# This file is part of cloud-init. See LICENSE file for license information.
"""Datasource for Oracle (OCI/Oracle Cloud Infrastructure)

Notes:
 * This datasource does not support OCI Classic. OCI Classic provides an EC2
   lookalike metadata service.
 * The UUID provided in DMI data is not the same as the meta-data provided
   instance-id, but has an equivalent lifespan.
 * We do need to support upgrade from an instance that cloud-init
   identified as OpenStack.
 * Bare metal instances use iSCSI root, virtual machine instances do not.
 * Both bare metal and virtual machine instances provide a chassis-asset-tag of
   OracleCloud.com.
"""

import base64
import ipaddress
from collections import namedtuple
from typing import Optional, Tuple

from cloudinit import atomic_helper, dmi
from cloudinit import log as logging
from cloudinit import net, sources, util
from cloudinit.distros.networking import NetworkConfig
from cloudinit.net import (
    cmdline,
    ephemeral,
    get_interfaces_by_mac,
    is_netfail_master,
)
from cloudinit.url_helper import UrlError, readurl

LOG = logging.getLogger(__name__)

BUILTIN_DS_CONFIG = {
    # Don't use IMDS to configure secondary NICs by default
    "configure_secondary_nics": False,
}
CHASSIS_ASSET_TAG = "OracleCloud.com"
METADATA_ROOT = "http://169.254.169.254/opc/v{version}/"
METADATA_PATTERN = METADATA_ROOT + "{path}/"
# https://docs.cloud.oracle.com/iaas/Content/Network/Troubleshoot/connectionhang.htm#Overview,
# indicates that an MTU of 9000 is used within OCI
MTU = 9000
V2_HEADERS = {"Authorization": "Bearer Oracle"}

OpcMetadata = namedtuple("OpcMetadata", "version instance_data vnics_data")


class KlibcOracleNetworkConfigSource(cmdline.KlibcNetworkConfigSource):
    """Override super class to lower the applicability conditions.

    If any `/run/net-*.cfg` files exist, then it is applicable. Even if
    `/run/initramfs/open-iscsi.interface` does not exist.
    """

    def is_applicable(self) -> bool:
        """Override is_applicable"""
        return bool(self._files)


def _ensure_netfailover_safe(network_config: NetworkConfig) -> None:
    """
    Search network config physical interfaces to see if any of them are
    a netfailover master.  If found, we prevent matching by MAC as the other
    failover devices have the same MAC but need to be ignored.

    Note: we rely on cloudinit.net changes which prevent netfailover devices
    from being present in the provided network config.  For more details about
    netfailover devices, refer to cloudinit.net module.

    :param network_config
       A v1 or v2 network config dict with the primary NIC, and possibly
       secondary nic configured.  This dict will be mutated.

    """
    # ignore anything that's not an actual network-config
    if "version" not in network_config:
        return

    if network_config["version"] not in [1, 2]:
        LOG.debug(
            "Ignoring unknown network config version: %s",
            network_config["version"],
        )
        return

    mac_to_name = get_interfaces_by_mac()
    if network_config["version"] == 1:
        for cfg in [c for c in network_config["config"] if "type" in c]:
            if cfg["type"] == "physical":
                if "mac_address" in cfg:
                    mac = cfg["mac_address"]
                    cur_name = mac_to_name.get(mac)
                    if not cur_name:
                        continue
                    elif is_netfail_master(cur_name):
                        del cfg["mac_address"]

    elif network_config["version"] == 2:
        for _, cfg in network_config.get("ethernets", {}).items():
            if "match" in cfg:
                macaddr = cfg.get("match", {}).get("macaddress")
                if macaddr:
                    cur_name = mac_to_name.get(macaddr)
                    if not cur_name:
                        continue
                    elif is_netfail_master(cur_name):
                        del cfg["match"]["macaddress"]
                        del cfg["set-name"]
                        cfg["match"]["name"] = cur_name


class DataSourceOracle(sources.DataSource):

    dsname = "Oracle"
    system_uuid = None
    vendordata_pure = None
    network_config_sources: Tuple[sources.NetworkConfigSource, ...] = (
        sources.NetworkConfigSource.CMD_LINE,
        sources.NetworkConfigSource.SYSTEM_CFG,
        sources.NetworkConfigSource.DS,
        sources.NetworkConfigSource.INITRAMFS,
    )

