#!/usr/bin/python
# -*- coding: utf-8 -*-

# SAT plugin for IP address discovery
# Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014, 2015 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from sat.core.i18n import _, D_
from sat.core.constants import Const as C
from sat.core.log import getLogger
log = getLogger(__name__)
from sat.tools import xml_tools
from twisted.web import client as webclient
from twisted.internet import defer
from twisted.internet import reactor
from twisted.internet import protocol
from twisted.internet import endpoints
from twisted.internet import error as internet_error
import urlparse
try:
    import netifaces
except ImportError:
    log.warning(u"netifaces is not available, it help discovering IPs, you can install it on https://pypi.python.org/pypi/netifaces")
    netifaces = None


PLUGIN_INFO = {
    "name": "IP discovery",
    "import_name": "IP",
    "type": C.PLUG_TYPE_MISC,
    "recommendations": ["NAT-PORT"],
    "main": "IPPlugin",
    "handler": "no",
    "description": _("""This plugin help to discover our external IP address.""")
}

GET_IP_PAGE = "http://www.goffi.org/sat_tools/get_ip.php" # This page must only return external IP of the requester
GET_IP_LABEL = D_(u"Allow external get IP")
GET_IP_CATEGORY = "General"
GET_IP_NAME = "allow_get_ip"
GET_IP_CONFIRM_TITLE = D_(u"Confirm external site request")
GET_IP_CONFIRM = D_(u"""To facilitate data transfer, we need to contact a website.
A request will be done on {page}
That means that administrators of {domain} can know that you use "{app_name}" and your IP Address.

IP address is an identifier to locate you on Internet (similar to a phone number).

Do you agree to do this request ?
""").format(
    page = GET_IP_PAGE,
    domain = urlparse.urlparse(GET_IP_PAGE).netloc,
    app_name = C.APP_NAME)

PARAMS = """
    <params>
    <general>
    <category name="{category}">
        <param name="{name}" label="{label}" type="bool" />
    </category>
    </general>
    </params>
    """.format(category=GET_IP_CATEGORY, name=GET_IP_NAME, label=GET_IP_LABEL)


class IPPlugin(object):
    # TODO: refresh IP if a new connection is detected
    # TODO: manage IPv6 when implemented in SàT
    # TODO: implement XEP-0279

    def __init__(self, host):
        log.info(_("plugin IP discovery initialization"))
        self.host = host
        host.memory.updateParams(PARAMS)

        # NAT-Port
        try:
            self._nat = host.plugins['NAT-PORT']
        except KeyError:
            log.debug(u"NAT port plugin not available")
            self._nat = None

        # XXX: cache is kept until SàT is restarted
        #      if IP may have changed, use self.refreshIP
        self._external_ip_cache = None
        self._local_ip_cache = None

    def refreshIP(self):
        # FIXME: use a trigger instead ?
        self._external_ip_cache = None
        self._local_ip_cache = None

    def _externalAllowed(self, profile):
        """Return value of parameter with autorisation of user to do external requests

        if parameter is not set, a dialog is shown to use to get its confirmation, and parameted is set according to answer
        @param profile: %(doc_profile)s
        @return (defer.Deferred[bool]): True if external request is autorised
        """
        allow_get_ip = self.host.memory.params.getParamA(GET_IP_NAME, GET_IP_CATEGORY, use_default=False)

        if allow_get_ip is None:
            # we don't have autorisation from user yet to use get_ip, we ask him
            def setParam(allowed):
                # FIXME: we need to use boolConst as setParam only manage str/unicode
                #        need to be fixed when params will be refactored
                self.host.memory.setParam(GET_IP_NAME, C.boolConst(allowed), GET_IP_CATEGORY)
                return allowed
            d = xml_tools.deferConfirm(self.host, _(GET_IP_CONFIRM), _(GET_IP_CONFIRM_TITLE), profile=profile)
            d.addCallback(setParam)
            return d

        return defer.succeed(allow_get_ip)

    def _filterAddresse(self, ip_addr):
        """Filter acceptable addresses

        For now, just remove IPv4 local addresses
        @param ip_addr(str): IP addresse
        @return (bool): True if addresse is acceptable
        """
        return not ip_addr.startswith('127.')

