Foundation.hs 8.6 KB
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{-# LANGUAGE FlexibleInstances #-}
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{-# LANGUAGE DataKinds #-}
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{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE InstanceSigs #-}

module Foundation where

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import Import.NoFoundation as Pre
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import Control.Monad.Logger        (LogSource)
import Text.Hamlet                 (hamletFile)
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import qualified Control.Monad.Catch as MC
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import Text.Jasmine                (minifym)
import Yesod.Core.Types            (Logger)
import Yesod.Default.Util          (addStaticContentExternal)
import qualified Yesod.Core.Unsafe as Unsafe
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import Network.Google.Auth (Credentials)
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import qualified Data.CaseInsensitive as CI
import qualified Data.Text.Encoding as TE

-- | The foundation datatype for your application. This can be a good place to
-- keep settings and values requiring initialization before your application
-- starts running, such as database connections. Every handler will have
-- access to the data present here.
data App = App
    { appSettings    :: AppSettings
    , appStatic      :: Static -- ^ Settings for static file serving.
    , appHttpManager :: Manager
    , appLogger      :: Logger
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    , appGoogleCreds :: Credentials CalendarScope
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    }

data MenuItem = MenuItem
    { menuItemLabel :: Text
    , menuItemRoute :: Route App
    , menuItemAccessCallback :: Bool
    }

data MenuTypes
    = NavbarLeft MenuItem
    | NavbarRight MenuItem

-- This is where we define all of the routes in our application. For a full
-- explanation of the syntax, please see:
-- http://www.yesodweb.com/book/routing-and-handlers
--
-- Note that this is really half the story; in Application.hs, mkYesodDispatch
-- generates the rest of the code. Please see the following documentation
-- for an explanation for this split:
-- http://www.yesodweb.com/book/scaffolding-and-the-site-template#scaffolding-and-the-site-template_foundation_and_application_modules
--
-- This function also generates the following type synonyms:
-- type Handler = HandlerT App IO
-- type Widget = WidgetT App IO ()
mkYesodData "App" $(parseRoutesFile "config/routes")

-- | A convenient synonym for creating forms.
type Form x = Html -> MForm (HandlerFor App) (FormResult x, Widget)

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instance MC.MonadCatch (HandlerFor App) where
  catch = Pre.catch

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-- Please see the documentation for the Yesod typeclass. There are a number
-- of settings which can be configured by overriding methods here.
instance Yesod App where
    -- Controls the base of generated URLs. For more information on modifying,
    -- see: https://github.com/yesodweb/yesod/wiki/Overriding-approot
    approot :: Approot App
    approot = ApprootRequest $ \app req ->
        case appRoot $ appSettings app of
            Nothing -> getApprootText guessApproot app req
            Just root -> root

    -- Store session data on the client in encrypted cookies,
    -- default session idle timeout is 120 minutes
    makeSessionBackend :: App -> IO (Maybe SessionBackend)
    makeSessionBackend _ = Just <$> defaultClientSessionBackend
        120    -- timeout in minutes
        "config/client_session_key.aes"

    -- Yesod Middleware allows you to run code before and after each handler function.
    -- The defaultYesodMiddleware adds the response header "Vary: Accept, Accept-Language" and performs authorization checks.
    -- Some users may also want to add the defaultCsrfMiddleware, which:
    --   a) Sets a cookie with a CSRF token in it.
    --   b) Validates that incoming write requests include that token in either a header or POST parameter.
    -- To add it, chain it together with the defaultMiddleware: yesodMiddleware = defaultYesodMiddleware . defaultCsrfMiddleware
    -- For details, see the CSRF documentation in the Yesod.Core.Handler module of the yesod-core package.
    yesodMiddleware :: ToTypedContent res => Handler res -> Handler res
    yesodMiddleware = defaultYesodMiddleware

    defaultLayout :: Widget -> Handler Html
    defaultLayout widget = do
        master <- getYesod
        mmsg <- getMessage

        mcurrentRoute <- getCurrentRoute

        -- Get the breadcrumbs, as defined in the YesodBreadcrumbs instance.
        (title, parents) <- breadcrumbs

