add params to redirect URL

auth.js

@@ -17,8 +17,15 @@ export class Auth {
     const url = new URL(
       this.remoteBaseUrl + '/'
     )
-    event.respondWith(new Response(
-      'extract query and redirect', {status: 200}
-    ))
+    const search = new URLSearchParams()
+    search.set('response_type', 'code')
+    search.set('client_id', this.giteaClientId)
+    search.set(
+      'redirect_uri',
+      this.remoteBaseUrl + '/auth/callback'
+    )
+    search.state = 'state'
+    url.search = search.toString()
+    return Response.redirect(url.toString())
   }
 }