get token from OAuth provider

auth/oauth_callback.go

@@ -1,8 +1,11 @@
 package auth
 
 import (
-	"fmt"
+	"context"
+	"log"
 	"net/http"
+
+	"golang.org/x/oauth2"
 )
 
 // this is usually served at /callback
@@ -27,5 +30,24 @@ func OAuthCallback(w http.ResponseWriter, r *http.Request) {
 		MaxAge: -1,
 	})
 
-	fmt.Printf("Handling some OAuth, %s\n", code)
+	verifierCookie, err := r.Cookie("pkce_verifier")
+	if err != nil {
+		http.Error(w, "Missing PKCE verifier", http.StatusBadRequest)
+		return
+	}
+
+	verifier := verifierCookie.Value
+
+	token, err := OAuthConfigs[0].Exchange(context.Background(), code, oauth2.VerifierOption(verifier))
+	if err != nil {
+		http.Error(w, "Failed to exchange token: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	// Store the token securely
+	if err := tokenStore.Save(token); err != nil {
+		log.Printf("Failed to save token: %v", err)
+	}
+
+	http.Redirect(w, r, "/user", http.StatusTemporaryRedirect)
 }