feat: notification improvements

.gitignore

@@ -33,3 +33,6 @@ yarn-error.*
 
 # typescript
 *.tsbuildinfo
+
+ios
+android

app.json

@@ -14,6 +14,13 @@
     },
     "assetBundlePatterns": ["**/*"],
     "plugins": [
+      [
+        "expo-notification-service-extension-plugin",
+        {
+          "mode": "production",
+          "iosNSEFilePath": "./assets/NotificationService.m"
+        }
+      ],
       [
         "expo-local-authentication",
         {
@@ -46,6 +53,9 @@
       "bundleIdentifier": "com.getalby.mobile",
       "config": {
         "usesNonExemptEncryption": false
+      },
+      "infoPlist": {
+        "UIBackgroundModes": ["remote-notification", "processing"]
       }
     },
     "android": {

app/(app)/settings/notifications.js

@@ -0,0 +1,5 @@
+import { Notifications } from "../../../pages/settings/Notifications";
+
+export default function Page() {
+  return <Notifications />;
+}

app/_layout.tsx

@@ -1,20 +1,23 @@
 import { Theme, ThemeProvider } from "@react-navigation/native";
 import { PortalHost } from "@rn-primitives/portal";
 import * as Font from "expo-font";
+import * as Notifications from "expo-notifications";
 import { Slot, SplashScreen } from "expo-router";
 import { StatusBar } from "expo-status-bar";
+import * as TaskManager from "expo-task-manager";
 import { swrConfiguration } from "lib/swr";
 import * as React from "react";
 import { SafeAreaView } from "react-native";
 import Toast from "react-native-toast-message";
 import PolyfillCrypto from "react-native-webview-crypto";
 import { SWRConfig } from "swr";
 import { toastConfig } from "~/components/ToastConfig";
+import { NotificationProvider } from "~/context/Notification";
 import { UserInactivityProvider } from "~/context/UserInactivity";
 import "~/global.css";
 import { useInfo } from "~/hooks/useInfo";
 import { SessionProvider } from "~/hooks/useSession";
-import { NAV_THEME } from "~/lib/constants";
+import { BACKGROUND_NOTIFICATION_TASK, NAV_THEME } from "~/lib/constants";
 import { isBiometricSupported } from "~/lib/isBiometricSupported";
 import { useAppStore } from "~/lib/state/appStore";
 import { useColorScheme } from "~/lib/useColorScheme";
@@ -33,6 +36,25 @@ export {
   ErrorBoundary,
 } from "expo-router";
 
+// FIXME: only use this in android (?)
+TaskManager.defineTask(
+  BACKGROUND_NOTIFICATION_TASK,
+  ({ data }: { data: Record<string, any> }) => {
+    console.info("Received a notification in the background!", data?.body);
+    // Do something with the notification data
+  },
+);
+
+Notifications.registerTaskAsync(BACKGROUND_NOTIFICATION_TASK)
+  .then(() => {
+    console.info(
+      `Notifications.registerTaskAsync success: ${BACKGROUND_NOTIFICATION_TASK}`,
+    );
+  })
+  .catch((reason) => {
+    console.info(`Notifications registerTaskAsync failed: ${reason}`);
+  });
+
 // Prevent the splash screen from auto-hiding before getting the color scheme.
 SplashScreen.preventAutoHideAsync();
 
@@ -89,24 +111,26 @@ export default function RootLayout() {
 
   return (
     <SWRConfig value={swrConfiguration}>
-      <ThemeProvider value={isDarkColorScheme ? DARK_THEME : LIGHT_THEME}>
-        <StatusBar style={isDarkColorScheme ? "light" : "dark"} />
-        <PolyfillCrypto />
-        <SafeAreaView className="w-full h-full bg-background">
-          <UserInactivityProvider>
-            <SessionProvider>
-              <Slot />
-            </SessionProvider>
-          </UserInactivityProvider>
-          <Toast
-            config={toastConfig}
-            position="bottom"
-            bottomOffset={140}
-            topOffset={140}
-          />
-          <PortalHost />
-        </SafeAreaView>
-      </ThemeProvider>
+      <NotificationProvider>
+        <ThemeProvider value={isDarkColorScheme ? DARK_THEME : LIGHT_THEME}>
+          <StatusBar style={isDarkColorScheme ? "light" : "dark"} />
+          <PolyfillCrypto />
+          <SafeAreaView className="w-full h-full bg-background">
+            <UserInactivityProvider>
+              <SessionProvider>
+                <Slot />
+              </SessionProvider>
+            </UserInactivityProvider>
+            <Toast
+              config={toastConfig}
+              position="bottom"
+              bottomOffset={140}
+              topOffset={140}
+            />
+            <PortalHost />
+          </SafeAreaView>
+        </ThemeProvider>
+      </NotificationProvider>
     </SWRConfig>
   );
 }

