Merge pull request #153 from akargi/feat/issue151

Author: Ahmad Abdulkareem

apps/api/src/main.ts

@@ -11,6 +11,7 @@ import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger';
 import { GlobalValidationPipe } from '@app/common/pipes/global-validation.pipe';
 import { GlobalExceptionFilter } from '@app/common/filters/global-exception.filter';
 import { LoggingInterceptor } from '@app/common/interceptors/logging.interceptor';
+import { ErrorResponse } from '@app/common/dto/error-response.dto';
 import helmet from 'helmet'; // Import Helmet
 import * as cors from 'cors'; // Import CORS
 import * as rateLimit from 'express-rate-limit'; // Import rateLimit
@@ -63,9 +64,17 @@ async function bootstrap() {
     .addBearerAuth()
     .build();
 
-  const document = SwaggerModule.createDocument(app, config);
+  const document = SwaggerModule.createDocument(app, config, {
+    extraModels: [ErrorResponse],
+  });
   SwaggerModule.setup('api/docs', app, document);
 
+  // Ensure unhandled promise rejections are logged and do not crash silently
+  process.on('unhandledRejection', (reason) => {
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-call
+    console.error('Unhandled Rejection at:', reason);
+  });
+
   await app.listen(process.env.PORT || DEFAULT_PORT);
 }
 void bootstrap();

libs/common/src/dto/error-response.dto.ts

@@ -0,0 +1,24 @@
+import { ApiProperty } from '@nestjs/swagger';
+
+export class ErrorResponse {
+  @ApiProperty({ example: 400 })
+  statusCode: number;
+
+  @ApiProperty({ example: 'BadRequest' })
+  error: string;
+
+  @ApiProperty({ example: 'A descriptive error message' })
+  message: string | string[];
+
+  @ApiProperty({ example: 'ERR_INVALID_TRADE', required: false })
+  code?: string;
+
+  @ApiProperty({ example: {}, required: false })
+  details?: unknown;
+
+  @ApiProperty({ example: '/api/trades' })
+  path: string;
+
+  @ApiProperty({ example: new Date().toISOString() })
+  timestamp: string;
+}

libs/common/src/exceptions/app-error.ts

@@ -0,0 +1,17 @@
+import { HttpException, HttpStatus } from '@nestjs/common';
+
+export class AppError extends HttpException {
+  public readonly code: string;
+  public readonly details?: unknown;
+
+  constructor(
+    code: string,
+    message: string | string[],
+    status: HttpStatus = HttpStatus.BAD_REQUEST,
+    details?: unknown,
+  ) {
+    super({ error: 'AppError', message, code, details }, status);
+    this.code = code;
+    this.details = details;
+  }
+}

libs/common/src/exceptions/error-codes.enum.ts

@@ -0,0 +1,5 @@
+export enum ErrorCodes {
+  GENERIC = 'ERR_GENERIC',
+  INSUFFICIENT_BALANCE = 'ERR_INSUFFICIENT_BALANCE',
+  INVALID_TRADE = 'ERR_INVALID_TRADE',
+}

libs/common/src/exceptions/insufficient-balance.exception.ts

@@ -0,0 +1,14 @@
+import { HttpStatus } from '@nestjs/common';
+import { AppError } from './app-error';
+import { ErrorCodes } from './error-codes.enum';
+
+export class InsufficientBalanceException extends AppError {
+  constructor(details?: unknown) {
+    super(
+      ErrorCodes.INSUFFICIENT_BALANCE,
+      'Insufficient balance to complete this operation',
+      HttpStatus.PAYMENT_REQUIRED,
+      details,
+    );
+  }
+}

libs/common/src/exceptions/invalid-trade.exception.ts

@@ -0,0 +1,14 @@
+import { HttpStatus } from '@nestjs/common';
+import { AppError } from './app-error';
+import { ErrorCodes } from './error-codes.enum';
+
+export class InvalidTradeException extends AppError {
+  constructor(details?: unknown) {
+    super(
+      ErrorCodes.INVALID_TRADE,
+      'The trade request is invalid or malformed',
+      HttpStatus.BAD_REQUEST,
+      details,
+    );
+  }
+}

libs/common/src/filters/global-exception.filter.ts

@@ -6,6 +6,8 @@ import {
   HttpStatus,
 } from '@nestjs/common';
 import { Request, Response } from 'express';
+import { AppError } from '../exceptions/app-error';
+import { ErrorCodes } from '../exceptions/error-codes.enum';
 
 @Catch()
 export class GlobalExceptionFilter implements ExceptionFilter {
@@ -15,31 +17,72 @@ export class GlobalExceptionFilter implements ExceptionFilter {
     const request = ctx.getRequest<Request>();
 
     let status = HttpStatus.INTERNAL_SERVER_ERROR;
-    let errorResponse: any = {
+    let payload: Record<string, unknown> = {
       statusCode: status,
       error: 'InternalServerError',
       message: 'An unexpected error occurred',
+      code: ErrorCodes.GENERIC,
       path: request.url,
       timestamp: new Date().toISOString(),
     };
 
-    if (exception instanceof HttpException) {
+    if (exception instanceof AppError) {
+      // AppError already structures message/code/details
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+      const res: any = exception.getResponse();
       status = exception.getStatus();
-      const res = exception.getResponse();
-
-      errorResponse = {
+      payload = {
+        statusCode: status,
+        error: res.error ?? exception.name,
+        message: res.message ?? exception.message,
+        code: res.code ?? (exception as AppError).code,
+        details: res.details ?? (exception as AppError).details,
+        path: request.url,
+        timestamp: new Date().toISOString(),
+      };
+    } else if (exception instanceof HttpException) {
+      status = exception.getStatus();
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+      const res: any = exception.getResponse();
+      payload = {
         statusCode: status,
-        // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-        error: res['error'] ?? exception.name,
-        // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-        message: res['message'] ?? exception.message,
-        // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-        details: res['details'],
+        error: res.error ?? exception.name,
+        message: res.message ?? exception.message,
+        code: res.code ?? ErrorCodes.GENERIC,
+        details: res.details,
         path: request.url,
         timestamp: new Date().toISOString(),
       };
     }
 
-    response.status(status).json(errorResponse);
+    // Structured error logging for observability / tracking
+    try {
+      const logPayload = {
+        level: 'error',
+        message:
+          // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+          (payload['message'] as unknown) ?? 'Unhandled exception',
+        error: exception instanceof Error ? exception.stack : exception,
+        request: {
+          method: request.method,
+          url: request.url,
+          params: request.params,
+          query: request.query,
+        },
+        code: payload['code'],
+        timestamp: new Date().toISOString(),
+      };
+
+      // Replace with an external tracker (Sentry, Datadog) integration here
+      // For now, print structured JSON to console so logs can be parsed.
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-call
+      console.error(JSON.stringify(logPayload));
+    } catch (logErr) {
+      // If logging fails, still respond to client
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-call
+      console.error('Failed to log error', logErr);
+    }
+
+    response.status(status).json(payload);
   }
 }

libs/common/src/index.ts

@@ -3,3 +3,8 @@ export * from './constants';
 export * from './interfaces';
 export * from './mailer';
 export * from './enums';
+export * from './dto/error-response.dto';
+export * from './exceptions/app-error';
+export * from './exceptions/error-codes.enum';
+export * from './exceptions/insufficient-balance.exception';
+export * from './exceptions/invalid-trade.exception';