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

module Pandora.Paradigm.Inventory.Optics where

import Pandora.Core.Functor (type (|->))
import Pandora.Pattern.Category ((.), ($))
import Pandora.Pattern.Functor.Covariant ((<$))
import Pandora.Pattern.Functor.Extractable (Extractable (extract))
import Pandora.Pattern.Functor.Representable (Representable (Representation, (<#>), tabulate))
import Pandora.Pattern.Object.Setoid (Setoid ((==)))
import Pandora.Paradigm.Primary.Functor.Product (Product ((:*:)))
import Pandora.Paradigm.Primary.Object.Boolean ((?))
import Pandora.Paradigm.Inventory.Store (Store (Store), access, position, retrofit)

infixr 0 :-.
type (:-.) src tgt = Lens src tgt

type Lens src tgt = src |-> Store tgt

-- | Lens composition infix operator
(|>) :: Lens src old -> Lens old new -> Lens src new
from |> to = \x -> ((<$) x . to) . position . from $ x

-- | Get the target of a lens
view :: Lens src tgt -> src -> tgt
view lens = position . lens

-- | Infix version of `view`
(^.) :: Lens src tgt -> src -> tgt
(^.) = view

-- | Replace the target of a lens
set :: Lens src tgt -> tgt -> src -> src
set lens new = access new . lens

-- | Infix version of `set`
(.~) :: Lens src tgt -> tgt -> src -> src
lens .~ new = set lens new

-- | Modify the target of a lens
over :: Lens src tgt -> (tgt -> tgt) -> src -> src
over lens f = extract . retrofit f . lens

-- | Infix version of `over`
(%~) :: Lens src tgt -> (tgt -> tgt) -> src -> src
lens %~ f = over lens f

represent :: (Representable t, Setoid (Representation t)) => Representation t -> t a :-. a
represent r x = Store $ (r <#> x) :*: \new -> tabulate (\r' -> r' == r ? new $ r' <#> x)