        -- Define the menu items of the header.
        let menuItems =
                [ NavbarLeft $ MenuItem
                    { menuItemLabel = "Home"
                    , menuItemRoute = HomeR
                    , menuItemAccessCallback = True
                    }
                ]

        let navbarLeftMenuItems = [x | NavbarLeft x <- menuItems]
        let navbarRightMenuItems = [x | NavbarRight x <- menuItems]

        let navbarLeftFilteredMenuItems = [x | x <- navbarLeftMenuItems, menuItemAccessCallback x]
        let navbarRightFilteredMenuItems = [x | x <- navbarRightMenuItems, menuItemAccessCallback x]

        -- We break up the default layout into two components:
        -- default-layout is the contents of the body tag, and
        -- default-layout-wrapper is the entire page. Since the final
        -- value passed to hamletToRepHtml cannot be a widget, this allows
        -- you to use normal widget features in default-layout.

        pc <- widgetToPageContent $ do
            addStylesheet $ StaticR css_bootstrap_css
            $(widgetFile "default-layout")
        withUrlRenderer $(hamletFile "templates/default-layout-wrapper.hamlet")

    isAuthorized
        :: Route App  -- ^ The route the user is visiting.
        -> Bool       -- ^ Whether or not this is a "write" request.
        -> Handler AuthResult
    -- Routes not requiring authenitcation.
    isAuthorized FaviconR _ = return Authorized
    isAuthorized RobotsR _ = return Authorized
    -- Default to Authorized for now.
    isAuthorized _ _ = return Authorized

    -- This function creates static content files in the static folder
    -- and names them based on a hash of their content. This allows
    -- expiration dates to be set far in the future without worry of
    -- users receiving stale content.
    addStaticContent
        :: Text  -- ^ The file extension
        -> Text -- ^ The MIME content type
        -> LByteString -- ^ The contents of the file
        -> Handler (Maybe (Either Text (Route App, [(Text, Text)])))
    addStaticContent ext mime content = do
        master <- getYesod
        let staticDir = appStaticDir $ appSettings master
        addStaticContentExternal
            minifym
            genFileName
            staticDir
            (StaticR . flip StaticRoute [])
            ext
            mime
            content
      where
        -- Generate a unique filename based on the content itself
        genFileName lbs = "autogen-" ++ base64md5 lbs

    -- What messages should be logged. The following includes all messages when
    -- in development, and warnings and errors in production.
    shouldLogIO :: App -> LogSource -> LogLevel -> IO Bool
    shouldLogIO app _source level =
        return $
        appShouldLogAll (appSettings app)
            || level == LevelWarn
            || level == LevelError

    makeLogger :: App -> IO Logger
    makeLogger = return . appLogger

-- Define breadcrumbs.
instance YesodBreadcrumbs App where
    -- Takes the route that the user is currently on, and returns a tuple
    -- of the 'Text' that you want the label to display, and a previous
    -- breadcrumb route.
    breadcrumb
        :: Route App  -- ^ The route the user is visiting currently.
        -> Handler (Text, Maybe (Route App))
    breadcrumb HomeR = return ("Home", Nothing)
    breadcrumb  _ = return ("home", Nothing)

-- This instance is required to use forms. You can modify renderMessage to
-- achieve customized and internationalized form validation messages.
instance RenderMessage App FormMessage where
    renderMessage :: App -> [Lang] -> FormMessage -> Text
    renderMessage _ _ = defaultFormMessage

-- Useful when writing code that is re-usable outside of the Handler context.
-- An example is background jobs that send email.
-- This can also be useful for writing code that works across multiple Yesod applications.
instance HasHttpManager App where
    getHttpManager :: App -> Manager
    getHttpManager = appHttpManager

unsafeHandler :: App -> Handler a -> IO a
unsafeHandler = Unsafe.fakeHandlerGetLogger appLogger

-- Note: Some functionality previously present in the scaffolding has been
-- moved to documentation in the Wiki. Following are some hopefully helpful
-- links:
--
-- https://github.com/yesodweb/yesod/wiki/Sending-email
-- https://github.com/yesodweb/yesod/wiki/Serve-static-files-from-a-separate-domain
-- https://github.com/yesodweb/yesod/wiki/i18n-messages-in-the-scaffolding