GitLab.hs

{-# LANGUAGE OverloadedStrings #-}
module Yesod.Auth.OAuth2.GitLab
  ( oauth2GitLab
  , oauth2GitLabHostScopes
  , defaultHost
  , defaultScopes
  ) where

import Yesod.Auth.OAuth2.Prelude

import qualified Data.Text as T

newtype User = User Int

instance FromJSON User where
  parseJSON = withObject "User" $ \o -> User <$> o .: "id"

pluginName :: Text
pluginName = "gitlab"

defaultHost :: URI
defaultHost = "https://gitlab.com"

defaultScopes :: [Text]
defaultScopes = ["read_user"]

-- | Authorize with @gitlab.com@ and @[\"read_user\"]@
--
-- To customize either of these values, use @'oauth2GitLabHostScopes'@ and pass
-- the default for the argument not being customized. Note that we require at
-- least @read_user@, so we can request the credentials identifier.
--
-- > oauth2GitLabHostScopes defaultHost ["api", "read_user"]
-- > oauth2GitLabHostScopes "https://gitlab.example.com" defaultScopes
--
oauth2GitLab :: YesodAuth m => Text -> Text -> AuthPlugin m
oauth2GitLab = oauth2GitLabHostScopes defaultHost defaultScopes

oauth2GitLabHostScopes
  :: YesodAuth m => URI -> [Text] -> Text -> Text -> AuthPlugin m
oauth2GitLabHostScopes host scopes clientId clientSecret =
  authOAuth2 pluginName oauth2 $ \manager token -> do
    (User userId, userResponse) <-
      authGetProfile pluginName manager token $ host `withPath` "/api/v4/user"

    pure Creds { credsPlugin = pluginName
               , credsIdent  = T.pack $ show userId
               , credsExtra  = setExtra token userResponse
               }
 where
  oauth2 = OAuth2
    { oauth2ClientId          = clientId
    , oauth2ClientSecret      = Just clientSecret
    , oauth2AuthorizeEndpoint = host
                                `withPath`  "/oauth/authorize"
                                `withQuery` [scopeParam " " scopes]
    , oauth2TokenEndpoint     = host `withPath` "/oauth/token"
    , oauth2RedirectUri       = Nothing
    }