module Handler.Utils.Course where

import Import
import Handler.Utils.Delete

import qualified Database.Esqueleto as E

import qualified Data.Set as Set
  

courseDeleteRoute :: Set CourseId -> DeleteRoute Course
courseDeleteRoute drRecords = DeleteRoute
  { drRecords
  , drGetInfo = \(course `E.InnerJoin` school) -> do
      E.on $ course E.^. CourseSchool E.==. school E.^. SchoolId
      E.orderBy [E.asc $ course E.^. CourseName]
      return (course E.^. CourseName, school E.^. SchoolShorthand, school E.^. SchoolName, course E.^. CourseTerm)
  , drUnjoin = \(course `E.InnerJoin` _) -> course
  , drRenderRecord = \(E.Value cName, _, E.Value sName, E.Value tid') ->
      return [whamlet|
        #{cName} (_{ShortTermIdentifier (unTermKey tid')}, #{sName})
      |]
  , drRecordConfirmString = \(E.Value cName, E.Value ssh', _, E.Value tid') -> 
      return [st|#{termToText (unTermKey tid')}/#{ssh'}/#{cName}|]
  , drCaption = SomeMessage MsgCourseDeleteQuestion
  , drSuccessMessage = SomeMessage MsgCourseDeleted
  , drFormMessage = const $ return Nothing
  , drAbort = error "drAbort undefined"
  , drSuccess = error "drSuccess undefined"
  , drDelete = const id  -- TODO: audit
  }

setUserSubmissionGroup :: ( MonadHandler m
                          , HandlerSite m ~ UniWorX
                          , backend ~ SqlBackend
                          , MonadCatch m
                          ) => CourseId -> UserId -> Maybe SubmissionGroupName -> ReaderT backend m Bool
setUserSubmissionGroup cid uid = fmap (> 0) . setUsersSubmissionGroup cid (Set.singleton uid)

setUsersSubmissionGroup :: ( MonadHandler m
                           , HandlerSite m ~ UniWorX
                           , backend ~ SqlBackend
                           , MonadCatch m
                           ) => CourseId -> Set UserId -> Maybe SubmissionGroupName -> ReaderT backend m Int64
setUsersSubmissionGroup cid uids Nothing = do
  didDelete <- fmap getSum . flip foldMapM uids $ \uid -> do
    didDelete <- fmap (> 0) . E.deleteCount . E.from $ \submissionGroupUser ->
      E.where_ $ submissionGroupUser E.^. SubmissionGroupUserUser E.==. E.val uid
           E.&&. E.subSelectForeign submissionGroupUser SubmissionGroupUserSubmissionGroup (E.^. SubmissionGroupCourse) E.==. E.val cid
    when didDelete $
      audit $ TransactionSubmissionGroupUnset cid uid
    return $ bool mempty (Sum 1) didDelete
  E.delete . E.from $ \submissionGroup ->
    E.where_ $ submissionGroup E.^. SubmissionGroupCourse E.==. E.val cid
         E.&&. E.not_ (E.exists . E.from $ \submissionGroupUser -> E.where_ $ submissionGroupUser E.^. SubmissionGroupUserSubmissionGroup E.==. submissionGroup E.^. SubmissionGroupId)
  return didDelete
setUsersSubmissionGroup cid uids (Just grp) = do
  Entity gId _ <- upsert (SubmissionGroup cid grp) [ SubmissionGroupName =. grp ]

  E.delete . E.from $ \submissionGroupUser ->
    E.where_ $ submissionGroupUser E.^. SubmissionGroupUserUser `E.in_` E.valList (Set.toList uids)
         E.&&. E.subSelectForeign submissionGroupUser SubmissionGroupUserSubmissionGroup (E.^. SubmissionGroupCourse) E.==. E.val cid
         E.&&. submissionGroupUser E.^. SubmissionGroupUserSubmissionGroup E.!=. E.val gId
  E.delete . E.from $ \submissionGroup ->
    E.where_ $ submissionGroup E.^. SubmissionGroupCourse E.==. E.val cid
         E.&&. E.not_ (E.exists . E.from $ \submissionGroupUser -> E.where_ $ submissionGroupUser E.^. SubmissionGroupUserSubmissionGroup E.==. submissionGroup E.^. SubmissionGroupId)
         E.&&. submissionGroup E.^. SubmissionGroupId E.!=. E.val gId
  fmap getSum . flip foldMapM uids $ \uid -> do
    didSet <- fmap (is _Just) . insertUnique $ SubmissionGroupUser gId uid
    when didSet $
      audit $ TransactionSubmissionGroupSet cid uid grp
    return $ bool mempty (Sum 1) didSet