"""投顾 Agent 草稿状态机基础规则。"""
from __future__ import annotations

from common.common_const import (
    DRAFT_STATUS_DISCARDED,
    DRAFT_STATUS_DRAFT,
    ERR_CODE_DRAFT_NOT_FOUND,
)


class DraftStateError(Exception):
    def __init__(self, code: int, message: str):
        self.code = code
        self.message = message
        super().__init__(message)


def transition_draft_status(status: str, operation: str) -> str:
    if status == DRAFT_STATUS_DRAFT and operation == "discard":
        return DRAFT_STATUS_DISCARDED
    if status == DRAFT_STATUS_DISCARDED:
        raise DraftStateError(ERR_CODE_DRAFT_NOT_FOUND, "草稿不存在或者已废弃")
    if status != DRAFT_STATUS_DRAFT:
        raise DraftStateError(ERR_CODE_DRAFT_NOT_FOUND, "草稿状态无效")
    if operation == "save":
        return DRAFT_STATUS_DRAFT
    raise DraftStateError(ERR_CODE_DRAFT_NOT_FOUND, "不支持的草稿操作")