From 77120ad757c308b6229daae8093af6b9b50da543 Mon Sep 17 00:00:00 2001
From: wys <wuyuson4903@gmail.com>
Date: Sat, 22 Nov 2025 18:07:32 +0800
Subject: [PATCH] [add] Simulate Telegram OAuth2 login

---
 telegram/telegram.go | 16 ++++++++++++++++
 token.go             |  6 ++++++
 2 files changed, 22 insertions(+)
 create mode 100644 telegram/telegram.go

diff --git a/telegram/telegram.go b/telegram/telegram.go
new file mode 100644
index 000000000..7cc0ba682
--- /dev/null
+++ b/telegram/telegram.go
@@ -0,0 +1,16 @@
+package telegram
+
+import "golang.org/x/oauth2"
+
+var Endpoint = oauth2.Endpoint{
+	AuthURL: "https://oauth.telegram.org/auth",
+}
+
+func SetTelegramAuthStyle(botID string, originDomain string, redirectURL string) []oauth2.AuthCodeOption {
+	return []oauth2.AuthCodeOption{
+		oauth2.SetAuthURLParam("bot_id", botID),
+		oauth2.SetAuthURLParam("origin", originDomain),
+		oauth2.SetAuthURLParam("return_to", redirectURL),
+		oauth2.SetAuthURLParam("request_access", "write&embed=0"),
+	}
+}
diff --git a/token.go b/token.go
index e995eebb5..f3607e39e 100644
--- a/token.go
+++ b/token.go
@@ -6,6 +6,7 @@ package oauth2
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net/http"
 	"net/url"
@@ -172,6 +173,11 @@ func tokenFromInternal(t *internal.Token) *Token {
 // This token is then mapped from *internal.Token into an *oauth2.Token which is returned along
 // with an error.
 func retrieveToken(ctx context.Context, c *Config, v url.Values) (*Token, error) {
+
+	if c.Endpoint.TokenURL == "" {
+		return nil, errors.New("oauth2: no token endpoint")
+	}
+
 	tk, err := internal.RetrieveToken(ctx, c.ClientID, c.ClientSecret, c.Endpoint.TokenURL, v, internal.AuthStyle(c.Endpoint.AuthStyle), c.authStyleCache.Get())
 	if err != nil {
 		if rErr, ok := err.(*internal.RetrieveError); ok {