# Web Migration TODO: Flask to FastAPI

This document contains tasks for migrating the web application from Flask to FastAPI. Each task should be marked as completed with [x] when finished.

## 📋 Project Analysis and Setup

### Initial Assessment
- [ ] Review current Flask application structure in `/src/web/` directory
- [ ] Identify all Flask routes and their HTTP methods
- [ ] Document current template engine usage (Jinja2)
- [ ] List all static file serving requirements
- [ ] Inventory all middleware and extensions currently used
- [ ] Document current error handling patterns
- [ ] Review authentication/authorization mechanisms

### FastAPI Setup
- [x] Install FastAPI dependencies: `pip install fastapi uvicorn jinja2 python-multipart`
- [x] Update `requirements.txt` or `pyproject.toml` with new dependencies
- [ ] Remove Flask dependencies: `flask`, `flask-*` packages
- [x] Create new FastAPI application entry point

## 🔧 Core Application Migration

### Main Application Structure
- [x] Create new `main.py` or update existing app entry point with FastAPI app instance
- [x] Migrate Flask app configuration to FastAPI settings using Pydantic BaseSettings
- [ ] Convert Flask blueprints to FastAPI routers
- [x] Update CORS configuration from Flask-CORS to FastAPI CORS middleware

### Route Conversion
- [ ] Convert all `@app.route()` decorators to FastAPI route decorators (`@app.get()`, `@app.post()`, etc.)
- [ ] Update route parameter syntax from `<int:id>` to `{id: int}` format
- [ ] Convert Flask request object usage (`request.form`, `request.json`) to FastAPI request models
- [ ] Update response handling from Flask `jsonify()` to FastAPI automatic JSON serialization
- [ ] Convert Flask `redirect()` and `url_for()` to FastAPI equivalents

### Request/Response Models
- [ ] Create Pydantic models for request bodies (replace Flask request parsing)
- [ ] Create Pydantic models for response schemas
- [ ] Update form handling to use FastAPI Form dependencies
- [ ] Convert file upload handling to FastAPI UploadFile

## 🎨 Template and Static Files Migration

### Template Engine Setup
- [ ] Configure Jinja2Templates in FastAPI application
- [ ] Set up template directory structure
- [ ] Create templates directory configuration in FastAPI app

### HTML Template Migration
- [ ] Review all `.html` files in templates directory
- [ ] Update template rendering from Flask `render_template()` to FastAPI `templates.TemplateResponse()`
- [ ] Verify Jinja2 syntax compatibility (should be mostly unchanged)
- [ ] Update template context passing to match FastAPI pattern
- [ ] Test all template variables and filters still work correctly

### Static Files Configuration
- [ ] Configure StaticFiles mount in FastAPI for CSS, JS, images
- [ ] Update static file URL generation in templates
- [ ] Verify all CSS file references work correctly
- [ ] Verify all JavaScript file references work correctly
- [ ] Test image and other asset serving

## 💻 JavaScript and Frontend Migration

### Inline JavaScript Review
- [ ] Scan all HTML templates for inline `<script>` tags
- [ ] Review JavaScript code for Flask-specific URL generation (e.g., `{{ url_for() }}`)
- [ ] Update AJAX endpoints to match new FastAPI route structure
- [ ] Convert Flask CSRF token handling to FastAPI security patterns

### External JavaScript Files
- [ ] Review all `.js` files in static directory
- [ ] Update API endpoint URLs to match FastAPI routing
- [ ] Verify fetch() or XMLHttpRequest calls use correct endpoints
- [ ] Update any Flask-specific JavaScript patterns
- [ ] Test all JavaScript functionality after migration

### CSS Files Review
- [ ] Verify all `.css` files are served correctly
- [ ] Check for any Flask-specific CSS patterns or URL references
- [ ] Test responsive design and styling after migration

## 🔐 Security and Middleware Migration

### Authentication/Authorization
- [ ] Convert Flask-Login or similar to FastAPI security dependencies
- [ ] Update session management (FastAPI doesn't have built-in sessions)
- [ ] Migrate password hashing and verification
- [ ] Convert authentication decorators to FastAPI dependencies

### Middleware Migration
- [ ] Convert Flask middleware to FastAPI middleware
- [ ] Update error handling from Flask error handlers to FastAPI exception handlers
- [ ] Migrate request/response interceptors
- [ ] Update logging middleware if used

## 🧪 Testing and Validation

### Functional Testing
- [ ] Test all web routes return correct responses
- [ ] Verify all HTML pages render correctly
- [ ] Test all forms submit and process data correctly
- [ ] Verify file uploads work (if applicable)
- [ ] Test authentication flows (login/logout/registration)

### Frontend Testing
- [ ] Test all JavaScript functionality
- [ ] Verify AJAX calls work correctly
- [ ] Test dynamic content loading
- [ ] Verify CSS styling is applied correctly
- [ ] Test responsive design on different screen sizes

### Integration Testing
- [ ] Test database connectivity and operations
- [ ] Verify API endpoints return correct data
- [ ] Test error handling and user feedback
- [ ] Verify security features work correctly

## 📚 Documentation and Cleanup

### Code Documentation
- [ ] Update API documentation to reflect FastAPI changes
- [ ] Add OpenAPI/Swagger documentation (automatic with FastAPI)
- [ ] Update README with new setup instructions
- [ ] Document any breaking changes or new patterns

### Code Cleanup
- [ ] Remove unused Flask imports and dependencies
- [ ] Clean up any Flask-specific code patterns
- [ ] Update imports to use FastAPI equivalents
- [ ] Remove deprecated or unused template files
- [ ] Clean up static files that are no longer needed

## 🚀 Deployment and Configuration

### Server Configuration
- [ ] Update server startup to use `uvicorn` instead of Flask development server
- [ ] Configure production ASGI server (uvicorn, gunicorn with uvicorn workers)
- [ ] Update any reverse proxy configuration (nginx, Apache)
- [ ] Test application startup and shutdown

### Environment Configuration
- [ ] Update environment variables for FastAPI
- [ ] Configure logging for FastAPI application
- [ ] Update any deployment scripts or Docker configurations
- [ ] Test application in different environments (dev, staging, prod)

## ✅ Final Verification

### Complete System Test
- [ ] Perform end-to-end testing of all user workflows
- [ ] Verify performance is acceptable or improved
- [ ] Test error scenarios and edge cases
- [ ] Confirm all original functionality is preserved
- [ ] Validate security measures are in place and working

### Monitoring and Observability
- [ ] Set up health check endpoints
- [ ] Configure metrics collection (if used)
- [ ] Set up error monitoring and alerting
- [ ] Test logging and debugging capabilities

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## 📝 Migration Notes

### Important FastAPI Concepts to Remember:
- FastAPI uses async/await by default (but sync functions work too)
- Automatic request/response validation with Pydantic
- Built-in OpenAPI documentation
- Dependency injection system
- Type hints are crucial for FastAPI functionality

### Common Gotchas:
- FastAPI doesn't have built-in session support (use external library if needed)
- Template responses need explicit media_type for HTML
- Static file mounting needs to be configured explicitly
- Request object structure is different from Flask

### Performance Considerations:
- FastAPI is generally faster than Flask
- Consider using async functions for I/O operations
- Use background tasks for long-running operations
- Implement proper caching strategies