module Main where

import Control.Applicative
import Control.Concurrent
import Control.Concurrent.STM
import Control.Monad
import Control.Monad.Except
import Control.Monad.Reader
import Control.Monad.State

import Data.List
import Data.Maybe
import Data.Scientific
import Data.Text (Text)
import qualified Data.Text as T
import qualified Data.Text.IO as T

import Text.Read (readMaybe)
import Text.Regex.TDFA
import Text.Regex.TDFA.Text

import System.Console.GetOpt
import System.Directory
import System.Environment
import System.Exit
import System.FilePath
import System.IO
import System.IO.Error
import System.Posix.Process
import System.Posix.Signals
import System.Process

import GDB
import Output
import Parser
import Process
import Test

data Network = Network
    { netNodes :: MVar [Node]
    , netProcesses :: MVar [Process]
    , netDir :: FilePath
    }

data Node = Node
    { nodeName :: NodeName
    , nodeNetwork :: Network
    , nodeDir :: FilePath
    }

data Options = Options
    { optDefaultTool :: String
    , optProcTools :: [(ProcName, String)]
    , optVerbose :: Bool
    , optTimeout :: Scientific
    , optGDB :: Bool
    }

defaultOptions :: Options
defaultOptions = Options
    { optDefaultTool = ""
    , optProcTools = []
    , optVerbose = False
    , optTimeout = 1
    , optGDB = False
    }

testDir :: FilePath
testDir = "./.test"


data TestEnv = TestEnv
    { teOutput :: Output
    , teFailed :: TVar Bool
    , teOptions :: Options
    }

data TestState = TestState
    { tsVars :: [(VarName, Text)]
    }

newtype TestRun a = TestRun { fromTestRun :: ReaderT TestEnv (StateT TestState (ExceptT () IO)) a }
    deriving (Functor, Applicative, Monad, MonadReader TestEnv, MonadState TestState, MonadIO)

instance MonadFail TestRun where
    fail str = do
        outLine OutputError Nothing $ T.pack str
        throwError ()

instance MonadError () TestRun where
    throwError () = do
        failedVar <- asks teFailed
        liftIO $ atomically $ writeTVar failedVar True
        TestRun $ throwError ()

    catchError (TestRun act) handler = TestRun $ catchError act $ fromTestRun . handler

instance MonadEval TestRun where
    lookupStringVar name = maybe (fail $ "variable not in scope: '" ++ unpackVarName name ++ "'") return =<< gets (lookup name . tsVars)

instance MonadOutput TestRun where
    getOutput = asks teOutput

forkTest :: TestRun () -> TestRun ()
forkTest act = do
    tenv <- ask
    tstate <- get
    void $ liftIO $ forkIO $ do
        runExceptT (flip evalStateT tstate $ flip runReaderT tenv $ fromTestRun act) >>= \case
            Left () -> atomically $ writeTVar (teFailed tenv) True
            Right () -> return ()

atomicallyTest :: STM a -> TestRun a
atomicallyTest act = do
    failedVar <- asks teFailed
    res <- liftIO $ atomically $ do
        failed <- readTVar failedVar
        if failed then return $ Left ()
                  else Right <$> act
    case res of
        Left e -> throwError e
        Right x -> return x

initNetwork :: TestRun Network
initNetwork = do
    net <- liftIO $ do
        exists <- doesPathExist testDir
        when exists $ ioError $ userError $ testDir ++ " exists"
        createDirectoryIfMissing True testDir

        callCommand "ip link add name br0 group 1 type bridge"
        callCommand "ip addr add 192.168.0.1/24 broadcast 192.168.0.255 dev br0"
        callCommand "ip link set dev br0 up"
        callCommand "ip link set dev lo up"
        Network <$> newMVar [] <*> newMVar [] <*> pure testDir

    void $ spawnOn (Left net) (ProcNameTcpdump) (Just softwareTermination) $
        "tcpdump -i br0 -w '" ++ testDir ++ "/br0.pcap' -U -Z root"

