#
# ex:ts=4:sw=4:sts=4:et
# -*- tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-
#
# Security Response Tool Implementation
#
# Copyright (C) 2013-2015 Intel Corp.
# Copyright (C) 2017-2018 Wind River Systems
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
# 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

from django.core.management.base import BaseCommand
from django.contrib.auth.models import Group

from orm.models import SrtSetting, DataSource
from orm.models import CweTable, CpeFilter

from users.models import SrtUser

import os
import sys
import re
import time
import pytz
from datetime import datetime

import json
import xml.etree.ElementTree as ET
import csv
import logging
import threading

logger = logging.getLogger("srt")

# quick development/debugging support
from srtgui.api import _log

# === Debugging limited database loading support ===
debug_cve_list = [] # empty list for any
#debug_cve_list = [
#    'CVE-2017-0001','CVE-2017-1000135','CVE-2017-10604','CVE-2017-0290',
#    'CVE-2017-8361','CVE-2017-8362','CVE-2017-8363','CVE-2017-8365','CVE-2017-8392','CVE-2017-8779',
#    ]
#debug_cve_count = 0   # 0 for all
#debug_cve_count = 10   # 0 for any
#debug_include_id_prefix = 'CVE-2018'   # always include CVEs with this prefix
#debug_include_id_prefix = 'XXX'   # always include CVEs with this prefix
#status_sustaining_limit = 0 # 0 for all
#status_sustaining_limit = 10
#debug_defect_limit = 0 # 0 for all
#debug_defect_limit = 10
#cpe_limit = 0
#cpe_limit = 10

class Spinner(threading.Thread):
    """ A simple progress spinner to indicate download/parsing is happening"""
    def __init__(self, *args, **kwargs):
        super(Spinner, self).__init__(*args, **kwargs)
        self.setDaemon(True)
        self.signal = True

    def run(self):
        os.system('setterm -cursor off')
        while self.signal:
            for char in ["/", "-", "\\", "|"]:
                sys.stdout.write("\r" + char)
                sys.stdout.flush()
                time.sleep(0.25)
        os.system('setterm -cursor on')

    def stop(self):
        self.signal = False


class Command(BaseCommand):
    args = ""
    help = "Updates locally cached information from the registered data sources"

    # === Debugging limited database loading support ===
    debug_cve_list = [] # empty list for any
    debug_cve_count = 0   # 0 for all
    debug_include_id_prefix = 'XXX'   # always include CVEs with this prefix
    status_sustaining_limit = 0 # 0 for all
    debug_defect_limit = 0 # 0 for all
    cpe_limit = 0

    def mini_progress(self, what, i, total):
        i = i + 1
        pec = (float(i)/float(total))*100

        sys.stdout.write("\rUpdating %s %d%%" %
                         (what,
                          pec))
        sys.stdout.flush()
        if int(pec) is 100:
            sys.stdout.write("\n")
            sys.stdout.flush()


    # Execute a shell script to import data, relative the SRT base
    def execute_script(self,command):
        SRT_BASE_DIR = os.environ.get('SRT_BASE_DIR')
        CWD = os.getcwd()
        os.chdir(SRT_BASE_DIR)
        script = os.path.join(SRT_BASE_DIR,command)
        print("====vvv Executing script '%s' vvv====" % script)
        ret = os.system(script)
        os.chdir(CWD)
        if 0 != ret:
            # NOTE: the error is already displayed in the normal STDERR, so
            # so need to repeat it here
            print("\n##########\nHALT: SCRIPT ERROR: %s=%s\n##########" % (ret,script))
            exit(1)
        print("====^^^ Script Done = %s ^^^====" % ret)

    # Mark database as loaded
    def source_loaded(self,id,update_modified=True):
        # Re-fetch record in case external script updates
        updated_source=DataSource.objects.get(id=id)
        updated_source.loaded = True
        if update_modified:
            updated_source.lastModifiedDate = datetime.today().strftime(DataSource.DATETIME_FORMAT)
        updated_source.lastUpdatedDate = datetime.today().strftime(DataSource.DATETIME_FORMAT)
        updated_source.save()

    def nist_cwe(self, content):
        # <td nowrap><span id="cweIdEntry-CWE-123">CWE-123</span></td>
        # <td nowrap><a href="http://cwe.mitre.org/data/definitions/123.html" target="_blank"> Write-what-where Condition</a></td>
        # <td>Any condition where the attacker has the ability to write an arbitrary value to an arbitrary location, often as the result of a buffer overflow.</td>

