#!/usr/bin/env python
import subprocess as sp
import re, sys
from getopt import *

# List of all the HTML 4 elements that you can validly leave unclosed if
# you want.
elements = ("colgroup", "dd", "dt", "li",
		"option", "p", "td", "tfoot", "th", "thead", "tr")

def cleanOpen(mo):
	return '<%s>' % mo.group(1).lower().strip()

def cleanClose(mo):
	return '</%s>' % mo.group(1).lower().strip()

def clean(data):
	"""Get rid of attributes and whitespace in opening and closing tags, and
	make them all lowercase."""
	pat = re.compile(r'<\s*([a-z]+).*?>', re.I | re.M | re.S)
	data = pat.sub(cleanOpen, data)

	pat = re.compile(r'</\s*([a-z]+)\s*>', re.I | re.M | re.S)
	data = pat.sub(cleanClose, data)
	return data

def checkData(fname, data, out=sys.stdout):
	global elements

	for el in elements:
		cmd = 'sgrep -o "%%i " \'"<%s>" not in inner("<%s>" .. "</%s>")\'' \
				% (el, el, el)
		p = sp.Popen(cmd, shell=True, stdin=sp.PIPE, stdout=sp.PIPE)
		result = p.communicate(data)[0]
		p.wait()
		if result:
			for pos in result.split():
				# Things might have moved a bit thanks to our "cleaning" of the
				# input data. sgrep is giving positions in the cleaned version,
				# which is wrong. If you get round to fixing it, it's probably
				# more helpful to convert everything to line numbers anyway.
				print "%s: Unclosed <%s> near position %s" % (fname, el, pos)

def checkUnclosed(fname, out=sys.stdout):
	f = open(fname)
	data = f.read()
	f.close()
	checkData(fname, clean(data))

def help():
	print """checkUnclosed.py [-h|-v] [filename ...]

Prints a warning message locating these validly unclosed HTML 4 elements in
files:

""", ", ".join(elements), """

Reads stdin if no files. Requires sgrep is installed and in your path. -h this,
-v version.
"""

def main():
	opts, args = getopt(sys.argv[1:], "hv")
	opts = [o[0] for o in opts]
	if "-h" in opts: return help()
	if "-v" in opts:
		print "Version 0.2"
		return

	if len(args) == 0:
		data = clean(sys.stdin.read())
		checkData("stdin", data)
		return

	for arg in args:
		checkUnclosed(arg)

if __name__ == "__main__":
	main()