    def _insertFirst(self, addresses, ip_addr):
        """Insert ip_addr as first item in addresses

        @param ip_addr(str): IP addresse
        @param addresses(list): list of IP addresses
        """
        if ip_addr in addresses:
            if addresses[0] != ip_addr:
                addresses.remove(ip_addr)
                addresses.insert(0, ip_addr)
        else:
            addresses.insert(0, ip_addr)

    def _getIPFromExternal(self, ext_url):
        """Get local IP by doing a connection on an external url

        @param ext_utl(str): url to connect to
        @return (D(str)): return local IP
        """
        url = urlparse.urlparse(ext_url)
        port = url.port
        if port is None:
            if url.scheme=='http':
                port = 80
            elif url.scheme=='https':
                port = 443
            else:
                log.error(u"Unknown url scheme: {}".format(url.scheme))
                defer.returnValue(None)
        if url.hostname is None:
            log.error(u"Can't find url hostname for {}".format(GET_IP_PAGE))

        point = endpoints.TCP4ClientEndpoint(reactor, url.hostname, port)
        def gotConnection(p):
            local_ip = p.transport.getHost().host
            p.transport.loseConnection()
            return local_ip

        d = endpoints.connectProtocol(point, protocol.Protocol())
        d.addCallback(gotConnection)
        return d


    @defer.inlineCallbacks
    def getLocalIPs(self, profile):
        """Try do discover local area network IPs

        @param profile): %(doc_profile)s
        @return (deferred): list of lan IP addresses
            or empty list if it can't be discovered
            if there are several addresses, the one used with the server is put first
        """
        # TODO: manage permission requesting (e.g. for UMTS link)
        if self._local_ip_cache is not None:
            defer.returnValue(self._local_ip_cache)
        client = self.host.getClient(profile)
        addresses = []

        # we first try our luck with netifaces
        if netifaces is not None:
            addresses = []
            for interface in netifaces.interfaces():
                if_addresses = netifaces.ifaddresses(interface)
                try:
                    inet_list = if_addresses[netifaces.AF_INET]
                except KeyError:
                    continue
                for data in inet_list:
                    addresse = data['addr']
                    if self._filterAddresse(addresse):
                        addresses.append(addresse)

        # we first try with our connection to server
        ip = client.xmlstream.transport.getHost().host
        if self._filterAddresse(ip):
            self._insertFirst(addresses, ip)
            defer.returnValue(addresses)

        # if not available, we try with NAT-Port
        if self._nat is not None:
            nat_ip = yield self._nat.getIP(local=True)
            if nat_ip is not None:
                self._insertFirst(addresses, nat_ip)
                defer.returnValue(addresses)

            if addresses:
                defer.returnValue(addresses)

            # still not luck, we need to contact external website
            allow_get_ip = yield self._externalAllowed(profile)

            if not allow_get_ip:
                defer.returnValue(addresses)

        try:
            ip_tuple = yield self._getIPFromExternal(GET_IP_PAGE)
        except Exception as internet_error.DNSLookupError:
            log.warning(u"Can't access Domain Name System")
            defer.returnValue(addresses)
        self._insertFirst(addresses, ip_tuple.local)
        defer.returnValue(addresses)


    @defer.inlineCallbacks
    def getExternalIP(self, profile):
        """Try to discover external IP

        @param profile: %(doc_profile)s
        @return (deferred): external IP address or None if it can't be discovered
        """
        if self._external_ip_cache is not None:
            defer.returnValue(self._external_ip_cache)

        # we first try with NAT-Port
        if self._nat is not None:
            nat_ip = yield self._nat.getIP()
            if nat_ip is not None:
                self._external_ip_cache = nat_ip
                defer.returnValue(nat_ip)

        # then by requesting external website
        allow_get_ip = yield self._externalAllowed(profile)
        try:
            ip = (yield webclient.getPage(GET_IP_PAGE)) if allow_get_ip else None
        except internet_error.DNSLookupError:
            log.warning(u"Can't access Domain Name System")
            ip = None
        else:
            self._external_ip_cache = ip
        defer.returnValue(ip)