1 files changed, 119 insertions, 0 deletions
diff --git a/packages/taler-wallet-webextension/src/utils/index.ts b/packages/taler-wallet-webextension/src/utils/index.ts
new file mode 100644
index 000000000..d83e6f472
--- /dev/null
+++ b/packages/taler-wallet-webextension/src/utils/index.ts
@@ -0,0 +1,119 @@
+/*
+ This file is part of GNU Taler
+ (C) 2022 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 { createElement, VNode } from "preact";
+import { useCallback, useMemo } from "preact/hooks";
+
+function getJsonIfOk(r: Response): Promise<any> {
+  if (r.ok) {
+    return r.json();
+  }
+
+  if (r.status >= 400 && r.status < 500) {
+    throw new Error(`URL may not be right: (${r.status}) ${r.statusText}`);
+  }
+
+  throw new Error(
+    `Try another server: (${r.status}) ${r.statusText || "internal server error"
+    }`,
+  );
+}
+
+export async function queryToSlashConfig<T>(url: string): Promise<T> {
+  return fetch(new URL("config", url).href)
+    .catch(() => {
+      throw new Error(`Network error`);
+    })
+    .then(getJsonIfOk);
+}
+
+function timeout<T>(ms: number, promise: Promise<T>): Promise<T> {
+  return new Promise((resolve, reject) => {
+    const timer = setTimeout(() => {
+      reject(
+        new Error(
+          `Timeout: the query took longer than ${Math.floor(ms / 1000)} secs`,
+        ),
+      );
+    }, ms);
+
+    promise
+      .then((value) => {
+        clearTimeout(timer);
+        resolve(value);
+      })
+      .catch((reason) => {
+        clearTimeout(timer);
+        reject(reason);
+      });
+  });
+}
+
+export async function queryToSlashKeys<T>(url: string): Promise<T> {
+  const endpoint = new URL("keys", url);
+
+  const query = fetch(endpoint.href)
+    .catch(() => {
+      throw new Error(`Network error`);
+    })
+    .then(getJsonIfOk);
+
+  return timeout(3000, query);
+}
+
+export type StateFunc<S> = (p: S) => VNode | null;
+
+export type StateViewMap<StateType extends { status: string }> = {
+  [S in StateType as S["status"]]: StateFunc<S>;
+};
+
+export type RecursiveState<S extends object> = S | (() => RecursiveState<S>);
+
+export function compose<SType extends { status: string }, PType>(
+  name: string,
+  hook: (p: PType) => RecursiveState<SType>,
+  viewMap: StateViewMap<SType>,
+): (p: PType) => VNode {
+  function withHook(stateHook: () => RecursiveState<SType>): () => VNode {
+    function TheComponent(): VNode {
+      //if the function is the same, do not compute
+      const state = stateHook();
+
+      if (typeof state === "function") {
+        const subComponent = withHook(state);
+        return createElement(subComponent, {});
+      }
+
+      const statusName = state.status as unknown as SType["status"];
+      const viewComponent = viewMap[statusName] as unknown as StateFunc<SType>;
+      return createElement(viewComponent, state);
+    }
+    // TheComponent.name = `${name}`;
+
+    return useMemo(() => {
+      return TheComponent
+    }, [stateHook]);
+  }
+
+  return (p: PType) => {
+    const h = withHook(() => hook(p));
+    return h();
+  };
+}
+
+export function assertUnreachable(x: never): never {
+  throw new Error("Didn't expect to get here");
+}