# This file is part of Gajim.
#
# Gajim 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; version 3 only.
#
# Gajim 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 Gajim.  If not, see <http://www.gnu.org/licenses/>.
#

from nbxmpp import NodeProcessed
from nbxmpp.protocol import Message
from nbxmpp.structs import StanzaHandler

from gajim.common import app
from gajim.common import ged
from gajim.common.modules.base import BaseModule

# Module name
name = 'AntiSpam'
zeroconf = False


class AntiSpam(BaseModule):
    def __init__(self, con):
        BaseModule.__init__(self, con, plugin=True)

        self.handlers = [
            StanzaHandler(name='message',
                          callback=self._message_received,
                          priority=48),
            StanzaHandler(name='presence',
                          callback=self._subscribe_received,
                          typ='subscribe',
                          priority=48),
        ]

        self.register_events([
            ('message-sent', ged.OUT_PRECORE, self._on_message_sent),
        ])

        for plugin in app.plugin_manager.plugins:
            if plugin.short_name == 'anti_spam':
                self._config = plugin.config

        self._contacted_jids = set()

    def _on_message_sent(self, event):
        if event.type_ not in ('chat', 'normal'):
            return

        # We need self._contacted_jids in order to prevent two
        # Anti Spam Plugins from chatting with each other.
        # This set contains JIDs of all outgoing chats.
        if isinstance(event.jid, list):
            for jid in event.jid:
                self._contacted_jids.add(jid)
        else:
            self._contacted_jids.add(event.jid)

    def _message_received(self, _con, _stanza, properties):
        if properties.is_sent_carbon:
            # Another device already sent a message
            self._contacted_jids.add(properties.jid)
            return

        msg_body = properties.body
        if not msg_body:
            return

        if self._ask_question(properties):
            raise NodeProcessed

        msg_from = properties.jid
        limit = self._config['msgtxt_limit']
        if limit > 0 and len(msg_body) > limit:
            self._log.info('Discarded message from %s: message '
                           'length exceeded' % msg_from)
            raise NodeProcessed

        if self._config['disable_xhtml_muc'] and properties.type.is_groupchat:
            properties.xhtml = None
            self._log.info('Stripped message from %s: message '
                           'contained XHTML' % msg_from)

        if self._config['disable_xhtml_pm'] and properties.is_muc_pm:
            properties.xhtml = None
            self._log.info('Stripped message from %s: message '
                           'contained XHTML' % msg_from)

    def _ask_question(self, properties):
        answer = self._config['msgtxt_answer']
        if len(answer) == 0:
            return False

        is_muc_pm = properties.is_muc_pm
        if is_muc_pm and not self._config['antispam_for_conference']:
            return False

        if (properties.type.value not in ('chat', 'normal') or
                properties.is_mam_message):
            return False

        msg_from = properties.jid if is_muc_pm else properties.jid.bare

        if msg_from in self._contacted_jids:
            return False

        # If we receive a PM or a message from an unknown user, our anti spam
        # question will silently be sent in the background
        whitelist = self._config['whitelist']
        if msg_from in whitelist:
            return False

        is_contact = app.contacts.get_contacts(self._account, msg_from)

        if is_muc_pm or not is_contact:
            if answer in properties.body.split('\n'):
                if msg_from not in whitelist:
                    whitelist.append(msg_from)
                    # We need to explicitly save, because 'append' does not
                    # implement the __setitem__ method
                    self._config.save()
            else:
                self._send_question(properties, msg_from)
                return True
        return False

    def _send_question(self, properties, jid):
        message = 'Anti Spam Question: %s' % self._config['msgtxt_question']
        stanza = Message(to=jid, body=message, typ=properties.type.value)
        self._con.connection.send_stanza(stanza)
        self._log.info('Anti spam question sent to %s', jid)

    def _subscribe_received(self, _con, _stanza, properties):
        msg_from = properties.jid
        block_sub = self._config['block_subscription_requests']
        is_contact = app.contacts.get_contacts(self._account, msg_from)
        if block_sub and not is_contact:
            self._con.get_module('Presence').unsubscribed(msg_from)
            self._log.info('Denied subscription request from %s' % msg_from)
            raise NodeProcessed


def get_instance(*args, **kwargs):
    return AntiSpam(*args, **kwargs), 'AntiSpam'