    _network_config: dict = {"config": [], "version": 1}

    def __init__(self, sys_cfg, *args, **kwargs):
        super(DataSourceOracle, self).__init__(sys_cfg, *args, **kwargs)
        self._vnics_data = None

        self.ds_cfg = util.mergemanydict(
            [
                util.get_cfg_by_path(sys_cfg, ["datasource", self.dsname], {}),
                BUILTIN_DS_CONFIG,
            ]
        )
        self._network_config_source = KlibcOracleNetworkConfigSource()

    def _has_network_config(self) -> bool:
        return bool(self._network_config.get("config", []))

    @staticmethod
    def ds_detect() -> bool:
        """Check platform environment to report if this datasource may run."""
        return _is_platform_viable()

    def _get_data(self):

        self.system_uuid = _read_system_uuid()

        network_context = ephemeral.EphemeralDHCPv4(
            self.distro,
            iface=net.find_fallback_nic(),
            connectivity_url_data={
                "url": METADATA_PATTERN.format(version=2, path="instance"),
                "headers": V2_HEADERS,
            },
        )
        fetch_primary_nic = not self._is_iscsi_root()
        fetch_secondary_nics = self.ds_cfg.get(
            "configure_secondary_nics",
            BUILTIN_DS_CONFIG["configure_secondary_nics"],
        )
        with network_context:
            fetched_metadata = read_opc_metadata(
                fetch_vnics_data=fetch_primary_nic or fetch_secondary_nics
            )

        data = self._crawled_metadata = fetched_metadata.instance_data
        self.metadata_address = METADATA_ROOT.format(
            version=fetched_metadata.version
        )
        self._vnics_data = fetched_metadata.vnics_data

        self.metadata = {
            "availability-zone": data["ociAdName"],
            "instance-id": data["id"],
            "launch-index": 0,
            "local-hostname": data["hostname"],
            "name": data["displayName"],
        }

        if "metadata" in data:
            user_data = data["metadata"].get("user_data")
            if user_data:
                self.userdata_raw = base64.b64decode(user_data)
            self.metadata["public_keys"] = data["metadata"].get(
                "ssh_authorized_keys"
            )

        return True

    def check_instance_id(self, sys_cfg) -> bool:
        """quickly check (local only) if self.instance_id is still valid

        On Oracle, the dmi-provided system uuid differs from the instance-id
        but has the same life-span."""
        return sources.instance_id_matches_system_uuid(self.system_uuid)

    def get_public_ssh_keys(self):
        return sources.normalize_pubkey_data(self.metadata.get("public_keys"))

    def _is_iscsi_root(self) -> bool:
        """Return whether we are on a iscsi machine."""
        return self._network_config_source.is_applicable()

    def _get_iscsi_config(self) -> dict:
        return self._network_config_source.render_config()

    @property
    def network_config(self):
        """Network config is read from initramfs provided files

        Priority for primary network_config selection:
        - iscsi
        - imds

        If none is present, then we fall back to fallback configuration.
        """
        if self._has_network_config():
            return self._network_config

        set_primary = False
        # this is v1
        if self._is_iscsi_root():
            self._network_config = self._get_iscsi_config()
        if not self._has_network_config():
            LOG.warning(
                "Could not obtain network configuration from initramfs. "
                "Falling back to IMDS."
            )
            set_primary = True

        set_secondary = self.ds_cfg.get(
            "configure_secondary_nics",
            BUILTIN_DS_CONFIG["configure_secondary_nics"],
        )
        if set_primary or set_secondary:
            try:
                # Mutate self._network_config to include primary and/or
                # secondary VNICs
                self._add_network_config_from_opc_imds(set_primary)
            except Exception:
                util.logexc(
                    LOG,
                    "Failed to parse IMDS network configuration!",
                )

        # we need to verify that the nic selected is not a netfail over
        # device and, if it is a netfail master, then we need to avoid
        # emitting any match by mac
        _ensure_netfailover_safe(self._network_config)

        return self._network_config

    def _add_network_config_from_opc_imds(self, set_primary: bool = False):
        """Generate primary and/or secondary NIC config from IMDS and merge it.

        It will mutate the network config to include the secondary VNICs.

