module Flavour
  ( Flavour (..), werror
  , DocTargets, DocTarget(..)
  , parseFlavour
    -- * Flavour transformers
  , flavourTransformers
  , addArgs
  , splitSections, splitSectionsIf
  , enableThreadSanitizer
  , enableDebugInfo, enableTickyGhc
  , viaLlvmBackend
  , enableProfiledGhc
  , disableDynamicGhcPrograms
  , disableProfiledLibs

  , completeSetting
  , applySettings
  ) where

import Expression
import Data.Either
import Data.Map (Map)
import qualified Data.Map as M
import Packages
import Flavour.Type
import Settings.Parser

import Text.Parsec.Prim as P
import Text.Parsec.Combinator as P
import Text.Parsec.Char as P
import Control.Monad.Except
import UserSettings


flavourTransformers :: Map String (Flavour -> Flavour)
flavourTransformers = M.fromList
    [ "werror" =: werror
    , "debug_info" =: enableDebugInfo
    , "ticky_ghc" =: enableTickyGhc
    , "split_sections" =: splitSections
    , "thread_sanitizer" =: enableThreadSanitizer
    , "llvm" =: viaLlvmBackend
    , "profiled_ghc" =: enableProfiledGhc
    , "no_dynamic_ghc" =: disableDynamicGhcPrograms
    , "no_profiled_libs" =: disableProfiledLibs
    , "omit_pragmas" =: omitPragmas
    , "ipe" =: enableIPE
    , "fully_static" =: fullyStatic
    ]
  where (=:) = (,)

type Parser = Parsec String ()

parseFlavour :: [Flavour]  -- ^ base flavours
             -> Map String (Flavour -> Flavour) -- ^ modifiers
             -> String
             -> Either String Flavour
parseFlavour baseFlavours transformers str =
    case P.runParser parser () "" str of
      Left perr -> Left $ unlines $
                    [ "error parsing flavour specifier: " ++ show perr
                    , ""
                    , "known flavours:"
                    ] ++
                    [ "  " ++ name f | f <- baseFlavours ] ++
                    [ ""
                    , "known flavour transformers:"
                    ] ++
                    [ "  " ++ nm | nm <- M.keys transformers ]
      Right f -> Right f
  where
    parser :: Parser Flavour
    parser = do
      base <- baseFlavour
      transs <- P.many flavourTrans
      P.eof
      return $ foldr ($) base transs

    baseFlavour :: Parser Flavour
    baseFlavour =
        P.choice [ f <$ P.try (P.string (name f))
                 | f <- reverse (sortOn name baseFlavours)
                 ]      -- needed to parse e.g. "quick-debug" before "quick"

    flavourTrans :: Parser (Flavour -> Flavour)
    flavourTrans = do
        void $ P.char '+'
        P.choice [ trans <$ P.try (P.string nm)
                 | (nm, trans) <- M.toList transformers
                 ]

-- | Add arguments to the 'args' of a 'Flavour'.
addArgs :: Args -> Flavour -> Flavour
addArgs args' fl = fl { args = args fl <> args' }

-- | Turn on -Werror for packages built with the stage1 compiler.
-- It mimics the CI settings so is useful to turn on when developing.
werror :: Flavour -> Flavour
werror = addArgs (builder Ghc ? notStage0 ? arg "-Werror")

-- | Build C and Haskell objects with debugging information.
enableDebugInfo :: Flavour -> Flavour
enableDebugInfo = addArgs $ notStage0 ? mconcat
    [ builder (Ghc CompileHs) ? arg "-g3"
    , builder (Cc CompileC) ? arg "-g3"
    , builder (Cabal Setup) ? arg "--disable-library-stripping"
    , builder (Cabal Setup) ? arg "--disable-executable-stripping"
    ]

-- | Enable the ticky-ticky profiler in stage2 GHC
enableTickyGhc :: Flavour -> Flavour
enableTickyGhc =
    addArgs $ stage1 ? mconcat
      [ builder (Ghc CompileHs) ? ticky
      , builder (Ghc LinkHs) ? ticky
      ]
  where
    ticky = mconcat
      [ arg "-ticky"
      , arg "-ticky-allocd"
      , arg "-ticky-dyn-thunk"
      -- You generally need STG dumps to interpret ticky profiles
      , arg "-ddump-to-file"
      , arg "-ddump-stg-final"
      ]

