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

# file: dsa.py
# date: 26.07.2020
# desc: Serves debians security alerts


import logging
import urllib3
import threading
from lxml import etree
from manager import Plugin
import common


logging = logging.getLogger()


class Plugin(Plugin):

    '''
    Fetchs debians security alerts, grabs title and links and sends it to
    the muc.
    '''

    __module = __name__
    __command = 'dsa'
    __description = 'Serves debians security alerts'

    @staticmethod
    def get_module():
        return Plugin.__module

    @staticmethod
    def get_command():
        return Plugin.__command

    @staticmethod
    def get_description():
        return Plugin.__description

    def __init__(self, callback=None):
        self.callback = callback

    def help(self):
        return ('!dsa serves the actual debian security alerts. A given '
                ' number reduces the count of alerts displayed to number. '
                'Not implemented at the moment.'
                '\nSyntax: !dsa <number>')

    def run(self, stanza):
        '''
        Starts a thread to grab debians security alerts returns
        immediately.
        param 1: stanza object
        '''
        call_msg = 'Call "!help {}"'.format(self.get_command())
        no_count_msg = ' '.join(('Not a valid count: "{}"!', call_msg))
        count = False

        muc_nick = common.get_nick_from_stanza(stanza)
        arguments = common.get_arguments_from_body(stanza)

        if arguments is not False:
            count = self.get_count(arguments[0])
            if count is False:
                self.callback(': '.join((muc_nick, no_count_msg)))
                return

        logging.debug('Start thread for debian security alerts')
        dsa_thread = DsaThread(self.callback, count)
        dsa_thread.run()
        logging.debug('DSA Thread started')

    def get_count(self, item):
        '''
        Try to convert a string into integer.
        param 1: string
        retuns: integer or false
        '''
        try:
            value = int(item.strip())
            return value
        except Exception as e:
            logging.warning('Invalid value for count: {}'.format(item))
            logging.warning('Exception: {}'.format(e))
        return False


class DsaThread(threading.Thread):
    '''
    The thread who fetched and returns the wp search. 
    '''
    def __init__(self, callback, count):
        threading.Thread.__init__(self)
        self.callback = callback
        self.count = count

    def run(self):
        '''
        Starts the thread.
        '''
        dsa_response = self.get_file()
        if dsa_response == False:
            self.callback('Error while fetching DSA')
        else:
            status = dsa_response.status
            logging.debug("Server returns {}".format(status))
            if status != 200:
                self.callback('Server returns {}'.format(status))
            xmldoc = etree.fromstring(dsa_response.data)
            message = self.string_factory(xmldoc)
            self.callback(message)

    def string_factory(self, xmldoc):
        '''
        Extracts interested things from the given dsa xml document and
        creates a string to post im muc.
        param 1: xml object
        '''
        message = 'Debian Security Alerts:'
        nsmap = {
            "purl": "http://purl.org/rss/1.0/",
            "rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
        }
        about_list = xmldoc.xpath('//purl:item/@rdf:about', namespaces=nsmap)
        for about in reversed(about_list):
            dsa_id = self.get_id_from_about(about)
            title = xmldoc.xpath(
                    '//purl:item[@rdf:about="{}"]/purl:title/text()'.format(
                    about), namespaces=nsmap)[0]
            message = '\n'.join((message, title))
        return message

    def get_file(self):
        '''
        Fetchs the security alerts from debian.org
        param 1: string
        returns: request object or false
        '''
        url = 'https://www.debian.org/security/dsa-long'
        logging.debug('Try to fetch {}'.format(url))
        http = urllib3.PoolManager()
        try:
            dsa_response = http.request('Get', url)
            return dsa_response
        except:
            logging.debug('{}: failed to fetch'.format(url))
        return False

    def get_id_from_about(self, about):
        '''
        Extracts the dsa id from tehe given string.
        param 1: string
        '''
        return int(about.split('/')[-1].split('-')[1])