--
-- Copyright (c) 2004 Don Stewart - http://www.cse.unsw.edu.au/~dons
-- GPL version 2 or later (see http://www.gnu.org/copyleft/gpl.html)
--

--
-- | Runplugs: use hs-plugins to run a Haskell expression under
-- controlled conditions.
--
import System.Eval.Haskell      (unsafeEval_)

import Data.Char                (chr)
import Data.Maybe               (isJust, fromJust)
import Control.Monad

import System.Random
import System.Exit              (exitWith, ExitCode(ExitSuccess))
import System.IO                (getContents, putStrLn)
import System.Posix.Resource    (setResourceLimit,
                                 Resource(ResourceCPUTime),
                                 ResourceLimits(ResourceLimits),
                                 ResourceLimit(ResourceLimit))

import qualified Control.Exception

rlimit = ResourceLimit 3

context = prelude ++ prehier ++ datas ++ qualifieds ++ controls ++ other ++ template ++ extras

prelude = ["qualified Prelude as P", "Prelude"]

other = ["Text.Printf"]

prehier = ["Char", "List", "Maybe", "Numeric", "Random" ]

qualifieds = ["qualified Data.Map as M"
             ,"qualified Data.Set as S"
             ,"qualified Data.IntSet as I"]

datas   = map ("Data." ++) [
                "Array", "Complex",
                "Bits", "Bool", "Char", "Dynamic", "Either", 
                "Graph", "Int", "Ix", "List",
                "Maybe", "Ratio", "Tree", "Tuple", "Typeable", "Word" 
              ]

controls = map ("Control." ++) ["Monad", "Monad.Cont", "Monad.State", "Monad.Reader", "Monad.Fix", "Arrow"]

--
-- See if TH is safe with runIO and friends hidden.
--
-- Be very careful here. The semantics of what is safe and unsafe is a
-- bit blurry. It depends on what GHC allows.
--
template = ["Language.Haskell.TH hiding (runIO,reify)"]
extras   = ["ShowQ"] -- a show instance for (Q a)

main = do
    setResourceLimit ResourceCPUTime (ResourceLimits rlimit rlimit)
    s <- getLine
    when (not . null $ s) $ do
        x <- sequence (take 3 (repeat $ getStdRandom (randomR (97,122)) >>= return . chr))
        s <- unsafeEval_ ("let { "++x++
                         " = \n# 1 \"<irc>\"\n"++s++
                         "\n} in P.take 2048 (P.show "++x++
                         ")") context ["-fth"] [] []
        case s of
            Left  e -> mapM_ putStrLn e
            Right v -> Control.Exception.catch
                (putStrLn v)
                (\e -> Control.Exception.handle (const $ putStrLn "Exception") $ do
                            e' <- Control.Exception.evaluate e
                            putStrLn $ "Exception: " ++ show e')
    exitWith ExitSuccess