{-# LANGUAGE OverloadedStrings #-}

module Model.Payment
  ( getPunctualPayments
  , getUserMonthlyPayments
  , getMonthlyPayments
  , createPayment
  , deleteOwnPayment
  , getPaymentsCount
  ) where

import Data.Text (Text)
import Data.Time.Clock (getCurrentTime)
import Data.Either (lefts)

import Control.Monad.IO.Class (liftIO)

import Database.Persist
import qualified Database.Persist as P

import qualified Validation

import Model.Database
import Model.Frequency
import qualified Model.Json.Payment as P
import qualified Model.Message.Key as K

getPunctualPayments :: Persist [P.Payment]
getPunctualPayments =
  map getJsonPayment <$> selectList
    [ PaymentDeletedAt P.==. Nothing
    , PaymentFrequency P.==. Punctual
    ]
    [ Desc PaymentCreation ]

getUserMonthlyPayments :: UserId -> Persist [P.Payment]
getUserMonthlyPayments userId =
  filter ((==) userId . P.userId) . map getJsonPayment <$> getMonthlyPayments

getMonthlyPayments :: Persist [Entity Payment]
getMonthlyPayments =
  selectList
    [ PaymentDeletedAt P.==. Nothing
    , PaymentFrequency P.==. Monthly
    ]
    [ Desc PaymentName ]

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

createPayment :: UserId -> Text -> Text -> Frequency -> Persist (Either [(Text, K.Key)] PaymentId)
createPayment userId name cost frequency =
  case validatePayment name cost of
    Left err ->
      return . Left $ err
    Right (validatedName, validatedCost) -> do
      now <- liftIO getCurrentTime
      Right <$> insert (Payment userId now validatedName validatedCost Nothing frequency)

validatePayment :: Text -> Text -> Either [(Text, K.Key)] (Text, Int)
validatePayment name cost =
  let eitherName = Validation.nonEmpty K.CategoryRequired name
      eitherCost = Validation.nonEmpty K.CostRequired cost >>= Validation.number K.CostRequired (/= 0)
  in  case (eitherName, eitherCost) of
        (Right validatedName, Right validatedCost) ->
          Right (validatedName, validatedCost)
        _ ->
          let nameErrors = map (\x -> ("name", x)) $ lefts [eitherName]
              costErrors = map (\x -> ("cost", x)) $ lefts [eitherCost]
          in  Left (nameErrors ++ costErrors)

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

getPaymentsCount :: Persist Int
getPaymentsCount =
  count
    [ PaymentDeletedAt P.==. Nothing
    , PaymentFrequency P.==. Punctual
    ]