module View.Payment.Pages
  ( widget
  , PagesIn(..)
  , PagesOut(..)
  ) where

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

import           Common.Model           (Frequency (..), Payment (..))

import           Component              (ButtonIn (..), ButtonOut (..))
import qualified Component              as Component

import qualified Icon
import qualified View.Payment.Constants as Constants

data PagesIn = PagesIn
  { _pagesIn_payments :: [Payment]
  }

data PagesOut t = PagesOut
  { _pagesOut_currentPage :: Dynamic t Int
  }

widget :: forall t m. MonadWidget t m => PagesIn -> m (PagesOut t)
widget pagesIn = do
  R.divClass "pages" $ do
    rec
      currentPage <- R.holdDyn 1 . R.leftmost $ [ firstPageClic, previousPageClic, pageClic, nextPageClic, lastPageClic ]

      firstPageClic <- pageButton (R.constDyn 0) (R.constDyn 1) Icon.doubleLeftBar

      previousPageClic <- pageButton (R.constDyn 0) (fmap (\x -> max (x - 1) 1) currentPage) Icon.doubleLeft

      pageClic <- pageEvent <$> (R.simpleList (fmap (range maxPage) currentPage) $ \p ->
        pageButton currentPage p (R.dynText $ fmap (T.pack . show) p))

      nextPageClic <- pageButton (R.constDyn 0) (fmap (\x -> min (x + 1) maxPage) currentPage) Icon.doubleRight

      lastPageClic <- pageButton (R.constDyn 0) (R.constDyn maxPage) Icon.doubleRightBar

    return $ PagesOut
      { _pagesOut_currentPage = currentPage
      }

    where paymentCount = length . filter ((==) Punctual . _payment_frequency) . _pagesIn_payments $ pagesIn
          maxPage = ceiling $ toRational paymentCount / toRational Constants.paymentsPerPage
          pageEvent = R.switchPromptlyDyn . fmap R.leftmost

range :: Int -> Int -> [Int]
range maxPage currentPage = [start..end]
  where sidePages = 2
        start = max 1 (currentPage - sidePages)
        end = min maxPage (start + sidePages * 2)

pageButton :: forall t m. MonadWidget t m => Dynamic t Int -> Dynamic t Int -> m () -> m (Event t Int)
pageButton currentPage page content = do
  clic <- _buttonOut_clic <$> (Component.button $ ButtonIn
    { _buttonIn_class   = do
        cp <- currentPage
        p <- page
        if cp == p then "page current" else "page"
    , _buttonIn_content = content
    , _buttonIn_waiting = R.never
    })
  return . fmap fst $ R.attach (R.current page) clic