1 files changed, 191 insertions, 0 deletions
diff --git a/packages/taler-wallet-core/src/remote.ts b/packages/taler-wallet-core/src/remote.ts
new file mode 100644
index 000000000..d7623baab
--- /dev/null
+++ b/packages/taler-wallet-core/src/remote.ts
@@ -0,0 +1,191 @@
+/*
+ This file is part of GNU Taler
+ (C) 2023 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 {
+  CoreApiRequestEnvelope,
+  CoreApiResponse,
+  Logger,
+  OpenedPromise,
+  openPromise,
+  TalerError,
+  WalletNotification,
+} from "@gnu-taler/taler-util";
+import { connectRpc, JsonMessage } from "@gnu-taler/taler-util/twrpc";
+import { WalletCoreApiClient } from "./wallet-api-types.js";
+
+const logger = new Logger("remote.ts");
+
+export interface RemoteWallet {
+  /**
+   * Low-level interface for making API requests to wallet-core.
+   */
+  makeCoreApiRequest(
+    operation: string,
+    payload: unknown,
+  ): Promise<CoreApiResponse>;
+
+  /**
+   * Close the connection to the remote wallet.
+   */
+  close(): void;
+}
+
+export interface RemoteWalletConnectArgs {
+  name?: string;
+  socketFilename: string;
+  notificationHandler?: (n: WalletNotification) => void;
+}
+
+export async function createRemoteWallet(
+  args: RemoteWalletConnectArgs,
+): Promise<RemoteWallet> {
+  let nextRequestId = 1;
+  let requestMap: Map<
+    string,
+    {
+      promiseCapability: OpenedPromise<CoreApiResponse>;
+    }
+  > = new Map();
+
+  const ctx = await connectRpc<RemoteWallet>({
+    socketFilename: args.socketFilename,
+    onEstablished(connection) {
+      const ctx: RemoteWallet = {
+        makeCoreApiRequest(operation, payload) {
+          const id = `req-${nextRequestId}`;
+          nextRequestId += 1;
+          const req: CoreApiRequestEnvelope = {
+            operation,
+            id,
+            args: payload,
+          };
+          const promiseCap = openPromise<CoreApiResponse>();
+          requestMap.set(id, {
+            promiseCapability: promiseCap,
+          });
+          connection.sendMessage(req as unknown as JsonMessage);
+          return promiseCap.promise;
+        },
+        close() {
+          connection.close();
+        },
+      };
+      return {
+        result: ctx,
+        onDisconnect() {
+          logger.info(`${args.name}: remote wallet disconnected`);
+        },
+        onMessage(m) {
+          // FIXME: use a codec for parsing the response envelope!
+
+          if (typeof m !== "object" || m == null) {
+            logger.warn(`${args.name}: message not understood (wrong type)`);
+            return;
+          }
+          const type = (m as any).type;
+          if (type === "response" || type === "error") {
+            const id = (m as any).id;
+            if (typeof id !== "string") {
+              logger.warn(
+                `${args.name}: message not understood (no id in response)`,
+              );
+              return;
+            }
+            const h = requestMap.get(id);
+            if (!h) {
+              logger.warn(
+                `${args.name}: no handler registered for response id ${id}`,
+              );
+              return;
+            }
+            h.promiseCapability.resolve(m as any);
+          } else if (type === "notification") {
+            if (args.notificationHandler) {
+              args.notificationHandler((m as any).payload);
+            }
+          } else {
+            logger.warn(`${args.name}: message not understood`);
+          }
+        },
+      };
+    },
+  });
+  return ctx;
+}
+
+/**
+ * Get a high-level API client from a remove wallet.
+ */
+export function getClientFromRemoteWallet(
+  w: RemoteWallet,
+): WalletCoreApiClient {
+  const client: WalletCoreApiClient = {
+    async call(op, payload): Promise<any> {
+      const res = await w.makeCoreApiRequest(op, payload);
+      switch (res.type) {
+        case "error":
+          throw TalerError.fromUncheckedDetail(res.error);
+        case "response":
+          return res.result;
+      }
+    },
+  };
+  return client;
+}
+
+export interface WalletNotificationWaiter {
+  notify(wn: WalletNotification): void;
+  waitForNotificationCond<T>(
+    cond: (n: WalletNotification) => T | false | undefined,
+  ): Promise<T>;
+}
+
+interface NotificationCondEntry<T> {
+  condition: (n: WalletNotification) => T | false | undefined;
+  promiseCapability: OpenedPromise<T>;
+}
+
+/**
+ * Helper that allows creating a promise that resolves when the
+ * wallet
+ */
+export function makeNotificationWaiter(): WalletNotificationWaiter {
+  // Bookkeeping for waiting on notification conditions
+  let nextCondIndex = 1;
+  const condMap: Map<number, NotificationCondEntry<any>> = new Map();
+  function onNotification(n: WalletNotification) {
+    condMap.forEach((cond, condKey) => {
+      const res = cond.condition(n);
+      if (res) {
+        cond.promiseCapability.resolve(res);
+      }
+    });
+  }
+  function waitForNotificationCond<T>(
+    cond: (n: WalletNotification) => T | false | undefined,
+  ) {
+    const promCap = openPromise<T>();
+    condMap.set(nextCondIndex++, {
+      condition: cond,
+      promiseCapability: promCap,
+    });
+    return promCap.promise;
+  }
+  return {
+    waitForNotificationCond,
+    notify: onNotification,
+  };
+}