"""Platform-specific paths and tool resolution for meshbay-node."""

import asyncio
import os
import shutil
import sys
from pathlib import Path

# ── Event loop ───────────────────────────────────────────────────────────────


def use_compatible_event_loop() -> None:
    """
    aiortc's ICE stack (aioice) does not run on Windows' default
    ProactorEventLoop — a DataChannel handshake never completes and the
    connection hangs. Select the SelectorEventLoop before the loop is created.

    Cost: SelectorEventLoop cannot spawn subprocesses on Windows, so ffmpeg
    streaming (asyncio.create_subprocess_exec in webrtc_server.py) does not work
    under it. The video path needs a thread-based runner on Windows — tracked
    for the port. No effect off Windows.
    """
    if sys.platform == "win32":
        asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())


# ── Directories ──────────────────────────────────────────────────────────────


def config_dir() -> Path:
    if sys.platform == "win32":
        return Path(os.environ.get("LOCALAPPDATA") or Path.home()) / "meshbay"
    return Path.home() / ".config" / "meshbay"


def data_dir() -> Path:
    if sys.platform == "win32":
        return Path(os.environ.get("LOCALAPPDATA") or Path.home()) / "meshbay" / "data"
    return Path.home() / ".local" / "share" / "meshbay"


def state_dir() -> Path:
    if sys.platform == "win32":
        return Path(os.environ.get("LOCALAPPDATA") or Path.home()) / "meshbay" / "state"
    return Path.home() / ".local" / "state" / "meshbay"


# ── File permissions ─────────────────────────────────────────────────────────


def chmod_private(path: Path, *, mode: int = 0o600) -> None:
    """Set restrictive permissions on a file. No-op on Windows (NTFS ignores mode bits)."""
    if sys.platform != "win32":
        path.chmod(mode)


# ── Media tools ──────────────────────────────────────────────────────────────

_ffmpeg_path: str = "ffmpeg"
_ffprobe_path: str = "ffprobe"


def check_media_tools(
    ffmpeg: str = "ffmpeg", ffprobe: str = "ffprobe",
) -> None:
    """Resolve ffmpeg/ffprobe at daemon startup. Raises RuntimeError if not found."""
    global _ffmpeg_path, _ffprobe_path
    resolved = shutil.which(ffmpeg)
    if not resolved:
        raise RuntimeError(
            f"{ffmpeg!r} not found in PATH. "
            "Install ffmpeg or set [node] ffmpeg_path in node.toml."
        )
    _ffmpeg_path = resolved
    resolved = shutil.which(ffprobe)
    if not resolved:
        raise RuntimeError(
            f"{ffprobe!r} not found in PATH. "
            "Install ffmpeg or set [node] ffprobe_path in node.toml."
        )
    _ffprobe_path = resolved


def ffmpeg_cmd() -> str:
    return _ffmpeg_path


def ffprobe_cmd() -> str:
    return _ffprobe_path