# vi: ts=4 expandtab
#
#    Copyright (C) 2009-2010 Canonical Ltd.
#    Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
#
#    Author: Scott Moser <scott.moser@canonical.com>
#    Author: Juerg Hafliger <juerg.haefliger@hp.com>
#    Author: Cosmin Luta <cosmin.luta@avira.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 cloudinit.DataSource as DataSource

from cloudinit import seeddir as base_seeddir
from cloudinit import log
import cloudinit.util as util
import socket
import urllib2
import time
import boto.utils as boto_utils
from struct import pack

class DataSourceCS(DataSource.DataSource):
    api_ver = 'latest'
    seeddir = base_seeddir + '/cs'
    metadata_address = None

    def __init__(self, sys_cfg=None):
        DataSource.DataSource.__init__(self, sys_cfg)
        # Cloudstack has its metadata/userdata URLs located on http://<default-gateway-ip>/latest/
        self.metadata_address = "http://" + self._get_default_gateway() + "/"
        
    def _get_default_gateway(self):
        f = None
        try:
            f = open("/proc/net/route", "r")
            for line in f.readlines():
                items = line.split("\t")
                if items[1] == "00000000":
                    # found the default route, get the gateway
                    gw = int(items[2], 16)
                    log.debug("found default route, gateway %s" % items[2])
                    return socket.inet_ntoa(pack("<L", gw))
            f.close()
        except:
            if f is not None:
                f.close()
            return "localhost"

    def __str__(self):
        return "DataSourceCS"

    def get_data(self):
        seedret = {}
        if util.read_optional_seed(seedret, base=self.seeddir + "/"):
            self.userdata_raw = seedret['user-data']
            self.metadata = seedret['meta-data']
            log.debug("using seeded cs data in %s" % self.seeddir)
            return True

        try:
            if not self.wait_for_metadata_service():
                return False
            start = time.time()
            self.userdata_raw = boto_utils.get_instance_userdata(self.api_ver,
                None, self.metadata_address)
            self.metadata = boto_utils.get_instance_metadata(self.api_ver,
                self.metadata_address)
            log.debug("crawl of metadata service took %ds" % (time.time() -
                                                              start))
            return True
        except Exception as e:
            log.exception(e)
            return False

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

    def get_availability_zone(self):
        return self.metadata['availability-zone']

    def wait_for_metadata_service(self):
        mcfg = self.ds_cfg

        if not hasattr(mcfg, "get"):
            mcfg = {}

        max_wait = 120
        try:
            max_wait = int(mcfg.get("max_wait", max_wait))
        except Exception:
            util.logexc(log)
            log.warn("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)
            log.warn("Failed to get timeout, using %s" % timeout)

        def_mdurls = [self.metadata_address]
        mdurls = mcfg.get("metadata_urls", def_mdurls)

        # Remove addresses from the list that wont resolve.
        filtered = [x for x in mdurls if util.is_resolvable_url(x)]

        if set(filtered) != set(mdurls):
            log.debug("removed the following from metadata urls: %s" %
                list((set(mdurls) - set(filtered))))

        if len(filtered):
            mdurls = filtered
        else:
            log.warn("Empty metadata url list! using default list")
            mdurls = def_mdurls

        urls = []
        url2base = {False: False}
        for url in mdurls:
            cur = "%s/%s/meta-data/instance-id" % (url, self.api_ver)
            urls.append(cur)
            url2base[cur] = url

        starttime = time.time()
        url = wait_for_metadata_service(urls=urls, max_wait=max_wait,
                  timeout=timeout, status_cb=log.warn)

        if url:
            log.debug("Using metadata source: '%s'" % url2base[url])
        else:
            log.critical("giving up on md after %i seconds\n" %
                         int(time.time() - starttime))

        self.metadata_address = url2base[url]
        return bool(url)


def wait_for_metadata_service(urls, max_wait=None, timeout=None,
                              status_cb=None):
    """
    urls:      a list of urls to try
    max_wait:  roughly the maximum time to wait before giving up
               The max time is *actually* len(urls)*timeout as each url will
               be tried once and given the timeout provided.
    timeout:   the timeout provided to urllib2.urlopen
    status_cb: call method with string message when a url is not available

    the idea of this routine is to wait for the EC2 metdata service to
    come up.  On both Eucalyptus and EC2 we have seen the case where
    the instance hit the MD before the MD service was up.  EC2 seems
    to have permenantely fixed this, though.

    In openstack, the metadata service might be painfully slow, and
    unable to avoid hitting a timeout of even up to 10 seconds or more
    (LP: #894279) for a simple GET.

    Offset those needs with the need to not hang forever (and block boot)
    on a system where cloud-init is configured to look for EC2 Metadata
    service but is not going to find one.  It is possible that the instance
    data host (169.254.169.254) may be firewalled off Entirely for a sytem,
    meaning that the connection will block forever unless a timeout is set.
    """
    starttime = time.time()

    sleeptime = 1

    def nullstatus_cb(msg):
        return

    if status_cb == None:
        status_cb = nullstatus_cb

    def timeup(max_wait, starttime):
        return((max_wait <= 0 or max_wait is None) or
               (time.time() - starttime > max_wait))

    loop_n = 0
    while True:
        sleeptime = int(loop_n / 5) + 1
        for url in urls:
            now = time.time()
            if loop_n != 0:
                if timeup(max_wait, starttime):
                    break
                if timeout and (now + timeout > (starttime + max_wait)):
                    # shorten timeout to not run way over max_time
                    timeout = int((starttime + max_wait) - now)

            try:
                req = urllib2.Request(url)
                resp = urllib2.urlopen(req, timeout=timeout)
                if resp.read() != "":
                    return url
                reason = "empty data [%s]" % resp.getcode()
            except urllib2.HTTPError as e:
                reason = "http error [%s]" % e.code
            except urllib2.URLError as e:
                reason = "url error [%s]" % e.reason
            except socket.timeout as e:
                reason = "socket timeout [%s]" % e
            except Exception as e:
                reason = "unexpected error [%s]" % e

            if log:
                status_cb("'%s' failed [%s/%ss]: %s" %
                          (url, int(time.time() - starttime), max_wait,
                           reason))

        if timeup(max_wait, starttime):
            break

        loop_n += 1
        time.sleep(sleeptime)

    return False


datasources = [
  (DataSourceCS, (DataSource.DEP_FILESYSTEM, DataSource.DEP_NETWORK)),
]

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