{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE TypeSynonymInstances #-}

-- |
-- Module      : Test.Tasty.DejaFu
-- Copyright   : (c) 2015--2017 Michael Walker
-- License     : MIT
-- Maintainer  : Michael Walker <mike@barrucadu.co.uk>
-- Stability   : stable
-- Portability : FlexibleContexts, FlexibleInstances, GADTs, LambdaCase, TypeSynonymInstances
--
-- This module allows using Deja Fu predicates with Tasty to test the
-- behaviour of concurrent systems.
module Test.Tasty.DejaFu
  ( -- * Unit testing

  -- | This is supported by an 'IsTest' instance for 'ConcIO'.  This
  -- instance tries all executions, reporting as failures the cases
  -- which return a 'Just' string.
  --
  -- @instance IsTest (ConcIO (Maybe String))@
  -- @instance IsOption Bounds@
  -- @instance IsOption MemType@

  -- * Unit testing
    testAuto
  , testDejafu
  , testDejafus

  , testAutoWay
  , testDejafuWay
  , testDejafusWay

  , testDejafuDiscard

  -- ** Re-exports
  , Predicate
  , ProPredicate(..)
  , Way
  , defaultWay
  , systematically
  , randomly
  , uniformly
  , swarmy
  , Bounds(..)
  , defaultBounds
  , MemType(..)
  , defaultMemType
  , Discard(..)
  , defaultDiscarder

  -- * Refinement property testing
  , testProperty
  , testPropertyFor

  -- ** Re-exports
  , R.Sig(..)
  , R.RefinementProperty
  , R.Testable(..)
  , R.Listable(..)
  , R.expectFailure
  , R.refines, (R.=>=)
  , R.strictlyRefines, (R.->-)
  , R.equivalentTo, (R.===)
  ) where

import           Data.Char              (toUpper)
import qualified Data.Foldable          as F
import           Data.List              (intercalate, intersperse)
import           Data.Proxy             (Proxy(..))
import           Data.Tagged            (Tagged(..))
import           Data.Typeable          (Typeable)
import           System.Random          (mkStdGen)
import           Test.DejaFu            hiding (Testable(..))
import qualified Test.DejaFu.Conc       as Conc
import qualified Test.DejaFu.Refinement as R
import qualified Test.DejaFu.SCT        as SCT
import qualified Test.DejaFu.Types      as D
import           Test.Tasty             (TestName, TestTree, testGroup)
import           Test.Tasty.Options     (IsOption(..), OptionDescription(..),
                                         lookupOption)
import           Test.Tasty.Providers   (IsTest(..), singleTest, testFailed,
                                         testPassed)

--------------------------------------------------------------------------------
-- Tasty-style unit testing

-- | @since 0.3.0.0
instance IsTest (Conc.ConcIO (Maybe String)) where
  testOptions = Tagged concOptions

  run options conc callback = do
    let memtype = lookupOption options
    let way     = lookupOption options
    let traces  = SCT.runSCTDiscard (pdiscard assertableP) way memtype conc
    run options (ConcTest traces (peval assertableP)) callback

concOptions :: [OptionDescription]
concOptions =
  [ Option (Proxy :: Proxy MemType)
  , Option (Proxy :: Proxy Way)
  ]

assertableP :: Predicate (Maybe String)
assertableP = alwaysTrue $ \case
  Right (Just _) -> False
  _ -> True

-- | @since 0.3.0.0
instance IsOption MemType where
  defaultValue = defaultMemType
  parseValue = shortName . map toUpper where
    shortName "SC"  = Just SequentialConsistency
    shortName "TSO" = Just TotalStoreOrder
    shortName "PSO" = Just PartialStoreOrder
    shortName _ = Nothing
  optionName = Tagged "memory-model"
  optionHelp = Tagged "The memory model to use. This should be one of \"sc\", \"tso\", or \"pso\"."

-- | @since 0.5.0.0
instance IsOption Way where
  defaultValue = defaultWay
  parseValue = shortName . map toUpper where
    shortName "SYSTEMATICALLY" = Just (systematically defaultBounds)
    shortName "RANDOMLY"       = Just (randomly (mkStdGen 42) 100)
    shortName _ = Nothing
  optionName = Tagged "way"
  optionHelp = Tagged "The execution method to use. This should be one of \"systematically\" or \"randomly\"."


