Erase the URL query on login unless the user opts in.

Users often open Votr with a saved link from their bookmarks or history. If the
link is bad (e.g. it has an invalid key for some reason), the user gets an error
every time they log in with it. Even for valid URLs, I'm not so sure whether the
user really wanted to visit that page or it's just a waste of resources.

The login page now has a checkbox to respect the current URL. It is false by
default, but it is persisted in localStorage. I hope this will be better for
users who use saved links by accident, while still allowing power users to
bookmark pages if they want.

Stats for 2023-01:
- 71% of logins had empty destination
- 21% of logins only had ?action= in destination
- 8% of logins had multiple query parameters

Updates #65. Updates #133.

votrfront/js/LoginPage.tsx

@@ -1,8 +1,10 @@
 import _ from "lodash";
-import React, { useState } from "react";
+import React, { useContext, useState } from "react";
 import { AboutModal } from "./About";
+import { actionTitles } from "./actions";
 import { Modal, ModalBase } from "./layout";
-import { FakeLink } from "./router";
+import { getLocalSetting, setLocalSetting } from "./LocalSettings";
+import { buildUrl, FakeLink, QueryContext } from "./router";
 
 var TYPE_NAMES: Record<string, string> = {
   "cosignproxy": "Cosign (automatické)",
@@ -12,6 +14,34 @@ var TYPE_NAMES: Record<string, string> = {
   "demo": "Demo",
 };
 
+function DestinationCheckbox() {
+  var query = useContext(QueryContext);
+  var { action, modal } = query;
+  var actionTitle = action && actionTitles[action];
+
+  // Don't show the checkbox if the query string is empty or it only contains
+  // foreign params (?fbclid=...).
+  if (!action && !modal) return null;
+
+  return (
+    <p>
+      <label>
+        <input
+          type="checkbox"
+          name="destination"
+          value={buildUrl(query)}
+          checked={getLocalSetting("useDestination") == "true"}
+          onChange={(event) => {
+            setLocalSetting("useDestination", String(event.target.checked));
+          }}
+        />{" "}
+        Začať tam kde predtým {actionTitle ? "(" + actionTitle + ") " : null}
+        podľa uloženej webovej adresy
+      </label>
+    </p>
+  );
+}
+
 function LoginForm({ onOpenError }: { onOpenError: () => void }) {
   var [state, setState] = useState({
     server: Votr.settings.server || 0,
@@ -62,7 +92,7 @@ function LoginForm({ onOpenError }: { onOpenError: () => void }) {
         </React.Fragment>
       )}
 
-      <input type="hidden" name="destination" value={location.search} />
+      <DestinationCheckbox />
 
       {Votr.settings.servers!.length > 1 ? (
         <p>

votrfront/js/actions.tsx

@@ -25,7 +25,6 @@ function makeNotFoundPage() {
 }
 
 var actions: Record<string, () => React.ReactNode> = {
-  index: makeIndexPage,
   priebezneHodnotenia: makePriebezneHodnoteniaPage,
   mojeHodnotenia: makeMojeHodnoteniaPage,
   mojePredmety: makeMojePredmetyPage,
@@ -37,6 +36,20 @@ var actions: Record<string, () => React.ReactNode> = {
   zapisZPonuky: makeZapisZPonukyPage,
 };
 
+// TODO: Reduce code duplication of page titles.
+// TODO: Set document.title immediately even if a ...Selector is loading.
+export const actionTitles: Record<string, string> = {
+  priebezneHodnotenia: "Priebežné hodnotenia",
+  mojeHodnotenia: "Moje hodnotenia",
+  mojePredmety: "Moje predmety",
+  mojeSkusky: "Moje skúšky",
+  prehladStudia: "Prehľad štúdia",
+  registerOsob: "Register osôb",
+  registerPredmetov: "Register predmetov",
+  zapisZPlanu: "Zápis predmetov",
+  zapisZPonuky: "Zápis predmetov",
+};
+
 var modalActions: Record<string, React.ComponentType> = {
   about: AboutModal,
   detailPredmetu: DetailPredmetuModal,
@@ -45,8 +58,8 @@ var modalActions: Record<string, React.ComponentType> = {
 
 export function App() {
   var query = useContext(QueryContext);
-  var action = query.action || "index";
-  var maker = actions[action] || makeNotFoundPage;
+  var action = query.action;
+  var maker = action ? actions[action] || makeNotFoundPage : makeIndexPage;
   var modalComponent = Votr.ajaxError
     ? ErrorModal
     : query.modal

votrfront/js/router.tsx

@@ -75,7 +75,7 @@ export function Root({ app }: { app: React.ComponentType }) {
   );
 }
 
-function buildUrl(href: string | Href) {
+export function buildUrl(href: string | Href) {
   if (_.isString(href)) return href;
   return "?" + $.param(_.omitBy(href, _.isUndefined), true);
 }

votrfront/login.py

@@ -125,7 +125,7 @@ def start_login(request, destination, params):
 
 def login(request):
     params = request.values.to_dict()
-    return start_login(request, params.pop('destination'), params)
+    return start_login(request, params.pop('destination', ''), params)
 
 
 def reset(request):