User accounts, login before the title screen, own savegames per user, standalone download

- Service: accounts with Argon2 password hashes and session tokens; the first login creates
  the admin (shared savegames of before move to the admin); the admin creates and deletes
  users; everybody can change the password; savegames are stored and listed per user
- Game: login page before the title (only when the service is reachable), with licence and
  repository link; account page (password, logout; users for the admin); text fields with
  Tab/Enter, masked passwords, browser dialog on touch screens; long status messages wrap
- Download Standalone: DungeonCraft.html with the game embedded (built in the Docker image,
  served to logged-in users via nginx auth_request); works from file:// without server and
  opens downloaded savegames
- Without the service (standalone, local files) there is no login, savegame files as before

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/main.rs

@@ -153,6 +153,61 @@ fn store_progress(p: &campaign::Progress) {
     platform::storage_set(PROGRESS_KEY, &serde_json::to_string(p).unwrap_or_default());
 }
 
+// login, account and standalone actions of the menu
+fn account_action(a: MenuAction, cloud: &mut Cloud, menu: &mut Menu, app: &mut App, now: f64) {
+    match a {
+        MenuAction::Login(name, pw) => {
+            if name.is_empty() || pw.is_empty() {
+                menu.error = Some(i18n::tr("login.err_invalid"));
+            } else if cloud.login(&name, &pw) {
+                menu.error = Some(i18n::tr("saves.wait"));
+            }
+        }
+        MenuAction::Logout => {
+            cloud.logout();
+            menu.open_login();
+            menu.error = None;
+        }
+        MenuAction::OpenAccount => {
+            if cloud.session.as_ref().map_or(false, |s| s.admin) {
+                cloud.load_users();
+            }
+        }
+        MenuAction::ChangePassword(old, new) => {
+            if new.chars().count() < 4 {
+                menu.error = Some(i18n::tr("login.err_invalid"));
+            } else {
+                cloud.change_password(&old, &new);
+            }
+        }
+        MenuAction::CreateUser(name, pw) => {
+            if name.is_empty() || pw.chars().count() < 4 {
+                menu.error = Some(i18n::tr("login.err_invalid"));
+            } else {
+                cloud.create_user(&name, &pw);
+            }
+        }
+        MenuAction::DeleteUser(name) => {
+            cloud.delete_user(&name);
+        }
+        MenuAction::DownloadStandalone => {
+            platform::fetch_download("standalone/DungeonCraft.html", "DungeonCraft.html");
+            app.set_status(i18n::tr("standalone.running"), now);
+        }
+        MenuAction::EditField(i) => {
+            // touch screens have no keyboard in the canvas: the browser asks
+            if ui::touch_ui() {
+                let secret = matches!((menu.page, i), (Some(Page::Login), 1) | (Some(Page::Account), 0 | 1 | 3));
+                let title = i18n::tr(if secret { "login.password" } else { "login.name" });
+                if let Some(t) = platform::prompt(&title, if secret { "" } else { &menu.fields[i] }) {
+                    menu.fields[i] = t.chars().filter(|c| !c.is_control()).take(40).collect();
+                }
+            }
+        }
+        _ => {}
+    }
+}
+
 fn next_seed(seed: u32) -> u32 {
     seed.wrapping_mul(1103515245).wrapping_add(12345) | 1
 }
@@ -378,21 +433,77 @@ async fn main() {
             CloudEvent::Saved(name) => app.set_status(i18n::trf("save.saved", &[name]), now),
             CloudEvent::Loaded(bytes) => app.load_bytes(&bytes, &mut ui, &mut menu, &mut r3d, now),
             CloudEvent::Deleted => app.set_status(i18n::tr("cloud.deleted"), now),
-            CloudEvent::Error(key) => app.set_status(i18n::tr(key), now),
+            CloudEvent::Error(key) => {
+                if matches!(menu.page, Some(Page::Account)) {
+                    menu.error = Some(i18n::tr(key));
+                } else {
+                    app.set_status(i18n::tr(key), now);
+                }
+            }
+            // accounts: the login page comes before the title screen
+            CloudEvent::LoginNeeded => {
+                if matches!(menu.page, Some(Page::Title) | None) {
+                    menu.open_login();
+                    menu.error = None;
+                }
+            }
+            CloudEvent::LoggedIn => {
+                if menu.page == Some(Page::Login) {
+                    menu.page = Some(Page::Title);
+                }
+                menu.error = None;
+                if let Some(s) = &cloud.session {
+                    app.set_status(i18n::trf("login.welcome", &[s.name.clone()]), now);
+                }
+            }
+            CloudEvent::LoginFailed(key) => menu.error = Some(i18n::tr(key)),
+            CloudEvent::PasswordChanged => {
+                menu.fields[0].clear();
+                menu.fields[1].clear();
+                menu.error = None;
+                app.set_status(i18n::tr("account.pw_changed"), now);
+            }
+            CloudEvent::UsersChanged => {
+                menu.fields[2].clear();
+                menu.fields[3].clear();
+                menu.error = None;
+                app.set_status(i18n::tr("account.users_changed"), now);
+            }
+        }
+        // download of the standalone file
+        match platform::fetch_download_state() {
+            2 => app.set_status(i18n::tr("standalone.done"), now),
+            3 => app.set_status(i18n::tr("standalone.failed"), now),
+            _ => {}
         }
 
