#
# Converted from homework solution to use modules
#

def find_zip(zipcode):
	"""Return town and population for "zipcode" by querying uszip.com"""
	import urllib
	conn = urllib.urlopen("http://www.uszip.com/zip/%s" % zipcode)
	town = "unknown"
	population = "unknown"
	for line in conn:
		if "is the zip code of " in line:
			town = _get_town(line)
		elif "Population:" in line:
			population = _get_population(line)
	conn.close()
	return town, population

def _get_town(line):
	"""Extract town name if present"""
	line = _strip_tags(line)
	key_string = "is the zip code of "
	try:
		n = line.index(key_string)
	except ValueError:
		return "unknown"
	else:
		return line[n + len(key_string):]

def _get_population(line):
	"""Extract population if present"""
	line = _strip_tags(line)
	key_string = "Population:"
	try:
		n = line.index(key_string)
	except ValueError:
		return "unknown"
	else:
		start = n + len(key_string)
		stop = start + 1
		while stop < len(line):
			if line[stop] not in "0123456789,":
				break
			stop += 1
		return line[start:stop]

def _strip_tags(line):
	"""Remove HTML tags from string, leaving only "real" text"""
	keep = []
	in_tag = False
	for c in line:
		if in_tag:
			if c == '>':
				in_tag = False
		else:
			if c == '<':
				in_tag = True
			else:
				keep.append(c)
	return ''.join(keep).strip()