module StreamPatch.ApplySpec ( spec ) where

import StreamPatch.Apply
import Test.Hspec
import Test.Hspec.QuickCheck
import Test.QuickCheck
import Util

import StreamPatch.Patch
import Data.Functor.Const
import Data.Vinyl
import GHC.Natural

spec :: Spec
spec = do
    let patch' ps = runPureFwdList $ makePatchscript ps
    it "applies valid simple forward in-place patches" $ do
      patch' []           "1234567890" `shouldBe` "1234567890"
      patch' [(0, "XXX")] "1234567890" `shouldBe` "XXX4567890"
      patch' [(1, "XXX")] "1234567890" `shouldBe` "1XXX567890"
      patch' [(7, "XXX")] "1234567890" `shouldBe` "1234567XXX"
    prop "applies valid generated simple forward in-place patches" $ do
      \n -> forAll (genPatchList @Char n) $
        \ps -> forAll (genBoundList @Char n n) $
          \a -> pendingWith "cba to reimplement patcher"
                -- patchListPure ps a `shouldBe` manualPatch ps a

-- | "Verified" implementation of a simple patch algorithm.
--
-- nah I cba lol just trust me
--manualPatch :: [Patch 'FwdSeek '[] [a]] -> [a] -> [a]

genPatchList :: Arbitrary a => Natural -> Gen [Patch Natural '[] [a]]
genPatchList = skip []
  where
    skip ps n = do
        -- why no Random Natural...
        nSkip <- choose (0, naturalToInteger n)
        gen ps (naturalFromInteger nSkip) $ n - (fromIntegral nSkip)
    gen ps _     0 = pure ps
    gen ps nSkip n = do
        a <- genBoundList n 1
        let n' = n - (fromIntegral (length a))
        skip (makePatch a nSkip : ps) n'

genBoundList :: Arbitrary a => Natural -> Natural -> Gen [a]
genBoundList x y =
    arbitrary `suchThat` \l -> fromIntegral (length l) <= x && fromIntegral (length l) >= y