module Jobs.Handler.QueueNotification
  ( dispatchJobQueueNotification
  ) where

import Import

import Jobs.Types

import qualified Database.Esqueleto as E
import Utils.Sql
import Jobs.Queue


dispatchJobQueueNotification :: Notification -> Handler ()
dispatchJobQueueNotification jNotification = runDBJobs . setSerializable $ do
  candidates <- hoist lift $ determineNotificationCandidates jNotification
  nClass <- hoist lift $ classifyNotification jNotification
  mapM_ (queueDBJob . flip JobSendNotification jNotification) $ do
    Entity uid User{userNotificationSettings} <- candidates
    guard $ notificationAllowed userNotificationSettings nClass
    return uid

  
determineNotificationCandidates :: Notification -> DB [Entity User]
determineNotificationCandidates NotificationSubmissionRated{..}
  = E.select . E.from $ \(user `E.InnerJoin` submissionUser) -> do
      E.on $ user E.^. UserId E.==. submissionUser E.^. SubmissionUserUser
      E.where_ $ submissionUser E.^. SubmissionUserSubmission E.==. E.val nSubmission
      return user
determineNotificationCandidates NotificationSheetActive{..}
  = E.select . E.from $ \(user `E.InnerJoin` courseParticipant `E.InnerJoin` sheet) -> do
      E.on $ sheet E.^. SheetCourse E.==. courseParticipant E.^. CourseParticipantCourse
      E.on $ user E.^. UserId E.==. courseParticipant E.^. CourseParticipantUser
      E.where_ $ sheet E.^. SheetId E.==. E.val nSheet
      return user
determineNotificationCandidates NotificationSheetSoonInactive{..}
  = E.select . E.from $ \(user `E.InnerJoin` courseParticipant `E.InnerJoin` sheet) -> do
      E.on $ sheet E.^. SheetCourse E.==. courseParticipant E.^. CourseParticipantCourse
      E.on $ user E.^. UserId E.==. courseParticipant E.^. CourseParticipantUser
      E.where_ $ sheet E.^. SheetId E.==. E.val nSheet
      return user
determineNotificationCandidates NotificationSheetInactive{..}
  = E.select . E.from $ \(user `E.InnerJoin` lecturer `E.InnerJoin` sheet) -> do  
      E.on $ lecturer E.^. LecturerCourse E.==. sheet E.^. SheetCourse 
      E.on $ lecturer E.^. LecturerUser   E.==. user E.^. UserId
      E.where_ $ sheet E.^. SheetId E.==. E.val nSheet
      return user
determineNotificationCandidates NotificationCorrectionsAssigned{..}
  = selectList [UserId ==. nUser] [] 
determineNotificationCandidates NotificationCorrectionsNotDistributed{nSheet}
  = E.select . E.from $ \(user `E.InnerJoin` lecturer `E.InnerJoin` sheet) -> do
      E.on $ lecturer E.^. LecturerCourse E.==. sheet E.^. SheetCourse
      E.on $ lecturer E.^. LecturerUser E.==. user E.^. UserId
      E.where_ $ sheet E.^. SheetId E.==. E.val nSheet
      return user
  
classifyNotification :: Notification -> DB NotificationTrigger
classifyNotification NotificationSubmissionRated{..} = do
  Sheet{sheetType} <- belongsToJust submissionSheet =<< getJust nSubmission
  return $ case sheetType of
    NotGraded -> NTSubmissionRated
    _other -> NTSubmissionRatedGraded
classifyNotification NotificationSheetActive{} = return NTSheetActive
classifyNotification NotificationSheetSoonInactive{} = return NTSheetSoonInactive
classifyNotification NotificationSheetInactive{} = return NTSheetInactive
classifyNotification NotificationCorrectionsAssigned{} = return NTCorrectionsAssigned
classifyNotification NotificationCorrectionsNotDistributed{} = return NTCorrectionsNotDistributed