module Model.Payment
  ( getPayments
  , createPayment
  , deleteOwnPayment
  , getTotalPayments
  , getPaymentsCount
  ) where

import Data.Text (Text)
import Data.Time.Clock (getCurrentTime)
import Data.Maybe (catMaybes)

import Control.Monad.IO.Class (liftIO)

import Database.Persist
import qualified Database.Persist as P
import Database.Esqueleto
import qualified Database.Esqueleto as E

import Model.Database
import qualified Model.Json.Payment as P
import qualified Model.Json.TotalPayment as TP

getPayments :: Int -> Int -> Persist [P.Payment]
getPayments page perPage = do
  xs <- select $
        from $ \(payment `InnerJoin` user) -> do
          on (payment ^. PaymentUserId E.==. user ^. UserId)
          where_ (isNothing (payment ^. PaymentDeletedAt))
          orderBy [desc (payment ^. PaymentCreation)]
          limit . fromIntegral $ perPage
          offset . fromIntegral $ (page - 1) * perPage
          return (payment, user)
  return (map getJsonPayment xs)

getJsonPayment :: (Entity Payment, Entity User) -> P.Payment
getJsonPayment (paymentEntity, userEntity) =
  let payment = entityVal paymentEntity
      user = entityVal userEntity
  in  P.Payment
        { P.id = entityKey paymentEntity
        , P.creation = paymentCreation payment
        , P.name = paymentName payment
        , P.cost = paymentCost payment
        , P.userId = entityKey userEntity
        }

createPayment :: UserId -> Text -> Int -> Persist PaymentId
createPayment userId name cost = do
  now <- liftIO getCurrentTime
  insert $ Payment userId now name cost Nothing

deleteOwnPayment :: Entity User -> PaymentId -> Persist Bool
deleteOwnPayment user paymentId = do
  mbPayment <- get paymentId
  case mbPayment of
    Just payment ->
      if paymentUserId payment == entityKey user
        then do
          now <- liftIO getCurrentTime
          P.update paymentId [PaymentDeletedAt P.=. Just now]
          return True
        else
          return False
    Nothing ->
      return False

getTotalPayments :: Persist [TP.TotalPayment]
getTotalPayments = do
  values <- select $
            from $ \(payment `InnerJoin` user) -> do
              on (payment ^. PaymentUserId E.==. user ^. UserId)
              where_ (isNothing (payment ^. PaymentDeletedAt))
              groupBy (payment ^. PaymentUserId)
              return (user ^. UserId, sum_ (payment ^. PaymentCost))
  return $ catMaybes . map (getTotalPayment . unValueTuple) $ values

getTotalPayment :: (UserId, Maybe Int) -> Maybe TP.TotalPayment
getTotalPayment (userId, Just cost) = Just (TP.TotalPayment userId cost)
getTotalPayment (_, Nothing) = Nothing

unValueTuple :: (Value a, Value b) -> (a, b)
unValueTuple (Value a, Value b) = (a, b)

getPaymentsCount :: Persist Int
getPaymentsCount =
  unValue . head <$>
    (select $
    from $ \payment -> do
      where_ (isNothing (payment ^. PaymentDeletedAt))
      return countRows) :: Persist Int