        :param set_primary: If True set primary interface.
        :raises:
            Exceptions are not handled within this function.  Likely
            exceptions are KeyError/IndexError
            (if the IMDS returns valid JSON with unexpected contents).
        """
        if self._vnics_data is None:
            LOG.warning("NIC data is UNSET but should not be")
            return

        if not set_primary and ("nicIndex" in self._vnics_data[0]):
            # TODO: Once configure_secondary_nics defaults to True, lower the
            # level of this log message.  (Currently, if we're running this
            # code at all, someone has explicitly opted-in to secondary
            # VNIC configuration, so we should warn them that it didn't
            # happen.  Once it's default, this would be emitted on every Bare
            # Metal Machine launch, which means INFO or DEBUG would be more
            # appropriate.)
            LOG.warning(
                "VNIC metadata indicates this is a bare metal machine; "
                "skipping secondary VNIC configuration."
            )
            return

        interfaces_by_mac = get_interfaces_by_mac()

        vnics_data = self._vnics_data if set_primary else self._vnics_data[1:]

        for index, vnic_dict in enumerate(vnics_data):
            is_primary = set_primary and index == 0
            mac_address = vnic_dict["macAddr"].lower()
            if mac_address not in interfaces_by_mac:
                LOG.warning(
                    "Interface with MAC %s not found; skipping",
                    mac_address,
                )
                continue
            name = interfaces_by_mac[mac_address]
            network = ipaddress.ip_network(vnic_dict["subnetCidrBlock"])

            if self._network_config["version"] == 1:
                if is_primary:
                    subnet = {"type": "dhcp"}
                else:
                    subnet = {
                        "type": "static",
                        "address": (
                            f"{vnic_dict['privateIp']}/{network.prefixlen}"
                        ),
                    }
                interface_config = {
                    "name": name,
                    "type": "physical",
                    "mac_address": mac_address,
                    "mtu": MTU,
                    "subnets": [subnet],
                }
                self._network_config["config"].append(interface_config)
            elif self._network_config["version"] == 2:
                # Why does this elif exist???
                # Are there plans to switch to v2?
                interface_config = {
                    "mtu": MTU,
                    "match": {"macaddress": mac_address},
                    "dhcp6": False,
                    "dhcp4": is_primary,
                }
                if not is_primary:
                    interface_config["addresses"] = [
                        f"{vnic_dict['privateIp']}/{network.prefixlen}"
                    ]
                self._network_config["ethernets"][name] = interface_config


def _read_system_uuid() -> Optional[str]:
    sys_uuid = dmi.read_dmi_data("system-uuid")
    return None if sys_uuid is None else sys_uuid.lower()


def _is_platform_viable() -> bool:
    asset_tag = dmi.read_dmi_data("chassis-asset-tag")
    return asset_tag == CHASSIS_ASSET_TAG


def _fetch(metadata_version: int, path: str, retries: int = 2) -> dict:
    return readurl(
        url=METADATA_PATTERN.format(version=metadata_version, path=path),
        headers=V2_HEADERS if metadata_version > 1 else None,
        retries=retries,
    )._response.json()


def read_opc_metadata(*, fetch_vnics_data: bool = False) -> OpcMetadata:
    """Fetch metadata from the /opc/ routes.

    :return:
        A namedtuple containing:
          The metadata version as an integer
          The JSON-decoded value of the instance data endpoint on the IMDS
          The JSON-decoded value of the vnics data endpoint if
            `fetch_vnics_data` is True, else None

    """
    # Per Oracle, there are short windows (measured in milliseconds) throughout
    # an instance's lifetime where the IMDS is being updated and may 404 as a
    # result.  To work around these windows, we retry a couple of times.
    metadata_version = 2
    try:
        instance_data = _fetch(metadata_version, path="instance")
    except UrlError:
        metadata_version = 1
        instance_data = _fetch(metadata_version, path="instance")

    vnics_data = None
    if fetch_vnics_data:
        try:
            vnics_data = _fetch(metadata_version, path="vnics")
        except UrlError:
            util.logexc(LOG, "Failed to fetch IMDS network configuration!")
    return OpcMetadata(metadata_version, instance_data, vnics_data)


# Used to match classes to dependencies
datasources = [
    (DataSourceOracle, (sources.DEP_FILESYSTEM,)),
]


# Return a list of data sources that match this set of dependencies
def get_datasource_list(depends):
    return sources.list_from_depends(depends, datasources)


if __name__ == "__main__":
    import argparse

    description = """
        Query Oracle Cloud metadata and emit a JSON object with two keys:
        `read_opc_metadata` and `_is_platform_viable`.  The values of each are
        the return values of the corresponding functions defined in
        DataSourceOracle.py."""
    parser = argparse.ArgumentParser(description=description)
    parser.parse_args()
    print(
        atomic_helper.json_dumps(
            {
                "read_opc_metadata": read_opc_metadata(),
                "_is_platform_viable": _is_platform_viable(),
            }
        )
    )
