1 files changed, 131 insertions, 0 deletions
diff --git a/packages/bank-ui/src/hooks/session.ts b/packages/bank-ui/src/hooks/session.ts
new file mode 100644
index 000000000..35f87e1be
--- /dev/null
+++ b/packages/bank-ui/src/hooks/session.ts
@@ -0,0 +1,131 @@
+/*
+ This file is part of GNU Taler
+ (C) 2022-2024 Taler Systems S.A.
+
+ GNU Taler is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+import {
+  AccessToken,
+  Codec,
+  buildCodecForObject,
+  buildCodecForUnion,
+  codecForBoolean,
+  codecForConstString,
+  codecForString,
+} from "@gnu-taler/taler-util";
+import { buildStorageKey, useLocalStorage } from "@gnu-taler/web-util/browser";
+import { mutate } from "swr";
+
+/**
+ * Has the information to reach and
+ * authenticate at the bank's backend.
+ */
+export type SessionState = LoggedIn | LoggedOut | Expired;
+
+interface LoggedIn {
+  status: "loggedIn";
+  isUserAdministrator: boolean;
+  username: string;
+  token: AccessToken;
+}
+interface Expired {
+  status: "expired";
+  isUserAdministrator: boolean;
+  username: string;
+}
+interface LoggedOut {
+  status: "loggedOut";
+}
+
+export const codecForSessionStateLoggedIn = (): Codec<LoggedIn> =>
+  buildCodecForObject<LoggedIn>()
+    .property("status", codecForConstString("loggedIn"))
+    .property("username", codecForString())
+    .property("token", codecForString() as Codec<AccessToken>)
+    .property("isUserAdministrator", codecForBoolean())
+    .build("SessionState.LoggedIn");
+
+export const codecForSessionStateExpired = (): Codec<Expired> =>
+  buildCodecForObject<Expired>()
+    .property("status", codecForConstString("expired"))
+    .property("username", codecForString())
+    .property("isUserAdministrator", codecForBoolean())
+    .build("SessionState.Expired");
+
+export const codecForSessionStateLoggedOut = (): Codec<LoggedOut> =>
+  buildCodecForObject<LoggedOut>()
+    .property("status", codecForConstString("loggedOut"))
+    .build("SessionState.LoggedOut");
+
+export const codecForSessionState = (): Codec<SessionState> =>
+  buildCodecForUnion<SessionState>()
+    .discriminateOn("status")
+    .alternative("loggedIn", codecForSessionStateLoggedIn())
+    .alternative("loggedOut", codecForSessionStateLoggedOut())
+    .alternative("expired", codecForSessionStateExpired())
+    .build("SessionState");
+
+export const defaultState: SessionState = {
+  status: "loggedOut",
+};
+
+export interface SessionStateHandler {
+  state: SessionState;
+  logOut(): void;
+  expired(): void;
+  logIn(info: { username: string; token: AccessToken }): void;
+}
+
+const SESSION_STATE_KEY = buildStorageKey("bank-state", codecForSessionState());
+
+/**
+ * Return getters and setters for
+ * login credentials and backend's
+ * base URL.
+ */
+export function useSessionState(): SessionStateHandler {
+  const { value: state, update } = useLocalStorage(
+    SESSION_STATE_KEY,
+    defaultState,
+  );
+
+  return {
+    state,
+    logOut() {
+      update(defaultState);
+    },
+    expired() {
+      if (state.status === "loggedOut") return;
+      const nextState: SessionState = {
+        status: "expired",
+        username: state.username,
+        isUserAdministrator: state.username === "admin",
+      };
+      update(nextState);
+    },
+    logIn(info) {
+      // admin is defined by the username
+      const nextState: SessionState = {
+        status: "loggedIn",
+        ...info,
+        isUserAdministrator: info.username === "admin",
+      };
+      update(nextState);
+      cleanAllCache();
+    },
+  };
+}
+
+function cleanAllCache(): void {
+  mutate(() => true, undefined, { revalidate: false });
+}