Exchange Token interop changes

@@ -28,7 +28,7 @@ export interface ExchangeTokenRequest {
 
 export interface ExchangeTokenRespose {
 accessToken: string;
-expiresIn: string;
+expiresInSec: string;
 }
 
 export async function exchangeToken(

@@ -629,6 +629,11 @@ export class AuthImpl implements AuthInternal, _FirebaseService {
 }
 }
 
+async getTokenForRegionalAuth():
+Promise<string> {
+if (Date.now() > this.tokenResponse?.expiresIn)
+}
+
 toJSON(): object {
 return {
 apiKey: this.config.apiKey,

@@ -43,6 +43,9 @@ export class AuthInterop implements FirebaseAuthInternal {
 ): Promise<{ accessToken: string } | null> {
 this.assertAuthConfigured();
 await this.auth._initializationPromise;
+if (this.auth.tenantConfig) {
+return this.getTokenRegionalAuth();
+}
 if (!this.auth.currentUser) {
 return null;
 }
@@ -51,6 +54,23 @@ export class AuthInterop implements FirebaseAuthInternal {
 return { accessToken };
 }
 
+async getTokenRegionalAuth() :
+Promise<{ accessToken: string } | null> {
+this.assertRegionalAuthConfigured();
+if (!this.auth.tokenResponse) {
+return null;
+}
+
+if (!this.auth.tokenResponse.expirationTime ||
+Date.now() > this.auth.tokenResponse.expirationTime) {
+await this.auth._updateTokenResponse(null);
+return null;
+}
+
+const accessToken = await this.auth.tokenResponse.token;
+return { accessToken };
+}
+
 addAuthTokenListener(listener: TokenListener): void {
 this.assertAuthConfigured();
 if (this.internalListeners.has(listener)) {
@@ -85,6 +105,10 @@ export class AuthInterop implements FirebaseAuthInternal {
 );
 }
 
+private assertRegionalAuthConfigured(): void {
+_assert(this.auth.tenantConfig, AuthErrorCode.OPERATION_NOT_ALLOWED);
+}
+
 private updateProactiveRefresh(): void {
 if (this.internalListeners.size > 0) {
 this.auth._startProactiveRefresh();