Update Shrine README.md

Change-Id: If7d26ddf8b79f912f5b58bd54c83a386cdeeb678

Shrine/README.md

@@ -17,6 +17,7 @@ This sample app implements the following use cases:
 * Generate a new passkey for an existing account
 * Store the credentials for created accounts in the user's Google Password Manager account.
 * Sign in flow with passkeys support
+* Sign in flow with restore credentials support
 * Logout from the account.
 
 ## Requirements
@@ -200,6 +201,38 @@ This section describes how to send a sign-in response to the server and authenti
 2.  If successful, the user has been signed in and you can redirect them to the home screen.
 
 
+### **Restore credentials of a returning user on a new device**
+
+This section describes how to implement restore credentials
+
+1. On a successful user authentication, create a Restore Key
+
+   1. Call `AuthRepository`'s `registerPasskeyCreationRequest` method 
+
+   2. With the PasskeyCreationRequest recieved from the above method, call `CredentialManagerUtils`'s `createRestoreKey` method 
+
+   3. Then call `AuthRepository`'s `registerPasskeyCreationResponse` method
+
+
+2. Once on a new device, check if there is any restore key present on the device or not (brought to the new device in the process of Backup and Restore)
+
+   1. Call `AuthRepository`'s `signInWithPasskeysRequest` method 
+
+   2. With the PasskeyCreationRequest recieved from the above method, call `CredentialManagerUtils`'s `getRestoreKey` method 
+
+   3. If there is a RestoreKey present this will return a `GenericCredentialManagerResponse.GetPasskeySuccess` else this will return a `GenericCredentialManagerResponse.Error`
+
+
+3. Sign in using the found Restore Key
+
+   1. If a restore key is found in the above step, simply use it to sign-in using `AuthRepository`'s `signInWithPasskeysResponse` method
+
+
+4. Delete a Restore Key
+
+   1. If a user logs out of the app, make sure to clear the stored restore key by calling `CredentialManagerUtils`'s `deleteRestoreKey`
+
+
 ## **Specific use case handling**
 
 -   When there are no passkeys associated with accounts registered, the developer should catch the exception code and let the user know that first he needs to create a passkey before they try to fetch it.
@@ -219,4 +252,4 @@ To build a debug signed version of this sample app, you need to update the `API_
 
 Shrine is distributed under the terms of the Apache License (Version 2.0). See the license for more information.
 
-**
+**

Shrine/app/src/main/java/com/example/android/authentication/shrine/CredentialManagerUtils.kt

@@ -162,7 +162,6 @@ class CredentialManagerUtils @Inject constructor(
                 restoreCredentialRequest,
             ) as CreateRestoreCredentialResponse
         } catch (e: Exception) {
-            e.printStackTrace()
             return GenericCredentialManagerResponse.Error(errorMessage = e.message ?: "")
         }
         return GenericCredentialManagerResponse.CreatePasskeySuccess(createPasskeyResponse = credentialResponse)

Shrine/app/src/main/java/com/example/android/authentication/shrine/ui/AuthenticationScreen.kt

@@ -70,13 +70,13 @@ fun AuthenticationScreen(
 ) {
     val uiState = viewModel.uiState.collectAsState().value
     val errorDialogViewModel: ErrorDialogViewModel = hiltViewModel()
-    var shouldCheckForRestoreKey by remember { mutableStateOf(true) }
+    var isFirstCheckForRestoreKey by remember { mutableStateOf(true) }
 
     // Passing in the lambda / context to the VM
     val context = LocalContext.current
     val createRestoreKey = {
         viewModel.createRestoreKey(
-            updateCredMan = { createRestoreCredObject ->
+            createRestoreKeyOnCredMan = { createRestoreCredObject ->
                 credentialManagerUtils.createRestoreKey(
                     context = context,
                     requestResult = createRestoreCredObject
@@ -100,8 +100,8 @@ fun AuthenticationScreen(
         )
     }
 
