#!/usr/bin/env python
'''
esm2markdown - McAfee ESM correlation rule XML export to markdown converter
Copyright (C) 2018 Michael Clemens

This program 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; either version 3 of the License, or
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 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
'''

import sys
from lxml import etree

style="**"
level1="* "
level2="  - "
level3="    - "

def line(level,key,value):

	lvl = ""	
	output = ""
	valout = ""
	if level == 1:
		lvl = level1	
	elif level == 2:
		lvl = level2	
	elif level == 3:
		lvl = level3	
	else:
		lvl = ""
	if value:
		valout = " " + value
	output = lvl + style + key + style + valout + "\n"
	return output

def main(xmlfile,outfile):

	file = open(outfile,"w")
	root = etree.parse(xmlfile)

	for rule in root.getiterator('rule'):
		# Get CDATA
		text = rule.findtext('text')
		cdata = etree.fromstring(text)
		# Print rule name as header
		message = "# " + rule.findtext('message')
		file.write(message + "\n")
		# Print rule description
		description = rule.findtext('description')
		file.write("## Description\n")
		file.write(description +"\n")
		# Print general rule information (ID, Normalization, Severity, all Tags, Group By)
		file.write("## General Information\n")
		file.write(line(1,"Rule ID:",rule.findtext('id')))
		file.write(line(1,"Normalization ID:",rule.findtext('normid')))
		file.write(line(1,"Severity:",rule.findtext('severity')))
		for tags in rule.getiterator('tag'):
			file.write(line(1,"Tag:",tags.text))
		for rs in cdata.getiterator('ruleset'):
			file.write(line(1,"Group By:",rs.get('correlationField')))
		file.write("## Correlation Details\n")
		# Print rule parameters
		file.write("### Parameters\n")
		for param in cdata.getiterator('param'):
			if (param.get('name')):
				file.write(line(1,param.get('name'),""))
				file.write(line(2,"Description:",param.get('description')))
				file.write(line(2,"Default Value:",param.get('defaultvalue')))
		# Print trigger information (Sequence, Timeout, Time Unit, Threshold)
		file.write("### Trigger\n")
		for trigger in cdata.getiterator('trigger'):
			if (trigger.get('name')):
				file.write(line(1,trigger.get('name'),""))
				file.write(line(2,"Timeout:",trigger.get('timeout') + " " + trigger.get('timeUnit')))
				file.write(line(2,"Threshold:",trigger.get('threshold')))
				if (trigger.get('ordered')):
					file.write(line(2,"Sequence:",trigger.get('ordered')))
		file.write("### Rules\n")
		# Parse CDATA element and print correlation rule match blocks
		for r in cdata.getiterator('rule'):
			o = ""
			v = ""
			t = ""
			file.write("#### " + r.get('name') + "\n")
			for e in r.iter():
				if str(e.tag) == 'activate':
					if (e.get('type')):
						file.write(line(1,"Activate:",e.get('type')))
				if str(e.tag) == 'action':
					file.write(line(1,"Action",""))
					if (e.get('type')):
						file.write(line(2,"Type:",e.get('type')))
					if (e.get('trigger')):
						file.write(line(2,"Trigger:",e.get('trigger')))
				if str(e.tag) == 'match':
					file.write(line(1,"Match",""))
					if (e.get('count')):
						file.write(line(2,"Count:",e.get('count')))
					if (e.get('matchType')):
						file.write(line(2,"Match Type:",e.get('matchType')))
				if str(e.tag) == 'matchFilter':
					file.write(line(1,"Match Filter",""))
					if (e.get('type')):
						file.write(line(2,"Logical Element Type:",e.get('type')))
				if str(e.tag) == 'singleFilterComponent':
					if (e.get('type')):
						t = e.get('type')
				if str(e.tag) == 'filterData':
					if (e.get('name') == "operator"):
						o = e.get('value')
					if (e.get('name') == "value"):
						v = e.get('value')
				if o and v and t:
					file.write(line(2,"Filter Component",""))
					file.write(line(3,"Condition:","'" + t + "' " + o + " '" + v + "'"))
		file.write("******\n")
	file.close()

if __name__=="__main__":
	if len(sys.argv) != 3:
		print('Invalid Numbers of Arguments. Script will be terminated.')
		print('Usage: python esm2markdown <rule xml file> <markdown output file>')
		print('Example: python esm2markdown RuleExport_2018_03_01_12_36_37.xml documentation.mk')
	else:
		main(sys.argv[1],sys.argv[2]);