# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.


"""
Domain Name Server
"""

import os, traceback

from twisted.python import usage
from twisted.names import dns
from twisted.application import internet, service

from twisted.names import server
from twisted.names import authority
from twisted.names import secondary

class Options(usage.Options):
    optParameters = [
        ["interface", "i", "",   "The interface to which to bind"],
        ["port",      "p", "53", "The port on which to listen"],
        ["resolv-conf", None, None,
            "Override location of resolv.conf (implies --recursive)"],
        ["hosts-file", None, None, "Perform lookups with a hosts file"],
    ]

    optFlags = [
        ["cache",       "c", "Enable record caching"],
        ["recursive",   "r", "Perform recursive lookups"],
        ["verbose",     "v", "Log verbosely"],
    ]

    compData = usage.Completions(
        optActions={"interface" : usage.CompleteNetInterfaces()}
        )

    zones = None
    zonefiles = None

    def __init__(self):
        usage.Options.__init__(self)
        self['verbose'] = 0
        self.bindfiles = []
        self.zonefiles = []
        self.secondaries = []


    def opt_pyzone(self, filename):
        """Specify the filename of a Python syntax zone definition"""
        if not os.path.exists(filename):
            raise usage.UsageError(filename + ": No such file")
        self.zonefiles.append(filename)

    def opt_bindzone(self, filename):
        """Specify the filename of a BIND9 syntax zone definition"""
        if not os.path.exists(filename):
            raise usage.UsageError(filename + ": No such file")
        self.bindfiles.append(filename)


    def opt_secondary(self, ip_domain):
        """Act as secondary for the specified domain, performing
        zone transfers from the specified IP (IP/domain)
        """
        args = ip_domain.split('/', 1)
        if len(args) != 2:
            raise usage.UsageError("Argument must be of the form IP/domain")
        self.secondaries.append((args[0], [args[1]]))

    def opt_verbose(self):
        """Increment verbosity level"""
        self['verbose'] += 1


    def postOptions(self):
        if self['resolv-conf']:
            self['recursive'] = True

        self.svcs = []
        self.zones = []
        for f in self.zonefiles:
            try:
                self.zones.append(authority.PySourceAuthority(f))
            except Exception, e:
                traceback.print_exc()
                raise usage.UsageError("Invalid syntax in " + f)
        for f in self.bindfiles:
            try:
                self.zones.append(authority.BindAuthority(f))
            except Exception, e:
                traceback.print_exc()
                raise usage.UsageError("Invalid syntax in " + f)
        for f in self.secondaries:
            self.svcs.append(secondary.SecondaryAuthorityService(*f))
            self.zones.append(self.svcs[-1].getAuthority())
        try:
            self['port'] = int(self['port'])
        except ValueError:
            raise usage.UsageError("Invalid port: %r" % (self['port'],))


def makeService(config):
    import client, cache, hosts

    ca, cl = [], []
    if config['cache']:
        ca.append(cache.CacheResolver(verbose=config['verbose']))
    if config['recursive']:
        cl.append(client.createResolver(resolvconf=config['resolv-conf']))
    if config['hosts-file']:
        cl.append(hosts.Resolver(file=config['hosts-file']))

    f = server.DNSServerFactory(config.zones, ca, cl, config['verbose'])
    p = dns.DNSDatagramProtocol(f)
    f.noisy = 0
    ret = service.MultiService()
    for (klass, arg) in [(internet.TCPServer, f), (internet.UDPServer, p)]:
        s = klass(config['port'], arg, interface=config['interface'])
        s.setServiceParent(ret)
    for svc in config.svcs:
        svc.setServiceParent(ret)
    return ret
