--  yammat - Yet Another MateMAT
--  Copyright (C) 2015  Amedeo Molnár
--
--  This program is free software: you can redistribute it and/or modify
--  it under the terms of the GNU Affero General Public License as published
--  by the Free Software Foundation, either version 3 of the License, or
--  (at your option) any later version.
--
--  This program is distributed in the hope that it will be useful,
--  but WITHOUT ANY WARRANTY; without even the implied warranty of
--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
--  GNU Affero General Public License for more details.
--
--  You should have received a copy of the GNU Affero General Public License
--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
module Handler.Buy where

import Import
import Handler.Common
import Text.Shakespeare.Text

getBuyR :: UserId -> BeverageId -> Handler Html
getBuyR uId bId = do
  mTup <- checkData uId bId
  case mTup of
    Just (user, bev) -> do
      master <- getYesod
      (buyWidget, enctype) <- generateFormPost
        $ renderBootstrap3 BootstrapBasicForm
        $ buyForm
      defaultLayout $
        $(widgetFile "buy")
    Nothing -> do
      setMessageI MsgUserOrArticleUnknown
      redirect HomeR

postBuyR :: UserId -> BeverageId -> Handler Html
postBuyR uId bId = do
  mTup <- checkData uId bId
  case mTup of
    Just (user, bev) -> do
      ((res, _), _) <- runFormPost
        $ renderBootstrap3 BootstrapBasicForm
        $ buyForm
      case res of
        FormSuccess quant -> do
          if quant > beverageAmount bev
            then do
              setMessageI MsgNotEnoughItems
              redirect $ BuyR uId bId
            else do
              let price = quant * (beveragePrice bev)
              let sw = price > (userBalance user)
              runDB $ update uId [UserBalance -=. price]
              runDB $ update bId [BeverageAmount -=. quant]
              checkAlert bId
              master <- getYesod
              liftIO $ notifyUser user bev price master
              case sw of
                False -> do
                  setMessageI MsgPurchaseSuccess
                  redirect HomeR
                True -> do
                  setMessageI MsgPurchaseDebtful
                  redirect HomeR
        _ -> do
          setMessageI MsgErrorOccured
          redirect HomeR
    Nothing -> do
      setMessageI MsgUserUnknown
      redirect HomeR

notifyUser :: User -> Beverage -> Int -> App -> IO ()
notifyUser user bev price master = do
  case userEmail user of
    Just email ->
      liftIO $ sendMail email "Einkauf beim Matematen"
        [stext|
Hallo #{userIdent user},

Du hast gerade beim Matematen für #{formatIntCurrency price}#{appCurrency $ appSettings master} #{beverageIdent bev} eingekauft.

Viele Grüsse,

Der Matemat
        |]
    Nothing ->
      return ()

getBuyCashR :: BeverageId -> Handler Html
getBuyCashR bId = do
  mBev <- runDB $ get bId
  case mBev of
    Just bev -> do
      master <- getYesod
      (buyCashWidget, enctype) <- generateFormPost
        $ renderBootstrap3 BootstrapBasicForm
        $ buyForm
      defaultLayout $
        $(widgetFile "buyCash")
    Nothing -> do
      setMessageI MsgItemUnknown
      redirect HomeR

postBuyCashR :: BeverageId -> Handler Html
postBuyCashR bId = do
  mBev <- runDB $ get bId
  case mBev of
    Just bev -> do
      ((res, _), _) <- runFormPost
        $ renderBootstrap3 BootstrapBasicForm
        $ buyForm
      case res of
        FormSuccess quant -> do
          if quant > beverageAmount bev
            then do
              setMessageI MsgNotEnoughItems
              redirect $ BuyCashR bId
            else do
              master <- getYesod
              let price = quant * (beveragePrice bev + appCashCharge (appSettings master))
              runDB $ update bId [BeverageAmount -=. quant]
              updateCashier price "Barzahlung"
              checkAlert bId
              let currency = appCurrency $ appSettings master
              setMessageI $ MsgPurchaseSuccessCash price currency
              redirect HomeR
        _ -> do
          setMessageI MsgItemDisappeared
          redirect HomeR
    Nothing -> do
      setMessageI MsgItemUnknown
      redirect HomeR

checkData :: UserId -> BeverageId -> Handler (Maybe (User, Beverage))
checkData uId bId = do
  mUser <- runDB $ get uId
  mBev <- runDB $ get bId
  case mUser of
    Just user -> do
      case mBev of
        Just bev -> return $ Just (user, bev)
        Nothing -> return Nothing
    Nothing -> return Nothing

buyForm :: AForm Handler Int
buyForm = areq amountField (bfs MsgAmount) (Just 1)
  <* bootstrapSubmit (msgToBSSubmit MsgPurchase)