from typing import Literal
from langchain_core.tools import tool
from pydantic import BaseModel, Field


class TerminateInput(BaseModel):
    """終止對話的輸入參數"""
    status: Literal["success", "failure"] = Field(
        description="互動結束的狀態：'success' 表示任務完成，'failure' 表示無法繼續",
        examples=["success", "failure"]
    )
    reason: str = Field(
        default="",
        description="可選：簡單說明為什麼結束（例如 '報告已生成' 或 '缺少關鍵資訊'）",
        examples=["報告已成功生成", "無法取得足夠資料"]
    )


@tool(args_schema=TerminateInput)
def terminate(status: str, reason: str = "") -> dict:
    """
    终止本次互动。
    """
    return {
        "messages": [],  # 清空追加消息
        "__end__": True,  # 结束标记
        "status": status,
        "reason": reason
    }