{-# OPTIONS_GHC -fno-warn-orphans #-}
{-# LANGUAGE AllowAmbiguousTypes #-}

module Pandora.Paradigm.Structure.Some.Splay where

import Pandora.Core.Functor (type (~>), type (:.), type (:=))
import Pandora.Pattern.Semigroupoid ((.))
import Pandora.Pattern.Category (($), (#))
import Pandora.Pattern.Functor.Covariant (Covariant ((-<$>-)))
import Pandora.Pattern.Functor.Bindable (Bindable ((=<<)))
import Pandora.Paradigm.Primary ()
import Pandora.Paradigm.Primary.Algebraic ((-<*>-), extract)
import Pandora.Paradigm.Primary.Algebraic.Product (twosome)
import Pandora.Paradigm.Primary.Functor.Maybe (Maybe (Just))
import Pandora.Paradigm.Primary.Functor.Tagged (type (:#))
import Pandora.Paradigm.Primary.Functor.Wye (Wye (Left, Right))
import Pandora.Paradigm.Primary.Transformer.Construction (Construction (Construct), deconstruct)
import Pandora.Paradigm.Controlflow.Effect.Interpreted (run, unite)
import Pandora.Paradigm.Inventory.Optics (over)
import Pandora.Paradigm.Schemes (TU (TU), type (<:.>))
import Pandora.Paradigm.Structure.Ability.Morphable (Morphable (Morphing, morphing), Morph (Rotate, Into), premorph, rotate, into)
import Pandora.Paradigm.Structure.Ability.Nonempty (Nonempty)
import Pandora.Paradigm.Structure.Ability.Substructure (sub)
import Pandora.Paradigm.Structure.Some.Binary (Binary)

data Splay a = Zig a | Zag a

instance Morphable (Rotate (Left Zig)) Binary where
	type Morphing (Rotate (Left Zig)) Binary = Binary
	morphing (premorph -> binary) = unite $ run . rotate @(Left Zig) =<< run binary

instance Morphable (Rotate (Right Zig)) Binary where
	type Morphing (Rotate (Right Zig)) Binary = Binary
	morphing (premorph -> binary) = unite $ run . rotate @(Right Zig) =<< run binary

instance Morphable (Rotate (Left (Zig Zig))) Binary where
	type Morphing (Rotate (Left (Zig Zig))) Binary = Binary
	morphing (premorph -> binary) = unite $ run . rotate @(Left (Zig Zig)) =<< run binary

instance Morphable (Rotate (Right (Zig Zig))) Binary where
	type Morphing (Rotate (Right (Zig Zig))) Binary = Binary
	morphing (premorph -> binary) = unite $ run . rotate @(Right (Zig Zig)) =<< run binary

instance Morphable (Rotate (Left (Zig Zag))) Binary where
	type Morphing (Rotate (Left (Zig Zag))) Binary = Binary
	morphing (premorph -> binary) = unite $ run . rotate @(Left (Zig Zag)) =<< run binary

instance Morphable (Rotate (Right (Zig Zag))) Binary where
	type Morphing (Rotate (Right (Zig Zag))) Binary = Binary
	morphing (premorph -> binary) = unite $ run . rotate @(Right (Zig Zag)) =<< run binary

-------------------------------------- Non-empty Splay tree ----------------------------------------

instance Morphable (Rotate (Left Zig)) (Construction Wye) where
	type Morphing (Rotate (Left Zig)) (Construction Wye) = Binary
	morphing :: forall a . (:#) (Rotate (Left Zig)) <:.> Construction Wye := a -> Binary a
	morphing (premorph -> Construct x xs) = TU $ Construct -<$>- parent -<*>- Just nodes where

		nodes :: Wye :. Nonempty Binary := a
		nodes = into @Wye . twosome (branch @Left xs) . Just . Construct x
			. into @Wye $ twosome (branch @Left =<< deconstruct -<$>- branch @Right xs)
				(branch @Right =<< deconstruct -<$>- branch @Right xs)

		parent :: Maybe a
		parent = extract -<$>- branch @Right xs

instance Morphable (Rotate (Right Zig)) (Construction Wye) where
	type Morphing (Rotate (Right Zig)) (Construction Wye) = Binary
	morphing :: forall a . (:#) (Rotate (Right Zig)) <:.> Construction Wye := a -> Binary a
	morphing (premorph -> Construct x xs) = TU $ Construct -<$>- parent -<*>- Just nodes where

		nodes :: Wye :. Nonempty Binary := a
		nodes = into @Wye . twosome (branch @Left =<< deconstruct -<$>- branch @Left xs) . Just . Construct x
			. into @Wye $ twosome (branch @Right =<< deconstruct -<$>- branch @Left xs) # branch @Right xs

		parent :: Maybe a
		parent = extract -<$>- branch @Left xs

-- TODO: Morphing ... = Conclussion Error <:.> Nonempty Binary
instance Morphable (Rotate (Left (Zig Zig))) (Construction Wye) where
	type Morphing (Rotate (Left (Zig Zig))) (Construction Wye) = Binary
	morphing (premorph -> tree) = TU $ run . rotate @(Left Zig) =<< run # rotate @(Left Zig) tree

-- TODO: Morphing ... = Conclussion Error <:.> Nonempty Binary
instance Morphable (Rotate (Right (Zig Zig))) (Construction Wye) where
	type Morphing (Rotate (Right (Zig Zig))) (Construction Wye) = Binary
	morphing (premorph -> tree) = TU $ run . rotate @(Right Zig) =<< run # rotate @(Right Zig) tree

-- TODO: Morphing ... = Conclussion Error <:.> Nonempty Binary
instance Morphable (Rotate (Left (Zig Zag))) (Construction Wye) where
	type Morphing (Rotate (Left (Zig Zag))) (Construction Wye) = Binary
	morphing = rotate @(Left Zig) . over (sub @Left) (run . rotate @(Right Zig) =<<) . premorph

-- TODO: Morphing ... = Conclussion Error <:.> Nonempty Binary
instance Morphable (Rotate (Right (Zig Zag))) (Construction Wye) where
	type Morphing (Rotate (Right (Zig Zag))) (Construction Wye) = Binary
	morphing = rotate @(Right Zig) . over (sub @Right) (run . rotate @(Left Zig) =<<) . premorph

branch :: forall b . Morphable (Into (b Maybe)) Wye => Wye ~> Morphing (Into (b Maybe)) Wye
branch = into @(b Maybe)