module View.Payment.Reducer
  ( perPage
  , reducer
  , In(..)
  ) where

import           Data.Text    (Text)
import qualified Data.Text    as T
import           Reflex.Dom   (Dynamic, Event, MonadWidget)
import qualified Reflex.Dom   as R

import           Common.Model (PaymentPage)

import           Loadable     (Loadable (..))
import qualified Loadable     as Loadable
import qualified Util.Ajax    as AjaxUtil

perPage :: Int
perPage = 7

data In t a b c = In
  { _in_newPage       :: Event t Int
  , _in_currentPage   :: Dynamic t Int
  , _in_addPayment    :: Event t a
  , _in_editPayment   :: Event t b
  , _in_deletePayment :: Event t c
  }

data Action
  = LoadPage Int
  | GetResult (Either Text PaymentPage)

reducer :: forall t m a b c. MonadWidget t m => In t a b c -> m (Dynamic t (Loadable PaymentPage))
reducer input = do

  postBuild <- R.getPostBuild

  let loadPage =
        R.leftmost
          [ 1 <$ postBuild
          , _in_newPage input
          , 1 <$ _in_addPayment input
          , R.tag (R.current $ _in_currentPage input) (_in_editPayment input)
          , R.tag (R.current $ _in_currentPage input) (_in_deletePayment input)
          ]

  getResult <- AjaxUtil.get $ fmap pageUrl loadPage

  R.foldDyn
    (\action _ -> case action of
      LoadPage _                 -> Loading
      GetResult (Left err)       -> Error err
      GetResult (Right payments) -> Loaded payments
    )
    Loading
    (R.leftmost
      [ LoadPage <$> loadPage
      , GetResult <$> getResult
      ])

  where
    pageUrl p =
      "api/payments?page="
      <> (T.pack . show $ p)
      <> "&perPage="
      <> (T.pack . show $ perPage)