import           Examples   (Bert (Add, Bert, Num), Ernie (Ernie, Multiply),
                             collapseBertSyntaxTree, collapseErnieSyntaxTree,
                             collapseErnieSyntaxTree')
import           Test.Hspec (describe, hspec, it, parallel, shouldBe)

bertSum :: Bert
bertSum = Add (Num 2) (Num 3)

ernieMult :: Ernie
ernieMult = Multiply (Ernie bertSum) (Ernie (Num 3))

bertNothing :: Bert
bertNothing = Bert ernieMult

ernieComplex :: Ernie
ernieComplex = Ernie bertNothing

bertComplex :: Bert
bertComplex = Add (Num 3) (Bert ernieMult)

resultErnie :: Ernie
resultErnie = Ernie (Num 15)

main :: IO ()
main = hspec $
    describe "dendro" $ parallel $ do
        it "collapses a simple syntax tree" $
            collapseBertSyntaxTree bertSum `shouldBe` Num 5
        it "collapses both parts of a syntax tree" $
            collapseErnieSyntaxTree ernieMult `shouldBe` resultErnie
        it "matches solution via catamorphism" $
            collapseErnieSyntaxTree' ernieMult `shouldBe` collapseErnieSyntaxTree ernieMult
        it "collapses complex syntax trees" $
            collapseBertSyntaxTree bertComplex `shouldBe` Num 18
        it "should work would when triply wrapped (1/4)" $
            collapseErnieSyntaxTree (Ernie (Bert (Ernie (Num 15)))) `shouldBe` resultErnie
        it "should work would when doubly wrapped" $
            collapseBertSyntaxTree (Bert (Ernie (Num 15))) `shouldBe` (Num 15)
        it "should work would when triply wrapped (2/4)" $
            collapseBertSyntaxTree (Bert (Ernie bertComplex)) `shouldBe` (Num 18)
        it "should work would when triply wrapped (3/4)" $
            collapseBertSyntaxTree (Bert ernieComplex) `shouldBe` (Num 15)
        it "should work would when triply wrapped (4/4)" $
            collapseErnieSyntaxTree (Ernie (Bert ernieComplex)) `shouldBe` resultErnie