-    if (shouldCheckForRestoreKey) {
-        shouldCheckForRestoreKey = false
+    if (isFirstCheckForRestoreKey) {
+        isFirstCheckForRestoreKey = false
         viewModel.checkForStoredRestoreKey(
             getRestoreKey = { requestResult ->
                 credentialManagerUtils.getRestoreKey(requestResult, context)

Shrine/app/src/main/java/com/example/android/authentication/shrine/ui/RegisterScreen.kt

@@ -85,7 +85,7 @@ fun RegisterScreen(
     val context = LocalContext.current
     val createRestoreKey = {
         viewModel.createRestoreKey(
-            updateCredMan = { createRestoreCredObject ->
+            createRestoreKeyOnCredMan = { createRestoreCredObject ->
                 credentialManagerUtils.createRestoreKey(
                     context = context,
                     requestResult = createRestoreCredObject

Shrine/app/src/main/java/com/example/android/authentication/shrine/ui/viewmodel/AuthenticationViewModel.kt

@@ -152,18 +152,18 @@ class AuthenticationViewModel @Inject constructor(
     /**
      * Creates a restore key by registering a new passkey.
      *
-     * @param updateCredMan A suspend function that takes a [JSONObject] and returns a
+     * @param createRestoreKeyOnCredMan A suspend function that takes a [JSONObject] and returns a
      * [GenericCredentialManagerResponse]. This function is responsible for creating
      * the restore key.
      *
      * @see GenericCredentialManagerResponse
      */
     fun createRestoreKey(
-        updateCredMan: suspend (createRestoreCredRequestObj: JSONObject) -> GenericCredentialManagerResponse
+        createRestoreKeyOnCredMan: suspend (createRestoreCredRequestObj: JSONObject) -> GenericCredentialManagerResponse
     ) {
         viewModelScope.launch {
             repository.registerPasskeyCreationRequest()?.let { data ->
-                val createRestoreKeyResponse = updateCredMan(data)
+                val createRestoreKeyResponse = createRestoreKeyOnCredMan(data)
                 if (createRestoreKeyResponse is GenericCredentialManagerResponse.CreatePasskeySuccess) {
                     repository.registerPasskeyCreationResponse(createRestoreKeyResponse.createPasskeyResponse)
                 }

Shrine/app/src/main/java/com/example/android/authentication/shrine/ui/viewmodel/HomeViewModel.kt

@@ -34,6 +34,9 @@ class HomeViewModel @Inject constructor(
 
     /**
      * Signs out the user.
+     *
+     * @param deleteRestoreKey Lambda function received from Composable that triggers
+     * Credential Manager's deleteRestoreKey
      */
     fun signOut(
         deleteRestoreKey: suspend () -> Unit,

Shrine/app/src/main/java/com/example/android/authentication/shrine/ui/viewmodel/RegistrationViewModel.kt

@@ -102,18 +102,18 @@ class RegistrationViewModel @Inject constructor(
     /**
      * Creates a restore key by registering a new passkey.
      *
-     * @param updateCredMan A suspend function that takes a [JSONObject] and returns a
+     * @param createRestoreKeyOnCredMan A suspend function that takes a [JSONObject] and returns a
      * [GenericCredentialManagerResponse]. This function is responsible for creating
      * the restore key.
      *
      * @see GenericCredentialManagerResponse
      */
     fun createRestoreKey(
-        updateCredMan: suspend (createRestoreCredRequestObj: JSONObject) -> GenericCredentialManagerResponse
+        createRestoreKeyOnCredMan: suspend (createRestoreCredRequestObj: JSONObject) -> GenericCredentialManagerResponse
     ) {
         viewModelScope.launch {
             repository.registerPasskeyCreationRequest()?.let { data ->
-                val createRestoreKeyResponse = updateCredMan(data)
+                val createRestoreKeyResponse = createRestoreKeyOnCredMan(data)
                 if (createRestoreKeyResponse is GenericCredentialManagerResponse.CreatePasskeySuccess) {
                     repository.registerPasskeyCreationResponse(createRestoreKeyResponse.createPasskeyResponse)
                 }