Mixin for named URL WizardViews with one form on the frontpage

from django.core.urlresolvers import reverse
from django.shortcuts import render, redirect
from django.contrib.formtools.wizard.views import (NamedUrlSessionWizardView,
                                                   NamedUrlCookieWizardView)


class RootStepWizard(object):
    """
    A wizard mixin for use cases with a wizard step on the frontpage
    of your site -- with a request path of ``'/'``.

    Just define the name of the step (e.g. ``root_step = 'landing'``)
    and it does the setup and redirection automatically.

    Example::

        # views.py
        class LandingWizardView(RootStepNamedUrlSessionWizardView):
            root_step = 'landing_page'

        # urls.py
        landing_forms = (
            ('landing_page', LandingPageForm),
            ('welcome', WelcomeForm),
            ('account', AccountForm),
        )

        landing_wizard = LandingWizardView.as_view(landing_forms,
                                                   url_name='landing_step')

    """
    root_step = None

    def get(self, *args, **kwargs):
        """
        Redirects to the root path if needed and sets the step
        variable if on the root path.
        """
        if self.request.path == '/':
            kwargs['step'] = self.root_step
        elif self.request.path == reverse(self.url_name,
                                          kwargs={'step': self.root_step}):
            return redirect('/')
        return super(RootStepWizard, self).get(*args, **kwargs)

    def get_step_url(self, step):
        """
        Returns a root path for the configured step.
        """
        if step == self.root_step:
            return '/'
        return super(RootStepWizard, self).get_step_url(step)


class RootStepNamedUrlSessionWizardView(RootStepWizard,
                                        NamedUrlSessionWizardView):
    pass


class RootStepNamedUrlCookieWizardView(RootStepWizard,
                                       NamedUrlCookieWizardView):
    pass