"""
    SleekXMPP: The Sleek XMPP Library
    Copyright (C) 2010  Nathanael C. Fritz
    This file is part of SleekXMPP.

    See the file LICENSE for copying permission.
"""

from __future__ import absolute_import

import logging
import base64
import sys
import hashlib

from sleekxmpp import plugins
from sleekxmpp import stanza
from sleekxmpp.basexmpp import BaseXMPP, SRV_SUPPORT
from sleekxmpp.xmlstream import XMLStream, RestartStream
from sleekxmpp.xmlstream import StanzaBase, ET
from sleekxmpp.xmlstream.matcher import *
from sleekxmpp.xmlstream.handler import *


class ComponentXMPP(BaseXMPP):

    """
    SleekXMPP's basic XMPP server component.

    Use only for good, not for evil.

    Methods:
        connect              -- Overrides XMLStream.connect.
        incoming_filter      -- Overrides XMLStream.incoming_filter.
        start_stream_handler -- Overrides XMLStream.start_stream_handler.
    """

    def __init__(self, jid, secret, host, port,
                 plugin_config={}, plugin_whitelist=[], use_jc_ns=False):
        """
        Arguments:
            jid              -- The JID of the component.
            secret           -- The secret or password for the component.
            host             -- The server accepting the component.
            port             -- The port used to connect to the server.
            plugin_config    -- A dictionary of plugin configurations.
            plugin_whitelist -- A list of desired plugins to load
                                when using register_plugins.
            use_js_ns        -- Indicates if the 'jabber:client' namespace
                                should be used instead of the standard
                                'jabber:component:accept' namespace.
                                Defaults to False.
        """
        if use_jc_ns:
            default_ns = 'jabber:client'
        else:
            default_ns = 'jabber:component:accept'
        BaseXMPP.__init__(self, default_ns)

        self.auto_authorize = None
        self.stream_header = "<stream:stream %s %s to='%s'>" % (
                'xmlns="jabber:component:accept"',
                'xmlns:stream="%s"' % self.stream_ns,
                jid)
        self.stream_footer = "</stream:stream>"
        self.server_host = host
        self.server_port = port
        self.set_jid(jid)
        self.secret = secret
        self.plugin_config = plugin_config
        self.plugin_whitelist = plugin_whitelist
        self.is_component = True

        self.register_handler(
                Callback('Handshake',
                         MatchXPath('{jabber:component:accept}handshake'),
                         self._handle_handshake))

    def connect(self):
        """
        Connect to the server.

        Overrides XMLStream.connect.
        """
        logging.debug("Connecting to %s:%s" % (self.server_host,
                                               self.server_port))
        return XMLStream.connect(self, self.server_host,
                                       self.server_port)

    def incoming_filter(self, xml):
        """
        Pre-process incoming XML stanzas by converting any 'jabber:client'
        namespaced elements to the component's default namespace.

        Overrides XMLStream.incoming_filter.

        Arguments:
            xml -- The XML stanza to pre-process.
        """
        if xml.tag.startswith('{jabber:client}'):
            xml.tag = xml.tag.replace('jabber:client', self.default_ns)

        # The incoming_filter call is only made on top level stanza
        # elements. So we manually continue filtering on sub-elements.
        for sub in xml:
            self.incoming_filter(sub)

        return xml

    def start_stream_handler(self, xml):
        """
        Once the streams are established, attempt to handshake
        with the server to be accepted as a component.

        Overrides XMLStream.start_stream_handler.

        Arguments:
            xml -- The incoming stream's root element.
        """
        # Construct a hash of the stream ID and the component secret.
        sid = xml.get('id', '')
        pre_hash = '%s%s' % (sid, self.secret)
        if sys.version_info >= (3, 0):
            # Handle Unicode byte encoding in Python 3.
            pre_hash = bytes(pre_hash, 'utf-8')

        handshake = ET.Element('{jabber:component:accept}handshake')
        handshake.text = hashlib.sha1(pre_hash).hexdigest().lower()
        self.send_xml(handshake)

    def _handle_handshake(self, xml):
        """
        The handshake has been accepted.

        Arguments:
            xml -- The reply handshake stanza.
        """
        self.event("session_start")