yammat/Handler/Common.hs

-- | Common handler functions.
module Handler.Common where

import Data.FileEmbed (embedFile)
import qualified Data.Text as T
import qualified Data.Text.Lazy.Encoding as E
import qualified Data.Text.Read as R
import Yesod.Form.Functions
import Text.Shakespeare.Text
import Network.Mail.Mime
import Text.Printf
import Import

-- These handlers embed files in the executable at compile time to avoid a
-- runtime dependency, and for efficiency.

getFaviconR :: Handler TypedContent
getFaviconR = return $ TypedContent "image/x-icon"
                     $ toContent $(embedFile "config/favicon.ico")

getRobotsR :: Handler TypedContent
getRobotsR = return $ TypedContent typePlain
                    $ toContent $(embedFile "config/robots.txt")

updateCashier :: Int -> Text -> Handler ()
updateCashier amount desc = do
  mCashier <- runDB $ selectFirst [] [Asc CashierId]
  trans <- liftIO $ (\time -> return $ Transaction desc amount time) =<< getCurrentTime
  case mCashier of
    Just entCash -> do
      runDB $ update (entityKey entCash) [CashierBalance +=. amount]
      runDB $ insert_ trans
    Nothing -> do
      runDB $ insert_ $ Cashier amount
      runDB $ insert_ trans

getCashierBalance :: Handler Int
getCashierBalance = do
  mCashier <- runDB $ selectFirst [] [Asc CashierId]
  case mCashier of
    Just cashier -> do
      return $ cashierBalance $ entityVal cashier
    Nothing -> do
      return 0 

currencyField :: (RenderMessage (HandlerSite m) FormMessage, Show a, Monad m, Integral a) => Field m a
currencyField = Field
  { fieldParse = parseHelper $ \rawVals ->
      case R.double (prependZero rawVals) of
        Right (a, "") -> Right $ floor $ 100 * a
        _             -> Left $ MsgInvalidNumber rawVals
  , fieldView = \theId name attr val req -> toWidget [hamlet|$newline never
      <input id='{theId} name=#{name} *{attr} type="number" step=0.01 min=0 :req:required="" value=#{showVal val}>
      |]
  , fieldEnctype = UrlEncoded
  }
  where
    showVal = either id (pack . showA)
    showA x = show ((fromIntegral x :: Double) / 100)

amountField :: (RenderMessage (HandlerSite m) FormMessage, Show a, Monad m, Integral a) => Field m a
amountField = Field
  { fieldParse = parseHelper $ \s ->
    case R.decimal s of
      Right (a, "") -> Right a
      _ -> Left $ MsgInvalidInteger s
  , fieldView = \theId name attr val req -> toWidget [hamlet|$newline never
    <input id=#{theId} name="#{name}" *{attr} type="number" step=1 min=0 :req:required="" value="#{showVal val}">
    |]
  , fieldEnctype = UrlEncoded
  }
  where
    showVal = either id (pack . showI)
    showI x = show (fromIntegral x :: Integer)

checkAlert :: BeverageId -> Handler ()
checkAlert bId = do
  bev <- runDB $ getJust bId
  case beverageAmount bev < beverageAlertAmount bev of
    True -> do
      master <- getYesod
      to <- return $ appEmail $ appSettings master 
      sendMail to "Niedriger Bestand"
        [stext|
          Hallo,

          Der Bestand an #{beverageIdent bev} ist unterhalb der Warnschwelle von #{beverageAlertAmount bev}.
          Der momentane Bestand ist bei #{beverageAmount bev} Artikeln.

          Viele Grüße,

          der Matemat
        |]
    False -> return () -- do nothing

--sendMail :: MonadIO m => Text -> Text -> Text -> m ()
sendMail to subject body =
  liftIO $ renderSendMail
    Mail
      { mailFrom = Address Nothing "noreply"
      , mailTo = [Address Nothing to]
      , mailCc = []
      , mailBcc = []
      , mailHeaders = [("Subject", subject)]
      , mailParts =[[Part
        { partType = "text/plain; charset=utf-8"
        , partEncoding = None
        , partFilename = Nothing
        , partHeaders = []
        , partContent = E.encodeUtf8 body
        }]]
      }

prependZero :: Text -> Text
prependZero t0 = if T.null t1
                 then t1
                 else if T.head t1 == '.'
                      then '0' `T.cons` t1
                      else if "-." `T.isPrefixOf` t1
                           then "-0." `T.append` (T.drop 2 t1)
                           else t1

  where t1 = T.dropWhile ((==) ' ') t0

formatFloat :: Double -> Text
formatFloat = T.pack . (printf "%.2f")

formatIntCurrency :: Int -> Text
formatIntCurrency x = formatFloat $ ((fromIntegral x) / 100)