-- |
-- Copyright : © 2009 CNRS - École Polytechnique - INRIA
-- License   : GPL
--
-- The batch driver. It compiles all given targets and all their dependencies,
-- also invoking the Haskell compiler on the generated source code.
module Dedukti.Driver.Batch (make) where

import Dedukti.Driver.Compile
import Dedukti.Analysis.Dependency
import Dedukti.Module
import Dedukti.Parser
import Dedukti.DkM
import qualified Dedukti.Config as Config
import qualified Control.Hmk.IO as IO
import Control.Hmk
import qualified Data.Text.Lazy.Encoding as T
import qualified Data.ByteString.Lazy as B
import qualified Data.Map as Map
import Control.Monad.State
import Control.Applicative
import Data.Typeable (Typeable)
import System.Directory (copyFile)
import Data.Char (toUpper)


cmp x y = do
  s <- io $ IO.isStale x y
  say Debug $ text "Compared" <+> text x <+> text y <> text ":" <+> text (show s)
  return s

-- | Trace a dependency graph in the form of a set of rules, starting from the
-- given root modules. Finding the dependencies of a module requires parsing
-- the corresponding source file. To avoid parsing each file twice, the AST is
-- kept in-memory in case it is needed later during compilation.
rules :: [MName] -> DkM [Rule DkM FilePath]
rules targets = evalStateT (rules' targets) Map.empty

-- Maintain a list of already seen modules to avoid parsing same modules twice
-- when the dependency graph is not a tree.
rules' targets = concat <$> mapM f targets where
    -- Collect dependencies.
    f mod = do
      seen <- get
      case Map.lookup mod seen of
        Just deps -> return deps
        Nothing -> do
          lift $ say Verbose $ text "Parsing" <+> text (show mod) <+> text "..."
          let path = srcPathFromModule mod
          src <- lift (parse path <$> io (liftM T.decodeUtf8 (B.readFile path)))
          let dependencies = collectDependencies src
              rs = g mod dependencies (task_compile mod src)
          -- Recursively construct rules for dependent modules.
          rsdeps <- rules' dependencies
          lift $ say Verbose $ text "Dependencies of" <+> text (show mod) <+> text ":"
                   <+> text (show dependencies)
          put (Map.insert mod (rs ++ rsdeps) seen)
          return $ rs ++ rsdeps
    -- Now that we have the dependencies of the module, we can enounce a few
    -- build rules concerning the module.
    g mod ds compile = let capitalize x = toUpper (head x) : tail x
                           dk  = srcPathFromModule mod
                           dko = objPathFromModule mod
                           dki = ifacePathFromModule mod
                           hi  = pathFromModule ".hi" mod
                           chi = capitalize hi
                           o   = pathFromModule ".o" mod
                           dephis = map (capitalize . pathFromModule ".hi") ds
                       in [ Rule dk [] Nothing cmp
                          , Rule dko [dk] (Just compile) cmp
                          , Rule dki [dk] (Just compile) cmp
                          , Rule hi (dko:dki:dephis) (Just $ task_hscomp dko) cmp
                          , Rule o (dko:dki:dephis) (Just $ task_hscomp dko) cmp
                          , Rule chi [hi] (Just $ task_himv hi chi) cmp ]
    task_hscomp dko _ = do
      hscomp <- parameter Config.hsCompiler
      io . IO.testExitCode =<< command hscomp [ "-c", "-w", "-x", "hs", dko
                                              , "-XOverloadedStrings"
                                              , "-XPatternGuards" ]
    -- GHC won't find the interface files if their names don't start with a
    -- capital letter. So alias the interface file with a capitalized name.
    task_himv hi chi _ = do
      io $ copyFile hi chi
      return TaskSuccess
    task_compile mod src _ = do
      compileAST mod src `onException`
          (say Quiet $ text "In module" <+> pretty mod <> text ":")
      return TaskSuccess

data CommandError = CommandError
    deriving Typeable

instance Show CommandError where
    show CommandError = "Command returned non-zero exit status."

instance Exception CommandError

-- | Perform each system action, aborting if an action returns
-- non-zero exit code.
abortOnError :: [DkM Result] -> DkM ()
abortOnError = mapM_ f where
    f cmd = do code <- cmd
               case code of
                 TaskSuccess -> return ()
                 TaskFailure -> throw CommandError

-- | Compile each of the modules given as input and all of their
-- dependencies, if necessary.
make :: [MName] -> DkM ()
make modules = do
  let targets = map (pathFromModule ".o") modules
  rs <- process cmp <$> rules modules
  schedule <- mk rs targets
  say Debug $ text "Tasks to execute:" <+> int (length schedule)
  abortOnError schedule