"""Datasource for LXD, reads /dev/lxd/sock representaton of instance data.

Notes:
 * This datasource replaces previous NoCloud datasource for LXD.
 * Older LXD images may not have updates for cloud-init so NoCloud may
   still be detected on those images.
 * Detect LXD datasource when /dev/lxd/sock is an active socket file.
 * Info on dev-lxd API: https://linuxcontainers.org/lxd/docs/master/dev-lxd
 * TODO( Hotplug support using websockets API 1.0/events )
"""

from json.decoder import JSONDecodeError
import os

import requests
from requests.adapters import HTTPAdapter

# pylint fails to import the two modules below.
# These are imported via requests.packages rather than urllib3 because:
#  a.) the provider of the requests package should ensure that urllib3
#      contained in it is consistent/correct.
#  b.) cloud-init does not specifically have a dependency on urllib3
#
# For future reference, see:
#   https://github.com/kennethreitz/requests/pull/2375
#   https://github.com/requests/requests/issues/4104
# pylint: disable=E0401
from requests.packages.urllib3.connection import HTTPConnection
from requests.packages.urllib3.connectionpool import HTTPConnectionPool

import socket
import stat

from cloudinit import log as logging
from cloudinit import sources, subp, util

LOG = logging.getLogger(__name__)

LXD_SOCKET_PATH = "/dev/lxd/sock"
LXD_SOCKET_API_VERSION = "1.0"

# Config key mappings to alias as top-level instance data keys
CONFIG_KEY_ALIASES = {
    "cloud-init.user-data": "user-data",
    "cloud-init.network-config": "network-config",
    "cloud-init.vendor-data": "vendor-data",
    "user.user-data": "user-data",
    "user.network-config": "network-config",
    "user.vendor-data": "vendor-data"
}


def generate_fallback_network_config() -> dict:
    """Return network config V1 dict representing instance network config."""
    network_v1 = {
        "version": 1,
        "config": [
            {
                "type": "physical", "name": "eth0",
                "subnets": [{"type": "dhcp", "control": "auto"}]
            }
        ]
    }
    if subp.which("systemd-detect-virt"):
        try:
            virt_type, _ = subp.subp(['systemd-detect-virt'])
        except subp.ProcessExecutionError as err:
            LOG.warning(
                "Unable to run systemd-detect-virt: %s."
                " Rendering default network config.", err
            )
            return network_v1
        if virt_type.strip() == "kvm":  # instance.type VIRTUAL-MACHINE
            arch = util.system_info()["uname"][4]
            if arch == "ppc64le":
                network_v1["config"][0]["name"] = "enp0s5"
            elif arch == "s390x":
                network_v1["config"][0]["name"] = "enc9"
            else:
                network_v1["config"][0]["name"] = "enp5s0"
    return network_v1


class SocketHTTPConnection(HTTPConnection):
    def __init__(self, socket_path):
        super().__init__('localhost')
        self.socket_path = socket_path

    def connect(self):
        self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
        self.sock.connect(self.socket_path)


class SocketConnectionPool(HTTPConnectionPool):
    def __init__(self, socket_path):
        self.socket_path = socket_path
        super().__init__('localhost')

    def _new_conn(self):
        return SocketHTTPConnection(self.socket_path)


class LXDSocketAdapter(HTTPAdapter):
    def get_connection(self, url, proxies=None):
        return SocketConnectionPool(LXD_SOCKET_PATH)


def _maybe_remove_top_network(cfg):
    """If network-config contains top level 'network' key, then remove it.

    Some providers of network configuration may provide a top level
    'network' key (LP: #1798117) even though it is not necessary.

    Be friendly and remove it if it really seems so.

    Return the original value if no change or the updated value if changed."""
    if "network" not in cfg:
        return cfg
    network_val = cfg["network"]
    bmsg = 'Top level network key in network-config %s: %s'
    if not isinstance(network_val, dict):
        LOG.debug(bmsg, "was not a dict", cfg)
        return cfg
    if len(list(cfg.keys())) != 1:
        LOG.debug(bmsg, "had multiple top level keys", cfg)
        return cfg
    if network_val.get('config') == "disabled":
        LOG.debug(bmsg, "was config/disabled", cfg)
    elif not all(('config' in network_val, 'version' in network_val)):
        LOG.debug(bmsg, "but missing 'config' or 'version'", cfg)
        return cfg
    LOG.debug(bmsg, "fixed by removing shifting network.", cfg)
    return network_val


def _raw_instance_data_to_dict(metadata_type: str, metadata_value) -> dict:
    """Convert raw instance data from str, bytes, YAML to dict

    :param metadata_type: string, one of as: meta-data, vendor-data, user-data
        network-config

    :param metadata_value: str, bytes or dict representing or instance-data.

