module Literate.Accounting.Move where

import Data.Function ((.))
import GHC.Stack (HasCallStack)
import Literate.Accounting.Chart
import Literate.Accounting.Math
import Literate.Accounting.Unit

{-
data Account = Account
data Amount qty = Amount
  { amountUnit :: Unit
  , amountQuantity :: qty
  }
instance Negable qty => Negable (Amount qty) where
  negate Amount{..} = Amount{ amountQuantity = negate amountQuantity, ..}
-}

type family AmountOf a
type family AccountOf a
type family AccountSectionOf a

type instance AmountOf [a] = AmountOf a
type instance AccountOf [a] = AccountOf a
type instance AccountSectionOf [a] = AccountSectionOf a

-- * Class 'Postable'

-- class Postable post where
-- post :: HasCallStack => AccountOf post -> AmountOf post -> post

class Postable acct unit qty post where
  (+=) ::
    HasCallStack =>
    Postable acct unit qty post =>
    Account acct ->
    Amounts unit qty ->
    post
  infixr 4 +=

(-=) ::
  HasCallStack =>
  Postable acct unit qty post =>
  Negable qty =>
  Account acct ->
  Amounts unit qty ->
  post
(-=) acct = (+=) acct . negate
infixr 4 -=