{-# LANGUAGE UnicodeSyntax #-}

module ALife.Creatur.UtilQC
  (
    test
  ) where

import ALife.Creatur.Util (cropRect, cropSquare, isqrt, replaceElement, 
  safeReplaceElement, shuffle)
import Control.Monad.Random (evalRand, mkStdGen)
import Data.Eq.Unicode ((≡))
import Data.Ix (range)
import Data.List (sort)
import Data.Ord.Unicode ((≤))
import Test.Framework as TF (Test, testGroup)
import Test.Framework.Providers.QuickCheck2 (testProperty)
import Test.QuickCheck (Property, property)

-- prop_constrain_obeys_bounds ∷ (Int, Int) → Int → Property
-- prop_constrain_obeys_bounds (a, b) x = property $ a ≤ x' && x' ≤ b
--  where x' = constrain (a, b) x

-- prop_constrain_works ∷ (Int, Int) → Int → Property
-- prop_constrain_works (a, b) x = property $ x' ≡ x || x ≤ a || b ≤ x || b < a
--  where x' = constrain (a, b) x

prop_cropRect_returns_correct_size ∷
  (Int, Int) → (Int, Int) → String → Int → Property
prop_cropRect_returns_correct_size (a,b) (c, d) xs k =
    property $ length xs' ≡ expectedSize || length xs < expectedSize
  where expectedSize = length is'
        is = range ((0,0),(lastRow,lastCol))
        is' = filter wanted is
        wanted (i,j) = a ≤ i && i ≤ c && b ≤ j && j ≤ d
        lastRow = if k ≡ 0 then -1 else (length xs `div` k) - 1 + delta
        lastCol = constrain (-1,length xs - 1) (k - 1)
        delta = if length xs `mod` k ≡ 0 then 0 else 1 --add partial row
        xs' = cropRect (a, b) (c, d) xs k

-- Warning: If b < a, returns either a or x
constrain ∷ Ord a ⇒ (a, a) → a → a
constrain (a,b) x | x < a     = a
                  | x > b     = b
                  | otherwise = x

prop_cropSquare_returns_correct_size ∷ Int → String → Property
prop_cropSquare_returns_correct_size n xs =
    property $ length xs' ≡ expectedSize
  where expectedRows = min n ((isqrt . length) xs)
        expectedSize = if n < 0 then 0 else expectedRows*expectedRows
        xs' = cropSquare n xs

prop_replaceElement_changes_the_right_element ∷ String → Int → Char → Property
prop_replaceElement_changes_the_right_element cs i c =
  property
    $
      if 0 ≤ i && i < length cs
        then replaceElement cs i c !! i ≡ c
        else replaceElement cs i c ≡ cs

prop_safeReplaceElement_doesnt_change_length ∷ String → Int → Char → Property
prop_safeReplaceElement_doesnt_change_length cs i c =
  property $ length cs ≡ length (safeReplaceElement cs i c)

prop_safeReplaceElement_changes_the_right_element ∷
  String → Int → Char → Property
prop_safeReplaceElement_changes_the_right_element cs i c =
  property
    $
      if 0 ≤ i && i < length cs
        then cs' !! i ≡ c
        else cs' ≡ cs
  where cs' = safeReplaceElement cs i c

prop_shuffle_doesnt_change_elements ∷ String → Int → Property
prop_shuffle_doesnt_change_elements xs k = property $ sort xs ≡ sort xs'
  where xs' = evalRand (shuffle xs) (mkStdGen k)

test ∷ Test
test = testGroup "QuickCheck ALife.Creatur.UtilQC"
  [
--    testProperty "prop_constrain_obeys_bounds"
--      prop_constrain_obeys_bounds,
--    testProperty "prop_constrain_works"
--      prop_constrain_works,
    testProperty "prop_safeReplaceElement_changes_the_right_element"
      prop_safeReplaceElement_changes_the_right_element,
    testProperty "prop_safeReplaceElement_doesnt_change_length"
      prop_safeReplaceElement_doesnt_change_length,
    testProperty "prop_cropRect_returns_correct_size"
      prop_cropRect_returns_correct_size,
    testProperty "prop_cropSquare_returns_correct_size"
      prop_cropSquare_returns_correct_size,
    testProperty "prop_replaceElement_changes_the_right_element"
      prop_replaceElement_changes_the_right_element,
    testProperty "prop_shuffle_doesnt_change_elements"
      prop_shuffle_doesnt_change_elements
  ]