module Handler.LMS
  ( getLmsR
  )
  where

import Import

import Handler.Utils

import qualified Data.Csv as Csv
import qualified Data.Conduit.List as C

type LmsUserIdent = Text -- Unique random use-once identifier for each individual e-learning course; i.e. users may have several active LmsUserIdents at once!

data LmsUserTableCsv = LmsUserTableCsv -- Export only
  { csvLmsUserIdent :: LmsUserIdent
  , csvLmsUserPin   :: Text 
  , csvLmsUserReset, cvsLmsUserRemove, cvsLmsUserIntern :: Bool
  }

data LmsUserlistTableCsv = LmsUserlistTableCsv -- Import only, all users that are currently enlisted at the e-learning plattform
  { csvLmsUserlistIdent   :: LmsUserIdent
  , csvLmsUserlistFailed  :: Bool             
  }

data LmsResultTableCsv = LmsResultTableCsv  -- Import only, all users that succeeded are returned ONCE only; must then be deleted via LmsUserTableCsv Export!
  { csvLmsResultIdent   :: LmsUserIdent
  , csvLmsResultSuccess :: UTCTime          -- datestamp user succeeded (might be local time, unclear)
  }
  
csvLmsUserFilename :: IO Text
csvLmsUserFilename = makeLmsFilename "user"

csvLmsUserlistFilename :: IO Text
csvLmsUserlistFilename = makeLmsFilename "userliste"

csvLmsResultFilename :: IO Text
csvLmsResultFilename = makeLmsFilename "ergebnisse"

-- | Create filenames as specified by the LMS interface agreed with Know How AG
makeLmsFilename :: Text -> IO Text 
makeLmsFilename ftag = do 
  ymth <- get_ymth 
  return $ "fradrive_f_" <> ftag <> "_" <> ymth <> ".csv"

-- | Return current datetime in YYYYMMDDHH format 
get_ymth :: IO Text 
get_ymth = do 
  now <- getCurrentTime
  return $ formatTime "%Y%m%d%h"


getLmsR :: Handler Html
getLmsR = do
  let dbtIdent     = "lmsUsers" :: Text
      dbtStyle     = def { dbsFilterLayout = defaultDBSFilterLayout }
      dbtSQLQuery q = error "TODO"
      dbtRowKey    = error "TODO"
      dbtProj      = dbtProjSimple $ \(userIdent, userPin, doUserPinReset, doDeleteUser, isUserIntern) -> do
        return ("abcdefgh", "12345678", False, False, True) -- Warum keine Liste? 
      dbtColonnade = colChoices
      dbtSorting   = mempty
      dbtFilter    = mempty
      dbtFilterUI  = mempty
      dbtParams    = def
      dbtCsvName = "lms.csv"
      -- TODO: wip, for reference, see e.g. Handler.Course.Users or Handler.Exam.
      dbtCsvEncode = do
        return $ DBTCsvEncode
          { dbtCsvExportForm = def
          , dbtCsvDoEncode = \UserCsvExportData{} -> C.mapM $ \(_, row) -> flip runReaderT row $
              LmsTableCsv  -- <- for each desired column one view
                <$> _t1
                <*> _t2
                <*> _t3
                <*> _t4
                <*> _t5
          , dbtCsvName
          , dbtCsvSheetName
          , dbtCsvNoExportData = Nothing -- ?
          , dbtCsvHeader = return . Vector.filter csvColumns' . userTableCsvHeader showSex tutorials sheets . fromMaybe def
          , dbtCsvExampleData = Nothing
          }
      -- TODO wip, for reference see e.g. Handler.Exam.Users
      dbtCsvDecode = Just DBTCsvDecode
        { dbtCsvRowKey = _1
        , dbtCsvComputeActions = _2
        , dbtCsvClassifyAction = _3
        , dbtCsvCoarsenActionClass = _4
        , dbtCsvValidateActions = _5
        , dbtCsvExecuteActions =  _6 -- <- actions based on sent data here
        , dbtCsvRenderKey = _7
        , dbtCsvRenderActionClass = _8
        , dbtCsvRenderException = _9
        }
      dbTable psValidator DBTable{..}
      heading = [whamlet|LMS|]
  siteLayout heading $ do
    setTitleI heading
    $(widgetFile "lms")