from django import template
from django.template import resolve_variable
from django.contrib.auth.models import Group

register = template.Library()
#
#  TODO: There must be a shorter way to do this...
#


@register.tag()
def ifusergroup(parser, token):
	""" Check to see if the currently logged in user belongs to a specific
	group. Requires the Django authentication contrib app and middleware.

	Usage: {% ifusergroup Admins %} ... {% endifusergroup %}
	"""
	try:
		tag, group = token.split_contents()
	except ValueError:
		raise template.TemplateSyntaxError("Tag 'ifusergroup' requires 1 argument.")
	nodelist = parser.parse(('endifusergroup',))
	parser.delete_first_token()
	return GroupCheckNode(group, nodelist)


@register.tag()
def ifuser(parser, token):
	""" Check to see if user is currently logged in.
	Usage: {% ifuser %} ... {% endifusergroup %}
	"""
	nodelist = parser.parse(('endifuser',))
	parser.delete_first_token()
	return UserCheckNode(nodelist)

@register.tag()
def ifnotuser(parser, token):
	""" Check to see if user is currently logged in.
	Usage: {% ifuser %} ... {% endifusergroup %}
	"""
	nodelist = parser.parse(('endifnotuser',))
	parser.delete_first_token()
	return NotUserCheckNode(nodelist)


class NotUserCheckNode(template.Node):
	def __init__(self, nodelist):
		self.nodelist = nodelist
	
	def render(self, context):
		user = resolve_variable('user', context)
		if user.is_authenticated():
			return ''
		return self.nodelist.render(context)


class UserCheckNode(template.Node):
	def __init__(self, nodelist):
		self.nodelist = nodelist
	
	def render(self, context):
		user = resolve_variable('user', context)
		if not user.is_authenticated():
			return ''
		return self.nodelist.render(context)


class GroupCheckNode(template.Node):
	def __init__(self, group, nodelist):
		self.group = group
		self.nodelist = nodelist
	def render(self, context):
		user = resolve_variable('user', context)
		if not user.is_authenticated():
			return ''
		try:
			group = Group.objects.get(name=self.group)
		except Group.DoesNotExist:
			return ''
		if group in user.groups.all():
			return self.nodelist.render(context)
		return ''