    :raises: InvalidMetaDataError on invalid instance-data content.
    """
    if isinstance(metadata_value, dict):
        return metadata_value
    if metadata_value is None:
        return {}
    try:
        parsed_metadata = util.load_yaml(metadata_value)
    except AttributeError as exc:  # not str or bytes
        raise sources.InvalidMetaDataException(
            "Invalid {md_type}. Expected str, bytes or dict but found:"
            " {value}".format(md_type=metadata_type, value=metadata_value)
        ) from exc
    if parsed_metadata is None:
        raise sources.InvalidMetaDataException(
            "Invalid {md_type} format. Expected YAML but found:"
            " {value}".format(md_type=metadata_type, value=metadata_value)
        )
    return parsed_metadata


class DataSourceLXD(sources.DataSource):

    dsname = 'LXD'

    _network_config = sources.UNSET
    _crawled_metadata = sources.UNSET

    sensitive_metadata_keys = (
        'merged_cfg', 'user.meta-data', 'user.vendor-data', 'user.user-data',
    )

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

    def _get_data(self) -> bool:
        """Crawl LXD socket API instance data and return True on success"""
        if not self._is_platform_viable():
            LOG.debug("Not an LXD datasource: No LXD socket found.")
            return False

        self._crawled_metadata = util.log_time(
            logfunc=LOG.debug, msg='Crawl of metadata service',
            func=read_metadata)
        self.metadata = _raw_instance_data_to_dict(
            "meta-data", self._crawled_metadata.get("meta-data")
        )
        if LXD_SOCKET_API_VERSION in self._crawled_metadata:
            config = self._crawled_metadata[LXD_SOCKET_API_VERSION].get(
                "config", {}
            )
            user_metadata = config.get("user.meta-data", {})
            if user_metadata:
                user_metadata = _raw_instance_data_to_dict(
                    "user.meta-data", user_metadata
                )
            if not isinstance(self.metadata, dict):
                self.metadata = util.mergemanydict(
                    [util.load_yaml(self.metadata), user_metadata]
                )
        if "user-data" in self._crawled_metadata:
            self.userdata_raw = self._crawled_metadata["user-data"]
        if "network-config" in self._crawled_metadata:
            self._network_config = _maybe_remove_top_network(
                _raw_instance_data_to_dict(
                    "network-config", self._crawled_metadata["network-config"]
                )
            )
        if "vendor-data" in self._crawled_metadata:
            self.vendordata_raw = self._crawled_metadata["vendor-data"]
        return True

    def _get_subplatform(self) -> str:
        """Return subplatform details for this datasource"""
        return "LXD socket API v. {ver} ({socket})".format(
            ver=LXD_SOCKET_API_VERSION, socket=LXD_SOCKET_PATH
        )

    def check_instance_id(self, sys_cfg) -> str:
        """Return True if instance_id unchanged."""
        response = read_metadata(metadata_only=True)
        md = response.get("meta-data", {})
        if not isinstance(md, dict):
            md = util.load_yaml(md)
        return md.get("instance-id") == self.metadata.get("instance-id")

    @property
    def network_config(self) -> dict:
        """Network config read from LXD socket config/user.network-config.

        If none is present, then we generate fallback configuration.
        """
        if self._network_config == sources.UNSET:
            if self._crawled_metadata.get("network-config"):
                self._network_config = self._crawled_metadata.get(
                    "network-config"
                )
            else:
                self._network_config = generate_fallback_network_config()
        return self._network_config


def is_platform_viable() -> bool:
    """Return True when this platform appears to have an LXD socket."""
    if os.path.exists(LXD_SOCKET_PATH):
        return stat.S_ISSOCK(os.lstat(LXD_SOCKET_PATH).st_mode)
    return False


def read_metadata(
    api_version: str = LXD_SOCKET_API_VERSION, metadata_only: bool = False
) -> dict:
    """Fetch metadata from the /dev/lxd/socket routes.

