Add InsertAdminState guard to check admin status

Introduces a new InsertAdminState guard to verify if the user is an admin by checking their authentication token and updating a custom header 'is_admin' accordingly. This guard fetches user details from the database and sets the 'is_admin' header to true or false based on the user's admin status.

apps/backend/src/app/auth/auth.guard.ts

@@ -87,3 +87,41 @@ export class AdminGuard implements CanActivate {
 		return true;
 	}
 }
+
+@Injectable()
+export class InsertAdminState implements CanActivate {
+	constructor(
+		@Inject(CredentialsService)
+		private readonly credentialService: CredentialsService,
+		@Inject(DbService) private readonly databaseService: DbService,
+	) {}
+	async canActivate(context: ExecutionContext): Promise<boolean> {
+		const request : Request = context.switchToHttp().getRequest();
+
+		const authHeader = request.headers.authorization;
+		if (!authHeader) {
+			request.headers.is_admin = false;
+			return true;
+		}
+		const token = authHeader.split(" ")[1];
+		const vToken = await this.credentialService.verifyAuthToken(token);
+
+		const user = await this.databaseService
+			.use()
+			.select()
+			.from(UsersTable)
+			.where(eq(UsersTable.uuid, vToken.payload.sub));
+
+		if (user.length !== 1)
+			throw new UnauthorizedException("No such user found.");
+
+		if (!user[0].isAdmin) {
+			request.headers.is_admin = false;
+			return true;
+		}
+
+		request.headers.is_admin = true
+
+		return true;
+	}
+}