index.md

Problems Module Overview

The Problems Module is one of the largest and most complex domains in the coding_arena backend. It manages the lifecycle of coding challenges, from basic CRUD operations and test case storage to automated AI generation.

Architecture

This module is split into three primary logical flows:

1. Standard CRUD (problem.*): Handles the retrieval, creation, and updating of coding problems. Uses Redis caching for high-traffic grid queries.
2. Test Case Management (problem-test.*): Manages the secret input/output pairs that validate user code. Strictly segregated from the main problem documents to prevent accidental leaking of hidden test cases to the frontend.
3. AI Generation Engine (ai-problem.* & testcase-*.ts): Utilizes LLMs via One API Gateway to automatically generate new coding problems from text prompts, automatically solve them, and automatically generate edge-case test validations.

Directory Structure

api/src/
├── controllers/problems/
│   ├── ai-problem.controller.ts           # AI Generation HTTP handlers
│   ├── problem-test.controller.ts         # Test Case HTTP handlers
│   └── problem.controller.ts              # Core Problem HTTP handlers
├── routes/problems/
│   ├── ai-problem.routes.ts               # AI Routes
│   ├── problem-test.routes.ts             # Test Case Routes
│   └── problem.routes.ts                  # Core Problem Routes
├── services/problems/
│   ├── ai-addsolve.service.ts             # Anthropic Claude logic
│   ├── ai-problem.service.ts              # AI problem generation logic
│   ├── testcase-generator.service.ts      # LLM Test Case generation
│   ├── problem.service.ts                 # Standard business logic
│   └── problem-test.service.ts            # Test Case validation logic
├── repositories/problems/
│   ├── problem.repository.ts              # Problem MongoDB Operations
│   └── problem-test.repository.ts         # Test Case MongoDB Operations
└── cache/problems/
    ├── problem.cache.ts                   # Core Problem Redis Cache
    └── problem-test.cache.ts              # Test Case Redis Cache

Documentation Layers

To explore the exact implementation details, please see the specific layer documentation:

• Routes: REST Endpoints and Auth
• Controllers: HTTP handling
• Services: Standard logic & AI Generation Engines
• Repositories: MongoDB Persistence Strategy
• Cache: Redis Caching Decorators