"""used to shuffle a list in a template
"""
import random

from django import template

class ShuffleNode(template.Node):
    """node for shuffling iterable object in place in template"""

    def __init__(self, iterable_var):
        self.iterable_var = template.Variable(iterable_var)

    def render(self, context):

        # resolve the article object from the context
        iterable_var = self.iterable_var.resolve(context)

        # shuffle it
        iterable_var = [x for x in iterable_var]
        random.shuffle(iterable_var)

        # save result in context and return
        context[self.iterable_var] = iterable_var
        return ''

register = template.Library()
@register.tag
def shuffle(parser, token):
    """shuffle a list within a template

    {% shuffle iterable_object %}
    """

    contents = token.split_contents()
    if len(contents) == 2:
        tag_name, iterable_var = contents
    else:
        msg = "%r tag requires 1 argument" % token.contents.split()[0]
        raise template.TemplateSyntaxError, msg

    return ShuffleNode(iterable_var)