# vi: ts=4 expandtab
#
#    Copyright (C) 2012 Canonical Ltd.
#    Copyright (C) 2012 Cosmin Luta
#    Copyright (C) 2012 Yahoo! Inc.
#    Copyright (C) 2012 Gerard Dethier
#    Copyright (C) 2013 Hewlett-Packard Development Company, L.P.
#
#    Author: Cosmin Luta <q4break@gmail.com>
#    Author: Scott Moser <scott.moser@canonical.com>
#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
#    Author: Gerard Dethier <g.dethier@gmail.com>
#    Author: Juerg Haefliger <juerg.haefliger@hp.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License version 3, as
#    published by the Free Software Foundation.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

import os
import time
from socket import inet_ntoa
from struct import pack

from six.moves import http_client

from cloudinit import ec2_utils as ec2
from cloudinit import log as logging
from cloudinit import url_helper as uhelp
from cloudinit import sources, util

LOG = logging.getLogger(__name__)


class CloudStackPasswordServerClient(object):
    """
    Implements password fetching from the CloudStack password server.

    http://cloudstack-administration.readthedocs.org/en/latest/templates.html#adding-password-management-to-your-templates
    has documentation about the system.  This implementation is following that
    found at
    https://github.com/shankerbalan/cloudstack-scripts/blob/master/cloud-set-guest-password-debian

    The CloudStack password server is, essentially, a broken HTTP
    server. It requires us to provide a valid HTTP request (including a
    DomU_Request header, which is the meat of the request), but just
    writes the text of its response on to the socket, without a status
    line or any HTTP headers.  This makes HTTP libraries sad, which
    explains the screwiness of the implementation of this class.

    This should be fixed in CloudStack by commit
    a72f14ea9cb832faaac946b3cf9f56856b50142a in December 2014.
    """

    def __init__(self, virtual_router_address):
        self.virtual_router_address = virtual_router_address

    def _do_request(self, domu_request):
        # We have to provide a valid HTTP request, but a valid HTTP
        # response is not returned. This means that getresponse() chokes,
        # so we use the socket directly to read off the response.
        # Because we're reading off the socket directly, we can't re-use the
        # connection.
        conn = http_client.HTTPConnection(self.virtual_router_address, 8080)
        try:
            conn.request('GET', '', headers={'DomU_Request': domu_request})
            conn.sock.settimeout(30)
            output = conn.sock.recv(1024).decode('utf-8').strip()
        finally:
            conn.close()
        return output

    def get_password(self):
        password = self._do_request('send_my_password')
        if password in ['', 'saved_password']:
            return None
        if password == 'bad_request':
            raise RuntimeError('Error when attempting to fetch root password.')
        self._do_request('saved_password')
        return password


class DataSourceCloudStack(sources.DataSource):
    def __init__(self, sys_cfg, distro, paths):
        sources.DataSource.__init__(self, sys_cfg, distro, paths)
        self.seed_dir = os.path.join(paths.seed_dir, 'cs')
        # Cloudstack has its metadata/userdata URLs located at
        # http://<virtual-router-ip>/latest/
        self.api_ver = 'latest'
        self.vr_addr = get_vr_address()
        if not self.vr_addr:
            raise RuntimeError("No virtual router found!")
        self.metadata_address = "http://%s/" % (self.vr_addr,)
        self.cfg = {}

    def _get_url_settings(self):
        mcfg = self.ds_cfg
        if not mcfg:
            mcfg = {}
        max_wait = 120
        try:
            max_wait = int(mcfg.get("max_wait", max_wait))
        except Exception:
            util.logexc(LOG, "Failed to get max wait. using %s", max_wait)

        if max_wait == 0:
            return False

        timeout = 50
        try:
            timeout = int(mcfg.get("timeout", timeout))
        except Exception:
            util.logexc(LOG, "Failed to get timeout, using %s", timeout)

        return (max_wait, timeout)

    def wait_for_metadata_service(self):
        mcfg = self.ds_cfg
        if not mcfg:
            mcfg = {}

