From e9b2c0bba94821a27786c9ebd9bf1fc7491a5742 Mon Sep 17 00:00:00 2001
From: CJ Avilla <cjavilla@stripe.com>
Date: Thu, 18 Jul 2019 19:03:26 -0700
Subject: [PATCH] Handle OAuth Errors

---
 error.go             |  4 ++++
 oauth.go             | 16 +++-------------
 oauth/client.go      |  5 +----
 oauth/client_test.go |  5 ++---
 stripe.go            |  9 ++++++++-
 5 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/error.go b/error.go
index 8fe28d7f47..3852e0372d 100644
--- a/error.go
+++ b/error.go
@@ -58,6 +58,10 @@ type Error struct {
 	SetupIntent    *SetupIntent   `json:"setup_intent,omitempty"`
 	Source         *PaymentSource `json:"source,omitempty"`
 	Type           ErrorType      `json:"type"`
+
+	// OAuth specific Error properties. Named OAuthError because of name conflict.
+	OAuthError            string `json:"error,omitempty"`
+	OAuthErrorDescription string `json:"error_description,omitempty"`
 }
 
 // Error serializes the error object to JSON and returns it as a string.
diff --git a/oauth.go b/oauth.go
index 3769d7b424..a89e9c2246 100644
--- a/oauth.go
+++ b/oauth.go
@@ -40,16 +40,6 @@ const (
 	OAuthStripeUserGenderMale   OAuthStripeUserGender = "male"
 )
 
-
-// DeauthorizeError the type of errors raised when failing authorization.
-type DeauthorizeError string
-
-// List of supported DeauthorizeError values.
-const (
-	DeauthorizeErrorInvalidClient  DeauthorizeError = "invalid_client"
-	DeauthorizeErrorInvalidRequest DeauthorizeError = "invalid_request"
-)
-
 // OAuthStripeUserParams for the stripe_user OAuth Authorize params.
 type OAuthStripeUserParams struct {
 	BlockKana          *string `form:"block_kana"`
@@ -61,9 +51,9 @@ type OAuthStripeUserParams struct {
 	City               *string `form:"city"`
 	Country            *string `form:"country"`
 	Currency           *string `form:"currency"`
-	DOBDay             *int64 `form:"dob_day"`
-	DOBMonth           *int64 `form:"dob_month"`
-	DOBYear            *int64 `form:"dob_year"`
+	DOBDay             *int64  `form:"dob_day"`
+	DOBMonth           *int64  `form:"dob_month"`
+	DOBYear            *int64  `form:"dob_year"`
 	Email              *string `form:"email"`
 	FirstName          *string `form:"first_name"`
 	FirstNameKana      *string `form:"first_name_kana"`
diff --git a/oauth/client.go b/oauth/client.go
index 106dabed6c..8c0adabd48 100644
--- a/oauth/client.go
+++ b/oauth/client.go
@@ -36,7 +36,7 @@ func (c Client) AuthorizeURL(params *stripe.AuthorizeURLParams) string {
 	form.AppendTo(qs, params)
 	return fmt.Sprintf(
 		"%s%s/oauth/authorize?%s",
-    stripe.ConnectURL,
+		stripe.ConnectURL,
 		express,
 		qs.Encode(),
 	)
@@ -53,9 +53,6 @@ func (c Client) New(params *stripe.OAuthTokenParams) (*stripe.OAuthToken, error)
 	if stripe.StringValue(params.ClientSecret) == "" {
 		params.ClientSecret = stripe.String(stripe.Key)
 	}
-	if stripe.StringValue(params.GrantType) == "" {
-		params.GrantType = stripe.String("authorization_code")
-	}
 
 	oauthToken := &stripe.OAuthToken{}
 	err := c.B.Call(http.MethodPost, "/oauth/token", c.Key, params, oauthToken)
diff --git a/oauth/client_test.go b/oauth/client_test.go
index 8bfc65b400..b0956c1316 100644
--- a/oauth/client_test.go
+++ b/oauth/client_test.go
@@ -235,10 +235,9 @@ func TestNewOAuthTokenWithError(t *testing.T) {
 	assert.NotNil(t, err)
 
 	stripeErr := err.(*stripe.Error)
-  // TODO: I think this is what I want to test once we get the structure right.
 	assert.Equal(t, 400, stripeErr.HTTPStatusCode)
-	assert.Equal(t, "Authorization code does not exist", stripeErr.Msg)
-	assert.Equal(t, "invalid_grant", stripeErr.Type)
+	assert.Equal(t, "Authorization code does not exist", stripeErr.OAuthErrorDescription)
+	assert.Equal(t, "invalid_grant", stripeErr.OAuthError)
 }
 
 func TestDeauthorize(t *testing.T) {
diff --git a/stripe.go b/stripe.go
index 6aa8cebf5b..4389e2cb1f 100644
--- a/stripe.go
+++ b/stripe.go
@@ -463,7 +463,14 @@ func (s *BackendImplementation) Do(req *http.Request, body *bytes.Buffer, v inte
 func (s *BackendImplementation) ResponseToError(res *http.Response, resBody []byte) error {
 	var raw rawError
 	if err := s.UnmarshalJSONVerbose(res.StatusCode, resBody, &raw); err != nil {
-		return err
+		// If deserializing the error json fails at the top level, we retry
+		// serializing at the error level because the shape of error response body
+		// for the API is different from the OAuth error response.
+		var topLevelError rawErrorInternal
+		if err := s.UnmarshalJSONVerbose(res.StatusCode, resBody, &topLevelError); err != nil {
+			return err
+		}
+		raw.E = &topLevelError
 	}
 
 	// no error in resBody