feat: global NATS interceptor implementation (#1091)

* global interceptor implementation for nats

Signed-off-by: Tipu_Singh <[email protected]>

* added type in exception

Signed-off-by: Tipu_Singh <[email protected]>

---------

Signed-off-by: Tipu_Singh <[email protected]>

Author: tipusinghaw

apps/api-gateway/common/exception-handler.ts

@@ -24,16 +24,21 @@ export class CustomExceptionFilter extends BaseExceptionFilter {
     }
     if (exception instanceof HttpException) {
       status = exception.getStatus();
+      
     }
 
-    let exceptionResponse: ExceptionResponse;
+    let exceptionResponse: ExceptionResponse = {} as ExceptionResponse;
+    const exceptionResponseData = exception.getResponse ? exception.getResponse() : exception;
 
-    if (exception['response']) {
-      exceptionResponse = exception['response'];
+    if ('string' === typeof exceptionResponseData) {
+      exceptionResponse.message = exceptionResponseData;
     } else {
-      exceptionResponse = exception as unknown as ExceptionResponse;
+      exceptionResponse = exceptionResponseData as unknown as ExceptionResponse;
     }
 
+    if (exceptionResponse.message && exceptionResponse.message.includes(ResponseMessages.nats.error.noSubscribers)) {
+      exceptionResponse.message = ResponseMessages.nats.error.noSubscribers;
+    }
     errorResponse = {
       statusCode: exceptionResponse.statusCode ? exceptionResponse.statusCode : status,
       message: exceptionResponse.message
@@ -43,7 +48,6 @@ export class CustomExceptionFilter extends BaseExceptionFilter {
         ? exceptionResponse.error
         : ResponseMessages.errorMessages.serverError
     };
-
     response.status(errorResponse.statusCode).json(errorResponse);
   }
 }

apps/api-gateway/src/main.ts

@@ -13,6 +13,7 @@ import { getNatsOptions } from '@credebl/common/nats.config';
 import helmet from 'helmet';
 import { CommonConstants } from '@credebl/common/common.constant';
 import NestjsLoggerServiceAdapter from '@credebl/logger/nestjsLoggerServiceAdapter';
+import { NatsInterceptor } from '../../../libs/interceptors/nats.interceptor';
 dotenv.config();
 
 async function bootstrap(): Promise<void> {
@@ -95,6 +96,7 @@ async function bootstrap(): Promise<void> {
       xssFilter: true
     })
   );
+  app.useGlobalInterceptors(new NatsInterceptor());
   await app.listen(process.env.API_GATEWAY_PORT, `${process.env.API_GATEWAY_HOST}`);
   Logger.log(`API Gateway is listening on port ${process.env.API_GATEWAY_PORT}`);
 }

libs/common/src/response-messages/index.ts

@@ -475,5 +475,14 @@ export const ResponseMessages = {
       notFoundBaseWallet: 'The base wallet record is missing.',
       walletRecordNotFound: 'Wallet record not found.'
     }
+  },
+  nats: {
+    success: {
+      
+    },
+    error: {
+     noSubscribers: 'No subscribers for the requested message. Error while connecting to NATS, service might not be started',
+     natsConnect: 'Empty response. There are no subscribers listening to that message'
+    }
   }
 };

libs/interceptors/nats.interceptor.ts

@@ -0,0 +1,28 @@
+import { ResponseMessages } from '@credebl/common/response-messages';
+import {
+    CallHandler,
+    ExecutionContext,
+    Injectable,
+    NestInterceptor,
+    HttpException,
+    Logger
+  } from '@nestjs/common';
+  import { Observable, throwError } from 'rxjs';
+  import { catchError } from 'rxjs/operators';
+  
+  @Injectable()
+  export class NatsInterceptor implements NestInterceptor {
+    private readonly logger = new Logger(NatsInterceptor.name);
+  
+    intercept(context: ExecutionContext, next: CallHandler): Observable<unknown> {
+      return next.handle().pipe(
+        catchError((error) => {
+          if (error.message.includes(ResponseMessages.nats.error.natsConnect)) {
+            this.logger.error(`No subscribers for message: ${error.message}`);
+            return throwError(() => new HttpException(ResponseMessages.nats.error.noSubscribers, 500));
+          }
+          return throwError(() => error);
+        })
+      );
+    }
+  }