        (max_wait, timeout) = self._get_url_settings()

        urls = [uhelp.combine_url(self.metadata_address,
                                  'latest/meta-data/instance-id')]
        start_time = time.time()
        url = uhelp.wait_for_url(urls=urls, max_wait=max_wait,
                                 timeout=timeout, status_cb=LOG.warn)

        if url:
            LOG.debug("Using metadata source: '%s'", url)
        else:
            LOG.critical(("Giving up on waiting for the metadata from %s"
                          " after %s seconds"),
                         urls, int(time.time() - start_time))

        return bool(url)

    def get_config_obj(self):
        return self.cfg

    def get_data(self):
        seed_ret = {}
        if util.read_optional_seed(seed_ret, base=(self.seed_dir + "/")):
            self.userdata_raw = seed_ret['user-data']
            self.metadata = seed_ret['meta-data']
            LOG.debug("Using seeded cloudstack data from: %s", self.seed_dir)
            return True
        try:
            if not self.wait_for_metadata_service():
                return False
            start_time = time.time()
            self.userdata_raw = ec2.get_instance_userdata(
                self.api_ver, self.metadata_address)
            self.metadata = ec2.get_instance_metadata(self.api_ver,
                                                      self.metadata_address)
            LOG.debug("Crawl of metadata service took %s seconds",
                      int(time.time() - start_time))
            password_client = CloudStackPasswordServerClient(self.vr_addr)
            try:
                set_password = password_client.get_password()
            except Exception:
                util.logexc(LOG,
                            'Failed to fetch password from virtual router %s',
                            self.vr_addr)
            else:
                if set_password:
                    self.cfg = {
                        'ssh_pwauth': True,
                        'password': set_password,
                        'chpasswd': {
                            'expire': False,
                        },
                    }
            return True
        except Exception:
            util.logexc(LOG, 'Failed fetching from metadata service %s',
                        self.metadata_address)
            return False

    def get_instance_id(self):
        return self.metadata['instance-id']

    @property
    def availability_zone(self):
        return self.metadata['availability-zone']


def get_default_gateway():
    # Returns the default gateway ip address in the dotted format.
    lines = util.load_file("/proc/net/route").splitlines()
    for line in lines:
        items = line.split("\t")
        if items[1] == "00000000":
            # Found the default route, get the gateway
            gw = inet_ntoa(pack("<L", int(items[2], 16)))
            LOG.debug("Found default route, gateway is %s", gw)
            return gw
    return None


def get_dhclient_d():
    # find lease files directory
    supported_dirs = ["/var/lib/dhclient", "/var/lib/dhcp"]
    for d in supported_dirs:
        if os.path.exists(d):
            LOG.debug("Using %s lease directory", d)
            return d
    return None


def get_latest_lease():
    # find latest lease file
    lease_d = get_dhclient_d()
    if not lease_d:
        return None
    lease_files = os.listdir(lease_d)
    latest_mtime = -1
    latest_file = None
    for file_name in lease_files:
        if file_name.endswith(".lease") or file_name.endswith(".leases"):
            abs_path = os.path.join(lease_d, file_name)
            mtime = os.path.getmtime(abs_path)
            if mtime > latest_mtime:
                latest_mtime = mtime
                latest_file = abs_path
    return latest_file


def get_vr_address():
    # Get the address of the virtual router via dhcp leases
    # see http://bit.ly/T76eKC for documentation on the virtual router.
    # If no virtual router is detected, fallback on default gateway.
    lease_file = get_latest_lease()
    if not lease_file:
        LOG.debug("No lease file found, using default gateway")
        return get_default_gateway()

    latest_address = None
    with open(lease_file, "r") as fd:
        for line in fd:
            if "dhcp-server-identifier" in line:
                words = line.strip(" ;\r\n").split(" ")
                if len(words) > 2:
                    dhcp = words[2]
                    LOG.debug("Found DHCP identifier %s", dhcp)
                    latest_address = dhcp
    if not latest_address:
        # No virtual router found, fallback on default gateway
        LOG.debug("No DHCP found, using default gateway")
        return get_default_gateway()
    return latest_address


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


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