-- | Transform the input 'Flavour' so as to build with
--   @-split-sections@ whenever appropriate. You can
--   select which package gets built with split sections
--   by passing a suitable predicate. If the predicate holds
--   for a given package, then @split-sections@ is used when
--   building it. If the given flavour doesn't build
--   anything in a @dyn@-enabled way, then 'splitSections' is a no-op.
splitSectionsIf :: (Package -> Bool) -> Flavour -> Flavour
splitSectionsIf pkgPredicate = addArgs $ do
    way <- getWay
    pkg <- getPackage
    (Dynamic `wayUnit` way) ? pkgPredicate pkg ?
        builder (Ghc CompileHs) ? arg "-split-sections"

-- | Like 'splitSectionsIf', but with a fixed predicate: use
--   split sections for all packages but the GHC library.
splitSections :: Flavour -> Flavour
splitSections = splitSectionsIf (/=ghc)
-- Disable section splitting for the GHC library. It takes too long and
-- there is little benefit.

enableThreadSanitizer :: Flavour -> Flavour
enableThreadSanitizer = addArgs $ mconcat
    [ builder (Ghc CompileHs) ? arg "-optc-fsanitize=thread"
    , builder (Ghc CompileCWithGhc) ? (arg "-optc-fsanitize=thread" <> arg "-DTSAN_ENABLED")
    , builder (Ghc LinkHs) ? arg "-optl-fsanitize=thread"
    , builder (Cc  CompileC) ? (arg "-fsanitize=thread" <> arg "-DTSAN_ENABLED")
    , builder (Cabal Flags) ? arg "thread-sanitizer"
    , builder Testsuite ? arg "--config=have_thread_sanitizer=True"
    ]

-- | Use the LLVM backend in stages 1 and later.
viaLlvmBackend :: Flavour -> Flavour
viaLlvmBackend = addArgs $ notStage0 ? builder Ghc ? arg "-fllvm"

-- | Build the GHC executable with profiling enabled. It is also recommended
-- that you use this with @'dynamicGhcPrograms' = False@ since GHC does not
-- support loading of profiled libraries with the dynamically-linker.
enableProfiledGhc :: Flavour -> Flavour
enableProfiledGhc flavour =
    flavour { rtsWays = addWays [profiling, threadedProfiling, debugProfiling, threadedDebugProfiling] (rtsWays flavour)
            , libraryWays = addWays [profiling] (libraryWays flavour)
            , ghcProfiled = True
            }
  where
    addWays :: [Way] -> Ways -> Ways
    addWays ways =
      fmap (++ ways)

-- | Disable 'dynamicGhcPrograms'.
disableDynamicGhcPrograms :: Flavour -> Flavour
disableDynamicGhcPrograms flavour = flavour { dynamicGhcPrograms = pure False }

-- | Don't build libraries in profiled 'Way's.
disableProfiledLibs :: Flavour -> Flavour
disableProfiledLibs flavour =
    flavour { libraryWays = prune $ libraryWays flavour
            , rtsWays     = prune $ rtsWays flavour
            }
  where
    prune :: Ways -> Ways
    prune = fmap $ filter (not . wayUnit Profiling)

-- | Build stage2 compiler with -fomit-interface-pragmas to reduce
-- recompilation.
omitPragmas :: Flavour -> Flavour
omitPragmas =
  let Right kv = parseKV "stage1.ghc.ghc.hs.opts += -fomit-interface-pragmas"
      Right transformer = applySetting kv
  in transformer

-- | Build stage2 dependencies with options to enable IPE debugging
-- information.
enableIPE :: Flavour -> Flavour
enableIPE =
  let Right kv = parseKV "stage1.*.ghc.hs.opts += -finfo-table-map -fdistinct-constructor-tables"
      Right transformer = applySetting kv
  in transformer

-- | Produce fully statically-linked executables and build libraries suitable
-- for static linking.
fullyStatic :: Flavour -> Flavour
fullyStatic flavour =
    addArgs staticExec
    $ flavour { dynamicGhcPrograms = return False
              , libraryWays = prune $ libraryWays flavour
              , rtsWays     = prune $ rtsWays flavour }
  where
    -- Remove any Way that contains a WayUnit of Dynamic
    prune :: Ways -> Ways
    prune = fmap $ filter staticCompatible

    staticCompatible :: Way -> Bool
    staticCompatible = not . wayUnit Dynamic

    staticExec :: Args
    {- Some packages, especially iserv, seem to force a set of build ways,
     - including some that are dynamic (in Rules.BinaryDist).  Trying to
     - build statically and dynamically at the same time breaks the build,
     - so we respect that overriding of the Ways.  Any code that overrides
     - the Ways will need to include a Way that's not explicitly dynamic
     - (like "vanilla").
     -}
    staticExec = staticCompatible <$> getWay ? mconcat
        {-
         - Disable dynamic linking by the built ghc executable because the
         - statically-linked musl doesn't support dynamic linking, but will
         - try and fail.
         -}
        [ package compiler ? builder (Cabal Flags) ? arg "-dynamic-system-linker"
        {-
         - The final executables don't work unless the libraries linked into
         - it are compiled with "-fPIC."  The PI stands for "position
         - independent" and generates libraries that work when inlined into
         - an executable (where their position is not at the beginning of
         - the file).
         -}
        , builder (Ghc CompileHs) ? pure [ "-fPIC", "-static" ]
        , builder (Ghc CompileCWithGhc) ? pure [ "-fPIC", "-optc", "-static"]
        , builder (Ghc LinkHs) ? pure [ "-optl", "-static" ]
        ]


