OpenSlides/openslides/utils/views.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
    openslides.utils.views
    ~~~~~~~~~~~~~~~~~~~~~~

    Views for OpenSlides.

    :copyright: 2011, 2012 by OpenSlides team, see AUTHORS.
    :license: GNU GPL, see LICENSE for more details.
"""

import json

try:
    from cStringIO import StringIO
except ImportError:
    # Is this exception realy necessary?
    from StringIO import StringIO

from reportlab.platypus import SimpleDocTemplate, Spacer
from reportlab.lib.units import cm

from django.contrib import messages
from django.contrib.auth.decorators import login_required
from django.core.context_processors import csrf
from django.core.exceptions import ImproperlyConfigured
from django.core.urlresolvers import reverse
from django.conf import settings
from django.dispatch import receiver
from django.http import HttpResponseServerError, HttpResponse, HttpResponseRedirect
from django.utils.decorators import method_decorator
from django.utils.translation import ugettext as _, ugettext_lazy
from django.utils.importlib import import_module
from django.template import RequestContext
from django.template.loader import render_to_string
from django.views.generic import (
    TemplateView as _TemplateView,
    RedirectView as _RedirectView,
    UpdateView as _UpdateView,
    CreateView as _CreateView,
    View as _View,
    FormView as _FormView,
    ListView as _ListView,
    DetailView as _DetailView,
)
from django.views.generic.detail import SingleObjectMixin
from django.views.generic.list import TemplateResponseMixin

from openslides.utils.utils import render_to_forbidden, html_strong
from openslides.utils.signals import template_manipulation
from openslides.utils.pdf import firstPage, laterPages


NO_PERMISSION_REQUIRED = 'No permission required'

View = _View


class SetCookieMixin(object):
    def render_to_response(self, context, **response_kwargs):
        response = TemplateResponseMixin.render_to_response(
            self, context, **response_kwargs)
        if 'cookie' in context:
            response.set_cookie(context['cookie'][0], context['cookie'][1])
        return response


class LoginMixin(object):
    @method_decorator(login_required)
    def dispatch(self, request, *args, **kwargs):
        return super(LoginMixin, self).dispatch(request, *args, **kwargs)


class PermissionMixin(object):
    permission_required = NO_PERMISSION_REQUIRED

    def has_permission(self, request, *args, **kwargs):
        if self.permission_required == NO_PERMISSION_REQUIRED:
            return True
        else:
            return request.user.has_perm(self.permission_required)

    def dispatch(self, request, *args, **kwargs):
        if not self.has_permission(request, *args, **kwargs):
            if not request.user.is_authenticated():
                path = request.get_full_path()
                return HttpResponseRedirect(
                    "%s?next=%s" % (settings.LOGIN_URL, path))
            else:
                return render_to_forbidden(request)
        return _View.dispatch(self, request, *args, **kwargs)


class AjaxMixin(object):
    def get_ajax_context(self, **kwargs):
        return {}

    def ajax_get(self, request, *args, **kwargs):
        return HttpResponse(json.dumps(self.get_ajax_context(**kwargs)))


class ExtraContextMixin(object):
    def get_context_data(self, **kwargs):
        context = super(ExtraContextMixin, self).get_context_data(**kwargs)
        template_manipulation.send(
            sender=self.__class__, request=self.request, context=context)
        return context


class UrlMixin(object):
    apply_url_name = None
    success_url_name = None
    success_url = None
    apply_url = None

    def get_apply_url(self):
        if self.apply_url_name:
            return reverse(self.apply_url_name)
        elif self.apply_url:
            return self.apply_url
        else:
            try:
                return self.object.get_absolute_url('edit')
            except AttributeError:
                raise ImproperlyConfigured(
                    "No URL to redirect to. Provide an apply_url_name.")

    def get_success_url(self):
        if 'apply' in self.request.POST:
            return self.get_apply_url()

        if self.success_url_name:
            return reverse(self.success_url_name)
        elif self.success_url:
            return self.success_url
        else:
            try:
                url = self.object.get_absolute_url()
            except AttributeError:
                raise ImproperlyConfigured(
                    "No URL to redirect to.  Either provide a url or define"
                    " a get_absolute_url method on the Model.")
        return url


class QuestionMixin(object):
    question = ugettext_lazy('Are you sure?')
    success_message = ugettext_lazy('Thank you for your answer')
    answer_options = [('yes', ugettext_lazy("Yes")), ('no', ugettext_lazy("No"))]

    def pre_redirect(self, request, *args, **kwargs):
        # Prints the question in a GET request
        self.confirm_form()

    def get_question(self):
        return unicode(self.question)

    def get_answer_options(self):
        return self.answer_options

    def get_answer_url(self):
        try:
            return self.answer_url
        except AttributeError:
            return self.request.path

    def confirm_form(self):
        option_fields = "\n".join([
            '<input type="submit" name="%s" value="%s">' % (option[0], unicode(option[1]))
            for option in self.get_answer_options()])
        messages.warning(
            self.request,
            """
            %(message)s
            <form action="%(url)s" method="post">
                <input type="hidden" value="%(csrf)s" name="csrfmiddlewaretoken">
                %(option_fields)s
            </form>
            """ % {'message': self.get_question(),
                   'url': self.get_answer_url(),
                   'csrf': csrf(self.request)['csrf_token'],
                   'option_fields': option_fields})

