"""不可变 run 目录读写。不认识 Muse 业务对象。"""

from __future__ import annotations

import json
import os
import re
from collections.abc import Iterator, Mapping
from contextlib import contextmanager
from pathlib import Path
from typing import Any, BinaryIO

DEFAULT_RUN_DIR_ROOT = Path("/tmp/muse-agent-runs")
_RUN_ID_PATTERN = re.compile(r"^[A-Za-z0-9_.-]{1,64}$")


class RunDirectoryError(OSError):
    """run 目录创建或写入失败。"""


def validate_run_id(run_id: str) -> bool:
    return isinstance(run_id, str) and _RUN_ID_PATTERN.fullmatch(run_id) is not None


def prepare_run_dir(run_id: str, run_dir: str | Path | None = None) -> Path:
    """创建仅当前用户可访问的 run 目录；默认根目录可复用，本次目录不可覆盖。"""

    run_dir_path = Path(run_dir) if run_dir is not None else DEFAULT_RUN_DIR_ROOT / run_id
    if run_dir is None:
        DEFAULT_RUN_DIR_ROOT.mkdir(parents=True, mode=0o700, exist_ok=True)
        DEFAULT_RUN_DIR_ROOT.chmod(0o700)
    run_dir_path.mkdir(parents=True, mode=0o700, exist_ok=False)
    run_dir_path.chmod(0o700)
    return run_dir_path


def write_private_text(path: Path, text: str) -> None:
    fd = os.open(path, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, 0o600)
    with os.fdopen(fd, "w", encoding="utf-8") as handle:
        handle.write(text)
    path.chmod(0o600)


def write_private_json(path: Path, value: Mapping[str, Any]) -> None:
    write_private_text(path, json.dumps(value, ensure_ascii=False, indent=2))


def seed_run_inputs(
    run_dir: Path,
    *,
    spec_text: str,
    system_prompt: str,
    user_message: str,
) -> None:
    write_private_text(run_dir / "task-spec.json", spec_text)
    write_private_text(run_dir / "system-prompt.txt", system_prompt)
    write_private_text(run_dir / "user-message.txt", user_message)


@contextmanager
def open_transcript(run_dir: Path) -> Iterator[BinaryIO]:
    path = run_dir / "transcript.jsonl"
    fd = os.open(path, os.O_WRONLY | os.O_CREAT | os.O_EXCL, 0o600)
    handle = os.fdopen(fd, "wb")
    try:
        yield handle
        path.chmod(0o600)
    finally:
        handle.close()


def read_transcript_text(run_dir: Path) -> str:
    return (run_dir / "transcript.jsonl").read_text(encoding="utf-8")


def remove_local_raw(run_dir: Path) -> None:
    for name in ("transcript.jsonl", "final-message.txt"):
        try:
            (run_dir / name).unlink(missing_ok=True)
        except OSError:
            pass