-- * CLI and <root>/hadrian.settings options

{-
Note [Hadrian settings]
~~~~~~~~~~~~~~~~~~~~~~~

Hadrian lets one customize GHC builds through the UserSettings module,
where Hadrian users can override existing 'Flavour's or create entirely
new ones, overriding/extending the options passed to some builder
building the RTS in more ways and much more.

It now also offers a more "old-school" interface, in the form of
@foo.bar.baz = v@ or @foo.bar.baz += v@ expressions, that one can
pass on the command line that invokes hadrian:

> $ hadrian/build --flavour=quickest -j "stage1.ghc-bin.ghc.link.opts += -v3"

or in a file at <build root>/hadrian.settings, where <build root>
is the build root to be used for the build, which is _build by default.
For example, you could create a file at _build/hadrian.settings with the
following contents:

> stage1.ghc-bin.ghc.link.opts += -v3
> stage1.base.ghc.hs.opts += -ddump-timings

and issue:

> $ hadrian/build

Hadrian would pick up the settings given in _build/hadrian.settings (as well as
any settings that you may additionally be passing on the command line) and
update the relevant flavour accordingly, to issue the additional arguments
specified by the user.

The supported settings are described by 'builderSetting' below, using
operations from Applicative + two new primitives, 'matchString' and
'matchOneOf', that come as members of the 'Match' class. This gives us
a simple but powerful vocabulary to describe settings and parse them
into values that we can use to compute interesting things, like a 'Predicate'
that we can use to emit additional arguments, or a list of possible completions.

> fmap, (<$>) :: Functor f => (a -> b) -> f a -> f b
> pure :: Applicative f => a -> f a
> (<*>) :: Applicative f => f (a -> b) -> f a -> f b
> (*>) :: Applicative f => f a -> f b -> f b
> (<*) :: Applicative f => f a -> f b -> f a
> (<$) :: Functor f => a -> f b -> f a
>
> str :: Match f => String -> f ()
> val :: Match f => String -> a -> f a
> oneOf :: Match f => [f a] -> f a
> choose :: Match f => [(String, a)] -> f a
> wild :: Match f => [(String, a)] -> f (Wildcard a)

For instance, to describe possible settings:
  foo.bar.{x, y}
  foo.baz.{a, b}.c

we could write:

> str "foo" *> oneOf [ str "bar" *> choose [ ("x", "x"), ("y", "y") ]
>                    , str "baz" *> choose [ ("a", "ac"), ("b", "bc") <* str "c" ]
>                    ]

'builderSetting' uses these combinators to describe the setting keys that
Hadrian supports. A user-oriented description of this mechanism is available
in hadrian/doc/user-settings.md.

-}

-- | Try to interpret all the 'KeyVal' as flavour updates, keeping
--   a list of errors for the ones which don't match known
--   settings.
applySettings :: [KeyVal] -> ([SettingError], Flavour -> Flavour)
applySettings kvs = case partitionEithers (map applySetting kvs) of
  (errs, fs) -> (errs, foldr (flip (.)) id fs)
  -- we need to compose the reverse way to have the following settings
  --     x  = -b
  --     x += -c
  -- produce the final x = "-b -c" value. With just (.) we would apply
  -- the x = -b assignment last, which would silently drop the -c adddition.
  --
  --     foldr (.) id [f, g, h] = f . g . h
  --        -- first function (f) is applied last, we're applying them in
  --        -- the wrong order!
  --
  --     foldr (flip (.)) id [f, g, h] = h . g . f
  --        -- last function (f) is applied last, as desired


-- | Try to interpret the given 'KeyVal' as a flavour update
--   function, returning an error if it doesn't match a known
--   setting.
applySetting :: KeyVal -> Either SettingError (Flavour -> Flavour)
applySetting (KeyVal ks op v) = case runSettingsM ks builderPredicate of
  Left err -> throwError $
      "error while setting `" ++ intercalate "`." ks ++ ": " ++ err
  Right pred -> Right $ \flav -> flav
    { args = update (args flav) pred }

  where override arguments predicate = do
          holds <- predicate
          if holds then pure (words v) else arguments

        augment arguments predicate =
          mconcat [arguments, predicate ? pure (words v)]

