"""Build a NoCloud cidata ISO for cloud-init.

Cirros 0.6.x — and most cloud images — look for a NoCloud datasource at
boot: an ISO9660 volume labeled ``cidata`` containing two files,
``user-data`` and ``meta-data``. We attach it as a second drive so
cloud-init proceeds without spending ~17 minutes timing out trying to
reach a non-existent metadata service.

This script is intentionally self-contained and uses only pycdlib (pure
Python) — no system mkisofs/xorriso/cloud-localds dependency.

Usage:

    uv run python tools/build_cidata.py vm/images/cidata.iso

The defaults bake in the ``cirros`` user with the documented Cirros
password, enable SSH password auth (so future Metasploit-class images
work without changes), and set a hostname. Override via flags if needed.
"""

from __future__ import annotations

import argparse
import io
import sys
from pathlib import Path

import pycdlib


DEFAULT_USER_DATA = """\
#cloud-config
hostname: cis490
manage_etc_hosts: true
users:
  - name: cis490
    plain_text_passwd: cis490
    lock_passwd: false
    sudo: ALL=(ALL) NOPASSWD:ALL
    shell: /bin/sh
ssh_pwauth: true
disable_root: false
chpasswd:
  expire: false
  list: |
    root:cis490
    cis490:cis490
runcmd:
  - [ sh, -c, "echo CIS490_BOOT_OK > /tmp/.cis490-boot" ]
"""

DEFAULT_META_DATA = """\
instance-id: cis490-vm-001
local-hostname: cis490
"""


def build_cidata(out_path: Path, user_data: bytes, meta_data: bytes) -> None:
    iso = pycdlib.PyCdlib()
    # Joliet=3 + Rock Ridge so cloud-init reads filenames correctly on Linux.
    iso.new(joliet=3, vol_ident="cidata", interchange_level=3, rock_ridge="1.09")

    iso.add_fp(
        io.BytesIO(user_data),
        len(user_data),
        iso_path="/USERDATA.;1",
        rr_name="user-data",
        joliet_path="/user-data",
    )
    iso.add_fp(
        io.BytesIO(meta_data),
        len(meta_data),
        iso_path="/METADATA.;1",
        rr_name="meta-data",
        joliet_path="/meta-data",
    )
    iso.write(str(out_path))
    iso.close()


def main() -> int:
    parser = argparse.ArgumentParser(prog="build_cidata")
    parser.add_argument("out_path", type=Path)
    parser.add_argument(
        "--user-data",
        type=Path,
        default=None,
        help="path to a custom cloud-config user-data file",
    )
    parser.add_argument(
        "--meta-data",
        type=Path,
        default=None,
        help="path to a custom meta-data file",
    )
    args = parser.parse_args()

    user_data = (
        args.user_data.read_bytes() if args.user_data else DEFAULT_USER_DATA.encode()
    )
    meta_data = (
        args.meta_data.read_bytes() if args.meta_data else DEFAULT_META_DATA.encode()
    )

    args.out_path.parent.mkdir(parents=True, exist_ok=True)
    build_cidata(args.out_path, user_data, meta_data)
    print(f"wrote {args.out_path} ({args.out_path.stat().st_size} bytes)")
    return 0


if __name__ == "__main__":
    sys.exit(main())