feat(auth): Enable resumable SignIn

packages/auth/src/providers/cognito/utils/signInStore.ts

@@ -1,6 +1,8 @@
 // Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
+import { ConsoleLogger } from '@aws-amplify/core';
+
 import { CognitoAuthSignInDetails } from '../types';
 
 import { ChallengeName } from './clients/CognitoIdentityProvider/types';
@@ -27,6 +29,22 @@
 
 type Reducer<State, Action> = (state: State, action: Action) => State;
 
+const logger = new ConsoleLogger('Auth signInStore');
+
+// Minutes until stored session invalidates
+const EXPIRATION_MINUTES = 5;
+const MS_TO_EXPIRY = 1000 * 60 * EXPIRATION_MINUTES;
+const SIGN_IN_STATE_KEYS = [
+	'username',
+	'challengeName',
+	'signInSession',
+	'expiry',
+].reduce((keys: Record<string, string>, key) => {
+	keys[key] = `CognitoSignInState.${key}`;
+
+	return keys;
+}, {});
+
 const signInReducer: Reducer<SignInState, SignInAction> = (state, action) => {
 	switch (action.type) {
 		case 'SET_SIGN_IN_SESSION':
@@ -49,22 +67,58 @@
 				username: action.value,
 			};
 		case 'SET_INITIAL_STATE':
-			return defaultState();
+			return getInitialState();
 		default:
 			return state;
 	}
 };
 
-function defaultState(): SignInState {
+const isExpired = (expiryDate: string): boolean => {
+	const expiryTimestamp = Number(expiryDate);
+	const currentTimestamp = Date.now();
+
+	return expiryTimestamp <= currentTimestamp;
+};
+
+const clearPersistedSignInState = () => {
+	for (const key in SIGN_IN_STATE_KEYS) {
+		sessionStorage.removeItem(key);
+	}
+};
+
+const getDefaultState = (): SignInState => ({
+	username: undefined,
+	challengeName: undefined,
+	signInSession: undefined,
+});
+
+// Hydrate signInStore from sessionStorage
+const getInitialState = (): SignInState => {
+	const expiry = sessionStorage.getItem(SIGN_IN_STATE_KEYS.expiry) as string;
+	if (isExpired(expiry)) {
+		logger.warn('Sign-in session expired');
+		clearPersistedSignInState();
+
+		return getDefaultState();
+	}
+
+	const username =
+		sessionStorage.getItem(SIGN_IN_STATE_KEYS.username) ?? ('' as string);
+	const challengeName = (sessionStorage.getItem(
+		SIGN_IN_STATE_KEYS.challengeName,
+	) ?? '') as ChallengeName;
+	const signInSession =
+		sessionStorage.getItem(SIGN_IN_STATE_KEYS.signInSession) ?? ('' as string);
+
 	return {
-		username: undefined,
-		challengeName: undefined,
-		signInSession: undefined,
+		username,
+		challengeName,
+		signInSession,
 	};
-}
+};
 
 const createStore: Store<SignInState, SignInAction> = reducer => {
-	let currentState = reducer(defaultState(), { type: 'SET_INITIAL_STATE' });
+	let currentState = reducer(getDefaultState(), { type: 'SET_INITIAL_STATE' });
 
 	return {
 		getState: () => currentState,
@@ -81,8 +135,27 @@
 		type: 'SET_SIGN_IN_STATE',
 		value: state,
 	});
+
+	// Save the local state into sessionStorage
+	persistSignInState(state);
 }
 
+// Free saved sign in states up from both memory and sessionStorage
 export function cleanActiveSignInState(): void {
 	signInStore.dispatch({ type: 'SET_INITIAL_STATE' });
+	clearPersistedSignInState();
 }
+
+const persistSignInState = ({
+	challengeName = '' as ChallengeName,
+	signInSession = '',
+	username = '',
+}: SignInState) => {
+	sessionStorage.setItem(SIGN_IN_STATE_KEYS.username, username);
+	sessionStorage.setItem(SIGN_IN_STATE_KEYS.challengeName, challengeName);
+	sessionStorage.setItem(SIGN_IN_STATE_KEYS.signInSession, signInSession);
+	sessionStorage.setItem(
+		SIGN_IN_STATE_KEYS.expiry,
+		String(Date.now() + MS_TO_EXPIRY),
+	);
+};