# -*- coding: utf-8 -*-
# server.py
# Copyright (C) 2014 LEAP
#
# 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/>.
"""
Leap IMAP4 Server Implementation.
"""
from copy import copy

from twisted import cred
from twisted.internet.defer import maybeDeferred
from twisted.mail import imap4
from twisted.python import log

from leap.common import events as leap_events
from leap.common.check import leap_assert, leap_assert_type
from leap.common.events.events_pb2 import IMAP_CLIENT_LOGIN
from leap.soledad.client import Soledad


class LeapIMAPServer(imap4.IMAP4Server):
    """
    An IMAP4 Server with mailboxes backed by soledad
    """
    def __init__(self, *args, **kwargs):
        # pop extraneous arguments
        soledad = kwargs.pop('soledad', None)
        uuid = kwargs.pop('uuid', None)
        userid = kwargs.pop('userid', None)

        leap_assert(soledad, "need a soledad instance")
        leap_assert_type(soledad, Soledad)
        leap_assert(uuid, "need a user in the initialization")

        self._userid = userid

        # initialize imap server!
        imap4.IMAP4Server.__init__(self, *args, **kwargs)

        # we should initialize the account here,
        # but we move it to the factory so we can
        # populate the test account properly (and only once
        # per session)

        from twisted.internet import reactor
        self.reactor = reactor

    def lineReceived(self, line):
        """
        Attempt to parse a single line from the server.

        :param line: the line from the server, without the line delimiter.
        :type line: str
        """
        if self.theAccount.closed is True and self.state != "unauth":
            log.msg("Closing the session. State: unauth")
            self.state = "unauth"

        if "login" in line.lower():
            # avoid to log the pass, even though we are using a dummy auth
            # by now.
            msg = line[:7] + " [...]"
        else:
            msg = copy(line)
        log.msg('rcv (%s): %s' % (self.state, msg))
        imap4.IMAP4Server.lineReceived(self, line)

    def authenticateLogin(self, username, password):
        """
        Lookup the account with the given parameters, and deny
        the improper combinations.

        :param username: the username that is attempting authentication.
        :type username: str
        :param password: the password to authenticate with.
        :type password: str
        """
        # XXX this should use portal:
        # return portal.login(cred.credentials.UsernamePassword(user, pass)
        if username != self._userid:
            # bad username, reject.
            raise cred.error.UnauthorizedLogin()
        # any dummy password is allowed so far. use realm instead!
        leap_events.signal(IMAP_CLIENT_LOGIN, "1")
        return imap4.IAccount, self.theAccount, lambda: None

    def do_FETCH(self, tag, messages, query, uid=0):
        """
        Overwritten fetch dispatcher to use the fast fetch_flags
        method
        """
        if not query:
            self.sendPositiveResponse(tag, 'FETCH complete')
            return

        cbFetch = self._IMAP4Server__cbFetch
        ebFetch = self._IMAP4Server__ebFetch

        if len(query) == 1 and str(query[0]) == "flags":
            self._oldTimeout = self.setTimeout(None)
            # no need to call iter, we get a generator
            maybeDeferred(
                self.mbox.fetch_flags, messages, uid=uid
            ).addCallback(
                cbFetch, tag, query, uid
            ).addErrback(ebFetch, tag)

        elif len(query) == 1 and str(query[0]) == "rfc822.header":
            self._oldTimeout = self.setTimeout(None)
            # no need to call iter, we get a generator
            maybeDeferred(
                self.mbox.fetch_headers, messages, uid=uid
            ).addCallback(
                cbFetch, tag, query, uid
            ).addErrback(ebFetch, tag)
        else:
            self._oldTimeout = self.setTimeout(None)
            # no need to call iter, we get a generator
            maybeDeferred(
                self.mbox.fetch, messages, uid=uid
            ).addCallback(
                cbFetch, tag, query, uid
            ).addErrback(
                ebFetch, tag)

    select_FETCH = (do_FETCH, imap4.IMAP4Server.arg_seqset,
                    imap4.IMAP4Server.arg_fetchatt)

    def notifyNew(self, ignored=None):
        """
        Notify new messages to listeners.
        """
        self.reactor.callFromThread(self.mbox.notify_new)

    def _cbSelectWork(self, mbox, cmdName, tag):
        """
        Callback for selectWork, patched to avoid conformance errors due to
        incomplete UIDVALIDITY line.
        """
        if mbox is None:
            self.sendNegativeResponse(tag, 'No such mailbox')
            return
        if '\\noselect' in [s.lower() for s in mbox.getFlags()]:
            self.sendNegativeResponse(tag, 'Mailbox cannot be selected')
            return

        flags = mbox.getFlags()
        self.sendUntaggedResponse(str(mbox.getMessageCount()) + ' EXISTS')
        self.sendUntaggedResponse(str(mbox.getRecentCount()) + ' RECENT')
        self.sendUntaggedResponse('FLAGS (%s)' % ' '.join(flags))

        # Patched -------------------------------------------------------
        # imaptest was complaining about the incomplete line, we're adding
        # "UIDs valid" here.
        self.sendPositiveResponse(
            None, '[UIDVALIDITY %d] UIDs valid' % mbox.getUIDValidity())
        # ----------------------------------------------------------------

        s = mbox.isWriteable() and 'READ-WRITE' or 'READ-ONLY'
        mbox.addListener(self)
        self.sendPositiveResponse(tag, '[%s] %s successful' % (s, cmdName))
        self.state = 'select'
        self.mbox = mbox

    def checkpoint(self):
        """
        Called when the client issues a CHECK command.

        This should perform any checkpoint operations required by the server.
        It may be a long running operation, but may not block.  If it returns
        a deferred, the client will only be informed of success (or failure)
        when the deferred's callback (or errback) is invoked.
        """
        # TODO return the output of _memstore.is_writing
        # XXX and that should return a deferred!
        return None