♻️ refactor: replace enum for union

Author: EdgarJMesquita

README.md

@@ -32,15 +32,16 @@ npx expo install expo-totp
 # Usage
 
 ```typescript
-import { HmacAlgorithm, useExpoTotp } from "expo-totp";
+import { useExpoTotp } from "expo-totp";
 import { Button, SafeAreaView, StyleSheet, Text } from "react-native";
 
 export default function App() {
   const totp = useExpoTotp();
 
   const start = () => {
+    // Supports only ASCII secret keys
     totp.start("MY_SUPER_SECRET_KEY", {
-      algorithm: HmacAlgorithm.SHA512,
+      algorithm: "SHA512",
       digits: 6,
       interval: 30,
     });
@@ -108,15 +109,15 @@ const { code, progress, remainingTime, start, stop } = useExpoTotp();
 
 ## Methods
 
-### `startUpdates()`
+### `getTotp()`
 
 Compute TOTP once
 
 ```typescript
 const totp = await ExpoTotp.getTotp("MY_SUPER_SECRET_KEY",
   interval: 30,
   digits: 6,
-  algorithm: HmacAlgorithm.SHA512
+  algorithm: "SHA512"
 )
 ```
 
@@ -128,7 +129,7 @@ Start TOTP generation
 ExpoTotp.startUpdates("YOUR_SUPER_SECRET_KEY", {
   interval: 30,
   digits: 6,
-  algorithm: HmacAlgorithm.SHA512,
+  algorithm: "SHA512",
 });
 ```
 
@@ -174,6 +175,14 @@ type TotpOptions = {
 };
 ```
 
+### `HmacAlgorithm`
+
+Defines options for TOTP generation
+
+```typescript
+type HmacAlgorithm = "SHA512" | "SHA384" | "SHA256" | "SHA1" | "MD5";
+```
+
 | Property    | Type            | Default  | Description           |
 | ----------- | --------------- | -------- | --------------------- |
 | `interval`  | `number `       | `30`     | Interval in seconds   |
@@ -192,20 +201,6 @@ export type TotpPayload = {
 };
 ```
 
-## Enums
-
-Defines the enum for algorithm.
-
-```typescript
-enum HmacAlgorithm {
-  SHA512 = "SHA512",
-  SHA384 = "SHA384",
-  SHA256 = "SHA256",
-  SHA1 = "SHA1",
-  MD5 = "MD5",
-}
-```
-
 # Contributing
 
 Contributions are very welcome! Please refer to guidelines described in the [contributing guide](https://github.com/expo/expo#contributing).

example/App.tsx

@@ -1,7 +1,8 @@
-import { HmacAlgorithm, useExpoTotp } from "expo-totp";
+import { useExpoTotp } from "expo-totp";
 import ExpoTotpModule from "expo-totp/ExpoTotpModule";
 import { useCallback, useEffect, useRef } from "react";
 import {
+  Alert,
   Animated,
   Button,
   SafeAreaView,
@@ -23,13 +24,25 @@ export default function App() {
     outputRange: ["0%", "100%"],
   });
 
-  const start = useCallback(() => {
-    ExpoTotpModule.getTotp("MY_SUPER_SECRET_KEY").then(console.log);
-    totp.start("MY_SUPER_SECRET_KEY", {
-      algorithm: HmacAlgorithm.SHA512,
-      digits: 6,
-      interval: 30,
-    });
+  const getSingleTotp = useCallback(async () => {
+    try {
+      const totpInfo = await ExpoTotpModule.getTotp("MY_SUPER_SECRET_KEY");
+      Alert.alert("TOTP", JSON.stringify(totpInfo, null, 2));
+    } catch (error) {
+      console.error(error);
+    }
+  }, []);
+
+  const start = useCallback(async () => {
+    try {
+      await totp.start("MY_SUPER_SECRET_KEY", {
+        algorithm: "SHA512",
+        digits: 6,
+        interval: 30,
+      });
+    } catch (error) {
+      console.error(error);
+    }
   }, []);
 
   const stop = useCallback(() => {
@@ -61,8 +74,9 @@ export default function App() {
       <ScrollView style={styles.container}>
         <Text style={styles.header}>Module API Example</Text>
         <Group name="Controls">
-          <Button title="Start" onPress={start} />
-          <Button title="Stop" onPress={stop} />
+          <Button title="Start Updates" onPress={start} />
+          <Button title="Stop Updates" onPress={stop} />
+          <Button title="Get Single Totp" onPress={getSingleTotp} />
         </Group>
         <Group name="Totp">
           {!!totp.code && (

ios/ExpoTotpModule.swift

@@ -4,8 +4,10 @@ import CommonCrypto
 fileprivate let CHANGE_EVENT_NAME = "onTotpUpdate"
 
 public class ExpoTotpModule: Module {
+    
     private var timer: Timer?
 
+    
     public func definition() -> ModuleDefinition {
         Name("ExpoTotp")
 
@@ -23,19 +25,30 @@ public class ExpoTotpModule: Module {
 
     }
 
-    private func getTotp(secretKey: String, options: TotpOptions?) -> [String: Any]? {
-        let secretBase64 = Data(secretKey.utf8).base64EncodedString()
+    
+    private func getTotp(secretKey: String, options: TotpOptions?) throws -> [String: Any] {
         let finalOptions = options ?? TotpOptions()
+        let secretBase64 = Data(secretKey.utf8).base64EncodedString()
 
-        return computeTotp(secretBase64: secretBase64, options: finalOptions)
+        guard let totpInfo = try? computeTotp(secretBase64: secretBase64, options: finalOptions) else {
+            throw Exceptions.InvalidSecretKey()
+        }
+        return totpInfo
     }
 
