{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
{-# LANGUAGE TemplateHaskell #-}

module Prednote.Core.Properties where

import Prednote.Core.Instances ()
import Prednote.Core
import Test.QuickCheck.Function
import Prelude hiding (not, any, all)
import qualified Prelude
import Test.Tasty
import Test.Tasty.QuickCheck
import Test.Tasty.TH

tests :: TestTree
tests = $(testGroupGenerator)

testInt :: Pred Int -> Int -> Bool
testInt = test

prop_andIsLazyInSecondArgument i
  = testInt (false &&& undefined) i || True

prop_orIsLazyInSecondArgument i
  = testInt (true ||| undefined) i || True

fst3 :: (a, b, c) -> a
fst3 (a, _, _) = a

prop_andIsLikePreludeAnd (Fun _ f1) (Fun _ f2) i
  = testInt (p1 &&& p2) i == (fst3 (f1 i) && fst3 (f2 i))
  where
    p1 = predicate f1
    p2 = predicate f2

prop_orIsLikePreludeOr (Fun _ f1) (Fun _ f2) i
  = testInt (p1 ||| p2) i == (fst3 (f1 i) || fst3 (f2 i))
  where
    p1 = predicate f1
    p2 = predicate f2

prop_notIsLikePreludeNot (Fun _ f1) i
  = testInt (not p1) i == Prelude.not (fst3 (f1 i))
  where
    p1 = predicate f1

prop_switchIsLazyInFirstArgument pb i
  = test (switch undefined pb) (Right i) || True
  where
    _types = pb :: Pred Int
    
prop_switchIsLazyInSecondArgument pa i
  = test (switch pa undefined) (Left i) || True
  where
    _types = pa :: Pred Int

prop_switch (Fun _ fa) (Fun _ fb) ei
  = test (switch pa pb) ei == expected
  where
    _types = ei :: Either Int Char
    expected = case ei of
      Left i -> fst3 (fa i)
      Right c -> fst3 (fb c)
    pa = predicate fa
    pb = predicate fb
    
prop_true = testInt true

prop_false = Prelude.not . testInt false

prop_same b = test same b == b

prop_any (Fun _ f) ls
  = test (any pa) ls == Prelude.any (fmap fst3 f) ls
  where
    pa = predicate f
    _types = ls :: [Int]
    
prop_all (Fun _ f) ls
  = test (all pa) ls == Prelude.all (fmap fst3 f) ls
  where
    pa = predicate f
    _types = ls :: [Int]