{-# LANGUAGE OverloadedLists #-}

module Test.Database.LSMTree.Internal.RawBytes (tests) where

import           Data.Bits (Bits (shiftL))
import qualified Data.List as List
import qualified Data.Vector.Primitive as VP
import           Database.LSMTree.Extras.Generators ()
import           Database.LSMTree.Internal.RawBytes (RawBytes (RawBytes))
import qualified Database.LSMTree.Internal.RawBytes as RB
import           Test.QuickCheck (Property, classify, collect, mapSize,
                     withDiscardRatio, withMaxSuccess, (.||.), (===), (==>))
import           Test.Tasty (TestTree, testGroup)
import           Test.Tasty.QuickCheck (testProperty)

-- * Tests

tests :: TestTree
tests = testGroup "Test.Database.LSMTree.Internal.RawBytes" $
        [
            testGroup "Eq laws" $
            [
                testProperty "Reflexivity"  prop_eqReflexivity,
                testProperty "Symmetry"     prop_eqSymmetry,
                testProperty "Transitivity" prop_eqTransitivity,
                testProperty "Negation"     prop_eqNegation
            ],
            testGroup "Ord laws" $
            [
                testProperty "Comparability" prop_ordComparability,
                testProperty "Transitivity"  prop_ordTransitivity,
                testProperty "Reflexivity"   prop_ordReflexivity,
                testProperty "Antisymmetry"  prop_ordAntisymmetry
            ],
            testProperty "prop_topBits64" prop_topBits64,
            testProperty "prop_topBits64_default0s" prop_topBits64_default0s
        ]

-- * Utilities

twoBlocksProp :: String -> RawBytes -> RawBytes -> Property -> Property
twoBlocksProp msgAddition block1 block2
    = withMaxSuccess 10000 .
      classify (block1 == block2) ("equal blocks" ++ msgAddition)

withFirstBlockSizeInfo :: RawBytes -> Property -> Property
withFirstBlockSizeInfo firstBlock
    = collect ("Size of first block is " ++ show (RB.size firstBlock))

-- * Properties to test

-- ** 'Eq' laws

prop_eqReflexivity :: RawBytes -> Property
prop_eqReflexivity block = block === block

prop_eqSymmetry :: RawBytes -> RawBytes -> Property
prop_eqSymmetry block1 block2 = twoBlocksProp "" block1 block2 $
                                (block1 == block2) === (block2 == block1)

prop_eqTransitivity :: Property
prop_eqTransitivity = mapSize (const 3)     $
                      withDiscardRatio 1000 $
                      untunedProp
    where

    untunedProp :: RawBytes -> RawBytes -> RawBytes -> Property
    untunedProp block1 block2 block3
        = withFirstBlockSizeInfo block1 $
          block1 == block2 && block2 == block3 ==> block1 === block3

prop_eqNegation :: RawBytes -> RawBytes -> Property
prop_eqNegation block1 block2 = twoBlocksProp "" block1 block2 $
                                (block1 /= block2) === not (block1 == block2)

-- ** 'Ord' laws

prop_ordComparability :: RawBytes -> RawBytes -> Property
prop_ordComparability block1 block2 = twoBlocksProp "" block1 block2 $
                                      block1 <= block2 .||. block2 <= block1

prop_ordTransitivity :: RawBytes -> RawBytes -> RawBytes -> Property
prop_ordTransitivity block1 block2 block3
    = twoBlocksProp " front-side"   block1 block2 $
      twoBlocksProp " rear-side"    block2 block3 $
      twoBlocksProp " at the edges" block1 block3 $
      block1 <= block2 && block2 <= block3 ==> block1 <= block3

prop_ordReflexivity :: RawBytes -> Bool
prop_ordReflexivity block = block <= block

prop_ordAntisymmetry :: Property
prop_ordAntisymmetry = mapSize (const 4)    $
                       withDiscardRatio 100 $
                       untunedProp
    where

    untunedProp :: RawBytes -> RawBytes -> Property
    untunedProp block1 block2
        = withFirstBlockSizeInfo block1 $
          block1 <= block2 && block2 <= block1 ==> block1 === block2

{-------------------------------------------------------------------------------
  Accessors
-------------------------------------------------------------------------------}

-- | Compare 'topBits64' against a model
prop_topBits64 :: RawBytes -> Property
prop_topBits64 x@(RawBytes v) =
    expected === RB.topBits64 x
  where
    expected =
      let ws = take 8 (VP.toList v ++ repeat 0)
      in  List.foldl' (\acc w -> acc `shiftL` 8 + fromIntegral w) 0 ws

-- | If @x@ has fewer than 8 bytes, then all missing bits in the result default
-- to 0s.
prop_topBits64_default0s :: RawBytes -> Property
prop_topBits64_default0s x =
    RB.topBits64 x === RB.topBits64 (x <> mconcat (replicate 8 [0]))