# vi: ts=4 expandtab
#
#    Copyright (C) 2011 Canonical Ltd.
#
#    Author: Scott Moser <scott.moser@canonical.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.util as util
from cloudinit.CloudConfig import per_always
import StringIO

frequency = per_always

def handle(name,cfg,cloud,log,args):
    ( hostname, fqdn ) = util.get_hostname_fqdn(cfg, cloud)

    use_template = util.get_cfg_option_bool(cfg,"manage_etc_hosts", False)
    if not use_template:
        # manage_etc_hosts not true, update the 127.0.1.1 entry via update_etc_hosts
        log.debug("manage_etc_hosts is not set, checking sanity of /etc/hosts")
        update_etc_hosts(hostname, fqdn, log)
        return

    # manage_etc_hosts is set, render from template file
    try:
        if not hostname:
            log.info("manage_etc_hosts was set, but no hostname found")
            return

        util.render_to_file('hosts', '/etc/hosts', \
            { 'hostname' : hostname, 'fqdn' : fqdn })

    except Exception as e:
        log.warn("failed to update /etc/hosts")
        raise

def update_etc_hosts(hostname, fqdn, log):
     with open('/etc/hosts', 'r') as etchosts:
         header = "# Added by cloud-init\n"
         hosts_line = "127.0.1.1\t%s %s\n" % (fqdn, hostname)
         need_write = False
         need_change = True
         new_etchosts = StringIO.StringIO()
         for line in etchosts:
             split_line = [s.strip() for s in line.split()]
             if len(split_line) < 2:
                new_etchosts.write(line)
                continue
             if line == header:
                continue
             ip, hosts = split_line[0], split_line[1:]
             if ip == "127.0.1.1":
                 if sorted([hostname, fqdn]) == sorted(hosts):
                     need_change = False
                 if need_change == True:
                     line = "%s%s" % (header, hosts_line)
                     need_change = False
                     need_write = True
             new_etchosts.write(line)
         etchosts.close()
         if need_change == True:
             new_etchosts.write("%s%s" % (header, hosts_line))
             need_write = True
         if need_write == True:
             new_etcfile = open ('/etc/hosts','wb')
             new_etcfile.write(new_etchosts.getvalue())
             new_etcfile.close()
         new_etchosts.close()
     return