{-# LANGUAGE ImportQualifiedPost #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE NoImplicitPrelude #-}

module Handler.Api where

import Data.Time.Clock.POSIX (posixSecondsToUTCTime)
import Database.Persist.Sql (rawSql)
import Import

getApiR :: Int -> Handler TypedContent
getApiR time = do
  -- TODO: use only one runDB (or use joins ?)
  userId <- getUserId
  let utcTime = posixSecondsToUTCTime (fromIntegral time)
  -- condition : parent user or group changed
  let sqlUpdatedGroups = "select ?? from \"group\" join group_user gu on \"group\".id = gu.group_id where gu.user = ? where \"group\".last_modified > ? or user.last_modified > ?;"
  -- condition : parent group or list changed
  let sqlUpdatedLists = "select ?? from todolist join group_user on todolist.group_id = group_user.group_id and group_user.user = ? join \"group\" as g on g.id = todolist.id where list.last_modified > ? or g.last_modified > ?;"
  -- condition : parent list changed
  let sqlUpdatedItems = "select ?? from todolist where todolist.last_modified > ? join group_user on todolist.group_id = group_user.group_id and group_user.user = ? join todolist_item on todolist_item.todolist_id = todolist.id;"
  runDB $ do
    user <- selectList [UserId ==. userId, UserLastModified >. utcTime] []
    groups <- rawSql sqlUpdatedGroups [toPersistValue userId, toPersistValue utcTime, toPersistValue utcTime]
    lists <- rawSql sqlUpdatedLists [toPersistValue userId, toPersistValue utcTime, toPersistValue utcTime]
    items <- rawSql sqlUpdatedItems [toPersistValue utcTime, toPersistValue userId]
    let t =
          unlines
            $ map userToCSV user
            <> map groupToCSV groups
            <> map todolistToCSV lists
            <> map todolistItemToCSV items
    return $ TypedContent typePlain $ toContent t