from fastapi import HTTPException, Request
from fastapi.responses import JSONResponse
from fastapi.exceptions import RequestValidationError
from app.schemas.response import ErrorResponse

class BusinessError(Exception):
    """业务错误异常，使用标准响应格式"""
    def __init__(self, message: str, code: int = 500):
        self.message = message
        self.code = code
        super().__init__(self.message)

# 业务异常处理器
async def business_exception_handler(request: Request, exc: BusinessError):
    """将业务异常转换为标准响应格式"""
    return JSONResponse(
        status_code=200,  # 返回200状态码，但在响应内容中设置业务错误码
        content=ErrorResponse(
            code=exc.code,
            message=exc.message
        ).model_dump()
    )

# 请求验证错误处理器
async def validation_exception_handler(request: Request, exc: RequestValidationError):
    """将请求验证错误转换为标准错误响应"""
    error_messages = []
    for error in exc.errors():
        loc = error.get("loc", [])
        loc_str = " -> ".join(str(l) for l in loc)
        error_messages.append(f"{loc_str}: {error.get('msg')}")
    
    error_message = ", ".join(error_messages)
    
    return JSONResponse(
        status_code=422,  # 保持422状态码，表示验证错误
        content=ErrorResponse(
            code=422,
            message=f"请求参数验证错误: {error_message}"
        ).model_dump()
    )

def add_exception_handlers(app):
    """添加异常处理器到FastAPI应用"""
    app.add_exception_handler(BusinessError, business_exception_handler)
    app.add_exception_handler(RequestValidationError, validation_exception_handler)