module Dingo.Widget.Panel ( Panel
                          , mkPanel
                          ) where

import Data.Aeson (FromJSON(..), ToJSON(..), Value(..))
import Data.Monoid (mempty)
import Data.Typeable (Typeable)
import Dingo.Callback
import Dingo.Widget
import Text.Blaze ((!), toValue)
import Text.Julius (julius)
import qualified Data.HashMap.Strict as M
import qualified Text.Blaze.Html4.Strict as H
import qualified Text.Blaze.Html4.Strict.Attributes as A

-- Panel type.
data Panel =
  Panel { panelId :: WidgetId
        }
  deriving (Show, Typeable)

data PanelState = PanelState ()
                deriving (Show, Typeable)

instance FromJSON PanelState where
  parseJSON _ = return $ PanelState ()

instance ToJSON PanelState where
  toJSON (PanelState ()) = Object M.empty

-- Panel is a widget.
instance Widget Panel PanelState where
  -- Get the widget ID.
  getWidgetId = panelId
  -- Render panel to HTML.
  renderWidget w =
    H.div ! A.id (toValue $ panelId w) $ do
      mempty
  -- Show widget.
  showWidget w s = show w ++ "->" ++ show s
  -- Client state handling.
  encodeClientStateJs _ = [julius| null |]
  decodeClientStateJs _ = [julius| null |]

-- Make a new panel.
mkPanel :: Widget w s => w -> CallbackM Panel
mkPanel pw = addWidget pw (\i -> return (Panel i, PanelState ()))