# Import Django's template library.
from django import template

# Import for determining the active URL.
from django.core import urlresolvers

# Get an instance of Django's template library.
register = template.Library()

@register.inclusion_tag('conntrackt/link.html')
def html_link(view, title, identifier = None, html_class = None):
    """
    A small wrapper for showing HTML links.

    Arguments:

    view - View name for which the URL should be shown.

    title - Title which will be shown as the link.

    identifier - Identifier which is passed to the view for processing.

    html_class - Class which should be assigned to the link.
    """

    return {'view': view, 'identifier': identifier, 'title': title, 'html_class': html_class}

@register.simple_tag(takes_context = True)
def active_link(context, url_name, return_value='active', **kwargs):
    """
    This template tag can be used to check if the provided URL matches against
    the path from the request or not.

    Arguments:

      context - Context of the current view being called.

      url_name - Name of the URL that's being checked against current path from
      request.
    """

    matches = current_url_equals(context, url_name, **kwargs)

    return return_value if matches else ''
 
 
def current_url_equals(context, url_name, **kwargs):
    """
    Helper function for checking if the specified URL corresponds to the current
    request path in the context.

    Arguments:

      - context - Context of the view being rendered.

      - url_name - Name of the URL against which the context request path is
      being checked.
    """

    # Assume that we have not been able to resolve the request path to an URL.
    resolved = False
    try:
        # Use the request path, and resolve it to a URL name.
        resolved = urlresolvers.resolve(context.get('request').path)
    except urlresolvers.Resolver404:
        # This means we haven't been able to resolve the path from request.
        pass

    # If the request was resolved and URL names match, verify that the kwargs
    # match as well.
    matches = resolved and resolved.url_name == url_name
    if matches and kwargs:
        for key in kwargs:
            kwarg = kwargs.get(key)
            resolved_kwarg = resolved.kwargs.get(key)
            if not resolved_kwarg or kwarg != resolved_kwarg:
                return False

    return matches