# coding: utf-8

# Copyright (c) 2011 - 2013, Pascal Volk

# See COPYING for distribution information.

"""

    VirtualMailManager.serviceset

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

    Virtual Mail Manager's ServiceSet class for simplified database access

    to the service_set table.

"""

SERVICES = ('smtp', 'pop3', 'imap', 'sieve')

class ServiceSet(object):

    """A wrapper class that provides access to the service_set table.

    Each ServiceSet object provides following - read only - attributes:

    `ssid` : int

      The id of the service set

    `smtp` : bool

      Boolean flag for service smtp

    `pop3` : bool

      Boolean flag for service pop3

    `imap` : bool

      Boolean flag for service imap

    `sieve` : bool

      Boolean flag for service sieve

    `services` : dict

      The four services above with boolean values

    """

    __slots__ = ('_ssid', '_services', '_dbh')

    _kwargs = (('ssid',) + SERVICES)

    def __init__(self, dbh, **kwargs):

        """Creates a new ServiceSet instance.

        Either the 'ssid' keyword argument or one or more of the service

        arguments ('smtp', 'pop3',  'imap', 'sieve') must be provided.

        Arguments:

        `dbh` : psycopg2.extensions.connection

          A database connection for the database access.

        Keyword arguments:

        `ssid` : int

          The id of the service set (>0)

        `smtp` : bool

          Boolean flag for service smtp - default `True`

        `pop3` : bool

          Boolean flag for service pop3 - default `True`

        `imap` : bool

          Boolean flag for service imap - default `True`

        `sieve` : bool

          Boolean flag for service sieve - default `True`

        """

        self._dbh = dbh

        self._ssid = 0

        self._services = dict.fromkeys(SERVICES, True)

        for key in kwargs.keys():

            if key not in self.__class__._kwargs:

                raise ValueError('unrecognized keyword: %r' % key)

            if key == 'ssid':

                assert not isinstance(kwargs[key], bool) and \

                       isinstance(kwargs[key], int) and kwargs[key] > 0

                self._load_by_ssid(kwargs[key])

                break

            else:

                assert isinstance(kwargs[key], bool)

                if not kwargs[key]:

                    self._services[key] = kwargs[key]

        if not self._ssid:

            self._load_by_services()

    def __eq__(self, other):

        if isinstance(other, self.__class__):

            return self._ssid == other._ssid

        return NotImplemented

    def __ne__(self, other):

        if isinstance(other, self.__class__):

            return self._ssid != other._ssid

        return NotImplemented

    def __getattr__(self, name):

        if name not in self.__class__._kwargs:

            raise AttributeError('%r object has no attribute %r' % (

                                 self.__class__.__name__, name))

        if name == 'ssid':

            return self._ssid

        else:

            return self._services[name]

    def __repr__(self):

        return '%s(%s, %s)' % (self.__class__.__name__, self._dbh,

                  ', '.join('%s=%r' % s for s in self._services.items()))

    def _load_by_services(self):

        """Try to load the service_set by it's service combination."""

        sql = ('SELECT ssid FROM service_set WHERE %s' %

               ' AND '.join('%s = %s' %

               (k, str(v).upper()) for k, v in self._services.items()))

        dbc = self._dbh.cursor()

        dbc.execute(sql)

        result = dbc.fetchone()

        dbc.close()

        if result:

            self._ssid = result[0]

        else:

            self._save()

    def _load_by_ssid(self, ssid):

        """Try to load the service_set by it's primary key."""

        dbc = self._dbh.cursor()

        dbc.execute('SELECT ssid, smtp, pop3, imap, sieve '

                    'FROM service_set WHERE ssid = %s', (ssid,))

        result = dbc.fetchone()

        dbc.close()

        if not result:

            raise ValueError('Unknown service_set id specified: %r' % ssid)

        self._ssid = result[0]

        self._services.update(list(zip(SERVICES, result[1:])))

    def _save(self):

        """Store a new service_set in the database."""

        sql = ('INSERT INTO service_set (ssid, smtp, pop3, imap, sieve) '

               'VALUES (%(ssid)s, %(smtp)s, %(pop3)s, %(imap)s, %(sieve)s)')

        self._set_ssid()

        values = {'ssid': self._ssid}

        values.update(self._services)

        dbc = self._dbh.cursor()

        dbc.execute(sql, values)

        self._dbh.commit()

        dbc.close()

    def _set_ssid(self):

        """Set the unique ID for the new service_set."""

        assert self._ssid == 0

        dbc = self._dbh.cursor()

        dbc.execute("SELECT nextval('service_set_id')")

        self._ssid = dbc.fetchone()[0]

        dbc.close()

    @property

    def services(self):

        """A dictionary: Keys: `smtp`, `pop3`, `imap` and `sieve` with

        boolean values."""

        return self._services.copy()