feat: account backup

---

Co-authored-by: @schowdhuri 
Reviewed-by: @schowdhuri

packages/preload/contracts.d.ts

@@ -20,6 +20,7 @@ interface Exposed {
   readonly nodeCrypto: Readonly<typeof import("./src/nodeCrypto").nodeCrypto>;
   readonly versions: Readonly<typeof import("./src/versions").versions>;
   readonly electronStore: Readonly<typeof import("./src/store").store>;
+  readonly haveno: Readonly<typeof import("./src/haveno").store>;
 }
 
 // eslint-disable-next-line @typescript-eslint/no-empty-interface

packages/preload/src/haveno.ts

@@ -0,0 +1,31 @@
+// =============================================================================
+//  Copyright 2022 Haveno
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+// =============================================================================
+
+import { ipcRenderer } from "electron";
+import { exposeInMainWorld } from "./exposeInMainWorld";
+import type { DownloadBackupInput } from "./types";
+import { IpcChannels } from "./types";
+
+// Export for types in contracts.d.ts
+export const haveno = {
+  downloadBackup: async (data: DownloadBackupInput): Promise<void> =>
+    ipcRenderer.invoke(IpcChannels.DownloadBackup, data),
+
+  getBackupData: async (): Promise<Uint8Array> =>
+    ipcRenderer.invoke(IpcChannels.RestoreBackup),
+};
+
+exposeInMainWorld("haveno", haveno);

packages/preload/src/index.ts

@@ -21,3 +21,4 @@
 import "./nodeCrypto";
 import "./versions";
 import "./store";
+import "./haveno";