# -*- coding: UTF-8 -*-

# Copyright (c) 2007 - 2013, Pascal Volk

# See COPYING for distribution information.

"""

    VirtualMailManager.alias

    ~~~~~~~~~~~~~~~~~~~~~~~~

    Virtual Mail Manager's Alias class to manage e-mail aliases.

"""

from VirtualMailManager.domain import get_gid

from VirtualMailManager.emailaddress import \

     EmailAddress, DestinationEmailAddress as DestAddr

from VirtualMailManager.errors import AliasError as AErr

from VirtualMailManager.ext.postconf import Postconf

from VirtualMailManager.constants import \

     ALIAS_EXCEEDS_EXPANSION_LIMIT, NO_SUCH_ALIAS, NO_SUCH_DOMAIN

_ = lambda msg: msg

cfg_dget = lambda option: None

class Alias(object):

    """Class to manage e-mail aliases."""

    __slots__ = ('_addr', '_dests', '_gid', '_dbh')

    def __init__(self, dbh, address):

        assert isinstance(address, EmailAddress)

        self._addr = address

        self._dbh = dbh

        self._gid = get_gid(self._dbh, self._addr.domainname)

        if not self._gid:

            raise AErr(_("The domain '%s' does not exist.") %

                       self._addr.domainname, NO_SUCH_DOMAIN)

        self._dests = []

        self._load_dests()

    def _load_dests(self):

        """Loads all known destination addresses into the _dests list."""

        dbc = self._dbh.cursor()

        dbc.execute('SELECT destination FROM alias WHERE gid = %s AND '

                    'address = %s ORDER BY destination',

                    (self._gid, self._addr.localpart))

        dests = dbc.fetchall()

        if dbc.rowcount > 0:

            self._dests.extend(DestAddr(dest[0], self._dbh) for dest in dests)

        dbc.close()

    def _check_expansion(self, count_new):

        """Checks the current expansion limit of the alias."""

        postconf = Postconf(cfg_dget('bin.postconf'))

        limit = int(postconf.read('virtual_alias_expansion_limit'))

        dcount = len(self._dests)

        failed = False

        if dcount == limit or dcount + count_new > limit:

            failed = True

            errmsg = _(

"""Cannot add %(count_new)i new destination(s) to alias '%(address)s'.

Currently this alias expands into %(count)i/%(limit)i recipients.

%(count_new)i additional destination(s) will render this alias unusable.

Hint: Increase Postfix' virtual_alias_expansion_limit""")

        elif dcount > limit:

            failed = True

            errmsg = _(

"""Cannot add %(count_new)i new destination(s) to alias '%(address)s'.

This alias already exceeds its expansion limit (%(count)i/%(limit)i).

So its unusable, all messages addressed to this alias will be bounced.

Hint: Delete some destination addresses.""")

        if failed:

            raise AErr(errmsg % {'address': self._addr, 'count': dcount,

                                 'limit': limit, 'count_new': count_new},

                       ALIAS_EXCEEDS_EXPANSION_LIMIT)

    def _delete(self, destinations=None):

        """Deletes the *destinations* from the alias, if ``destinations``

        is not ``None``.  If ``destinations`` is None, the alias with all

        its destination addresses will be deleted.

        """

        dbc = self._dbh.cursor()

        if not destinations:

            dbc.execute('DELETE FROM alias WHERE gid = %s AND address = %s',

                        (self._gid, self._addr.localpart))

        else:

            dbc.executemany("DELETE FROM alias WHERE gid = %d AND address = "

                            "'%s' AND destination = %%s" % (self._gid,

                                                         self._addr.localpart),

                            ((str(dest),) for dest in destinations))

        if dbc.rowcount > 0:

            self._dbh.commit()

        dbc.close()

    def __len__(self):

        """Returns the number of destinations of the alias."""

        return len(self._dests)

    @property

    def address(self):

        """The Alias' EmailAddress instance."""

        return self._addr

    def add_destinations(self, destinations, warnings=None):

        """Adds the `EmailAddress`es from *destinations* list to the

        destinations of the alias.

        Destinations, that are already assigned to the alias, will be

        removed from *destinations*.  When done, this method will return

        a set with all destinations, that were saved in the database.

        """

        destinations = set(destinations)

        assert destinations and \

                all(isinstance(dest, EmailAddress) for dest in destinations)

        if not warnings is None:

            assert isinstance(warnings, list)

        if self._addr in destinations:

            destinations.remove(self._addr)

            if not warnings is None:

                warnings.append(self._addr)

        duplicates = destinations.intersection(set(self._dests))

        if duplicates:

            destinations.difference_update(set(self._dests))

            if not warnings is None:

                warnings.extend(duplicates)

        if not destinations:

            return destinations

        self._check_expansion(len(destinations))

        dbc = self._dbh.cursor()

        dbc.executemany("INSERT INTO alias (gid, address, destination) "

                        "VALUES (%d, '%s', %%s)" % (self._gid,

                                                    self._addr.localpart),

                        ((str(destination),) for destination in destinations))

        self._dbh.commit()

        dbc.close()

        self._dests.extend(destinations)

        return destinations

    def del_destinations(self, destinations, warnings=None):

        """Delete the specified `EmailAddress`es of *destinations* from

        the alias's destinations.

        """

        destinations = set(destinations)

        assert destinations and \

                all(isinstance(dest, EmailAddress) for dest in destinations)

        if not warnings is None:

            assert isinstance(warnings, list)

        if self._addr in destinations:

            destinations.remove(self._addr)

            if not warnings is None:

                warnings.append(self._addr)

        if not self._dests:

            raise AErr(_("The alias '%s' does not exist.") % self._addr,

                       NO_SUCH_ALIAS)

        unknown = destinations.difference(set(self._dests))

        if unknown:

            destinations.intersection_update(set(self._dests))

            if not warnings is None:

                warnings.extend(unknown)

        if not destinations:

            raise AErr(_("No suitable destinations left to remove from alias "

                         "'%s'.") % self._addr, NO_SUCH_ALIAS)

        self._delete(destinations)

        for destination in destinations:

            self._dests.remove(destination)

    def get_destinations(self):

        """Returns an iterator for all destinations of the alias."""

        if not self._dests:

            raise AErr(_("The alias '%s' does not exist.") % self._addr,

                       NO_SUCH_ALIAS)

        return iter(self._dests)

    def delete(self):

        """Deletes the alias with all its destinations."""

        if not self._dests:

            raise AErr(_("The alias '%s' does not exist.") % self._addr,

                       NO_SUCH_ALIAS)

        self._delete()

        del self._dests[:]

del _, cfg_dget