{-# LANGUAGE TypeApplications #-}

module Main where

import Data.Word.Zigzag

import Numeric.Natural (Natural)
import Test.Tasty (TestTree,defaultMain,testGroup)
import Test.Tasty.HUnit (testCase,(@=?))
import Test.Tasty.QuickCheck (Arbitrary(..),suchThat)
import Test.Tasty.QuickCheck (testProperty,(===))


main :: IO ()
main = defaultMain tests

tests :: TestTree
tests = testGroup "zigzag"
  [ testGroup "inverses"
    [ testProperty "to-from-bigint" $ \i ->
      (fromZigzag . toZigzag) i === i
    , testProperty "from-to-bigint" $ \i ->
      (toZigzag . fromZigzag) i === i
    , testProperty "to-from-int" $ \i ->
      (fromZigzagNative . toZigzagNative) i === i
    , testProperty "from-to-int" $ \i ->
      (toZigzagNative . fromZigzagNative) i === i
    , testProperty "to-from-i32" $ \i ->
      (fromZigzag32 . toZigzag32) i === i
    , testProperty "from-to-i32" $ \i ->
      (toZigzag32 . fromZigzag32) i === i
    , testProperty "to-from-i64" $ \i ->
      (fromZigzag64 . toZigzag64) i === i
    , testProperty "from-to-i64" $ \i ->
      (toZigzag64 . fromZigzag64) i === i
    ]
  , testGroup "spec-examples"
    [ testGroup "bigint"
      [ testCase "0" $ toZigzag 0 @=? 0
      , testCase "1" $ toZigzag 1 @=? 2
      , testCase "-1" $ toZigzag (-1) @=? 1
      , testCase "-2" $ toZigzag (-2) @=? 3
      , testCase "2147483647" $ toZigzag 2147483647 @=? 4294967294
      , testCase "-2147483648" $ toZigzag (-2147483648)  @=? 4294967295
      ]
    , testGroup "native"
      [ testCase "0" $ toZigzagNative 0 @=? 0
      , testCase "1" $ toZigzagNative 1 @=? 2
      , testCase "-1" $ toZigzagNative (-1) @=? 1
      , testCase "-2" $ toZigzagNative (-2) @=? 3
      , testCase "2147483647" $ toZigzagNative 2147483647 @=? 4294967294
      , testCase "-2147483648" $ toZigzagNative (-2147483648)  @=? 4294967295
      ]
    , testGroup "i32"
      [ testCase "0" $ toZigzag32 0 @=? 0
      , testCase "1" $ toZigzag32 1 @=? 2
      , testCase "-1" $ toZigzag32 (-1) @=? 1
      , testCase "-2" $ toZigzag32 (-2) @=? 3
      , testCase "2147483647" $ toZigzag32 2147483647 @=? 4294967294
      , testCase "-2147483648" $ toZigzag32 (-2147483648)  @=? 4294967295
      ]
    , testGroup "i64"
      [ testCase "0" $ toZigzag64 0 @=? 0
      , testCase "1" $ toZigzag64 1 @=? 2
      , testCase "-1" $ toZigzag64 (-1) @=? 1
      , testCase "-2" $ toZigzag64 (-2) @=? 3
      , testCase "2147483647" $ toZigzag64 2147483647 @=? 4294967294
      , testCase "-2147483648" $ toZigzag64 (-2147483648)  @=? 4294967295
      ]
    ]
  ]

instance Arbitrary Natural where
  arbitrary = fromIntegral @Integer @Natural <$> arbitrary `suchThat` (>=0)
  shrink = fmap (fromIntegral @Integer @Natural)
         . shrink
         . fromIntegral @Natural @Integer