voxblog/apps/api/REFACTORING_SUMMARY.md

AI Generate Refactoring Summary

Overview

Refactored src/ai-generate.ts (453 lines) into a clean, maintainable architecture with proper separation of concerns.

New Structure

apps/api/src/
├── routes/
│   └── ai.routes.ts                    # 85 lines - Clean route handlers
├── services/
│   ├── ai/
│   │   ├── AIService.ts                # 48 lines - Main orchestrator
│   │   ├── contentGenerator.ts         # 145 lines - Content generation
│   │   ├── metadataGenerator.ts        # 63 lines - Metadata generation
│   │   └── altTextGenerator.ts         # 88 lines - Alt text generation
│   └── openai/
│       └── client.ts                   # 36 lines - Singleton client
├── utils/
│   ├── imageUtils.ts                   # 65 lines - Image utilities
│   ├── contextBuilder.ts               # 59 lines - Context building
│   ├── responseParser.ts               # 63 lines - Response parsing
│   └── errorHandler.ts                 # 60 lines - Error handling
├── types/
│   └── ai.types.ts                     # 87 lines - Type definitions
└── config/
    └── prompts.ts                      # 104 lines - Prompt templates

Benefits Achieved

✅ Maintainability

• Before: 453 lines in one file
• After: 12 focused files, largest is 145 lines
• Each module has a single, clear responsibility
• Easy to locate and fix bugs

✅ Testability

• Service methods can be unit tested independently
• Utilities can be tested in isolation
• OpenAI client can be easily mocked
• Clear interfaces for all components

✅ Reusability

• Utils can be used across different endpoints
• Service can be used outside routes (CLI, jobs, etc.)
• Prompts centralized and easy to modify
• Image handling logic shared

✅ Type Safety

• Full TypeScript coverage with explicit interfaces
• Request/response types defined
• Compile-time error detection
• Better IDE autocomplete and refactoring support

✅ Error Handling

• Centralized error handling with consistent format
• Detailed logging with request IDs
• Debug mode for development
• Structured error responses

Key Improvements

1. Separation of Concerns

• Routes: Only handle HTTP request/response
• Services: Business logic and AI orchestration
• Utils: Reusable helper functions
• Config: Static configuration and prompts
• Types: Type definitions and interfaces

2. OpenAI Client Singleton

• Single instance with optimized configuration
• 10-minute timeout for long requests
• 2 retry attempts for transient failures
• Shared across all AI operations

3. Specialized Generators

• ContentGenerator: Handles gpt-5-2025-08-07 with Chat Completions API
• MetadataGenerator: Handles gpt-5-2025-08-07 for metadata
• AltTextGenerator: Handles gpt-5-2025-08-07 for accessibility

4. Utility Functions

• imageUtils: Presigned URLs, format validation, placeholder extraction
• contextBuilder: Build context from transcriptions and images
• responseParser: Parse AI responses, strip HTML, handle JSON
• errorHandler: Consistent error logging and responses

5. Request Tracking

• Every request gets a unique UUID
• Logs include request ID for correlation
• Elapsed time tracking
• Detailed error context

Migration Status

✅ Completed

• Type definitions
• Configuration extraction
• Utility functions
• OpenAI client singleton
• Service layer implementation
• Route handlers refactored
• TypeScript compilation verified

🔄 Active

• New routes active at /api/ai/*
• Old ai-generate.ts kept as backup (commented out)

📋 Next Steps

1. Test all endpoints:

   • POST /api/ai/generate
   • POST /api/ai/generate-metadata
   • POST /api/ai/generate-alt-text

2. Verify functionality:

   • Content generation with reference images
   • Metadata generation from HTML
   • Alt text with and without captions
   • Error handling and logging

3. Remove old code (after validation):

   • Delete src/ai-generate.ts
   • Remove commented import in index.ts

Testing Commands

# Start API server
cd apps/api
pnpm run dev

# Test content generation
curl -X POST http://localhost:3301/api/ai/generate \
  -H "Content-Type: application/json" \
  -d '{"prompt": "Write about TypeScript best practices"}'

# Test metadata generation
curl -X POST http://localhost:3301/api/ai/generate-metadata \
  -H "Content-Type: application/json" \
  -d '{"contentHtml": "<h1>Test Article</h1><p>Content here</p>"}'

# Test alt text generation
curl -X POST http://localhost:3301/api/ai/generate-alt-text \
  -H "Content-Type: application/json" \
  -d '{"placeholderDescription": "dashboard_screenshot"}'

Rollback Plan

If issues arise, rollback is simple:

1. Edit src/index.ts:

   // Comment out new routes
   // app.use('/api/ai', aiRoutesNew);
   
   // Uncomment old routes
   app.use('/api/ai', aiGenerateRouter);
   

2. Restart server

3. Old functionality restored immediately

File Size Comparison

Metric	Before	After
Single file	453 lines	-
Largest file	453 lines	145 lines
Total files	1	12
Average file size	453 lines	~70 lines
Cyclomatic complexity	High	Low

Code Quality Metrics

• ✅ Single Responsibility Principle
• ✅ Dependency Injection ready
• ✅ Easy to mock for testing
• ✅ Clear module boundaries
• ✅ Consistent error handling
• ✅ Comprehensive logging
• ✅ Type-safe throughout

Conclusion

The refactoring successfully transformed a complex 453-line file into a clean, maintainable architecture with 12 focused modules. Each component has a clear purpose, is independently testable, and follows TypeScript best practices.

Status: ✅ Ready for testing Risk: Low (old code preserved for easy rollback) Impact: High (significantly improved maintainability)