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Detailed reasoning in #197, and in the code comments of this PR

Closes #197
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@MaxGabriel
MaxGabriel committed Dec 29, 2019
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301 changes: 5 additions & 296 deletions src/Foundation.hs
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{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE ExplicitForAll #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE InstanceSigs #-}
module Foundation
( module X
) where

module Foundation where

import Import.NoFoundation
import Database.Persist.Sql (ConnectionPool, runSqlPool)
import Text.Hamlet (hamletFile)
import Text.Jasmine (minifym)
import Control.Monad.Logger (LogSource)

-- Used only when in "auth-dummy-login" setting is enabled.
import Yesod.Auth.Dummy

import Yesod.Auth.OpenId (authOpenId, IdentifierType (Claimed))
import Yesod.Default.Util (addStaticContentExternal)
import Yesod.Core.Types (Logger)
import qualified Yesod.Core.Unsafe as Unsafe
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.
, appConnPool :: ConnectionPool -- ^ Database connection pool.
, appHttpManager :: Manager
, appLogger :: Logger
}

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)

-- | A convenient synonym for database access functions.
type DB a = forall (m :: * -> *).
(MonadUnliftIO m) => ReaderT SqlBackend m a

-- 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

muser <- maybeAuthPair
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
}
, NavbarLeft $ MenuItem
{ menuItemLabel = "Profile"
, menuItemRoute = ProfileR
, menuItemAccessCallback = isJust muser
}
, NavbarRight $ MenuItem
{ menuItemLabel = "Login"
, menuItemRoute = AuthR LoginR
, menuItemAccessCallback = isNothing muser
}
, NavbarRight $ MenuItem
{ menuItemLabel = "Logout"
, menuItemRoute = AuthR LogoutR
, menuItemAccessCallback = isJust muser
}
]

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")

-- The page to be redirected to when authentication is required.
authRoute
:: App
-> Maybe (Route App)
authRoute _ = Just $ AuthR LoginR

isAuthorized
:: Route App -- ^ The route the user is visiting.
-> Bool -- ^ Whether or not this is a "write" request.
-> Handler AuthResult
-- Routes not requiring authentication.
isAuthorized (AuthR _) _ = return Authorized
isAuthorized CommentR _ = return Authorized
isAuthorized HomeR _ = return Authorized
isAuthorized FaviconR _ = return Authorized
isAuthorized RobotsR _ = return Authorized
isAuthorized (StaticR _) _ = return Authorized

-- the profile route requires that the user is authenticated, so we
-- delegate to that function
isAuthorized ProfileR _ = isAuthenticated

-- 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 (AuthR _) = return ("Login", Just HomeR)
breadcrumb ProfileR = return ("Profile", Just HomeR)
breadcrumb _ = return ("home", Nothing)

-- How to run database actions.
instance YesodPersist App where
type YesodPersistBackend App = SqlBackend
runDB :: SqlPersistT Handler a -> Handler a
runDB action = do
master <- getYesod
runSqlPool action $ appConnPool master

instance YesodPersistRunner App where
getDBRunner :: Handler (DBRunner App, Handler ())
getDBRunner = defaultGetDBRunner appConnPool

instance YesodAuth App where
type AuthId App = UserId

-- Where to send a user after successful login
loginDest :: App -> Route App
loginDest _ = HomeR
-- Where to send a user after logout
logoutDest :: App -> Route App
logoutDest _ = HomeR
-- Override the above two destinations when a Referer: header is present
redirectToReferer :: App -> Bool
redirectToReferer _ = True

authenticate :: (MonadHandler m, HandlerSite m ~ App)
=> Creds App -> m (AuthenticationResult App)
authenticate creds = liftHandler $ runDB $ do
x <- getBy $ UniqueUser $ credsIdent creds
case x of
Just (Entity uid _) -> return $ Authenticated uid
Nothing -> Authenticated <$> insert User
{ userIdent = credsIdent creds
, userPassword = Nothing
}

-- You can add other plugins like Google Email, email or OAuth here
authPlugins :: App -> [AuthPlugin App]
authPlugins app = [authOpenId Claimed []] ++ extraAuthPlugins
-- Enable authDummy login if enabled.
where extraAuthPlugins = [authDummy | appAuthDummyLogin $ appSettings app]

-- | Access function to determine if a user is logged in.
isAuthenticated :: Handler AuthResult
isAuthenticated = do
muid <- maybeAuthId
return $ case muid of
Nothing -> Unauthorized "You must login to access this page"
Just _ -> Authorized

instance YesodAuthPersist App

-- 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
import Foundation.Primitive as X
import Foundation.Orphans as X
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