        update
          | op == Equal = override
          | otherwise   = augment

-- | Try to auto-complete the given @Key@ using
--   all known settings, as described by 'builderSetting'.
--
-- > completeSetting ["stage1","base", "ghc"]
-- >   -- returns [ ["stage1","base","ghc","c","opts"]
-- >   --         , ["stage1","base","ghc","hs","opts"]
-- >   --         , ["stage1","base","ghc","link","opts"]
-- >   --         , ["stage1","base","ghc","deps","opts"]
-- >   --         , ["stage1","base","ghc","toolargs","opts"]
-- >   --         ]
completeSetting :: Key -> [Key]
completeSetting ks = map snd (complete ks builderSetting)

-- | Interpret a 'builderSetting' as a 'Predicate' that
--   potentially constrains on the stage, package or
--   (ghc or cc) builder mode.
--
--   For example, @stage1.base.ghc.link.opts@ gets mapped to
--   a predicate that applies @'stage' 'Stage1'@,
--   @'package' 'base'@ and @'builder' ('Ghc' 'LinkHs')@.
builderPredicate :: SettingsM Predicate
builderPredicate = builderSetting <&> (\(wstg, wpkg, builderMode) ->
  wildcard (pure True) stage wstg <&&>
  wildcard (pure True) package wpkg <&&>
    (case builderMode of
       BM_Ghc ghcMode -> wildcard (builder Ghc) (builder . Ghc) ghcMode
       BM_Cc  ccMode  -> wildcard (builder Cc) (builder . Cc) ccMode
       BM_CabalConfigure -> builder (Cabal Setup)
       BM_RunTest     -> builder Testsuite
    )
  )

  where (<&&>) = liftA2 (&&)

-- | Which builder a setting should apply to
data BuilderMode = BM_Ghc (Wildcard GhcMode)
                 | BM_Cc  (Wildcard CcMode)
                 | BM_CabalConfigure
                 | BM_RunTest

-- | Interpretation-agnostic description of the builder settings
--   supported by Hadrian.
--
--   Supported settings (to be kept in sync with the code):
--
--   > (<stage> or *).(<package name> or *).ghc.(<ghc mode> or *).opts
--   > (<stage> or *).(<package name> or *).cc.(<cc mode> or *).opts
--   > (<stage> or *).(<package name> or *).cabal.configure.opts
--   > runtest.opts
--
--   where:
--     - @<stage>@ is one of @stage0@, @stage1@, @stage2@ or @stage3@;
--     - @<package name>@ is the (Cabal) name of a package (@base@,
--       @template-haskell@, ...);
--     - @<ghc mode>@ is one of @c@ (building C files), @hs@ (building Haskell
--       modules), @link@ (linking object files), @deps@ (finding Haskell
--       dependencies with @ghc -M@) or @toolargs@ (getting necessary flags to
--       make hadrian/ghci work;
--     - @<cc mode>@ is one of @c@ (building C files) or @deps@ (finding C
--       dependencies);
--     - locations that support a wildcard (@*@) entry are here to avoid
--       repetition, a wildcard entry being equivalent to writing all the
--       settings that the wildcard matches over; in our case, we can
--       apply GHC or C compiler options uniformly over all stages, packages
--       and compiler modes, if we so desire, by using a wildcard in the
--       appropriate spot.
builderSetting :: Match f
               => f (Wildcard Stage, Wildcard Package, BuilderMode)
builderSetting =
    matchOneOf
    [ (,,)
       <$> wild stages
       <*> wild pkgs
       <*> matchOneOf
             [ str "ghc" *> fmap BM_Ghc (wild ghcBuilder) <* str "opts"
             , str "cc" *> fmap BM_Cc (wild ccBuilder) <* str "opts"
             , BM_CabalConfigure <$ str "cabal" <* str "configure" <* str "opts"
             ]
    , (Wildcard, Wildcard, BM_RunTest)
      <$ str "runtest" <* str "opts"
    ]
  where ghcBuilder =
          [ ("c", CompileCWithGhc)
          , ("cpp", CompileCppWithGhc)
          , ("deps", FindHsDependencies)
          , ("hs", CompileHs)
          , ("link", LinkHs)
          , ("toolargs", ToolArgs)
          ]

        ccBuilder =
          [ ("c", CompileC)
          -- Not sure how to handle the FindCDependencies CxxDep case
          , ("deps", FindCDependencies CDep)
          ]

        stages = map (\stg -> (stageString stg, stg)) [minBound..maxBound]

        pkgs = map (\pkg -> (pkgName pkg, pkg)) (ghcPackages ++ userPackages)