"""伺服和 flexiv_hardware 之间的 MoveL 交接。

两边不在一个进程里，硬件接口也没有自己的 ROS 节点。用三个文件：

* ``/tmp/flexiv_movel_req``  一行 ``seq x y z keep_z vel``
* ``/tmp/flexiv_movel_ack``  硬件接住请求后立刻写序号
* ``/tmp/flexiv_movel_done`` 一行 ``seq ok`` 或 ``seq fail 原因``

先写临时文件再改名，避免对面读到半行。
"""

from __future__ import annotations

from pathlib import Path

REQ = Path("/tmp/flexiv_movel_req")
ACK = Path("/tmp/flexiv_movel_ack")
DONE = Path("/tmp/flexiv_movel_done")


def format_request(seq: int, x: float, y: float, z: float, keep_z: bool, vel: float) -> str:
    return (
        f"{int(seq)} {float(x):.6f} {float(y):.6f} {float(z):.6f} "
        f"{1 if keep_z else 0} {float(vel):.4f}\n"
    )


def write_request(seq: int, x: float, y: float, z: float, keep_z: bool, vel: float) -> None:
    text = format_request(seq, x, y, z, keep_z, vel)
    tmp = REQ.with_name(REQ.name + ".tmp")
    tmp.write_text(text, encoding="utf-8")
    tmp.replace(REQ)


def parse_done(text: str):
    """返回 ``(seq, ok, detail)``。行不完整时返回 None。"""
    parts = text.strip().split(maxsplit=2)
    if len(parts) < 2:
        return None
    try:
        seq = int(parts[0])
    except ValueError:
        return None
    if parts[1] not in ("ok", "fail"):
        return None
    detail = parts[2] if len(parts) > 2 else ""
    return seq, parts[1] == "ok", detail


def read_done():
    try:
        text = DONE.read_text(encoding="utf-8")
    except OSError:
        return None
    return parse_done(text)


def read_ack() -> int:
    try:
        text = ACK.read_text(encoding="utf-8").strip()
    except OSError:
        return -1
    try:
        return int(text.split()[0])
    except (ValueError, IndexError):
        return -1