"""cloud-init's NoCloud seed: user-data, meta-data, network-config on an ISO.

NoCloud rather than VMware's guestinfo datasource because it needs nothing in
the guest: guestinfo is read through open-vm-tools, which a generic cloud
image does not ship -- it is one of the things the user-data installs.
"""

from __future__ import annotations

import io
from typing import Any

import pycdlib
import yaml

#: The volume label cloud-init's NoCloud datasource looks for.
_LABEL = "cidata"


def user_data(cloud_init_config: dict[str, Any], ssh_public_keys: list[str] | None) -> str:
    """The ``#cloud-config`` document, with ``ssh_public_keys`` merged in."""
    config = dict(cloud_init_config)
    if ssh_public_keys:
        keys = list(config.get("ssh_authorized_keys") or [])
        keys += [k for k in ssh_public_keys if k not in keys]
        config["ssh_authorized_keys"] = keys
    return "#cloud-config\n" + yaml.safe_dump(config, sort_keys=False)


def meta_data(hostname: str, instance_id: str) -> str:
    return yaml.safe_dump({"instance-id": instance_id, "local-hostname": hostname}, sort_keys=False)


def network_config(nics: list[tuple[str, bool]]) -> dict[str, Any] | None:
    """Netplan v2 config: DHCP on every ``(mac, dhcp)`` NIC that asks for it.

    ``None`` when no NIC does -- cloud-init then leaves networking alone
    rather than being told to configure nothing.
    """
    ethernets = {
        f"nic{i}": {"match": {"macaddress": mac}, "dhcp4": True}
        for i, (mac, dhcp) in enumerate(nics)
        if dhcp
    }
    return {"version": 2, "ethernets": ethernets} if ethernets else None


def nocloud_iso(user: str, meta: str, network: dict[str, Any] | None) -> bytes:
    """An ISO 9660 image (Rock Ridge + Joliet) holding the seed files."""
    files = {"user-data": user, "meta-data": meta}
    if network is not None:
        files["network-config"] = yaml.safe_dump(network, sort_keys=False)
    iso = pycdlib.PyCdlib()
    iso.new(interchange_level=3, joliet=3, rock_ridge="1.09", vol_ident=_LABEL)
    for index, (name, content) in enumerate(files.items()):
        data = content.encode()
        iso.add_fp(
            io.BytesIO(data),
            len(data),
            f"/SEED{index}.;1",
            rr_name=name,
            joliet_path=f"/{name}",
        )
    out = io.BytesIO()
    iso.write_fp(out)
    iso.close()
    return out.getvalue()