add launcher oauth exchange api

src/auth/auth.controller.ts

@@ -1,4 +1,4 @@
-import { Body, Controller, Delete, Get, Post, Put, Req, Res } from '@nestjs/common';
+import { BadRequestException, Body, Controller, Delete, Get, Post, Put, Req, Res } from '@nestjs/common';
 import type { Request, Response } from 'express';
 
 import { AuthService } from './auth.service';
@@ -32,6 +32,23 @@ export class AuthController {
     return this.authService.refresh(request.headers.cookie, response);
   }
 
+  @Post('oauth/exchange')
+  exchangeOAuthLoginToken(
+    @Body() body: { loginToken?: string },
+    @Req() request: Request,
+    @Res({ passthrough: true }) response: Response,
+  ) {
+    if (!body.loginToken) {
+      throw new BadRequestException('loginToken is required');
+    }
+
+    return this.authService.exchangeOAuthLoginToken(
+      body.loginToken,
+      request.headers.cookie,
+      response,
+    );
+  }
+
   @Post('logout')
   logout(
     @Req() request: Request,

src/auth/auth.service.ts

@@ -63,6 +63,25 @@ export class AuthService {
     return this.frontendTokenResponse(authResponse);
   }
 
+  async exchangeOAuthLoginToken(
+    loginToken: string,
+    cookieHeader: string | undefined,
+    response: Response,
+  ) {
+    const authResponse = await this.request<AuthTokenResponse>(
+      '/auth/oauth/exchange',
+      {
+        method: 'POST',
+        body: { loginToken },
+        cookieHeader,
+        response,
+        unauthorizedMessage: 'Invalid Google login session',
+      },
+    );
+
+    return this.frontendTokenResponse(authResponse);
+  }
+
   async logout(
     cookieHeader: string | undefined,
     response: Response,