{-# LANGUAGE TemplateHaskell, MultiParamTypeClasses, PatternGuards #-}
-- Copyright (c) 6 DonStewart - http://www.cse.unsw.edu.au/~dons
-- GPL version 2 or later (see http://www.gnu.org/copyleft/gpl.html)

-- | Test a property with QuickCheck
module Plugin.Check where

import File (findFile)
import Plugin
import Lambdabot.Parser

import qualified Text.Regex as R
import Codec.Binary.UTF8.String (decodeString)

$(plugin "Check")

instance Module CheckModule () where
    moduleCmds   _     = ["check"]
    moduleHelp _ _     = "check <expr>\nYou have QuickCheck and 3 seconds. Prove something."
    process _ _ to _ s = ios80 to (check s)

binary :: String
binary = "mueval"

check :: String -> IO String
check src = do
    -- first, verify the source is actually a Haskell 98 expression, to
    -- avoid code injection bugs.
    case parseExpr (decodeString src) of
        Left  e -> return e
        Right _ -> do
            l <- findFile "L.hs"
            (out,err,_) <- popen binary ["--loadfile=", l, "-E", "-e", "myquickcheck $ " ++ src] Nothing
            case (out,err) of
                ([],[]) -> return "Terminated\n"
                _       -> do
                    let o = munge out
                        e = munge err
                    return $ case () of {_
                        | null o && null e -> "Terminated\n"
                        | null o           -> " " ++ e
                        | otherwise        -> " " ++ o
                    }

munge :: String -> String
munge = expandTab . dropWhile (=='\n') . dropNL . clean_

-- Clean up check's output
clean_ :: String -> String
clean_ s|  no_io      `matches'`    s = "No IO allowed\n"
        |  terminated `matches'`    s = "Terminated\n"
        |  hput       `matches'`    s = "Terminated\n"
        |  stack_o_f  `matches'`    s = "Stack overflow\n"
        |  loop       `matches'`    s = "Loop\n"
        |  undef      `matches'`    s = "Undefined\n"
        |  type_sig   `matches'`    s = "Add a type signature\n"

        | Just (_,m,_,_) <- ambiguous  `R.matchRegexAll` s = m
        | Just (_,_,b,_) <- inaninst   `R.matchRegexAll` s = clean_ b
        | Just (_,_,b,_) <- irc        `R.matchRegexAll` s = clean_ b
        | Just (_,m,_,_) <- nomatch    `R.matchRegexAll` s = m
        | Just (_,m,_,_) <- notinscope `R.matchRegexAll` s = m
        | Just (_,m,_,_) <- hsplugins  `R.matchRegexAll`  s = m
        | Just (a,_,_,_) <- columnnum  `R.matchRegexAll`  s = a
        | Just (a,_,_,_) <- extraargs  `R.matchRegexAll`  s = a
        | Just (_,_,b,_) <- filename'  `R.matchRegexAll`  s = clean_ b
        | Just (a,_,b,_) <- filename   `R.matchRegexAll`  s = a ++ clean_ b
        | Just (a,_,b,_) <- filepath   `R.matchRegexAll`   s = a ++ clean_ b
        | Just (a,_,b,_) <- runplugs   `R.matchRegexAll`  s = a ++ clean_ b
        | otherwise      = s
    where
        -- s/<[^>]*>:[^:]: //
        type_sig   = regex' "add a type signature that fixes these type"
        no_io      = regex' "No instance for \\(Show \\(IO"
        terminated = regex' "waitForProc"
        stack_o_f  = regex' "Stack space overflow"
        loop       = regex' "runplugs: <<loop>>"
        irc        = regex' "\n*<irc>:[^:]*:[^:]*:\n*"
        filename   = regex' "\n*<[^>]*>:[^:]*:\\?[^:]*:\\?\n* *"
        filename'  = regex' "/tmp/.*\\.hs[^\n]*\n"
        filepath   = regex' "\n*/[^\\.]*.hs:[^:]*:\n* *"
        undef      = regex' "Prelude.undefined"
        ambiguous  = regex' "Ambiguous type variable `a\' in the constraints"
        runplugs   = regex' "runplugs: "
        notinscope = regex' "Variable not in scope:[^\n]*"
        hsplugins  = regex' "Compiled, but didn't create object"
        extraargs  = regex' "[ \t\n]*In the [^ ]* argument"
        columnnum  = regex' " at <[^\\.]*\\.[^\\.]*>:[^ ]*"
        nomatch    = regex' "Couldn't match[^\n]*\n"
        inaninst   = regex' "^[ \t]*In a.*$"
        hput       = regex' "<stdout>: hPutStr"