"""
全局异常处理器

处理各类异常并返回统一格式的错误响应
需求: 7.3, 8.1, 8.2, 8.3, 8.4
"""
import logging
from fastapi import Request, FastAPI, HTTPException
from fastapi.responses import JSONResponse
from fastapi.exceptions import RequestValidationError
from sqlalchemy.exc import SQLAlchemyError

logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
)
logger = logging.getLogger(__name__)


def register_exception_handlers(app: FastAPI):
    """注册全局异常处理器"""

    @app.exception_handler(HTTPException)
    async def http_exception_handler(request: Request, exc: HTTPException):
        """HTTP异常处理"""
        logger.warning(f"HTTP error {exc.status_code}: {exc.detail}")
        if isinstance(exc.detail, dict):
            payload = {"data": None}
            payload.update(exc.detail)
        else:
            payload = {
                "code": exc.status_code,
                "message": exc.detail,
                "detail": exc.detail,
                "data": None
            }
        return JSONResponse(
            status_code=exc.status_code,
            content=payload
        )
    
    @app.exception_handler(RequestValidationError)
    async def validation_exception_handler(request: Request, exc: RequestValidationError):
        """参数验证错误处理"""
        errors = exc.errors()
        logger.warning(f"Validation error: {errors}")
        # 提取第一条错误的友好提示，避免将原始列表暴露给前端
        if errors:
            first_error = errors[0]
            message = first_error.get("msg", "请求参数错误")
            # 去掉 Pydantic 自动添加的 "Value error, " 前缀
            if message.startswith("Value error, "):
                message = message[len("Value error, "):]
        else:
            message = "请求参数错误"
        return JSONResponse(
            status_code=400,
            content={"code": 400, "message": message, "data": None}
        )
    
    @app.exception_handler(SQLAlchemyError)
    async def database_exception_handler(request: Request, exc: SQLAlchemyError):
        """数据库错误处理"""
        logger.error(f"Database error: {exc}")
        return JSONResponse(
            status_code=500,
            content={"code": 500, "message": "Database error", "data": None}
        )
    
    @app.exception_handler(Exception)
    async def global_exception_handler(request: Request, exc: Exception):
        """全局异常处理"""
        logger.error(f"Unhandled exception: {exc}")
        return JSONResponse(
            status_code=500,
            content={"code": 500, "message": "Internal server error", "data": None}
        )