{-# LANGUAGE NoImplicitPrelude
           , RecordWildCards
           , FlexibleContexts
  #-}

module Jobs.Crontab
  ( determineCrontab
  ) where

import Import

import qualified Data.HashMap.Strict as HashMap
import Jobs.Types

import Data.Time
import Data.Time.Zones

import Control.Monad.Trans.Writer (execWriterT)
import Control.Monad.Writer.Class (MonadWriter(..))

import qualified Data.Conduit.List as C


determineCrontab :: DB (Crontab JobCtl)
-- ^ Extract all future jobs from the database (sheet deadlines, ...)
determineCrontab = execWriterT $ do
  AppSettings{..} <- getsYesod appSettings

  case appJobFlushInterval of
    Just interval -> tell $ HashMap.singleton
      JobCtlFlush
      Cron
        { cronInitial = CronAsap
        , cronRepeat = CronRepeatScheduled CronAsap
        , cronRateLimit = interval
        }
    Nothing -> return ()

  tell $ HashMap.singleton
    JobCtlDetermineCrontab
    Cron
      { cronInitial = CronAsap
      , cronRepeat = CronRepeatScheduled CronAsap
      , cronRateLimit = appJobCronInterval
      }

  let
    sheetJobs (Entity nSheet Sheet{..}) = do
      tell $ HashMap.singleton
        (JobCtlQueue $ JobQueueNotification NotificationSheetActive{..})
        Cron
          { cronInitial = CronTimestamp $ utcToLocalTimeTZ appTZ sheetActiveFrom
          , cronRepeat = CronRepeatOnChange -- Allow repetition of the notification (if something changes), but wait at least an hour
          , cronRateLimit = appNotificationRateLimit
          }
      tell $ HashMap.singleton
        (JobCtlQueue $ JobQueueNotification NotificationSheetInactive{..})
        Cron
          { cronInitial = CronTimestamp . utcToLocalTimeTZ appTZ . max sheetActiveFrom $ addUTCTime (-nominalDay) sheetActiveTo
          , cronRepeat = CronRepeatOnChange
          , cronRateLimit = appNotificationRateLimit
          }
  runConduit $ transPipe lift (selectSource [] []) .| C.mapM_ sheetJobs