[auth] add useSignInWithCustomToken hook

auth/README.md

@@ -14,6 +14,7 @@ List of Auth hooks:
 - [useIdToken](#useidtoken)
 - [useCreateUserWithEmailAndPassword](#usecreateuserwithemailandpassword)
 - [useSignInWithEmailAndPassword](#usesigninwithemailandpassword)
+- [useSignInWithCustomToken](#usesigninwithcustomtoken)
 - [useSignInWithApple](#usesigninwithapple)
 - [useSignInWithFacebook](#usesigninwithfacebook)
 - [useSignInWithGithub](#usesigninwithgithub)
@@ -266,6 +267,30 @@ Returns:
 - `loading`: A `boolean` to indicate whether the the user login is processing
 - `error`: Any `Error` returned by Firebase when trying to login the user, or `undefined` if there is no error
 
+### useSignInWithCustomToken
+
+```js
+const [
+  signInWithCustomToken,
+  user,
+  loading,
+  error,
+] = useSignInWithCustomToken(auth);
+```
+
+Login a user with secure JSON Web Tokens (JWTs) generated by your servers. Wraps the underlying `auth.signInWithCustomToken` method and provides additional `loading` and `error` information.
+
+The `useSignInWithCustomToken` hook takes the following parameters:
+
+- `auth`: `Auth` instance for the app you would like to monitor
+
+Returns:
+
+- `signInWithCustomToken(token: string) => Promise<auth.UserCredential>`: A function you can call to start the login. Returns the `auth.UserCredential` if the user was signed in successfully, or `undefined` if there was an error.
+- `user`: The `auth.UserCredential` if the user was logged in or `undefined` if not
+- `loading`: A `boolean` to indicate whether the the user login is processing
+- `error`: Any `Error` returned by Firebase when trying to login the user, or `undefined` if there is no error
+
 #### Full Example
 
 ```jsx

auth/types.ts

@@ -23,6 +23,10 @@ export type SignInWithEmailLinkHook = AuthActionHook<
   (email: string, emailLink?: string) => Promise<UserCredential | undefined>
 >;
 
+export type SignInWithCustomTokenHook = AuthActionHook<
+  (token: string) => Promise<UserCredential | undefined>
+>;
+
 export type SignInWithPopupHook = AuthActionHook<
   (
     scopes?: string[],

auth/useSignInWithCustomToken.ts

@@ -0,0 +1,34 @@
+import {
+  Auth,
+  AuthError,
+  signInWithCustomToken as firebaseSignInWithCustomToken,
+  UserCredential,
+} from 'firebase/auth';
+import { useCallback, useState } from 'react';
+import { SignInWithCustomTokenHook } from './types';
+
+export default (auth: Auth): SignInWithCustomTokenHook => {
+  const [error, setError] = useState<AuthError>();
+  const [loggedInUser, setLoggedInUser] = useState<UserCredential>();
+  const [loading, setLoading] = useState<boolean>(false);
+
+  const signInWithCustomToken = useCallback(
+    async (token: string) => {
+      setLoading(true);
+      setError(undefined);
+      try {
+        const user = await firebaseSignInWithCustomToken(auth, token);
+        setLoggedInUser(user);
+
+        return user;
+      } catch (err) {
+        setError(err as AuthError);
+      } finally {
+        setLoading(false);
+      }
+    },
+    [auth]
+  );
+
+  return [signInWithCustomToken, loggedInUser, loading, error];
+};