--------------------------------------------------------------------------------
-- DejaFu-style unit testing

-- | Automatically test a computation. In particular, look for
-- deadlocks, uncaught exceptions, and multiple return values.
--
-- @since 1.0.0.0
testAuto :: (Eq a, Show a)
  => Conc.ConcIO a
  -- ^ The computation to test.
  -> TestTree
testAuto = testAutoWay defaultWay defaultMemType

-- | Variant of 'testAuto' which tests a computation under a given
-- execution way and memory model.
--
-- @since 1.0.0.0
testAutoWay :: (Eq a, Show a)
  => Way
  -- ^ How to execute the concurrent program.
  -> MemType
  -- ^ The memory model to use for non-synchronised @CRef@ operations.
  -> Conc.ConcIO a
  -- ^ The computation to test.
  -> TestTree
testAutoWay way memtype = testDejafusWay way memtype autocheckCases

-- | Predicates for the various autocheck functions.
autocheckCases :: Eq a => [(TestName, Predicate a)]
autocheckCases =
  [("Never Deadlocks", representative deadlocksNever)
  , ("No Exceptions", representative exceptionsNever)
  , ("Consistent Result", alwaysSame)
  ]

-- | Check that a predicate holds.
--
-- @since 1.0.0.0
testDejafu :: Show b
  => TestName
  -- ^ The name of the test.
  -> ProPredicate a b
  -- ^ The predicate to check.
  -> Conc.ConcIO a
  -- ^ The computation to test.
  -> TestTree
testDejafu = testDejafuWay defaultWay defaultMemType

-- | Variant of 'testDejafu' which takes a way to execute the program
-- and a memory model.
--
-- @since 1.0.0.0
testDejafuWay :: Show b
  => Way
  -- ^ How to execute the concurrent program.
  -> MemType
  -- ^ The memory model to use for non-synchronised @CRef@ operations.
  -> TestName
  -- ^ The name of the test.
  -> ProPredicate a b
  -- ^ The predicate to check.
  -> Conc.ConcIO a
  -- ^ The computation to test.
  -> TestTree
testDejafuWay = testDejafuDiscard (const Nothing)

-- | Variant of 'testDejafuWay' which can selectively discard results.
--
-- @since 1.0.0.0
testDejafuDiscard :: Show b
  => (Either Failure a -> Maybe Discard)
  -- ^ Selectively discard results.
  -> Way
  -- ^ How to execute the concurrent program.
  -> MemType
  -- ^ The memory model to use for non-synchronised @CRef@ operations.
  -> String
  -- ^ The name of the test.
  -> ProPredicate a b
  -- ^ The predicate to check.
  -> Conc.ConcIO a
  -- ^ The computation to test.
  -> TestTree
testDejafuDiscard discard way memtype name test =
  testconc discard way memtype [(name, test)]

-- | Variant of 'testDejafu' which takes a collection of predicates to
-- test. This will share work between the predicates, rather than
-- running the concurrent computation many times for each predicate.
--
-- @since 1.0.0.0
testDejafus :: Show b
  => [(TestName, ProPredicate a b)]
  -- ^ The list of predicates (with names) to check.
  -> Conc.ConcIO a
  -- ^ The computation to test.
  -> TestTree
testDejafus = testDejafusWay defaultWay defaultMemType

-- | Variant of 'testDejafus' which takes a way to execute the program
-- and a memory model.
--
-- @since 1.0.0.0
testDejafusWay :: Show b
  => Way
  -- ^ How to execute the concurrent program.
  -> MemType
  -- ^ The memory model to use for non-synchronised @CRef@ operations.
  -> [(TestName, ProPredicate a b)]
  -- ^ The list of predicates (with names) to check.
  -> Conc.ConcIO a
  -- ^ The computation to test.
  -> TestTree
testDejafusWay = testconc (const Nothing)


-------------------------------------------------------------------------------
-- Refinement property testing