-    private func startUpdates(secretKey: String, options: TotpOptions?){
+    
+    private func startUpdates(secretKey: String, options: TotpOptions?) throws {
+        
         stopUpdates()
 
+        let finalOptions = options ?? TotpOptions()
+        
         let secretBase64 = Data(secretKey.utf8).base64EncodedString()
 
-        let finalOptions = options ?? TotpOptions()
+        guard let totpInfo = computeTotp(secretBase64: secretBase64, options: finalOptions) else {
+            throw Exceptions.InvalidSecretKey()
+        }
+        sendEvent(CHANGE_EVENT_NAME, totpInfo)
 
         DispatchQueue.main.async { [weak self] in
             guard let self else { return }
@@ -47,21 +60,26 @@ public class ExpoTotpModule: Module {
                 sendEvent(CHANGE_EVENT_NAME, totpInfo)
             }
         }
+        
     }
 
+    
     private func stopUpdates(){
+        
         timer?.invalidate()
         timer = nil
+        
     }
 
+    
     private func computeTotp(secretBase64: String, options: TotpOptions) -> [String: Any]? {
+       
         let currentTime = Int(Date().timeIntervalSince1970)
         let remainingTime = options.interval - currentTime % options.interval
         let currentInterval = currentTime / options.interval
 
         guard let keyData = Data(base64Encoded: secretBase64) else {
-          NSLog("Invalid secret provided")
-          return nil
+            return nil
         }
 
         // Create message for HMAC
@@ -92,5 +110,7 @@ public class ExpoTotpModule: Module {
           "remainingTime": remainingTime,
           "progress": (Double(remainingTime) / Double(options.interval)) * 100
         ]
+        
     }
+
 }

ios/TotpExceptions.swift

@@ -0,0 +1,19 @@
+//
+//  TotpExceptions.swift
+//  ExpoTotp
+//
+//  Created by Edgar Jonas Mesquita da Silva on 08/02/25.
+//
+
+import ExpoModulesCore
+
+
+extension Exceptions {
+    
+    internal final class InvalidSecretKey: Exception {
+        override var reason: String {
+          "Invalid secret key."
+        }
+    }
+    
+}

ios/TotpOptions.swift

@@ -17,6 +17,7 @@ enum HmacAlgorithm: String, Enumerable {
     case MD5
 
     func getAlgorithm() -> Int {
+        
         switch self {
             case .SHA512:
                 return kCCHmacAlgSHA512
@@ -29,6 +30,7 @@ enum HmacAlgorithm: String, Enumerable {
             case .MD5:
                 return kCCHmacAlgMD5
         }
+        
     }
 
 
@@ -50,6 +52,7 @@ enum HmacAlgorithm: String, Enumerable {
 }
 
 struct TotpOptions: Record {
+    
     @Field
     var interval: Int = 30
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "expo-totp",
-  "version": "0.1.2",
+  "version": "2.0.0",
   "description": "Allow TOTP(Time-based One-Time Password) code generation for react native expo",
   "main": "build/index.js",
   "types": "build/index.d.ts",

src/ExpoTotp.types.ts

@@ -8,30 +8,24 @@ export type TotpPayload = {
   progress: number;
 };
 
-export enum HmacAlgorithm {
-  SHA512 = "SHA512",
-  SHA384 = "SHA384",
-  SHA256 = "SHA256",
-  SHA1 = "SHA1",
-  MD5 = "MD5",
-}
+export type HmacAlgorithm = "SHA512" | "SHA384" | "SHA256" | "SHA1" | "MD5";
 
 export type TotpOptions = {
   /**
    * @default
    * 30
    */
-  interval: number;
+  interval?: number;
 
   /**
    * @default
    * 6
    */
-  digits: number;
+  digits?: number;
 
   /**
    * @default
    * SHA512
    */
-  algorithm: HmacAlgorithm;
+  algorithm?: HmacAlgorithm;
 };

src/ExpoTotpModule.ts

@@ -4,11 +4,8 @@ import { EventSubscription } from "expo-modules-core";
 import { ExpoTotpModuleEvents, TotpOptions } from "./ExpoTotp.types";
 
 declare class ExpoTotpModule extends NativeModule<ExpoTotpModuleEvents> {
-  getTotp(secretKey: string, options?: Partial<TotpOptions>): Promise<void>;
-  startUpdates(
-    secretKey: string,
-    options?: Partial<TotpOptions>
-  ): Promise<void>;
+  getTotp(secretKey: string, options?: TotpOptions): Promise<void>;
+  startUpdates(secretKey: string, options?: TotpOptions): Promise<void>;
   stopUpdates(): Promise<void>;
   addListener<EventName extends "onTotpUpdate">(
     eventName: EventName,
@@ -17,7 +14,7 @@ declare class ExpoTotpModule extends NativeModule<ExpoTotpModuleEvents> {
   /**
    * @deprecated
    */
-  start(secretKey: string, options?: Partial<TotpOptions>): Promise<void>;
+  start(secretKey: string, options?: TotpOptions): Promise<void>;
   /**
    * @deprecated
    */

src/hooks/useExpoTotp.ts

@@ -6,9 +6,12 @@ import { TotpOptions, TotpPayload } from "../ExpoTotp.types";
 export function useExpoTotp() {
   const [totp, setTotp] = useState<TotpPayload | null>(null);
 
-  const start = useCallback((secretKey: string, options?: TotpOptions) => {
-    ExpoTotp.startUpdates(secretKey, options);
-  }, []);
+  const start = useCallback(
+    async (secretKey: string, options?: TotpOptions) => {
+      return ExpoTotp.startUpdates(secretKey, options);
+    },
+    []
+  );
 
   const stop = useCallback(() => {
     ExpoTotp.stopUpdates();