module Examples.Test.Random(main) where

import Development.Shake
import Examples.Util
import Control.Exception
import Control.Monad
import Data.List
import System.Random
import System.Mem


inputRange = [1..10]

data Value = Single Int | Multiple [[Value]]
    deriving (Read,Show,Eq)

data Source = Input Int | Output Int | Bang
    deriving (Read,Show)

data Logic = Logic Int [[Source]]
           | Want [Int]
    deriving (Read,Show)


main = shaken test $ \args obj -> do
    let toFile (Input i) = obj $ "input-" ++ show i ++ ".txt"
        toFile (Output i) = obj $ "output-" ++ show i ++ ".txt"
        toFile Bang = error "BANG"

    let randomSleep = liftIO $ do
            i <- randomRIO (0, 25)
            sleep $ fromInteger i / 100

    forM_ (map read args) $ \x -> case x of
        Want xs -> want $ map (toFile . Output) xs
        Logic out srcs -> toFile (Output out) *> \out -> do
            res <- fmap (show . Multiple) $ forM srcs $ \src -> do
                randomSleep
                need $ map toFile src
                mapM (liftIO . fmap read . readFile . toFile) src
            randomSleep
            writeFileChanged out res


test build obj = forM_ [1..] $ \count -> do
    putStrLn $ "* PERFORMING RANDOM TEST " ++ show count
    performGC -- close any handles left by crashing
    build ["clean"]
    build [] -- to create the directory
    forM inputRange $ \i ->
        writeFile (obj $ "input-" ++ show i ++ ".txt") $ show $ Single i
    logic <- randomLogic
    runLogic [] logic
    chng <- filterM (const randomIO) inputRange   
    forM chng $ \i ->
        writeFile (obj $ "input-" ++ show i ++ ".txt") $ show $ Single $ negate i
    runLogic chng logic
    forM inputRange $ \i ->
        writeFile (obj $ "input-" ++ show i ++ ".txt") $ show $ Single i
    logic <- addBang =<< addBang logic
    j <- randomRIO (1::Int,8)
    res <- try $ build $ ("--threads" ++ show j) : map show (logic ++ [Want [i | Logic i _ <- logic]])    
    case res of
        Left err
            | "BANG" `isInfixOf` show (err :: SomeException) -> return () -- error I expected
            | otherwise -> error $ "UNEXPECTED ERROR: " ++ show err
        _ -> return () -- occasionally we only put BANG in places with no dependenies that don't get rebuilt
    where
        runLogic :: [Int] -> [Logic] -> IO ()
        runLogic negated xs = do
            let poss = [i | Logic i _ <- xs]
            i <- randomRIO (0, 7)
            wants <- replicateM i $ do
                i <- randomRIO (0, 5)
                replicateM i $ randomElem poss
            sleepFileTime
            j <- randomRIO (1::Int,8)
            build $ ("--threads" ++ show j) : map show (xs ++ map Want wants)

            let value i = case [ys | Logic j ys <- xs, j == i] of
                    [ys] -> Multiple $ flip map ys $ map $ \i -> case i of
                        Input i -> Single $ if i `elem` negated then negate i else i
                        Output i -> value i
            forM_ (concat wants) $ \i -> do
                let wanted = value i
                got <- fmap read $ readFile $ obj $ "output-" ++ show i ++ ".txt"
                when (wanted /= got) $
                    error $ "INCORRECT VALUE for " ++ show i


addBang :: [Logic] -> IO [Logic]
addBang xs = do
    i <- randomRIO (0, length xs - 1)
    let (before,now:after) = splitAt i xs
    now <- f now
    return $ before ++ now : after
    where
        f (Logic log xs) = do
            i <- randomRIO (0, length xs)
            let (before,after) = splitAt i xs
            return $ Logic log $ before ++ [Bang] : after


randomLogic :: IO [Logic] -- only Logic constructors
randomLogic = do
    rules <- randomRIO (1,100)
    f rules $ map Input inputRange
    where
        f 0 avail = return []
        f i avail = do
            needs <- randomRIO (0,3)
            xs <- replicateM needs $ do
                ns <- randomRIO (0,3)
                replicateM ns $ randomElem avail
            let r = Logic i xs
            fmap (r:) $ f (i-1) (Output i:avail)


randomElem :: [a] -> IO a
randomElem xs = do
    i <- randomRIO (0, length xs - 1)
    return $ xs !! i