        state = 0
        for line in content.split('\n'):
            if (0 == state) and (0 < line.find('cweIdEntry')):
                # <td nowrap><span id="cweIdEntry-CWE-613">CWE-613</span></td>
                m = re.search('cweIdEntry.*>(.+?)<', line)
                if m:
                    name = m.group(1)
                else:
                    print("ERROR ID:%s" % line)
                    continue
                state = 1
            elif (1 == state) and (0 < line.find('href')):
                # <td nowrap><a href="http://cwe.mitre.org/data/definitions/613.html" target="_blank"> Insufficient Session Expiration</a></td>
                m = re.search('href="(.+?)"', line)
                if m:
                    href = m.group(1)
                else:
                    print("ERROR HREF:%s" % line)
                    continue
                m = re.search('href.*>(.+?)<', line)
                if m:
                    summary = m.group(1)
                else:
                    print("ERROR Summary:%s" % line)
                    continue
                state = 2
            elif (1 == state) and (0 < line.find('<td nowrap>')):
                # <td nowrap>Insufficient Information</td>
                href = ''
                m = re.search('nowrap>(.+?)<', line)
                if m:
                    summary = m.group(1)
                else:
                    print("ERROR Summary:%s" % line)
                    continue
                state = 2
            elif (2 == state) and (0 < line.find('<td>')):
                # <td>Weaknesses in this category are related to improper calculation or conversion of numbers.</td>
                m = re.search('<td>(.*?)</td>', line)
                if m:
                    description = m.group(1)
                else:
                    print("ERROR Desc:%s" % line)
                    continue

                cwe, created = CweTable.objects.get_or_create(name=name)
                index = name.find('-')
                if name[index+1].isdigit():
                    cwe.name_sort = '%s-%04d' % (name[0:index],int(name[index+1:]))
                else:
                    cwe.name_sort = name
                cwe.href = href
                cwe.summary = summary
                cwe.description = description
                cwe.save()
                state = 0

    def nist_cpe(self, root):
        #<cpe-list
        #  <cpe-item name="cpe:/a:1024cms:1024_cms:0.7">
        #    <title xml:lang="en-US">1024cms.org 1024 CMS 0.7</title>
        #    <cpe-23:cpe23-item name="cpe:2.3:a:1024cms:1024_cms:0.7:*:*:*:*:*:*:*"/>
        #  </cpe-item>

        i = 1
        last_key_prime = ''
        last_key_sub = ''
        for child_1 in root:
            if 'cpe-item' in child_1.tag:
                for child_2 in child_1:
                    if 'cpe23-item' in child_2.tag:
                        cpe23Uri = child_2.attrib['name']
                        # Add to general CPE Table
                        if not cpe23Uri:
                            cpe23Uri = 'cpe:2.3:o:missing:missing:*:*:*:*:*:*:*:*'
                        cpe_fields = cpe23Uri.split(':')
                        key_prime = cpe_fields[3]
                        key_sub = cpe_fields[4]
                        if (key_prime == last_key_prime) and (key_sub == last_key_sub):
                            continue
                        last_key_prime = key_prime
                        last_key_sub = key_sub
                        # add top-level key_prime
                        cpe_filter, created = CpeFilter.objects.get_or_create(key_prime=key_prime,key_sub='')
                        if created:
                            cpe_filter.save()
                        # add full key_prime:key_sub
                        cpe_filter, created = CpeFilter.objects.get_or_create(key_prime=key_prime,key_sub=key_sub)
                        if created:
                            cpe_filter.save()
                        print("[%d]cpe23Uri='%s',%s,%s" % (i,cpe23Uri,key_prime,key_sub))
                        i += 1

    def nist_cpe_csv(self, csvfile_name):
        # Status,Company,Product,Auto

        i=0
        with open(csvfile_name, newline='') as csvfile:
            CPE_reader = csv.reader(csvfile, delimiter=',', quotechar='"')
            last_company = ''
            last_product = ''
            for row in CPE_reader:
                i += 1
                if (i>1) and len(row):
                    if 'i' == row[0]:
                        status = CpeFilter.INCLUDE
                    elif 'x' == row[0]:
                        status = CpeFilter.EXCLUDE
                    elif 'r' == row[0]:
                        status = CpeFilter.UNDECIDED
                    else:
                        status = CpeFilter.UNDECIDED
                    company = row[1]
                    product = row[2]
                    if 'a' == row[3]:
                        auto = True
                    else:
                        auto = False

                    if (last_company == company) and (last_product == product):
                        continue
                    last_company = company
                    last_product = product
                    # add top-level last_company
                    cpe_filter, created = CpeFilter.objects.get_or_create(key_prime=company,key_sub='')
                    cpe_filter.status = status
                    cpe_filter.automatic = auto
                    cpe_filter.save()
                    # add full last_company:product
                    cpe_filter, created = CpeFilter.objects.get_or_create(key_prime=company,key_sub=product)
                    cpe_filter.status = status
                    cpe_filter.automatic = auto
                    cpe_filter.save()

                    if 0 == i % 10:
                        print('%04d: %20s\r' % (i,company), end='')
#                    print("[%d]cpe23Uri=%s,%s" % (i,company,product))


