box-nestjs-monorepo/REFACTOR_SUMMARY.md

API Refactor Summary

Overview

This refactor modernizes the API response handling, error management, security, and observability features of the box-mgnt-api application.

Changes Implemented

1. ✅ Unified API Response Interface

Location: libs/common/src/interfaces/api-response.interface.ts

New Response Format:

interface ApiResponse<T> {
  success: boolean;
  code: string;
  message: string;
  data: T;
  timestamp: string;
}

Before:

{
  "error": "",
  "status": 1,
  "data": { ... }
}

After:

{
  "success": true,
  "code": "OK",
  "message": "success",
  "data": { ... },
  "timestamp": "2025-11-20T10:30:00.000Z"
}

Benefits:

• Type-safe generic response with ApiResponse<T>
• Clearer success/error semantics
• Standardized error codes for client handling
• Timestamp for audit trails

---

2. ✅ HTTP Status Code Preservation

Location: libs/common/src/filters/http-exception.filter.ts

Key Changes:

• Replaced AllExceptionsFilter (always returned HTTP 200)
• New HttpExceptionFilter preserves actual HTTP status codes
• Maps status codes to semantic error codes

Status Code Mapping:

• 400 → BAD_REQUEST
• 401 → UNAUTHORIZED
• 403 → FORBIDDEN
• 404 → NOT_FOUND
• 429 → RATE_LIMITED
• 500 → INTERNAL_ERROR

Example Error Response:

HTTP/1.1 401 Unauthorized
{
  "success": false,
  "code": "UNAUTHORIZED",
  "message": "User not authenticated",
  "data": null,
  "timestamp": "2025-11-20T10:30:00.000Z"
}

---

3. ✅ Environment Configuration Validation

Location: apps/box-mgnt-api/src/config/env.validation.ts

Validated Variables:

• MYSQL_URL - MySQL connection string (required, URL format)
• MONGO_URL - MongoDB connection string (required, URL format)
• JWT_SECRET - Secret for signing JWTs (required)
• JWT_EXPIRES_IN_SECONDS - Token TTL (optional, 60-86400, default: 43200)
• NODE_ENV - Environment (optional, enum: development/production/test)
• PORT - Server port (optional, 1024-65535, default: 3000)
• ENCRYPTION_KEY - For 2FA encryption (optional)

Benefits:

• App fails fast on startup with invalid config
• Clear error messages for missing/invalid values
• Type-safe environment variables

Usage in app.module.ts:

ConfigModule.forRoot({
  isGlobal: true,
  envFilePath: ['.env.mgnt.dev', '.env'],
  validate: validateEnvironment, // ← Added
});

---

4. ✅ Correlation ID Tracking

Location: libs/common/src/interceptors/correlation.interceptor.ts

How it Works:

• Extracts x-request-id or x-correlation-id from incoming headers
• Generates UUID if not present
• Attaches to request object as req.correlationId
• Returns in response headers

Response Headers:

x-request-id: 550e8400-e29b-41d4-a716-446655440000
x-correlation-id: 550e8400-e29b-41d4-a716-446655440000

Benefits:

• End-to-end request tracing
• Easier debugging across distributed services
• Log aggregation by correlation ID

---

5. ✅ Rate Limiting Guard

Location: libs/common/src/guards/rate-limit.guard.ts

Configuration:

• Limit: 10 requests per window
• Window: 60 seconds (1 minute)
• Scope: Per IP + endpoint combination
• Storage: In-memory (production should use Redis)

Applied to Endpoints:

• POST /auth/login
• POST /auth/login2fa
• POST /auth/oauth-login
• POST /auth/oauth-login-2fa
• POST /auth/2fa/setup
• POST /auth/2fa/enable

Rate Limit Response:

HTTP/1.1 429 Too Many Requests
{
  "success": false,
  "code": "RATE_LIMITED",
  "message": "Too many requests. Please try again in 45 seconds.",
  "data": null,
  "timestamp": "2025-11-20T10:30:00.000Z"
}

Features:

• Automatic cleanup of expired buckets
• Real IP detection (handles x-forwarded-for, x-real-ip)
• Detailed logging of rate limit violations

---

6. ✅ MFA Guard (Separated)

Location: libs/common/src/guards/mfa.guard.ts

Purpose: Enforce MFA verification for protected endpoints

Logic:

1. Check if user has 2FA enabled (user.twoFA field)
2. If enabled, require req.mfaVerified === true
3. Throw UNAUTHORIZED with code MFA_REQUIRED if not verified

Usage Example:

@UseGuards(JwtAuthGuard, MfaGuard)
@Get('sensitive-data')
async getSensitiveData(@AuthUser() user: User) {
  // Only accessible after MFA verification
}

---

Updated Module Wiring

CommonModule (libs/common/src/common.module.ts)

New Interceptors Order:

1. CorrelationInterceptor (first - adds request ID)
2. LoggingInterceptor (logs with correlation ID)
3. OperationLogInterceptor (business operation logging)
4. ResponseInterceptor (wraps response in ApiResponse)

New Filter:

• HttpExceptionFilter (replaces AllExceptionsFilter)

---

Migration Notes

Breaking Changes

Response Format

Before:

interface HttpResponse {
  error: string;
  status: 1 | 0;
  data: unknown | null;
}

After:

interface ApiResponse<T> {
  success: boolean;
  code: string;
  message: string;
  data: T;
  timestamp: string;
}

Frontend Update Required:

// Before
if (response.status === 1) {
  /* success */
}

// After
if (response.success) {
  /* success */
}

HTTP Status Codes

• Errors now return proper HTTP status codes (401, 403, 404, etc.)
• Frontend error handling should check response.status (HTTP) not response.body.status

Environment Variables

• Add required env vars: MYSQL_URL, MONGO_URL, JWT_SECRET
• Optional but recommended: JWT_EXPIRES_IN_SECONDS, ENCRYPTION_KEY

---

Testing Recommendations

1. Test Rate Limiting

# Should succeed first 10 times, then fail with 429
for i in {1..15}; do
  curl -X POST http://localhost:3000/mgnt/auth/login \
    -H "Content-Type: application/json" \
    -d '{"username":"test","password":"test"}'
  echo "\nRequest $i"
  sleep 1
done

2. Test Correlation IDs

# Send request with custom correlation ID
curl -H "x-request-id: my-custom-id-123" \
  http://localhost:3000/mgnt/auth/permission

# Check response headers contain same ID

3. Test Error Responses

# Should return 401 with proper format
curl -X GET http://localhost:3000/mgnt/users/me

# Response:
# HTTP/1.1 401 Unauthorized
# { "success": false, "code": "UNAUTHORIZED", ... }

4. Test Config Validation

# Remove JWT_SECRET from .env and restart
# Should fail with clear error message
pnpm start:mgnt
# Error: Environment validation failed:
# JWT_SECRET should not be empty

---

Performance Optimizations

Parallel Queries in AuthService

Already optimized in login() method:

const [roleIds, userMenus] = await Promise.all([
  this.userService.getUserRoleIds(user.id, true),
  this.userService.getUserMenus(user.id),
]);

Recommended Next Steps

1. Add database indexes:

   CREATE INDEX idx_user_role_user_id ON sys_user_role(user_id);
   CREATE INDEX idx_user_role_role_id ON sys_user_role(role_id);
   CREATE INDEX idx_role_menu_role_id ON sys_role_menu(role_id);
   CREATE INDEX idx_menu_parent_id ON sys_menu(parent_id);
   

2. Add caching layer for frequently accessed data:

   • User roles
   • Menu permissions
   • API permissions

3. Implement Redis for rate limiting (production):

   // Replace in-memory Map with Redis
   await redis.incr(`ratelimit:${key}`);
   await redis.expire(`ratelimit:${key}`, windowSeconds);
   

---

Monitoring & Observability

Logging Enhancements

• All errors now include correlation IDs
• Rate limit violations logged at WARN level
• Server errors (5xx) logged at ERROR level with stack traces

Metrics Recommendations

Add Prometheus metrics for:

• Request count by endpoint
• Request duration histogram
• Rate limit hit count
• MFA verification success/failure
• Login success/failure by type

---

Security Improvements

1. Rate Limiting: Prevents brute force attacks on login endpoints
2. MFA Guard: Enforces 2FA verification for sensitive operations
3. Config Validation: Prevents running with insecure defaults
4. Correlation IDs: Enables security event tracking and forensics
5. Proper HTTP Status Codes: Doesn't leak information (no more HTTP 200 for errors)

---

Files Created/Modified

Created Files

• libs/common/src/interfaces/api-response.interface.ts
• libs/common/src/filters/http-exception.filter.ts
• libs/common/src/interceptors/correlation.interceptor.ts
• libs/common/src/guards/rate-limit.guard.ts
• libs/common/src/guards/mfa.guard.ts
• apps/box-mgnt-api/src/config/env.validation.ts

Modified Files

• libs/common/src/common.module.ts (wiring)
• libs/common/src/interceptors/response.interceptor.ts (new format)
• libs/common/src/interceptors/operation-log.interceptor.ts (type update)
• libs/common/src/services/exception.service.ts (new format)
• apps/box-mgnt-api/src/app.module.ts (config validation)
• apps/box-mgnt-api/src/mgnt-backend/core/auth/auth.controller.ts (rate limiting)

---

Rollback Plan

If issues arise, revert these commits in order:

1. Remove rate limiting from auth controller
2. Remove correlation interceptor from CommonModule
3. Restore AllExceptionsFilter in CommonModule
4. Restore old response format in ResponseInterceptor
5. Remove config validation from app.module.ts

---

Questions or Issues?

Check the following if something doesn't work:

1. Build errors: Run pnpm install and pnpm prisma:generate
2. Type errors: Ensure tsconfig.base.json includes new paths
3. Runtime errors: Check .env file has all required variables
4. Rate limiting not working: Verify RateLimitGuard is before LocalAuthGuard
5. Correlation IDs missing: Check CorrelationInterceptor is first in provider list