    def pre_post_redirect(self, request, *args, **kwargs):
        # Reacts on the response of the user in a POST-request.
        # TODO: call the methodes for all possible answers.
        if self.get_answer() == 'yes':
            self.case_yes()
            messages.success(request, self.get_success_message())

    def get_answer(self):
        for option in self.get_answer_options():
            if option[0] in self.request.POST:
                return option[0]
        return None

    def case_yes(self):
        # TODO: raise a warning
        pass

    def get_success_message(self):
        return self.success_message


class TemplateView(PermissionMixin, ExtraContextMixin, _TemplateView):
    pass


class ListView(PermissionMixin, SetCookieMixin, ExtraContextMixin, _ListView):
    pass

class AjaxView(PermissionMixin, AjaxMixin, View):
    def get(self, request, *args, **kwargs):
        return self.ajax_get(request, *args, **kwargs)


class RedirectView(PermissionMixin, AjaxMixin, _RedirectView):
    permanent = False
    allow_ajax = False

    def pre_redirect(self, request, *args, **kwargs):
        pass

    def pre_post_redirect(self, request, *args, **kwargs):
        pass

    def get(self, request, *args, **kwargs):
        if request.method == 'GET':
            self.pre_redirect(request, *args, **kwargs)
        elif request.method == 'POST':
            self.pre_post_redirect(request, *args, **kwargs)

        if self.request.is_ajax() and self.allow_ajax:
            return self.ajax_get(request, *args, **kwargs)
        return super(RedirectView, self).get(request, *args, **kwargs)

    def get_redirect_url(self, **kwargs):
        return reverse(super(RedirectView, self).get_redirect_url(**kwargs))


class FormView(PermissionMixin, ExtraContextMixin, UrlMixin, _FormView):
    def form_invalid(self, form):
        messages.error(self.request, _('Please check the form for errors.'))
        return super(FormView, self).form_invalid(form)


class ModelFormMixin(object):
    def form_valid(self, form):
        self.object = form.save(commit=False)
        self.manipulate_object(form)
        self.object.save()
        self.post_save(form)
        return HttpResponseRedirect(self.get_success_url())

    def manipulate_object(self, form):
        pass

    def post_save(self, form):
        form.save_m2m()


class UpdateView(PermissionMixin, UrlMixin, ExtraContextMixin,
        ModelFormMixin, _UpdateView):
    def form_invalid(self, form):
        messages.error(self.request, _('Please check the form for errors.'))
        return super(UpdateView, self).form_invalid(form)

    def get_success_message(self):
        return _('%s was successfully modified.') % html_strong(self.object)


class CreateView(PermissionMixin, UrlMixin, ExtraContextMixin,
        ModelFormMixin, _CreateView):
    def form_invalid(self, form):
        messages.error(self.request, _('Please check the form for errors.'))
        return super(CreateView, self).form_invalid(form)

    def get_success_message(self):
        return _('%s was successfully created.') % html_strong(self.object)


class DeleteView(SingleObjectMixin, QuestionMixin, RedirectView):
    def get(self, request, *args, **kwargs):
        self.object = self.get_object()
        return super(DeleteView, self).get(request, *args, **kwargs)

    def get_question(self):
        return _('Do you really want to delete %s?') % html_strong(self.object)

    def case_yes(self):
        self.object.delete()

    def get_success_message(self):
        return _('%s was successfully deleted.') % html_strong(self.object)


class DetailView(PermissionMixin, ExtraContextMixin, _DetailView):
    def get(self, request, *args, **kwargs):
        self.object = self.get_object()
        return super(DetailView, self).get(request, *args, **kwargs)


class PDFView(PermissionMixin, View):
    filename = _('undefined-filename')
    top_space = 3
    document_title = None

    def get_top_space(self):
        return self.top_space

    def get_document_title(self):
        if self.document_title:
            return unicode(self.document_title)
        else:
            return ''

    def get_filename(self):
        return self.filename

    def get_template(self, buffer):
        return SimpleDocTemplate(buffer)

    def build_document(self, pdf_document, story):
        pdf_document.build(
            story, onFirstPage=firstPage, onLaterPages=laterPages)

    def render_to_response(self, filename):
        response = HttpResponse(mimetype='application/pdf')
        filename = u'filename=%s.pdf;' % self.get_filename()
        response['Content-Disposition'] = filename.encode('utf-8')

        buffer = StringIO()
        pdf_document = self.get_template(buffer)
        pdf_document.title = self.get_document_title()
        story = [Spacer(1, self.get_top_space() * cm)]

        self.append_to_pdf(story)

        self.build_document(pdf_document, story)

        pdf = buffer.getvalue()
        buffer.close()
        response.write(pdf)
        return response

    def get(self, request, *args, **kwargs):
        return self.render_to_response(self.get_filename())


def server_error(request, template_name='500.html'):
    """
    500 error handler.

    Templates: `500.html`
    """
    return HttpResponseServerError(render_to_string(
        template_name, context_instance=RequestContext(request)))


@receiver(template_manipulation, dispatch_uid="send_register_tab")
def send_register_tab(sender, request, context, **kwargs):
    tabs = []
    for app in settings.INSTALLED_APPS:
        try:
            mod = import_module(app + '.views')
            tabs.append(mod.register_tab(request))
        except (ImportError, AttributeError):
            continue

    context.update({
        'tabs': tabs,
    })