    # We explicit use Django to add users to avoid attempting to hash passwords in a shell script
    # NOTE: extra items or fields (like "_comment_") are explicitly ignored
    def users_load(self, dct):
        User_Items = dct['User_Items']
        for i, User_Item in enumerate(User_Items):
            # Required fields
            name = User_Item['name']
            email = User_Item['email']
            group_name = User_Item['group']
            # Optional fields (but schema requires definition)
            first_name = User_Item['first_name'] if 'first_name' in User_Item else ''
            last_name = User_Item['last_name'] if 'last_name' in User_Item else ''
            role = User_Item['role'] if 'role' in User_Item else 'srtool'
            is_staff = User_Item['is_staff'] if 'is_staff' in User_Item else False
            is_active = User_Item['is_active'] if 'is_active' in User_Item else True
            date_joined = User_Item['date_joined'] if 'date_joined' in User_Item else datetime.now(pytz.utc)
            # Provide default password so that they can change after first login (form prevents blank passwords)
            password = User_Item['password'] if 'password' in User_Item else 'srtool'

            srtuser, created = SrtUser.objects.get_or_create(username = name)
            if created:
                srtuser.email = email
                srtuser.role = role
                srtuser.password = ''
                srtuser.first_name = first_name
                srtuser.last_name = last_name
                srtuser.is_staff = is_staff
                srtuser.is_active = is_active
                srtuser.date_joined = date_joined
                srtuser.set_password(password)  # hash the password
                srtuser.save()

                group = Group.objects.get(name = group_name)
                group.user_set.add(srtuser)


    def update(self):
        """
            Fetches CVE data from the registered data sources
        """
        os.system('setterm -cursor off')

        logger.info("***LS UPDATES***")

        # Process the data sources in strict pk order to insure dependencies
        data_sources=DataSource.objects.all().order_by('key')
        for source in data_sources:

            if source.loaded and not (source.update_frequency == DataSource.ONSTARTUP):
                logger.info("Skipping source data from %s",source.description)
                print("Skipping datasource %s (already loaded)" % (source.description))
                _log("Skipping datasource %s (already loaded)" % (source.description))
                continue
            elif not source.init:
                # No Init action?
                print("Skipping datasource %s (no init action)" % (source.description))
                continue
            else:
                logger.info("Fetching datasource %s:%s" % (source.source,source.description))
                print("Fetching datasource '%s:%s'" % (source.source,source.description))
                _log("Fetching datasource '%s:%s'" % (source.source,source.description))

            # Development/testing shortcut
            if ('cve' == source.data) and ('yes' == SrtSetting.objects.get(name='SRTDBG_SKIP_CVE_IMPORT').value):
                continue
            if ('cpe' == source.data) and ('yes' == SrtSetting.objects.get(name='SRTDBG_SKIP_CPE_IMPORT').value):
                continue
            if ('defect' == source.data) and ('yes' == SrtSetting.objects.get(name='SRTDBG_SKIP_DEFECT_IMPORT').value):
                continue

            # Script-based init?
            if not source.init.startswith('file:'):
                self.execute_script(source.init)
                self.source_loaded(source.id)
                continue

            # Get the init content with local methods
            dct = None
            root = None
            content = None
            source_doc = None
            # load the file
            source_doc = source.init.replace('file:','')
            if not source_doc.startswith('/'):
                source_doc = os.path.join(os.getenv('SRT_BASE_DIR'), source_doc)
            if not os.path.isfile(source_doc):
                logger.error("Data file not found '%s'" % (source_doc))
                continue
            if source_doc.endswith('.json'):
                with open(source_doc) as json_data:
                    dct = json.load(json_data)
            elif source_doc.endswith('xml'):
                tree = ET.parse(source_doc)
                root = tree.getroot()
            elif source_doc.endswith('csv'):
                csvfile_name = source_doc
            else:
                with open(source_doc) as text_data:
                    content = text_data.read()

            # Common data sources
            pass

            # Common Weakness Enumeration
            if 'cwe' == source.data:
                if 'nist' == source.source:
                    self.nist_cwe(content)
                    self.source_loaded(source.id)
                    continue

            # Common User load
            if 'users' == source.data:
                self.users_load(dct)
                self.source_loaded(source.id)
                continue

            # data source not handled
            logger.error("Unknown data source type for (%s,%s,%s) " % (source.data,source.source,source.name))
            _log("Unknown data source type for %s,%s,%s) " % (source.data,source.source,source.name))

        os.system('setterm -cursor on')

    def handle(self, *args, **options):

        # testing shortcuts
        if 'yes' == SrtSetting.objects.get(name='SRTDBG_MINIMAL_DB').value:
            print("TEST: MINIMAL DATABASE LOADING")
            Command.debug_cve_count = 10   # 0 for any
            Command.debug_include_id_prefix = 'XXX'   # always include CVEs with this prefix
            Command.status_sustaining_limit = 10
            Command.debug_defect_limit = 10
            Command.cpe_limit = 10

        self.update()