Support.hs

data SupportData = SupportData
    { issues :: [Maybe (Entity Issue)]
    , customer :: Maybe (Entity Customer)
    , followUps :: [Entity FollowUp]
    , customerFollowUps :: [(Entity FollowUp, Entity Customer)]
    }

getSupportRData :: CustomerId -> Handler SupportData
getSupportRData customerId = do
  issue_mfollowUp_customer_list :: [(Entity Issue, Maybe (Entity FollowUp), Entity Customer)] <- runDB $
    E.select $
    E.from $ \(c `E.InnerJoin` i `E.LeftOuterJoin` f) -> do
    E.on (E.just (i ^. IssueId) ==. f ?. FollowUpIssueId)
    E.on (c ^. CustomerId ==. i ^. IssueCustomerId)
    E.where_ (i ^. IssueCustomerId ==. E.val customerId)
    return (i, f, c)
  let followUps :: [Entity FollowUp] = catMaybes . snd3 . unzip3 $ issue_mfollowUp_customer_list
  authors_followUps <- forM followUps $ \(followUp :: Entity FollowUp) -> do
    runDB $
      E.select $
      E.from $ \c -> do
      E.where_ (c ^. CustomerId ==. E.val (followUpFollowUpAuthor . entityVal $ followUp))
      return c
  let customers_followUps = zip followUps (concat $ authors_followUps)
  let issues :: [Maybe (Entity Issue)] = map listToMaybe . group . sort . fst3 . unzip3 $ issue_mfollowUp_customer_list
  let customer = listToMaybe . thd3 . unzip3 $ issue_mfollowUp_customer_list
  return SupportData
    { issues = issues
    , customer = customer
    , followUps = followUps
    , customerFollowUps = customers_followUps
    }