1 files changed, 40 insertions, 0 deletions
diff --git a/auth/oauth.go b/auth/oauth.go
new file mode 100644
index 0000000..b8f1d47
--- /dev/null
+++ b/auth/oauth.go
@@ -0,0 +1,40 @@
+package auth
+
+import (
+    "net/http"
+    "golang.org/x/oauth2"
+)
+
+type authCodeFn func(string) func() string
+
+func NewOauthClient(clientId, clientSecret, tokenFile string, authFn authCodeFn) (*http.Client, error) {
+    conf := &oauth2.Config{
+        ClientID:     clientId,
+        ClientSecret: clientSecret,
+        Scopes:       []string{"https://www.googleapis.com/auth/drive"},
+        RedirectURL:  "urn:ietf:wg:oauth:2.0:oob",
+        Endpoint: oauth2.Endpoint{
+            AuthURL:  "https://accounts.google.com/o/oauth2/auth",
+            TokenURL: "https://accounts.google.com/o/oauth2/token",
+        },
+    }
+
+    // Read cached token
+    token, exists, err := ReadToken(tokenFile)
+    if err != nil {
+        return nil, err
+    }
+
+    // Require auth code if token file does not exist
+    // or refresh token is missing
+    if !exists || token.RefreshToken == "" {
+        authUrl := conf.AuthCodeURL("state", oauth2.AccessTypeOffline)
+        authCode := authFn(authUrl)()
+        token, err = conf.Exchange(oauth2.NoContext, authCode)
+    }
+
+    return oauth2.NewClient(
+        oauth2.NoContext,
+        FileSource(tokenFile, token, conf),
+    ), nil
+}