#!/usr/bin/env python3
"""Read-only environment report used before installing the persistent node."""

from __future__ import annotations

import argparse
import json
import os
import platform
import shutil
import subprocess
from pathlib import Path
from typing import Any


def command(argv: list[str], timeout: int = 20) -> dict[str, Any]:
    if shutil.which(argv[0]) is None:
        return {"available": False}
    try:
        result = subprocess.run(
            argv,
            stdin=subprocess.DEVNULL,
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
            text=True,
            timeout=timeout,
            shell=False,
        )
        return {
            "available": True,
            "exit_code": result.returncode,
            "output": result.stdout[:32_000],
        }
    except subprocess.TimeoutExpired:
        return {"available": True, "error": "timeout"}


def inspect() -> dict[str, Any]:
    efi = command(["efibootmgr", "-v"])
    disks = command(["lsblk", "-J", "-o", "NAME,FSTYPE,LABEL,MOUNTPOINTS"])
    virt = command(["systemd-detect-virt"])
    boot_text = str(efi.get("output", "")).lower()
    disk_text = str(disks.get("output", "")).lower()
    windows_hint = any(
        marker in boot_text or marker in disk_text
        for marker in ("windows boot manager", "microsoft", "ntfs", "bitlocker")
    )
    return {
        "schema": "canger-node-preflight/v1",
        "hostname": platform.node(),
        "platform": platform.platform(),
        "machine": platform.machine(),
        "systemd_running": os.path.isdir("/run/systemd/system"),
        "virtualization": virt,
        "efi_boot_entries": efi,
        "block_filesystems": disks,
        "possible_windows_dual_boot": windows_hint,
        "continuity": {
            "while_linux_is_booted": "supported",
            "after_reboot_back_into_linux": "supported",
            "while_another_dual_boot_os_is_active": "not_possible_from_linux",
        },
        "note": (
            "A dual-boot switch powers off Linux. Cross-OS continuity requires "
            "a companion agent in the other OS, a virtual machine, or separate hardware."
        ),
    }


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument("--output")
    args = parser.parse_args()
    report = inspect()
    text = json.dumps(report, ensure_ascii=False, indent=2) + "\n"
    if args.output:
        target = Path(args.output)
        target.parent.mkdir(parents=True, exist_ok=True)
        target.write_text(text, encoding="utf-8")
        os.chmod(target, 0o600)
    print(text, end="")


if __name__ == "__main__":
    main()