    useGDB <- asks $ optGDB . teOptions
    when useGDB $ do
        gdbInit =<< spawnOn (Left net) ProcNameGDB Nothing gdbCmd

    return net

exitNetwork :: Network -> TestRun ()
exitNetwork net = do
    processes <- liftIO $ readMVar (netProcesses net)
    liftIO $ forM_ processes $ \p -> do
        when (procName p /= ProcNameGDB) $ do
            hClose (procStdin p)
        case procKillWith p of
             Nothing -> return ()
             Just sig -> getPid (procHandle p) >>= \case
                Nothing -> return ()
                Just pid -> signalProcess sig pid

    forM_ processes $ \p -> do
        when (procName p == ProcNameGDB) $ do
            outPrompt $ T.pack "gdb> "
            gdbSession p
            outClearPrompt
            liftIO $ hClose (procStdin p)

    forM_ processes $ \p -> do
        liftIO (waitForProcess (procHandle p)) >>= \case
            ExitSuccess -> return ()
            ExitFailure code -> do
                outLine OutputChildFail (Just $ procName p) $ T.pack $ "exit code: " ++ show code
                liftIO . atomically . flip writeTVar False =<< asks teFailed

    liftIO $ do
        callCommand $ "ip -all netns del"
        callCommand $ "ip link del group 1"

    failed <- liftIO . atomically . readTVar =<< asks teFailed
    liftIO $ if failed then exitFailure
                       else removeDirectoryRecursive $ netDir net

getNode :: Network -> NodeName -> TestRun Node
getNode net nname@(NodeName tnname) = (find ((nname==).nodeName) <$> liftIO (readMVar (netNodes net))) >>= \case
    Just node -> return node
    _ -> do
        let name = T.unpack tnname
            dir = netDir net </> ("erebos_" ++ name)
            node = Node { nodeName = nname
                        , nodeNetwork = net
                        , nodeDir = dir
                        }

        ip <- liftIO $ do
            exists <- doesPathExist dir
            when exists $ ioError $ userError $ dir ++ " exists"
            createDirectoryIfMissing True dir

            modifyMVar (netNodes net) $ \nodes -> do
                let ip = "192.168.0." ++ show (11 + length nodes)
                callCommand $ "ip netns add \""++ name ++ "\""
                callCommand $ "ip link add \"veth_" ++ name ++ ".0\" group 1 type veth peer name \"veth_" ++ name ++ ".1\" netns \"" ++ name ++ "\""
                callCommand $ "ip link set dev \"veth_" ++ name ++ ".0\" master br0 up"
                callOn node $ "ip addr add " ++ ip ++ "/24 broadcast 192.168.0.255 dev \"veth_" ++ name ++ ".1\""
                callOn node $ "ip link set dev \"veth_" ++ name++ ".1\" up"
                callOn node $ "ip link set dev lo up"
                return $ (node : nodes, ip)

        modify $ \s -> s { tsVars = (VarName [tnname, T.pack "ip"], T.pack ip) : tsVars s }
        return node

callOn :: Node -> String -> IO ()
callOn node cmd = callCommand $ "ip netns exec \"" ++ unpackNodeName (nodeName node) ++ "\" " ++ cmd

spawnOn :: Either Network Node -> ProcName -> Maybe Signal -> String -> TestRun Process
spawnOn target pname killWith cmd = do
    let prefix = either (const "") (\node -> "ip netns exec \"" ++ unpackNodeName (nodeName node) ++ "\" ") target
    (Just hin, Just hout, Just herr, handle) <- liftIO $ createProcess (shell $ prefix ++ cmd)
        { std_in = CreatePipe, std_out = CreatePipe, std_err = CreatePipe
        , env = Just [("EREBOS_DIR", either netDir nodeDir target)]
        }
    pout <- liftIO $ newTVarIO []

