{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
module Handler.ExpenseFile where

import Import
import Handler.Expense (expenseFileForm)
import Data.Csv (decodeByName)
import qualified Data.ByteString as B

postExpenseFileR :: Handler Html
postExpenseFileR = do
    ((result, _), _) <- runFormPost expenseFileForm
    case result of
        FormSuccess fileInfo -> handleFormSuccess fileInfo
        _ -> handleFormUnsuccess

-- what we need to do here is use fileSource :: FileInfo -> Source m ByteString
handleFormSuccess :: FileInfo -> Handler Html
handleFormSuccess fileInfo = do
    expenseShells <- runConduit $ fileSource fileInfo .| toExpenseShell .| sinkList
    redirect ExpenseR

handleFormUnsuccess :: Handler Html
handleFormUnsuccess = do
    setMessage "Invalid File Form Submitted"
    redirect ExpenseR

-- Conduit Components
-- Source m ByteString ~ ConduitM () ByteString m ()
-- ConduitM ByteString downstream m ()
-- toExpenseShell :: ConduitM i (Either String (Vector ExpenseShell)) m ()
toExpenseShell :: ConduitM B.ByteString (Either String (Vector ExpenseShell)) m ()
toExpenseShell = mapC $ \bs -> fmap snd (decodeByName bs)

-- probaly goes in another module
data ExpenseShell = ExpenseShell { esAmount :: !Int, esItem :: !Text, esVendor :: !Text }