from typing import Any, Callable, Dict, Optional
from fastapi import FastAPI, Request, Response
from fastapi.responses import JSONResponse
import json
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.types import ASGIApp
from app.schemas.response import StandardResponse, ErrorResponse

class ResponseMiddleware(BaseHTTPMiddleware):
    """
    中间件：统一处理API响应格式
    
    请求正确：{code:200, data:Any}
    业务错误：{code:500, message:""}
    """
    
    async def dispatch(self, request: Request, call_next: Callable) -> Response:
        # 不需要处理的路径
        exclude_paths = ["/docs", "/redoc", "/openapi.json"]
        if any(request.url.path.startswith(path) for path in exclude_paths):
            return await call_next(request)
        
        # 获取原始响应    
        response = await call_next(request)
        
        # 如果不是200系列响应或不是JSON响应，直接返回
        if response.status_code >= 300 or response.headers.get("content-type") != "application/json":
            return response
            
        # 读取响应内容
        try:
            # 使用JSONResponse的_render方法获取内容
            if isinstance(response, JSONResponse):
                # 获取原始数据
                raw_data = response.body.decode("utf-8")
                data = json.loads(raw_data)
                
                # 已经是标准格式，不再封装
                if isinstance(data, dict) and "code" in data and ("data" in data or "message" in data):
                    return response
                
                # 创建新的标准响应
                std_response = StandardResponse(code=200, data=data)
                
                # 创建新的JSONResponse
                return JSONResponse(
                    content=std_response.model_dump(),
                    status_code=response.status_code,
                    headers=dict(response.headers)
                )
            # 处理流式响应或其他类型响应
            else:
                return response
                
        except Exception as e:
            # 出现异常，返回原始响应
            return response

def add_response_middleware(app: FastAPI) -> None:
    """添加响应处理中间件到FastAPI应用"""
    app.add_middleware(ResponseMiddleware)