module Handler.Utils
  ( module Handler.Utils
  ) where

import Import

import qualified Data.Text as T
-- import qualified Data.Set (Set)
import qualified Data.Set as Set

import Language.Haskell.TH (Q, Exp)
-- import Language.Haskell.TH.Datatype

import Handler.Utils.DateTime as Handler.Utils
import Handler.Utils.Form as Handler.Utils
import Handler.Utils.Table as Handler.Utils
import Handler.Utils.Table.Pagination as Handler.Utils

import Handler.Utils.Zip        as Handler.Utils
import Handler.Utils.Rating     as Handler.Utils hiding (extractRatings)
-- import Handler.Utils.Submission as Handler.Utils
import Handler.Utils.Sheet      as Handler.Utils
import Handler.Utils.Templates  as Handler.Utils
import Handler.Utils.Mail       as Handler.Utils


downloadFiles :: (MonadHandler m, HandlerSite m ~ UniWorX) => m Bool
downloadFiles = do
  mauth <- liftHandlerT maybeAuth
  case mauth of
    Just (Entity _ User{..}) -> return userDownloadFiles
    Nothing -> do
      AppSettings{ appUserDefaults = UserDefaultConf{..} } <- getsYesod appSettings
      return userDefaultDownloadFiles

tidFromText :: Text -> Maybe TermId
tidFromText = fmap TermKey . maybeRight . termFromText

simpleLink :: Widget -> Route UniWorX -> Widget
simpleLink lbl url = [whamlet|<a href=@{url}>^{lbl}|]

nameWidget :: Text -> Text -> Widget
nameWidget displayName surname = toWidget $ nameHtml displayName surname

nameHtml :: Text -> Text -> Html
nameHtml displayName surname
  | null surname = toHtml displayName
  | otherwise = case reverse $ T.splitOn surname displayName of
      [_notContained] -> [shamlet|$newline never
                            #{displayName} (
                            <b .surname>#{surname}
                            )|]
      (suffix:prefixes) ->
        let prefix = T.intercalate surname $ reverse prefixes
        in [shamlet|$newline never
              #{prefix}
              <b .surname>#{surname}
              #{suffix}
            |]
      [] -> error "Data.Text.splitOn returned empty list in violation of specification."


warnTermDays :: TermId -> [Maybe UTCTime] -> DB ()
warnTermDays tid times = do
  Term{..} <- get404 tid
  let alldays       = Set.map utctDay $ Set.fromList $ catMaybes times
      warnholidays  = Set.intersection alldays $ Set.fromList termHolidays
      outoftermdays = Set.filter (\d -> d < termStart        || d > termEnd       ) alldays
      outoflecture  = Set.filter (\d -> d < termLectureStart || d > termLectureEnd) alldays
                        `Set.difference` outoftermdays -- out of term implies out of lecture-time
      warnI msg d = formatTime SelFormatDate d >>= \dt -> addMessageI Warning $ msg tid dt
  forM_ warnholidays  $ warnI MsgDayIsAHoliday
  forM_ outoflecture  $ warnI MsgDayIsOutOfLecture
  forM_ outoftermdays $ warnI MsgDayIsOutOfTerm

-- | Add language dependent template files
--   For large files which are translated as a whole.
--   Argument musst be a directory under templates,
--   which contains a file for each language,
--   eg. /templates/imprint/de.hamlet and /templates/imprint/en.hamlet
i18nWidgetFile :: FilePath -> Q Exp
i18nWidgetFile =
  -- TODO write code to distinguish languages here
  widgetFile . (</> "de")