Feature: Middleware Enhancement

[NFUChen]

🚀 Feature: Advanced Middleware Architecture System

📋 Overview

This PR introduces significant improvements to the middleware architecture in PySpring, providing developers with powerful tools for managing middleware execution order with fine-grained control and a comprehensive API for middleware manipulation.

✨ New Features

🔧 Middleware Architecture Overhaul

• Concrete MiddlewareRegistry: Transformed from abstract class to fully functional concrete implementation
• MiddlewareConfiguration: New configuration class for declarative middleware setup
• Advanced Middleware Management: Fine-grained control over middleware execution order
• Comprehensive API: Rich set of methods for middleware manipulation
• Enhanced Type Safety: Full type annotation coverage with generic support
• Execution Order Control: Precise positioning with before/after/index-based placement

🔄 Breaking Changes

MiddlewareRegistry Changes

• Before: MiddlewareRegistry was an abstract class requiring subclassing
• After: MiddlewareRegistry is now a concrete class with full implementation
• Migration: Replace custom registry subclasses with MiddlewareConfiguration implementations

Old Pattern:

class MyMiddlewareRegistry(MiddlewareRegistry):
    def get_middleware_classes(self) -> list[Type[Middleware]]:
        return [AuthMiddleware, LoggingMiddleware]

New Pattern:

class MyMiddlewareConfiguration(MiddlewareConfiguration):
    def configure_middlewares(self, registry: MiddlewareRegistry) -> None:
        registry.add_middleware(AuthMiddleware)
        registry.add_middleware(LoggingMiddleware)

⚙️ MiddlewareConfiguration

class AppMiddlewareConfig(MiddlewareConfiguration):
    def configure_middlewares(self, registry: MiddlewareRegistry) -> None:
        # Security first
        registry.add_middleware(SecurityMiddleware)
        
        # Authentication
        registry.add_middleware(AuthMiddleware)
        
        # Request processing
        registry.add_middleware(ValidationMiddleware)
        registry.add_middleware(LoggingMiddleware)
        
        # Advanced positioning
        registry.add_before(ValidationMiddleware, RateLimitMiddleware)
        registry.add_after(AuthMiddleware, PermissionMiddleware)

🎯 Complete API Reference

Method	Description	Example
add_middleware(middleware)	Add middleware to end of chain	registry.add_middleware(AuthMiddleware)
add_before(target, new)	Add middleware before target	registry.add_before(AuthMiddleware, CorsMiddleware)
add_after(target, new)	Add middleware after target	registry.add_after(AuthMiddleware, LoggingMiddleware)
add_at_index(index, middleware)	Add middleware at specific index	registry.add_at_index(0, SecurityMiddleware)
remove_middleware(middleware)	Remove specific middleware	registry.remove_middleware(OldMiddleware)
has_middleware(middleware)	Check if middleware exists	registry.has_middleware(AuthMiddleware)
get_middleware_index(middleware)	Get middleware position	registry.get_middleware_index(AuthMiddleware)
get_middleware_count()	Get total middleware count	registry.get_middleware_count()
get_middleware_classes()	Get all middlewares list	registry.get_middleware_classes()
clear_middlewares()	Remove all middlewares	registry.clear_middlewares()