-- | @yesod-auth@ authentication plugin using Facebook's
-- server-side authentication flow.
module Yesod.Auth.Facebook.ServerSide
( -- * Authentication plugin
authFacebook
, facebookLogin
, facebookLogout
-- * Useful functions
, getUserAccessToken
, setUserAccessToken
-- * Advanced
, beta_authFacebook
, deleteUserAccessToken
) where
import Control.Applicative ((<$>))
import Control.Monad (when)
import Control.Monad.IO.Class (MonadIO, liftIO)
import Control.Monad.Trans.Maybe (MaybeT(..))
import Data.Monoid (mappend)
import Data.Text (Text)
import Network.Wai (queryString)
import Yesod.Auth
import Yesod.Handler
import Yesod.Widget
import qualified Data.Text as T
import qualified Data.Text.Encoding as TE
import qualified Facebook as FB
import qualified Yesod.Auth.Message as Msg
import qualified Data.Conduit as C
-- | Route for login using this authentication plugin.
facebookLogin :: AuthRoute
facebookLogin = PluginR "fb" ["login"]
-- | Route for logout using this authentication plugin. This
-- will log your user out of your site /and/ log him out of
-- Facebook since, at the time of writing, Facebook's policies
-- () specified that the
-- user needs to be logged out from Facebook itself as well. If
-- you want to always logout from just your site (and not from
-- Facebook), use 'LogoutR'.
facebookLogout :: AuthRoute
facebookLogout = PluginR "fb" ["logout"]
-- | Yesod authentication plugin using Facebook.
authFacebook :: YesodAuth master
=> FB.Credentials -- ^ Your application's credentials.
-> [FB.Permission] -- ^ Permissions to be requested.
-> AuthPlugin master
authFacebook = authFacebookHelper False
-- | Same as 'authFacebook', but uses Facebook's beta tier.
-- Usually this is /not/ what you want, so use 'authFacebook'
-- unless you know what you're doing.
--
-- /Since: 0.10.1/
beta_authFacebook :: YesodAuth master
=> FB.Credentials
-> [FB.Permission]
-> AuthPlugin master
beta_authFacebook = authFacebookHelper True
-- | Helper function for 'authFacebook' and 'beta_authFacebook'.
authFacebookHelper :: YesodAuth master
=> Bool -- ^ @useBeta@
-> FB.Credentials
-> [FB.Permission]
-> AuthPlugin master
authFacebookHelper useBeta creds perms = AuthPlugin "fb" dispatch login
where
-- Run a Facebook action.
runFB :: YesodAuth master =>
FB.FacebookT FB.Auth (C.ResourceT IO) a
-> GHandler sub master a
runFB act = do
manager <- authHttpManager <$> getYesod
liftIO $ C.runResourceT $
(if useBeta then FB.beta_runFacebookT else FB.runFacebookT)
creds manager act
-- Get the URL in facebook.com where users are redirected to.
getRedirectUrl :: YesodAuth master =>
(Route Auth -> Route master)
-> GHandler sub master Text
getRedirectUrl tm = do
render <- getUrlRender
let proceedUrl = render (tm proceedR)
runFB $ FB.getUserAccessTokenStep1 proceedUrl perms
proceedR = PluginR "fb" ["proceed"]
-- Redirect the user to Facebook.
dispatch "GET" ["login"] = do
m <- getYesod
when (redirectToReferer m) setUltDestReferer
redirect =<< getRedirectUrl =<< getRouteToMaster
-- Take Facebook's code and finish authentication.
dispatch "GET" ["proceed"] = do
tm <- getRouteToMaster
render <- getUrlRender
query <- queryString <$> waiRequest
let proceedUrl = render (tm proceedR)
query' = [(a,b) | (a, Just b) <- query]
token <- runFB $ FB.getUserAccessTokenStep2 proceedUrl query'
setUserAccessToken token
setCreds True (createCreds token)
-- Logout the user from our site and from Facebook.
dispatch "GET" ["logout"] = do
m <- getYesod
tm <- getRouteToMaster
mtoken <- getUserAccessToken
when (redirectToReferer m) setUltDestReferer
-- Facebook doesn't redirect back to our chosen address
-- when the user access token is invalid, so we need to
-- check its validity before anything else.
valid <- maybe (return False) (runFB . FB.isValid) mtoken
case (valid, mtoken) of
(True, Just token) -> do
render <- getUrlRender
dest <- runFB $ FB.getUserLogoutUrl token (render $ tm $ PluginR "fb" ["kthxbye"])
redirect dest
_ -> dispatch "GET" ["kthxbye"]
-- Finish the logout procedure. Unfortunately we have to
-- replicate yesod-auth's postLogoutR code here since it's
-- not accessible for us. We also can't just redirect to
-- LogoutR since it would otherwise call setUltDestReferrer
-- again.
dispatch "GET" ["kthxbye"] = do
m <- getYesod
deleteSession "_ID"
deleteUserAccessToken
onLogout
redirectUltDest $ logoutDest m
-- Anything else gives 404
dispatch _ _ = notFound
-- Small widget for multiple login websites.
login :: YesodAuth master =>
(Route Auth -> Route master)
-> GWidget sub master ()
login tm = do
redirectUrl <- lift (getRedirectUrl tm)
[whamlet|
_{Msg.Facebook}
|]
-- | Create an @yesod-auth@'s 'Creds' for a given
-- @'FB.UserAccessToken'@.
createCreds :: FB.UserAccessToken -> Creds m
createCreds (FB.UserAccessToken userId _ _) = Creds "fb" id_ []
where id_ = "http://graph.facebook.com/" `mappend` TE.decodeUtf8 userId
-- | Set the Facebook's user access token on the user's session.
-- Usually you don't need to call this function, but it may
-- become handy together with 'FB.extendUserAccessToken'.
setUserAccessToken :: FB.UserAccessToken
-> GHandler sub master ()
setUserAccessToken (FB.UserAccessToken userId data_ exptime) = do
setSession "_FBID" (TE.decodeUtf8 userId)
setSession "_FBAT" (TE.decodeUtf8 data_)
setSession "_FBET" (T.pack $ show exptime)
-- | Get the Facebook's user access token from the session.
-- Returns @Nothing@ if it's not found (probably because the user
-- is not logged in via @yesod-auth-fb@). Note that the returned
-- access token may have expired, we recommend using
-- 'FB.hasExpired' and 'FB.isValid'.
getUserAccessToken :: GHandler sub master (Maybe FB.UserAccessToken)
getUserAccessToken = runMaybeT $ do
userId <- MaybeT $ lookupSession "_FBID"
data_ <- MaybeT $ lookupSession "_FBAT"
exptime <- MaybeT $ lookupSession "_FBET"
return $ FB.UserAccessToken (TE.encodeUtf8 userId)
(TE.encodeUtf8 data_)
(read $ T.unpack exptime)
-- | Delete Facebook's user access token from the session. /Do/
-- /not use/ this function unless you know what you're doing.
deleteUserAccessToken :: GHandler sub master ()
deleteUserAccessToken = do
deleteSession "_FBID"
deleteSession "_FBAT"
deleteSession "_FBET"