          | otherwise = take (length str - length oldSuffix) str
                     ++ newSuffix

compileNonHsObject
  :: [(Resource, Int)] -> FilePath -> BuildPath Object -> NonHsObject
  -> Action ()
compileNonHsObject rs objpath b@(BuildPath _root stage _path _o) nonhsobj =
  case nonhsobj of
    NonHsObject lang _basename _way ->
      go (builderFor lang) (toSrcFor lang)

  where builderFor C = Ghc CompileCWithGhc
        builderFor _ = Ghc CompileHs

        toSrcFor Asm = obj2src "S"   (const False)
        toSrcFor C   = obj2src "c"   (const False)
        toSrcFor Cmm = obj2src "cmm" isGeneratedCmmFile

        go builder tosrc = do
          ctx <- objectContext b
          src <- tosrc ctx objpath
          need [src]
          needDependencies ctx src (objpath <.> "d")
          buildWithResources rs $ target ctx (builder stage) [src] [objpath]

compileObject
  :: [(Resource, Int)] -> FilePath -> BuildPath Object -> Action ()
compileObject rs objpath b@(BuildPath _root _stage _path (Hs o)) =
  compileHsObject rs objpath b o
compileObject rs objpath b@(BuildPath _root _stage _path (NonHs o)) =
  compileNonHsObject rs objpath b o

-- * Helpers

-- | Discover dependencies of a given source file by iteratively calling @gcc@
-- in the @-MM -MG@ mode and building generated dependencies if they are missing
-- until reaching a fixed point.
needDependencies :: Context -> FilePath -> FilePath -> Action ()
needDependencies context@Context {..} src depFile = discover
  where
    discover = do
        build $ target context (Cc FindCDependencies stage) [src] [depFile]
        deps <- parseFile depFile
        -- Generated dependencies, if not yet built, will not be found and hence
        -- will be referred to simply by their file names.
        let notFound = filter (\file -> file == takeFileName file) deps
        -- We find the full paths to generated dependencies, so we can request
        -- to build them by calling 'need'.
        todo <- catMaybes <$> mapM (fullPathIfGenerated context) notFound

        if null todo
        then need deps -- The list of dependencies is final, need all
        else do
            need todo  -- Build newly discovered generated dependencies
            discover   -- Continue the discovery process

    parseFile :: FilePath -> Action [String]
    parseFile file = do
        input <- liftIO $ readFile file
        case parseMakefile input of
            [(_file, deps)] -> return deps
            _               -> return []

-- | Find a given 'FilePath' in the list of generated files in the given
-- 'Context' and return its full path.
fullPathIfGenerated :: Context -> FilePath -> Action (Maybe FilePath)
fullPathIfGenerated context file = interpretInContext context $ do
    generated <- generatedDependencies
    return $ find ((== file) . takeFileName) generated

obj2src :: String -> (FilePath -> Bool) -> Context -> FilePath -> Action FilePath
obj2src extension isGenerated context@Context {..} obj
    | isGenerated src = return src
    | otherwise       = (pkgPath package ++) <$> suffix
  where
    src    = obj -<.> extension
    suffix = do
        path <- buildPath context
        return $ fromMaybe ("Cannot determine source for " ++ obj)
               $ stripPrefix (path -/- extension) src