    let readingLoop :: Handle -> (Text -> TestRun ()) -> TestRun ()
        readingLoop h act =
            liftIO (tryIOError (T.hGetLine h)) >>= \case
                Left err
                    | isEOFError err -> return ()
                    | otherwise -> outLine OutputChildFail (Just pname) $ T.pack $ "IO error: " ++ show err
                Right line -> do
                    act line
                    readingLoop h act

    forkTest $ readingLoop hout $ \line -> do
        outLine OutputChildStdout (Just pname) line
        liftIO $ atomically $ modifyTVar pout (++[line])
    forkTest $ readingLoop herr $ \line -> do
        case pname of
             ProcNameTcpdump -> return ()
             _ -> outLine OutputChildStderr (Just pname) line

    let process = Process
            { procName = pname
            , procHandle = handle
            , procStdin = hin
            , procOutput = pout
            , procKillWith = killWith
            }

    let net = either id nodeNetwork target
    when (pname /= ProcNameGDB) $ liftIO $ do
        getPid handle >>= \case
            Just pid -> void $ do
                ps <- readMVar (netProcesses net)
                forM_ ps $ \gdb -> do
                    when (procName gdb == ProcNameGDB) $ do
                        addInferior gdb (length ps) pid
            Nothing -> return ()

    liftIO $ modifyMVar_ (netProcesses net) $ return . (process:)
    return process

getProcess :: Network -> ProcName -> TestRun Process
getProcess net pname = liftIO $ do
    Just p <- find ((pname==).procName) <$> readMVar (netProcesses net)
    return p

tryMatch :: Regex -> [Text] -> Maybe ((Text, [Text]), [Text])
tryMatch re (x:xs) | Right (Just (_, _, _, capture)) <- regexec re x = Just ((x, capture), xs)
                   | otherwise = fmap (x:) <$> tryMatch re xs
tryMatch _ [] = Nothing

expect :: SourceLine -> Process -> Expr Regex -> [VarName] -> TestRun ()
expect (SourceLine sline) p expr vars = do
    re <- eval expr
    timeout <- asks $ optTimeout . teOptions
    delay <- liftIO $ registerDelay $ ceiling $ 1000000 * timeout
    mbmatch <- atomicallyTest $ (Nothing <$ (check =<< readTVar delay)) <|> do
        line <- readTVar (procOutput p)
        case tryMatch re line of
             Nothing -> retry
             Just (m, out') -> do
                 writeTVar (procOutput p) out'
                 return $ Just m
    case mbmatch of
         Just (line, capture) -> do
             when (length vars /= length capture) $ do
                 outLine OutputMatchFail (Just $ procName p) $ T.pack "mismatched number of capture variables on " `T.append` sline
                 throwError ()

             forM_ vars $ \name -> do
                 cur <- gets (lookup name . tsVars)
                 when (isJust cur) $ do
                     outLine OutputError (Just $ procName p) $ T.pack "variable '" `T.append` textVarName name `T.append` T.pack "' already exists on " `T.append` sline
                     throwError ()

             modify $ \s -> s { tsVars = zip vars capture ++ tsVars s }
             outLine OutputMatch (Just $ procName p) line
         Nothing -> do
             outLine OutputMatchFail (Just $ procName p) $ T.pack "expect failed on " `T.append` sline
             exprVars <- gatherVars expr
             forM_ exprVars $ \(name, value) ->
                 outLine OutputMatchFail (Just $ procName p) $ T.concat [T.pack "  ", textVarName name, T.pack " = ", T.pack (show value)]
             throwError ()

testStepGuard :: SourceLine -> Expr Bool -> TestRun ()
testStepGuard (SourceLine sline) expr = do
    x <- eval expr
    when (not x) $ do
         outLine OutputMatchFail Nothing $ T.pack "guard failed on " `T.append` sline
         throwError ()

allM :: Monad m => [a] -> (a -> m Bool) -> m Bool
allM (x:xs) p = p x >>= \case True -> allM xs p; False -> return False
allM [] _ = return True

