# 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>
#
#    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 errno
import oauth.oauth as oauth
import os.path
import socket
import urllib2
import time


class DataSourceMaaS(DataSource.DataSource):
    """
    DataSourceMaaS reads instance information from MaaS.
    Given a config metadata_url, and oauth tokens, it expects to find
    files under the root named:
      instance-id
      user-data
      hostname
    """
    seeddir = base_seeddir + '/maas'
    baseurl = None

    def __str__(self):
        return("DataSourceMaaS[%s]" % self.baseurl)

    def get_data(self):
        mcfg = self.ds_cfg

        try:
            (userdata, metadata) = read_maas_seed_dir(self.seeddir)
            self.userdata_raw = userdata
            self.metadata = metadata
            self.baseurl = self.seeddir
            return True
        except MaasSeedDirNone:
            pass
        except MaasSeedDirMalformed as exc:
            log.warn("%s was malformed: %s\n" % (self.seeddir, exc))
            raise

        try:
            # if there is no metadata_url, then we're not configured
            url = mcfg.get('metadata_url', None)
            if url == None:
                return False

            if not self.wait_for_metadata_service(url):
                return False

            self.baseurl = url

            (userdata, metadata) = read_maas_seed_url(self.baseurl,
                self.md_headers)
            return True
        except Exception:
            util.logexc(log)
            return False

    def md_headers(self, url):
        mcfg = self.ds_cfg

        # if we are missing token_key, token_secret or consumer_key
        # then just do non-authed requests
        for required in ('token_key', 'token_secret', 'consumer_key'):
            if required not in mcfg:
                return({})

        consumer_secret = mcfg.get('consumer_secret', "")

        return(oauth_headers(url=url, consumer_key=mcfg['consumer_key'],
            token_key=mcfg['token_key'], token_secret=mcfg['token_secret'],
            consumer_secret=consumer_secret))

    def wait_for_metadata_service(self, url):
        mcfg = self.ds_cfg

        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)

        starttime = time.time()
        check_url = "%s/instance-id" % url
        url = wait_for_metadata_service(urls=[check_url], max_wait=max_wait,
            timeout=timeout, status_cb=log.warn,
            headers_cb=self.md_headers)

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

        return (bool(url))


def wait_for_metadata_service(urls, max_wait=None, timeout=None,
                              status_cb=None, headers_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 == 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)

            reason = ""
            try:
                if headers_cb != None:
                    headers = headers_cb(url)
                else:
                    headers = {}

                req = urllib2.Request(url, data=None, headers=headers)
                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 = loop_n + 1
        time.sleep(sleeptime)

    return False


def read_maas_seed_dir(seed_d):
    """
    Return user-data and metadata for a maas seed dir in seed_d.
    Expected format of seed_d are the following files:
      * instance-id
      * hostname
      * user-data
    """
    md_required = set(('hostname', 'instance-id'))
    files = md_required.union(set(('userdata',)))
    userdata = None
    md = {}

    if not os.path.isdir(seed_d):
        raise MaasSeedDirNone("%s: not a directory")

    for fname in files:
        try:
            with open(os.path.join(seed_d, fname)) as fp:
                if fname == 'userdata':
                    userdata = fp.read()
                else:
                    md[fname] = fp.read()
                fp.close()
        except IOError as e:
            if e.errno != errno.ENOENT:
                raise

    if userdata == None and len(md) == 0:
        raise MaasSeedDirNone("%s: no data files found" % seed_d)

    if userdata == None:
        raise MaasSeedDirMalformed("%s: missing userdata" % seed_d)

    missing = md_required - set(md.keys())
    if len(missing):
        raise MaasSeedDirMalformed("%s: missing files %s" %
            (seed_d, str(missing)))

    return(userdata, md)


def read_maas_seed_url(seed_url, header_cb=None):
    """
    Read the maas datasource at seed_url.
    header_cb is a method that should return a headers dictionary that will
    be given to urllib2.Request()

    Expected format of seed_url is are the following files:
      * <seed_url>/instance-id
      * <seed_url>/hostname
      * <seed_url>/user-data
    """
    userdata = ""
    metadata = {'instance-id': 'i-maas-url', 'hostname': 'maas-url-hostname'}

    return(userdata, metadata)


def oauth_headers(url, consumer_key, token_key, token_secret, consumer_secret):
    consumer = oauth.OAuthConsumer(consumer_key, consumer_secret)
    token = oauth.OAuthToken(token_key, token_secret)
    params = {
        'oauth_version': "1.0",
        'oauth_nonce': oauth.generate_nonce(),
        'oauth_timestamp': int(time.time()),
        'oauth_token': token.key,
        'oauth_consumer_key': consumer.key,
    }
    req = oauth.OAuthRequest(http_url=url, parameters=params)
    req.sign_request(oauth.OAuthSignatureMethod_PLAINTEXT(),
        consumer, token)
    return(req.to_header())


class MaasSeedDirNone(Exception):
    pass


class MaasSeedDirMalformed(Exception):
    pass


datasources = [
  (DataSourceMaaS, (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))