-- |

module Xanthous.DataSpec (main, test) where

import Test.Prelude hiding (Right, Left, Down)
import Xanthous.Data
import Data.Group

main :: IO ()
main = defaultMain test

test :: TestTree
test = testGroup "Xanthous.Data"
  [ testGroup "Position"
    [ testBatch $ monoid @Position mempty
    , testProperty "group laws" $ \(pos :: Position) ->
        pos <> invert pos == mempty && invert pos <> pos == mempty
    , testGroup "stepTowards laws"
      [ testProperty "takes only one step" $ \src tgt ->
          src /= tgt ==>
            isUnit (src `diffPositions` (src `stepTowards` tgt))
      -- , testProperty "moves in the right direction" $ \src tgt ->
      --     stepTowards src tgt == move (directionOf src tgt) src
      ]
    , testProperty "directionOf laws" $ \pos dir ->
        directionOf pos (move dir pos) == dir
    , testProperty "diffPositions is add inverse" $ \pos₁ pos₂ ->
        diffPositions pos₁ pos₂ == addPositions pos₁ (invert pos₂)

    ]
  , testGroup "Direction"
    [ testProperty "opposite is involutive" $ \(dir :: Direction) ->
        opposite (opposite dir) == dir
    , testProperty "opposite provides inverse" $ \dir ->
        invert (asPosition dir) == asPosition (opposite dir)
    , testProperty "asPosition isUnit" $ \dir ->
        dir /= Here ==> isUnit (asPosition dir)
    , testGroup "Move"
      [ testCase "Up"        $ move Up mempty        @?= Position 0 (-1)
      , testCase "Down"      $ move Down mempty      @?= Position 0 1
      , testCase "Left"      $ move Left mempty      @?= Position (-1) 0
      , testCase "Right"     $ move Right mempty     @?= Position 1 0
      , testCase "UpLeft"    $ move UpLeft mempty    @?= Position (-1) (-1)
      , testCase "UpRight"   $ move UpRight mempty   @?= Position 1 (-1)
      , testCase "DownLeft"  $ move DownLeft mempty  @?= Position (-1) 1
      , testCase "DownRight" $ move DownRight mempty @?= Position 1 1
      ]
    ]
  ]