    Perform a number of HTTP GETs on known routes on the devlxd socket API.
    Minimally all containers must respond to http://lxd/1.0/meta-data when
    the LXD configuration setting `security.devlxd` is true.

    When `security.devlxd` is false, no /dev/lxd/socket file exists. This
    datasource will return False from `is_platform_viable` in that case.

    Perform a GET of <LXD_SOCKET_API_VERSION>/config` and walk all `user.*`
    configuration keys, storing all keys and values under a dict key
        LXD_SOCKET_API_VERSION: config {...}.

    In the presence of the following optional user config keys,
    create top level aliases:
      - user.user-data -> user-data
      - user.vendor-data -> vendor-data
      - user.network-config -> network-config

    :return:
        A dict with the following mandatory key: meta-data.
        Optional keys: user-data, vendor-data, network-config, network_mode

        Below <LXD_SOCKET_API_VERSION> is a dict representation of all raw
        configuration keys and values provided to the container surfaced by
        the socket under the /1.0/config/ route.
    """
    md = {}
    lxd_url = "http://lxd"
    version_url = lxd_url + "/" + api_version + "/"
    with requests.Session() as session:
        session.mount(version_url, LXDSocketAdapter())
        # Raw meta-data as text
        md_route = "{route}meta-data".format(route=version_url)
        response = session.get(md_route)
        LOG.debug("[GET] [HTTP:%d] %s", response.status_code, md_route)
        if not response.ok:
            raise sources.InvalidMetaDataException(
                "Invalid HTTP response [{code}] from {route}: {resp}".format(
                    code=response.status_code,
                    route=md_route,
                    resp=response.text
                )
            )

        md["meta-data"] = response.text
        if metadata_only:
            return md  # Skip network-data, vendor-data, user-data

        md[LXD_SOCKET_API_VERSION] = {
            "config": {},
            "meta-data": md["meta-data"]
        }

        config_url = version_url + "config"
        # Represent all advertized/available config routes under
        # the dict path {LXD_SOCKET_API_VERSION: {config: {...}}.
        response = session.get(config_url)
        LOG.debug("[GET] [HTTP:%d] %s", response.status_code, config_url)
        if not response.ok:
            raise sources.InvalidMetaDataException(
                "Invalid HTTP response [{code}] from {route}: {resp}".format(
                    code=response.status_code,
                    route=config_url,
                    resp=response.text
                )
            )
        try:
            config_routes = response.json()
        except JSONDecodeError as exc:
            raise sources.InvalidMetaDataException(
                "Unable to determine cloud-init config from {route}."
                " Expected JSON but found: {resp}".format(
                    route=config_url,
                    resp=response.text
                )
            ) from exc

        # Sorting keys to ensure we always process in alphabetical order.
        # cloud-init.* keys will sort before user.* keys which is preferred
        # precedence.
        for config_route in sorted(config_routes):
            url = "http://lxd{route}".format(route=config_route)
            response = session.get(url)
            LOG.debug("[GET] [HTTP:%d] %s", response.status_code, url)
            if response.ok:
                cfg_key = config_route.rpartition("/")[-1]
                # Leave raw data values/format unchanged to represent it in
                # instance-data.json for cloud-init query or jinja template
                # use.
                md[LXD_SOCKET_API_VERSION]["config"][cfg_key] = response.text
                # Promote common CONFIG_KEY_ALIASES to top-level keys.
                if cfg_key in CONFIG_KEY_ALIASES:
                    # Due to sort of config_routes, promote cloud-init.*
                    # aliases before user.*. This allows user.* keys to act as
                    # fallback config on old LXD, with new cloud-init images.
                    if CONFIG_KEY_ALIASES[cfg_key] not in md:
                        md[CONFIG_KEY_ALIASES[cfg_key]] = response.text
                    else:
                        LOG.warning(
                            "Ignoring LXD config %s in favor of %s value.",
                            cfg_key, cfg_key.replace("user", "cloud-init", 1)
                        )
            else:
                LOG.debug(
                    "Skipping %s on [HTTP:%d]:%s",
                    url, response.status_code, response.text
                )
    return md


# Used to match classes to dependencies
datasources = [
    (DataSourceLXD, (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 LXD metadata and emit a JSON object."""
    parser = argparse.ArgumentParser(description=description)
    parser.parse_args()
    print(util.json_dumps(read_metadata()))
# vi: ts=4 expandtab