assets/NotificationService.m

@@ -0,0 +1,117 @@
+#import "NotificationService.h"
+#import <CommonCrypto/CommonCryptor.h>
+
+@interface NotificationService ()
+
+@property (nonatomic, strong) void (^contentHandler)(UNNotificationContent *contentToDeliver);
+@property (nonatomic, strong) UNNotificationRequest *receivedRequest;
+@property (nonatomic, strong) UNMutableNotificationContent *bestAttemptContent;
+
+@end
+
+@implementation NotificationService
+
+// Helper function to convert hex string to NSData
+NSData* dataFromHexString(NSString *hexString) {
+  NSMutableData *data = [NSMutableData data];
+  int idx;
+  for (idx = 0; idx+2 <= hexString.length; idx+=2) {
+    NSRange range = NSMakeRange(idx, 2);
+    NSString *hexByte = [hexString substringWithRange:range];
+    unsigned int byte;
+    if ([[NSScanner scannerWithString:hexByte] scanHexInt:&byte]) {
+      [data appendBytes:&byte length:1];
+    } else {
+      return nil; // invalid hex string
+    }
+  }
+  return data;
+}
+
+- (void)didReceiveNotificationRequest:(UNNotificationRequest *)request withContentHandler:(void (^)(UNNotificationContent * _Nonnull))contentHandler {
+  self.receivedRequest = request;
+  self.contentHandler = contentHandler;
+  self.bestAttemptContent = [request.content mutableCopy];
+
+  NSUserDefaults *sharedDefaults = [[NSUserDefaults alloc] initWithSuiteName:@"group.com.getalby.mobile.nse"];
+  NSDictionary *walletsDict = [sharedDefaults objectForKey:@"wallets"];
+
+  NSString *appPubkey = request.content.userInfo[@"body"][@"appPubkey"];
+  if (!appPubkey) {
+    return;
+  }
+
+  NSDictionary *walletInfo = walletsDict[appPubkey];
+  if (!walletInfo) {
+    return;
+  }
+
+  NSString *sharedSecretString = walletInfo[@"sharedSecret"];
+  NSString *walletName = walletInfo[@"name"];
+  if (!sharedSecretString) {
+    return;
+  }
+
+  NSData *sharedSecretData = dataFromHexString(sharedSecretString);
+  if (!sharedSecretData || sharedSecretData.length != kCCKeySizeAES256) {
+    return;
+  }
+
+  NSString *encryptedContent = request.content.userInfo[@"body"][@"content"];
+  NSArray *parts = [encryptedContent componentsSeparatedByString:@"?iv="];
+  if (parts.count < 2) {
+    return;
+  }
+
+  NSString *ciphertextBase64 = parts[0];
+  NSString *ivBase64 = parts[1];
+
+  NSData *ciphertextData = [[NSData alloc] initWithBase64EncodedString:ciphertextBase64 options:0];
+  NSData *ivData = [[NSData alloc] initWithBase64EncodedString:ivBase64 options:0];
+
+  if (!ciphertextData || !ivData || ivData.length != kCCBlockSizeAES128) {
+    return;
+  }
+
+  // Prepare for decryption
+  size_t decryptedDataLength = ciphertextData.length + kCCBlockSizeAES128;
+  NSMutableData *plaintextData = [NSMutableData dataWithLength:decryptedDataLength];
+
+  size_t numBytesDecrypted = 0;
+  CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding, sharedSecretData.bytes, sharedSecretData.length, ivData.bytes, ciphertextData.bytes, ciphertextData.length, plaintextData.mutableBytes, decryptedDataLength, &numBytesDecrypted);
+
+  if (cryptStatus == kCCSuccess) {
+    plaintextData.length = numBytesDecrypted;
+
+    NSError *jsonError = nil;
+    NSDictionary *parsedContent = [NSJSONSerialization JSONObjectWithData:plaintextData options:0 error:&jsonError];
+
+    if (!parsedContent || jsonError) {
+      return;
+    }
+
+    NSString *notificationType = parsedContent[@"notification_type"];
+    if (![notificationType isEqualToString:@"payment_received"]) {
+      return;
+    }
+
+    NSDictionary *notificationDict = parsedContent[@"notification"];
+    NSNumber *amountNumber = notificationDict[@"amount"];
+    if (!amountNumber) {
+      return;
+    }
+
+    double amountInSats = [amountNumber doubleValue] / 1000.0;
+    self.bestAttemptContent.title = walletName;
+    self.bestAttemptContent.body = [NSString stringWithFormat:@"You just received %.0f sats ⚡️", amountInSats];
+  }
+
+  self.contentHandler(self.bestAttemptContent);
+}
+
+- (void)serviceExtensionTimeWillExpire {
+  self.bestAttemptContent.body = @"expired noitification";
+  self.contentHandler(self.bestAttemptContent);
+}
+
+@end

