# -*- test-case-name: twisted.names.test.test_names -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

from __future__ import absolute_import, division

__all__ = ['SecondaryAuthority', 'SecondaryAuthorityService']

from twisted.internet import task, defer
from twisted.names import dns
from twisted.names import common
from twisted.names import client
from twisted.names import resolve
from twisted.names.authority import FileAuthority

from twisted.python import log, failure
from twisted.application import service

class SecondaryAuthorityService(service.Service):
    calls = None

    _port = 53

    def __init__(self, primary, domains):
        """
        @param primary: The IP address of the server from which to perform
        zone transfers.
        @type primary: L{str}

        @param domains: A sequence of domain names for which to perform
        zone transfers.
        @type domains: L{list} of L{bytes}
        """
        self.primary = primary
        self.domains = [SecondaryAuthority(primary, d) for d in domains]


    @classmethod
    def fromServerAddressAndDomains(cls, serverAddress, domains):
        """
        Construct a new L{SecondaryAuthorityService} from a tuple giving a
        server address and a C{str} giving the name of a domain for which this
        is an authority.

        @param serverAddress: A two-tuple, the first element of which is a
            C{str} giving an IP address and the second element of which is a
            C{int} giving a port number.  Together, these define where zone
            transfers will be attempted from.

        @param domain: A C{bytes} giving the domain to transfer.

        @return: A new instance of L{SecondaryAuthorityService}.
        """
        service = cls(None, [])
        service.primary = serverAddress[0]
        service._port = serverAddress[1]
        service.domains = [
            SecondaryAuthority.fromServerAddressAndDomain(serverAddress, d)
            for d in domains]
        return service


    def getAuthority(self):
        return resolve.ResolverChain(self.domains)

    def startService(self):
        service.Service.startService(self)
        self.calls = [task.LoopingCall(d.transfer) for d in self.domains]
        i = 0
        from twisted.internet import reactor
        for c in self.calls:
            # XXX Add errbacks, respect proper timeouts
            reactor.callLater(i, c.start, 60 * 60)
            i += 1

    def stopService(self):
        service.Service.stopService(self)
        for c in self.calls:
            c.stop()



class SecondaryAuthority(FileAuthority):
    """
    An Authority that keeps itself updated by performing zone transfers.

    @ivar primary: The IP address of the server from which zone transfers will
        be attempted.
    @type primary: C{str}

    @ivar _port: The port number of the server from which zone transfers will be
        attempted.
    @type: C{int}

    @ivar _reactor: The reactor to use to perform the zone transfers, or L{None}
        to use the global reactor.
    """

    transferring = False
    soa = records = None
    _port = 53
    _reactor = None

    def __init__(self, primaryIP, domain):
        """
        @param domain: The domain for which this will be the secondary
            authority.
        @type domain: L{bytes}
        """
        # Yep.  Skip over FileAuthority.__init__.  This is a hack until we have
        # a good composition-based API for the complicated DNS record lookup
        # logic we want to share.
        common.ResolverBase.__init__(self)
        self.primary = primaryIP
        self.domain = domain


    @classmethod
    def fromServerAddressAndDomain(cls, serverAddress, domain):
        """
        Construct a new L{SecondaryAuthority} from a tuple giving a server
        address and a C{bytes} giving the name of a domain for which this is an
        authority.

        @param serverAddress: A two-tuple, the first element of which is a
            C{str} giving an IP address and the second element of which is a
            C{int} giving a port number.  Together, these define where zone
            transfers will be attempted from.

        @param domain: A C{bytes} giving the domain to transfer.

        @return: A new instance of L{SecondaryAuthority}.
        """
        secondary = cls(None, None)
        secondary.primary = serverAddress[0]
        secondary._port = serverAddress[1]
        secondary.domain = domain
        return secondary


    def transfer(self):
        if self.transferring:
            return
        self.transfering = True

        reactor = self._reactor
        if reactor is None:
            from twisted.internet import reactor

        resolver = client.Resolver(
            servers=[(self.primary, self._port)], reactor=reactor)
        return resolver.lookupZone(self.domain
            ).addCallback(self._cbZone
            ).addErrback(self._ebZone
            )


    def _lookup(self, name, cls, type, timeout=None):
        if not self.soa or not self.records:
            return defer.fail(failure.Failure(dns.DomainError(name)))
        return FileAuthority._lookup(self, name, cls, type, timeout)


    def _cbZone(self, zone):
        ans, _, _ = zone
        self.records = r = {}
        for rec in ans:
            if not self.soa and rec.type == dns.SOA:
                self.soa = (str(rec.name).lower(), rec.payload)
            else:
                r.setdefault(str(rec.name).lower(), []).append(rec.payload)


    def _ebZone(self, failure):
        log.msg("Updating %s from %s failed during zone transfer" % (self.domain, self.primary))
        log.err(failure)


    def update(self):
        self.transfer().addCallbacks(self._cbTransferred, self._ebTransferred)


    def _cbTransferred(self, result):
        self.transferring = False


    def _ebTransferred(self, failure):
        self.transferred = False
        log.msg("Transferring %s from %s failed after zone transfer" % (self.domain, self.primary))
        log.err(failure)