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

import qualified Util.Reflex as ReflexUtil
import qualified View.Icon   as Icon

data PagesIn t = PagesIn
  { _pagesIn_total   :: Dynamic t Int
  , _pagesIn_perPage :: Int
  , _pagesIn_reset   :: Event t ()
  }

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

widget :: forall t m. MonadWidget t m => PagesIn t -> m (PagesOut t)
widget pagesIn = do
  currentPage <- ReflexUtil.divVisibleIf ((> 0) <$> total) $ pageButtons total perPage reset

  return $ PagesOut
    { _pagesOut_currentPage = currentPage
    }

  where
    total = _pagesIn_total pagesIn
    perPage = _pagesIn_perPage pagesIn
    reset = _pagesIn_reset pagesIn

pageButtons :: forall t m. MonadWidget t m => Dynamic t Int -> Int -> Event t () -> m (Dynamic t Int)
pageButtons total perPage reset = do
  R.divClass "pages" $ do
    rec
      currentPage <- R.holdDyn 1 . R.leftmost $
        [ firstPageClic
        , previousPageClic
        , pageClic
        , nextPageClic
        , lastPageClic
        , 1 <$ reset
        ]

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

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

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

      nextPageClic <- pageButton noCurrentPage ((\c m -> min (c + 1) m) <$> currentPage <*> maxPage) Icon.doubleRight

      lastPageClic <- pageButton noCurrentPage maxPage Icon.doubleRightBar

    return currentPage

    where maxPage = R.ffor total (\t -> ceiling $ toRational t / toRational perPage)
          pageEvent = R.switch . R.current . fmap R.leftmost
          noCurrentPage = R.constDyn Nothing

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

pageButton :: forall t m. MonadWidget t m => Dynamic t (Maybe 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 == Just p then "page current" else "page"
    , _buttonIn_content = content
    , _buttonIn_waiting = R.never
    , _buttonIn_tabIndex = Nothing
    , _buttonIn_submit = False
    })
  return . fmap fst $ R.attach (R.current page) clic