1 files changed, 255 insertions, 0 deletions
diff --git a/packages/merchant-backoffice-ui/src/context/session.ts b/packages/merchant-backoffice-ui/src/context/session.ts
new file mode 100644
index 000000000..fa5e14ab3
--- /dev/null
+++ b/packages/merchant-backoffice-ui/src/context/session.ts
@@ -0,0 +1,255 @@
+/*
+ This file is part of GNU Taler
+ (C) 2021-2024 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,
+  TalerMerchantApi,
+  buildCodecForObject,
+  codecForString,
+  codecForURL,
+  codecOptional,
+} from "@gnu-taler/taler-util";
+import {
+  buildStorageKey,
+  useLocalStorage,
+  useMerchantApiContext,
+} from "@gnu-taler/web-util/browser";
+import { ComponentChildren, VNode, createContext, h } from "preact";
+import { useContext, useEffect, useState } from "preact/hooks";
+import { mutate } from "swr";
+import { MerchantLib } from "../../../web-util/lib/context/activity.js";
+
+/**
+ * Has the information to reach and
+ * authenticate at the bank's backend.
+ */
+export type SessionState = LoggedIn | LoggedOut;
+
+interface LoggedIn {
+  status: "loggedIn";
+
+  // is this instance admin? usually "default" name
+  isAdmin: boolean;
+
+  // url where all the request will be made
+  // usually this is from where the SPA was loaded
+  // unless it's using impersonate feature
+  backendUrl: URL;
+
+  // instance name
+  instance: string;
+
+  // session is not the same from where it was loaded
+  impersonated: boolean;
+
+  //instance access token
+  token: AccessToken | undefined;
+}
+
+interface LoggedOut {
+  status: "loggedOut";
+  backendUrl: URL;
+  instance: string;
+  isAdmin: boolean;
+  token: AccessToken | undefined;
+}
+
+interface SavedSession {
+  backendUrl: URL;
+  token: AccessToken | undefined;
+  prevToken: AccessToken | undefined;
+}
+
+export const codecForSessionState = (): Codec<SavedSession> =>
+  buildCodecForObject<SavedSession>()
+    .property("backendUrl", codecForURL())
+    .property("token", codecOptional(codecForString() as Codec<AccessToken>))
+    .property(
+      "prevToken",
+      codecOptional(codecForString() as Codec<AccessToken>),
+    )
+    .build("SavedSession");
+
+function inferInstanceName(url: URL) {
+  const match = INSTANCE_ID_LOOKUP.exec(url.href);
+  return !match || !match[1] ? DEFAULT_ADMIN_USERNAME : match[1];
+}
+
+export const defaultState = (url: URL): SavedSession => {
+  return {
+    backendUrl: url,
+    token: undefined,
+    prevToken: undefined,
+  };
+};
+
+export interface SessionStateHandler {
+  lib: MerchantLib;
+  config: TalerMerchantApi.VersionResponse;
+
+  state: SessionState;
+  /**
+   * from every state to logout state
+   */
+  logOut(): void;
+  /**
+   * from impersonate to loggedIn
+   */
+  deImpersonate(): void;
+  /**
+   * from any to loggedIn
+   * @param info
+   */
+  logIn(token: AccessToken | undefined): void;
+  /**
+   * from loggedIn to impersonate
+   * @param info
+   */
+  impersonate(baseUrl: URL): void;
+}
+
+const SESSION_STATE_KEY = buildStorageKey(
+  "merchant-session",
+  codecForSessionState(),
+);
+
+export const DEFAULT_ADMIN_USERNAME = "default";
+
+export const INSTANCE_ID_LOOKUP = /\/instances\/([^/]*)\/?$/;
+
+export function cleanAllCache(): void {
+  mutate(() => true, undefined, { revalidate: false });
+}
+
+const Context = createContext<SessionStateHandler>(undefined!);
+
+export const useSessionContext = (): SessionStateHandler => useContext(Context);
+
+/**
+ * Creates the session in loggedIn state.
+ * Infer the instance name based on the URL.
+ * Create the instance of the merchant api http rest.
+ * Returns API that handle impersonation.
+ * 
+ * @param param0 
+ * @returns 
+ */
+export const SessionContextProvider = ({
+  children,
+  // value,
+}: {
+  // value: MerchantUiSettings;
+  children: ComponentChildren;
+}): VNode => {
+  const {
+    lib: rootLib,
+    config: rootConfig,
+    url: merchantUrl,
+  } = useMerchantApiContext();
+  const [status, setStatus] = useState<"loggedIn" | "loggedOut">("loggedIn");
+  const [currentConfig, setCurrentConfig] =
+    useState<TalerMerchantApi.VersionResponse>();
+  const { value: state, update } = useLocalStorage(
+    SESSION_STATE_KEY,
+    defaultState(merchantUrl),
+  );
+
+  const currentInstance = inferInstanceName(state.backendUrl);
+
+  let lib: MerchantLib;
+  let config: TalerMerchantApi.VersionResponse;
+  const doingImpersonation = state.backendUrl.href !== merchantUrl.href;
+  if (doingImpersonation) {
+    /**
+     * FIXME: can't impersonate other than local instances
+     */
+    lib = rootLib.subInstanceApi(inferInstanceName(state.backendUrl));
+
+    config = currentConfig ?? rootConfig;
+  } else {
+    lib = rootLib;
+    config = rootConfig;
+  }
+
+  useEffect(() => {
+    // FIXME: handle what happen if the subinstance /config
+    // fails
+    if (!doingImpersonation) return;
+    lib.instance.getConfig().then((resp) => {
+      if (resp.type === "ok") {
+        setCurrentConfig(resp.body);
+      }
+    });
+  }, [state.backendUrl.href]);
+
+  const value: SessionStateHandler = {
+    state: {
+      backendUrl: state.backendUrl,
+      token: state.token,
+      impersonated: doingImpersonation,
+      instance: currentInstance,
+      isAdmin: currentInstance === DEFAULT_ADMIN_USERNAME,
+      status: status,
+    },
+    lib,
+    config,
+    logOut() {
+      setStatus("loggedOut");
+      update({
+        backendUrl: merchantUrl,
+        token: undefined,
+        prevToken: undefined,
+      });
+      cleanAllCache();
+    },
+    deImpersonate() {
+      cleanAllCache();
+      update({
+        backendUrl: merchantUrl,
+        token: state.prevToken,
+        prevToken: undefined,
+      });
+      setStatus("loggedIn");
+    },
+    impersonate(baseUrl) {
+      /**
+       * FIXME: can't impersonate other than local instances
+       */
+      update({
+        backendUrl: baseUrl,
+        token: undefined,
+        prevToken: state.token,
+      });
+      setStatus("loggedIn");
+      cleanAllCache();
+    },
+    logIn(token) {
+      cleanAllCache();
+      setStatus("loggedIn");
+      update({
+        backendUrl: state.backendUrl,
+        token: token,
+        prevToken: state.prevToken,
+      });
+    },
+  };
+
+  return h(Context.Provider, {
+    value,
+    children,
+  });
+};