"""业务异常与全局异常处理器：统一转成 {code, message, data, trace_id}。"""
from fastapi import FastAPI, Request
from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse
from starlette.exceptions import HTTPException as StarletteHTTPException

from utils.logger import get_logger
from utils.response import Code, fail

logger = get_logger("api")


class ApiError(Exception):
    """业务异常基类。code 见 utils.response.Code。"""

    def __init__(self, code: int, message: str, data=None):
        self.code = code
        self.message = message
        self.data = data
        super().__init__(message)


class ParamError(ApiError):
    def __init__(self, message: str = "参数错误"):
        super().__init__(Code.PARAM_ERROR, message)


class AuthError(ApiError):
    def __init__(self, message: str = "未登录或登录已过期"):
        super().__init__(Code.UNAUTHORIZED, message)


class ForbiddenError(ApiError):
    def __init__(self, message: str = "无权限执行该操作"):
        super().__init__(Code.FORBIDDEN, message)


class NotFoundError(ApiError):
    def __init__(self, message: str = "资源不存在"):
        super().__init__(Code.NOT_FOUND, message)


class LLMFailError(ApiError):
    """LLM 调用失败（重试耗尽，§1001）。"""

    def __init__(self, message: str = "LLM 调用失败，请稍后再试"):
        super().__init__(Code.LLM_FAIL, message)


class RiskTriggeredError(ApiError):
    """交易被风控拦截（§1004）。"""

    def __init__(self, message: str = "交易被风控拦截，请在订单列表查看处理进度", data=None):
        super().__init__(Code.RISK_TRIGGERED, message, data)


class NotSuitableError(ApiError):
    """适当性不匹配（§1005）。"""

    def __init__(self, message: str = "客户风险等级与产品风险等级不匹配", data=None):
        super().__init__(Code.NOT_SUITABLE, message, data)


def _http_status(code: int) -> int:
    """业务码若为标准 HTTP 状态码则原样返回，自定义业务码（1001+）统一返回 200。"""
    return code if 400 <= code < 600 else 200


def register_exception_handlers(app: FastAPI) -> None:
    @app.exception_handler(StarletteHTTPException)
    async def http_handler(request: Request, exc: StarletteHTTPException):
        return JSONResponse(status_code=exc.status_code, content=fail(exc.status_code, str(exc.detail)).model_dump())

    @app.exception_handler(RequestValidationError)
    async def validation_handler(request: Request, exc: RequestValidationError):
        return JSONResponse(
            status_code=422,
            content=fail(Code.PARAM_ERROR, "参数校验失败", exc.errors()).model_dump(),
        )

    @app.exception_handler(ApiError)
    async def api_error_handler(request: Request, exc: ApiError):
        status = _http_status(exc.code)
        return JSONResponse(status_code=status, content=fail(exc.code, exc.message, exc.data).model_dump())

    @app.exception_handler(Exception)
    async def unhandled_handler(request: Request, exc: Exception):
        logger.exception("unhandled error on %s", request.url.path)
        return JSONResponse(status_code=500, content=fail(Code.SERVER_ERROR, "服务内部错误").model_dump())