-- | Check a refinement property with a variety of seed values and
-- variable assignments.
--
-- @since 0.6.0.0
testProperty :: (R.Testable p, R.Listable (R.X p), Eq (R.X p), Show (R.X p), Show (R.O p))
  => TestName
  -- ^ The name of the test.
  -> p
  -- ^ The property to check.
  -> TestTree
testProperty = testPropertyFor 10 100

-- | Like 'testProperty', but takes a number of cases to check.
--
-- The maximum number of cases tried by @testPropertyFor n m@ will be
-- @n * m@.
--
-- @since 0.7.1.0
testPropertyFor :: (R.Testable p, R.Listable (R.X p), Eq (R.X p), Show (R.X p), Show (R.O p))
  => Int
  -- ^ The number of seed values to try.
  -> Int
  -- ^ The number of variable assignments per seed value to try.
  -> TestName
  -- ^ The name of the test.
  -> p
  -- ^ The property to check.
  -> TestTree
testPropertyFor = testprop


--------------------------------------------------------------------------------
-- Tasty integration

data ConcTest where
  ConcTest :: Show b => IO [(Either Failure a, Conc.Trace)] -> ([(Either Failure a, Conc.Trace)] -> Result b) -> ConcTest
  deriving Typeable

data PropTest where
  PropTest :: (R.Testable p, R.Listable (R.X p), Eq (R.X p), Show (R.X p), Show (R.O p)) => Int -> Int -> p -> PropTest
  deriving Typeable

instance IsTest ConcTest where
  testOptions = pure []

  run _ (ConcTest iotraces p) _ = do
    traces <- iotraces
    let err = showErr $ p traces
    pure (if null err then testPassed "" else testFailed err)

instance IsTest PropTest where
  testOptions = pure []

  run _ (PropTest sn vn p) _ = do
    ce <- R.checkFor sn vn p
    pure $ case ce of
      Just c -> testFailed . init $ unlines
        [ "*** Failure: " ++
          (if null (R.failingArgs c) then "" else unwords (R.failingArgs c) ++ " ") ++
          "(seed " ++ show (R.failingSeed c) ++ ")"
        , "    left:  " ++ show (F.toList $ R.leftResults  c)
        , "    right: " ++ show (F.toList $ R.rightResults c)
        ]
      Nothing -> testPassed ""

-- | Produce a Tasty 'Test' from a Deja Fu unit test.
testconc :: Show b
  => (Either Failure a -> Maybe Discard)
  -> Way
  -> MemType
  -> [(TestName, ProPredicate a b)]
  -> Conc.ConcIO a
  -> TestTree
testconc discard way memtype tests concio = case map toTest tests of
  [t] -> t
  ts  -> testGroup "Deja Fu Tests" ts

  where
    toTest (name, p) =
      let discarder = D.strengthenDiscard discard (pdiscard p)
          traces    = SCT.runSCTDiscard discarder way memtype concio
      in singleTest name $ ConcTest traces (peval p)

-- | Produce a Tasty 'TestTree' from a Deja Fu refinement property test.
testprop :: (R.Testable p, R.Listable (R.X p), Eq (R.X p), Show (R.X p), Show (R.O p))
  => Int -> Int -> TestName -> p -> TestTree
testprop sn vn name = singleTest name . PropTest sn vn

-- | Convert a test result into an error message on failure (empty
-- string on success).
showErr :: Show a => Result a -> String
showErr res
  | _pass res = ""
  | otherwise = "Failed:\n" ++ msg ++ unlines failures ++ rest where

  msg = if null (_failureMsg res) then "" else _failureMsg res ++ "\n"

  failures = intersperse "" . map (\(r, t) -> indent $ either Conc.showFail show r ++ " " ++ Conc.showTrace t) . take 5 $ _failures res

  rest = if moreThan (_failures res) 5 then "\n\t..." else ""

-- | Check if a list has more than some number of elements.
moreThan :: [a] -> Int -> Bool
moreThan [] n = n < 0
moreThan _ 0  = True
moreThan (_:xs) n = moreThan xs (n-1)

-- | Indent every line of a string.
indent :: String -> String
indent = intercalate "\n" . map ('\t':) . lines