context/Notification.tsx

@@ -0,0 +1,55 @@
+import { useEffect, useRef } from "react";
+
+import * as ExpoNotifications from "expo-notifications";
+import { useAppStore } from "~/lib/state/appStore";
+
+ExpoNotifications.setNotificationHandler({
+  handleNotification: async () => {
+    return {
+      shouldShowAlert: true,
+      shouldPlaySound: true,
+      shouldSetBadge: false,
+    };
+  },
+});
+
+export const NotificationProvider = ({ children }: any) => {
+  const notificationListener = useRef<ExpoNotifications.Subscription>();
+  const responseListener = useRef<ExpoNotifications.Subscription>();
+  const isNotificationsEnabled = useAppStore(
+    (store) => store.isNotificationsEnabled,
+  );
+
+  useEffect(() => {
+    if (!isNotificationsEnabled) {
+      return;
+    }
+
+    notificationListener.current =
+      ExpoNotifications.addNotificationReceivedListener((notification) => {
+        // triggers when app is foregrounded
+        console.info("received from server just now");
+      });
+
+    responseListener.current =
+      ExpoNotifications.addNotificationResponseReceivedListener((response) => {
+        // triggers when notification is clicked (only when foreground or background)
+        // see https://docs.expo.dev/versions/latest/sdk/notifications/#notification-events-listeners
+        // TODO: to also redirect when the app is killed, use useLastNotificationResponse
+        // TODO: redirect the user to transaction page after switching to the right wallet
+      });
+
+    return () => {
+      notificationListener.current &&
+        ExpoNotifications.removeNotificationSubscription(
+          notificationListener.current,
+        );
+      responseListener.current &&
+        ExpoNotifications.removeNotificationSubscription(
+          responseListener.current,
+        );
+    };
+  }, [isNotificationsEnabled]);
+
+  return children;
+};

lib/constants.ts

@@ -19,6 +19,10 @@ export const NAV_THEME = {
   },
 };
 
+export const SUITE_NAME = "group.com.getalby.mobile.nse";
+
+export const BACKGROUND_NOTIFICATION_TASK = "BACKGROUND-NOTIFICATION-TASK";
+
 export const INACTIVITY_THRESHOLD = 5 * 60 * 1000;
 
 export const CURSOR_COLOR = "hsl(47 100% 72%)";
@@ -29,6 +33,7 @@ export const DEFAULT_CURRENCY = "USD";
 export const DEFAULT_WALLET_NAME = "Default Wallet";
 export const ALBY_LIGHTNING_ADDRESS = "[email protected]";
 export const ALBY_URL = "https://getalby.com";
+export const NOSTR_API_URL = "https://api.getalby.com/nwc";
 
 export const REQUIRED_CAPABILITIES: Nip47Capability[] = [
   "get_balance",

lib/sharedSecret.ts

@@ -0,0 +1,8 @@
+import { secp256k1 } from "@noble/curves/secp256k1";
+import { Buffer } from "buffer";
+
+export function computeSharedSecret(pub: string, sk: string): string {
+  const sharedSecret = secp256k1.getSharedSecret(sk, "02" + pub);
+  const normalizedKey = sharedSecret.slice(1);
+  return Buffer.from(normalizedKey).toString("hex");
+}