-        // ---------------- name field of the savegame page
+        // ---------------- text fields (savegame name, login, account)
         if menu.typing() {
+            // Tab switches the field right away (the following characters go to the next one)
+            let mut tab_char = false;
             while let Some(c) = get_char_pressed() {
-                menu.type_char(c);
+                if c == '\t' {
+                    tab_char = true;
+                    menu.next_field();
+                } else {
+                    menu.type_char(c);
+                }
+            }
+            if is_key_pressed(KeyCode::Tab) && !tab_char {
+                menu.next_field();
             }
             if is_key_pressed(KeyCode::Backspace) {
-                menu.save_name.pop();
+                menu.backspace();
             }
             if is_key_pressed(KeyCode::Enter) || is_key_pressed(KeyCode::KpEnter) {
-                let name = menu.save_name.trim().to_string();
-                if cloud.save(None, &name, &app.autosave_json()) {
-                    app.set_status(i18n::tr("saves.wait"), now);
+                if matches!(menu.page, Some(Page::Saves { .. })) {
+                    let name = menu.save_name.trim().to_string();
+                    if cloud.save(None, &name, &app.autosave_json()) {
+                        app.set_status(i18n::tr("saves.wait"), now);
+                    }
+                } else {
+                    let a = menu.submit();
+                    account_action(a, &mut cloud, &mut menu, &mut app, now);
                 }
             }
         }
@@ -680,6 +791,14 @@ async fn main() {
                         autosave_t = 0.0;
                     }
                     MenuAction::OpenRepo => platform::open_url(menu::REPO_URL),
+                    a @ (MenuAction::Login(..)
+                    | MenuAction::Logout
+                    | MenuAction::OpenAccount
+                    | MenuAction::ChangePassword(..)
+                    | MenuAction::CreateUser(..)
+                    | MenuAction::DeleteUser(..)
+                    | MenuAction::DownloadStandalone
+                    | MenuAction::EditField(..)) => account_action(a, &mut cloud, &mut menu, &mut app, now),
                     MenuAction::EditName => {
                         if let Some(n) = platform::prompt(&i18n::tr("saves.name"), &menu.save_name) {
                             menu.save_name = n.chars().filter(|c| !c.is_control()).take(40).collect();
@@ -865,7 +984,13 @@ async fn main() {
         let on_title = menu.page == Some(Page::Title)
             || matches!(
                 menu.page,
-                Some(Page::Settings { from_title: true, .. }) | Some(Page::KeyCapture { from_title: true, .. }) | Some(Page::NewGame) | Some(Page::Campaign) | Some(Page::Briefing { ingame: false, .. })
+                Some(Page::Settings { from_title: true, .. })
+                    | Some(Page::KeyCapture { from_title: true, .. })
+                    | Some(Page::NewGame)
+                    | Some(Page::Campaign)
+                    | Some(Page::Briefing { ingame: false, .. })
+                    | Some(Page::Login)
+                    | Some(Page::Account)
             );
         music.update(&app.game, on_title, (app.cam.tx, app.cam.tz));
         for m in app.game.msgs.drain(..) {
@@ -914,7 +1039,13 @@ fn draw_frame(app: &mut App, gfx: &Gfx, r3d: &mut R3d, ui: &mut Ui, menu: &mut M
     r3d.draw(&app.game, gfx, &app.cam, now, &ov);
     let title_screen = matches!(
         menu.page,
-        Some(Page::Title) | Some(Page::Settings { from_title: true, .. }) | Some(Page::KeyCapture { from_title: true, .. }) | Some(Page::Campaign) | Some(Page::Briefing { ingame: false, .. })
+        Some(Page::Title)
+            | Some(Page::Settings { from_title: true, .. })
+            | Some(Page::KeyCapture { from_title: true, .. })
+            | Some(Page::Campaign)
+            | Some(Page::Briefing { ingame: false, .. })
+            | Some(Page::Login)
+            | Some(Page::Account)
     );
     if !title_screen {
         let info = if over_ui || (touch && inp.inspect.is_none()) {