# Authors: Karl MacMillan <kmacmill@redhat.com>
#
# Copyright (C) 2007  Red Hat
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# 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 ConfigParser
from optparse import Option, Values, OptionParser, IndentedHelpFormatter, OptionValueError
from copy import copy
from dns import resolver, rdatatype
from dns.exception import DNSException
from ipapython.dn import DN
import dns.name

import socket
import re
import urlparse

class IPAConfigError(Exception):
    def __init__(self, msg=''):
        self.msg = msg
        Exception.__init__(self, msg)

    def __repr__(self):
        return self.msg

    __str__ = __repr__

class IPAFormatter(IndentedHelpFormatter):
    """Our own optparse formatter that indents multiple lined usage string."""
    def format_usage(self, usage):
        usage_string = "Usage:"
        spacing = " " * len(usage_string)
        lines = usage.split("\n")
        ret = "%s %s\n" % (usage_string, lines[0])
        for line in lines[1:]:
            ret += "%s %s\n" % (spacing, line)
        return ret

def check_ip_option(option, opt, value):
    from ipapython.ipautil import CheckedIPAddress

    ip_local = option.ip_local is True
    ip_netmask = option.ip_netmask is True
    try:
        return CheckedIPAddress(value, parse_netmask=ip_netmask, match_local=ip_local)
    except Exception as e:
        raise OptionValueError("option %s: invalid IP address %s: %s" % (opt, value, e))

def check_dn_option(option, opt, value):
    try:
        return DN(value)
    except Exception, e:
        raise OptionValueError("option %s: invalid DN: %s" % (opt, e))

class IPAOption(Option):
    """
    optparse.Option subclass with support of options labeled as
    security-sensitive such as passwords.
    """
    ATTRS = Option.ATTRS + ["sensitive", "ip_local", "ip_netmask"]
    TYPES = Option.TYPES + ("ip", "dn")
    TYPE_CHECKER = copy(Option.TYPE_CHECKER)
    TYPE_CHECKER["ip"] = check_ip_option
    TYPE_CHECKER["dn"] = check_dn_option

class IPAOptionParser(OptionParser):
    """
    optparse.OptionParser subclass that uses IPAOption by default
    for storing options.
    """
    def __init__(self,
                 usage=None,
                 option_list=None,
                 option_class=IPAOption,
                 version=None,
                 conflict_handler="error",
                 description=None,
                 formatter=None,
                 add_help_option=True,
                 prog=None):
        OptionParser.__init__(self, usage, option_list, option_class,
                              version, conflict_handler, description,
                              formatter, add_help_option, prog)

    def get_safe_opts(self, opts):
        """
        Returns all options except those with sensitive=True in the same
        fashion as parse_args would
        """
        all_opts_dict = dict([ (o.dest, o) for o in self._get_all_options() if hasattr(o, 'sensitive') ])
        safe_opts_dict = {}

        for option, value in opts.__dict__.iteritems():
            if all_opts_dict[option].sensitive != True:
                safe_opts_dict[option] = value

        return Values(safe_opts_dict)

def verify_args(parser, args, needed_args = None):
    """Verify that we have all positional arguments we need, if not, exit."""
    if needed_args:
        needed_list = needed_args.split(" ")
    else:
        needed_list = []
    len_need = len(needed_list)
    len_have = len(args)
    if len_have > len_need:
        parser.error("too many arguments")
    elif len_have < len_need:
        parser.error("no %s specified" % needed_list[len_have])

class IPAConfig:
    def __init__(self):
        self.default_realm = None
        self.default_server = []
        self.default_domain = None

    def get_realm(self):
        if self.default_realm:
            return self.default_realm
        else:
            raise IPAConfigError("no default realm")

    def get_server(self):
        if len(self.default_server):
            return self.default_server
        else:
            raise IPAConfigError("no default server")

    def get_domain(self):
        if self.default_domain:
            return self.default_domain
        else:
            raise IPAConfigError("no default domain")

# Global library config
config = IPAConfig()

def __parse_config(discover_server = True):
    p = ConfigParser.SafeConfigParser()
    p.read("/etc/ipa/default.conf")

    try:
        if not config.default_realm:
            config.default_realm = p.get("global", "realm")
    except:
        pass
    if discover_server:
        try:
            s = p.get("global", "xmlrpc_uri")
            server = urlparse.urlsplit(s)
            config.default_server.append(server.netloc)
        except:
            pass
    try:
        if not config.default_domain:
            config.default_domain = p.get("global", "domain")
    except:
        pass

def __discover_config(discover_server = True):
    servers = []
    try:
        if not config.default_realm:
            try:
                # only import krbV when we need it
                import krbV
                krbctx = krbV.default_context()
                config.default_realm = krbctx.default_realm
            except ImportError:
                pass
            if not config.default_realm:
                return False

        if not config.default_domain:
            # try once with REALM -> domain
            domain = str(config.default_realm).lower()
            name = "_ldap._tcp." + domain

            try:
                servers = resolver.query(name, rdatatype.SRV)
            except DNSException:
                # try cycling on domain components of FQDN
                try:
                    domain = dns.name.from_text(socket.getfqdn())
                except DNSException:
                    return False

                while True:
                    domain = domain.parent()

                    if str(domain) == '.':
                        return False
                    name = "_ldap._tcp.%s" % domain
                    try:
                        servers = resolver.query(name, rdatatype.SRV)
                        break
                    except DNSException:
                        pass

            config.default_domain = str(domain).rstrip(".")

        if discover_server:
            if not servers:
                name = "_ldap._tcp.%s." % config.default_domain
                try:
                    servers = resolver.query(name, rdatatype.SRV)
                except DNSException:
                    pass

            for server in servers:
                hostname = str(server.target).rstrip(".")
                config.default_server.append(hostname)

    except:
        pass

def add_standard_options(parser):
    parser.add_option("--realm", dest="realm", help="Override default IPA realm")
    parser.add_option("--server", dest="server", help="Override default IPA server")
    parser.add_option("--domain", dest="domain", help="Override default IPA DNS domain")

def init_config(options=None):
    if options:
        config.default_realm = options.realm
        config.default_domain = options.domain
        if options.server:
            config.default_server.extend(options.server.split(","))

    if len(config.default_server):
        discover_server = False
    else:
        discover_server = True
    __parse_config(discover_server)
    __discover_config(discover_server)

    # make sure the server list only contains unique items
    new_server = []
    for server in config.default_server:
        if server not in new_server:
            new_server.append(server)
    config.default_server = new_server

    if not config.default_realm:
        raise IPAConfigError("IPA realm not found in DNS, in the config file (/etc/ipa/default.conf) or on the command line.")
    if not config.default_server:
        raise IPAConfigError("IPA server not found in DNS, in the config file (/etc/ipa/default.conf) or on the command line.")
    if not config.default_domain:
        raise IPAConfigError("IPA domain not found in the config file (/etc/ipa/default.conf) or on the command line.")
