# vi: ts=4 expandtab
#
#    Author: Vaidas Jablonskis <jablonskis@gmail.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/>.


from cloudinit import log as logging
from cloudinit import util
from cloudinit import sources
from cloudinit import url_helper

LOG = logging.getLogger(__name__)

BUILTIN_DS_CONFIG = {
    'metadata_url': 'http://metadata.google.internal./computeMetadata/v1/'
}
REQUIRED_FIELDS = ('instance-id', 'availability-zone', 'local-hostname')


class DataSourceGCE(sources.DataSource):
    def __init__(self, sys_cfg, distro, paths):
        sources.DataSource.__init__(self, sys_cfg, distro, paths)
        self.metadata = {}
        self.ds_cfg = util.mergemanydict([
            util.get_cfg_by_path(sys_cfg, ["datasource", "GCE"], {}),
            BUILTIN_DS_CONFIG])
        self.metadata_address = self.ds_cfg['metadata_url']

    # GCE takes sshKeys attribute in the format of '<user>:<public_key>'
    # so we have to trim each key to remove the username part
    def _trim_key(self, public_key):
        try:
            index = public_key.index(':')
            if index > 0:
                return public_key[(index + 1):]
        except:
            return public_key

    def get_data(self):
        # GCE metadata server requires a custom header since v1
        headers = {'X-Google-Metadata-Request': True}

        url_map = {
            'instance-id': self.metadata_address + 'instance/id',
            'availability-zone': self.metadata_address + 'instance/zone',
            'public-keys': self.metadata_address + 'project/attributes/sshKeys',
            'local-hostname': self.metadata_address + 'instance/hostname',
            'user-data': self.metadata_address + 'instance/attributes/user-data',
        }

        # if we cannot resolve the metadata server, then no point in trying
        if not util.is_resolvable(self.metadata_address):
            LOG.debug("%s is not resolvable", self.metadata_address)
            return False

        for mkey in url_map.iterkeys():
            try:
                resp = url_helper.readurl(url=url_map[mkey], headers=headers,
                                          retries=0)
            except IOError:
                return False
            if resp.ok():
                if mkey == 'public-keys':
                    pub_keys = [self._trim_key(k) for k in resp.contents.splitlines()]
                    self.metadata[mkey] = pub_keys
                else:
                    self.metadata[mkey] = resp.contents
            else:
                if mkey in REQUIRED_FIELDS:
                    LOG.warn("required metadata '%s' not found in metadata",
                        url_map[mkey])
                    return False
                        
                self.metadata[mkey] = None
                return False

        self.user_data_raw = self.metadata['user-data']
        return True

    @property
    def launch_index(self):
        # GCE does not provide lauch_index property
        return None

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

    def get_public_ssh_keys(self):
        return self.metadata['public-keys']

    def get_hostname(self, fqdn=False):
        return self.metadata['local-hostname']

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

# Used to match classes to dependencies
datasources = [
    (DataSourceGCE, (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)