"""工作流脚本回调。用法：import agentwf as wf。

请求写到 fd 3，响应从 fd 4 按行读回。宿主一次只处理一条。
"""

import json
import os

_seq = 0
_out = os.fdopen(3, "w", encoding="utf-8", buffering=1)
_inp = os.fdopen(4, "r", encoding="utf-8", buffering=1)


def _rpc(op, **fields):
    global _seq
    _seq += 1
    msg = {"id": str(_seq), "op": op}
    msg.update(fields)
    _out.write(json.dumps(msg, ensure_ascii=False) + "\n")
    _out.flush()
    line = _inp.readline()
    if not line:
        raise RuntimeError("workflow host closed")
    resp = json.loads(line)
    if not resp.get("ok"):
        raise RuntimeError(resp.get("error") or "workflow call failed")
    return resp.get("output", "")


def tool(name, args=None):
    return _rpc("tool.call", name=name, args=args or {})


def ask(question, choices=None):
    return _rpc("hitl.ask", question=question, choices=choices or [])


def agent(name, task):
    return _rpc("agent.spawn", agent=name, task=task)


def artifact(name, content):
    return _rpc("artifact.register", name=name, content=content)


def card(title, kind="result"):
    return _rpc("card.create", title=title, kind=kind)


def step(step_id, title, status):
    return _rpc("step", stepId=step_id, title=title, status=status)