runTest :: Output -> Options -> Test -> IO Bool
runTest out opts test = do
    tenv <- TestEnv
        <$> pure out
        <*> newTVarIO False
        <*> pure opts
    tstate <- TestState
        <$> pure []
    (fmap $ either (const False) id) $ runExceptT $ flip evalStateT tstate $ flip runReaderT tenv $ fromTestRun $ do
        net <- initNetwork

        let sigHandler SignalInfo { siginfoSpecific = chld } = do
                processes <- readMVar (netProcesses net)
                forM_ processes $ \p -> do
                    mbpid <- getPid (procHandle p)
                    when (mbpid == Just (siginfoPid chld)) $ flip runReaderT out $ do
                        let err detail = outLine OutputChildFail (Just $ procName p) detail
                        case siginfoStatus chld of
                             Exited ExitSuccess -> outLine OutputChildInfo (Just $ procName p) $ T.pack $ "child exited successfully"
                             Exited (ExitFailure code) -> err $ T.pack $ "child process exited with status " ++ show code
                             Terminated sig _ -> err $ T.pack $ "child terminated with signal " ++ show sig
                             Stopped sig -> err $ T.pack $ "child stopped with signal " ++ show sig
        oldHandler <- liftIO $ installHandler processStatusChanged (CatchInfo sigHandler) Nothing

        flip catchError (const $ return ()) $ forM_ (testSteps test) $ \case
            Let (SourceLine sline) name expr -> do
                 cur <- gets (lookup name . tsVars)
                 when (isJust cur) $ do
                     outLine OutputError Nothing $ T.pack "variable '" `T.append` textVarName name `T.append` T.pack "' already exists on " `T.append` sline
                     throwError ()
                 value <- eval expr
                 modify $ \s -> s { tsVars = (name, value) : tsVars s }

            Spawn pname nname -> do
                node <- getNode net nname
                void $ spawnOn (Right node) pname Nothing $
                    fromMaybe (optDefaultTool opts) (lookup pname $ optProcTools opts)

            Send pname expr -> do
                p <- getProcess net pname
                line <- eval expr
                send p line

            Expect line pname expr captures -> do
                p <- getProcess net pname
                expect line p expr captures

            Guard line expr -> do
                testStepGuard line expr

            Wait -> do
                outPrompt $ T.pack "Waiting..."
                void $ liftIO $ getLine
                outClearPrompt

        _ <- liftIO $ installHandler processStatusChanged oldHandler Nothing
        exitNetwork net

        atomicallyTest $ return True


options :: [OptDescr (Options -> Options)]
options =
    [ Option ['T'] ["tool"]
        (ReqArg (\str opts -> case break (==':') str of
                                   (path, []) -> opts { optDefaultTool = path }
                                   (pname, (_:path)) -> opts { optProcTools = (ProcName (T.pack pname), path) : optProcTools opts }
                ) "PATH")
        "test tool to be used"
    , Option ['v'] ["verbose"]
        (NoArg (\opts -> opts { optVerbose = True }))
        "show output of processes and successful tests"
    , Option ['t'] ["timeout"]
        (ReqArg (\str opts -> case readMaybe str of
                                   Just timeout -> opts { optTimeout = timeout }
                                   Nothing -> error "timeout must be a number") "SECONDS")
        "default timeout in seconds with microsecond precision"
    , Option ['g'] ["gdb"]
        (NoArg (\opts -> opts { optGDB = True }))
        "run GDB and attach spawned processes"
    ]

main :: IO ()
main = do
    envtool <- fromMaybe (error "No test tool defined") <$> lookupEnv "EREBOS_TEST_TOOL"
    args <- getArgs
    (opts, files) <- case getOpt Permute options args of
        (o, files, []) -> return (foldl (flip id) defaultOptions { optDefaultTool = envtool } o, files)
        (_, _, errs) -> ioError (userError (concat errs ++ usageInfo header options))
            where header = "Usage: erebos-tester [OPTION...]"

    optDefaultTool opts `seq` return ()

    out <- startOutput $ optVerbose opts
    forM_ files $ mapM_ (runTest out opts) <=< parseTestFile