from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse
from fastapi.exceptions import RequestValidationError
from starlette.exceptions import HTTPException as StarletteHTTPException
import os
import traceback
import logging

from app.models.api_response import APIResponseModel

# 根据环境变量决定是否使用标准响应格式
use_standard_response = os.environ.get("USE_STANDARD_RESPONSE") == "1"
logger = logging.getLogger(__name__)

class CustomHTTPException(Exception):
    """自定义HTTP异常类，用于抛出自定义的HTTP错误"""
    def __init__(self, status_code: int, detail: str = None):
        self.status_code = status_code
        self.detail = detail

async def http_exception_handler(request: Request, exc: CustomHTTPException):
    """处理自定义HTTP异常的处理器"""
    logger.error(f"HTTP错误: {exc.status_code} - {exc.detail}")
    
    return JSONResponse(
        status_code=exc.status_code,
        content=APIResponseModel(
            code=exc.status_code, 
            message=exc.detail or "请求处理失败"
        ).dict()
    )

async def starlette_exception_handler(request: Request, exc: StarletteHTTPException):
    """处理FastAPI内置的HTTP异常的处理器"""
    logger.error(f"Starlette HTTP错误: {exc.status_code} - {exc.detail}")
    
    return JSONResponse(
        status_code=exc.status_code,
        content=APIResponseModel(
            code=exc.status_code,
            message=str(exc.detail)
        ).dict()
    )

async def validation_exception_handler(request: Request, exc: RequestValidationError):
    """处理请求验证错误的处理器"""
    error_detail = exc.errors()
    error_messages = [f"{e['loc'][-1]}: {e['msg']}" for e in error_detail]
    error_message = ", ".join(error_messages)
    logger.error(f"请求验证错误: {error_message}")
    
    return JSONResponse(
        status_code=422,
        content=APIResponseModel(
            code=422, 
            message=f"请求参数验证失败: {error_message}",
            data=error_detail
        ).dict()
    )

async def general_exception_handler(request: Request, exc: Exception):
    """处理一般性异常的处理器"""
    # 记录详细的错误信息
    error_msg = str(exc)
    logger.error(f"服务器错误: {error_msg}")
    logger.error(traceback.format_exc())
    
    return JSONResponse(
        status_code=500,
        content=APIResponseModel(
            code=500, 
            message="服务器内部错误",
            data={"detail": error_msg} if os.environ.get("DEBUG") == "1" else None
        ).dict()
    )

def setup_exception_handlers(app: FastAPI):
    """为FastAPI应用设置所有异常处理器"""
    app.add_exception_handler(CustomHTTPException, http_exception_handler)
    app.add_exception_handler(StarletteHTTPException, starlette_exception_handler)
    app.add_exception_handler(RequestValidationError, validation_exception_handler)
    app.add_exception_handler(Exception, general_exception_handler)