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
from cStringIO 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 super(PermissionMixin, self).dispatch(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)
        context.setdefault('extra_javascript', [])
        template_manipulation.send(
            sender=self.__class__, request=self.request, context=context)
        return context


class UrlMixin(object):
    """
    Mixin to provide the use of url names in views with success url and
    apply url.

    The initial value of url_name_args is None, but the default given by
    the used get_url_name_args method is [], because in the future, the
    method might return another default value. Compare this with the QuestionMixin.
    """
    apply_url_name = None
    success_url_name = None
    url_name_args = None
    success_url = None
    apply_url = None

    def get_apply_url(self):
        if self.apply_url_name:
            return reverse(self.apply_url_name, args=self.get_url_name_args())
        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, args=self.get_url_name_args())
        elif self.success_url:
            return self.success_url
        else:
            try:
                return self.object.get_absolute_url()
            except AttributeError:
                raise ImproperlyConfigured(
                    "No URL to redirect to. Either provide an URL or define "
                    "a get_absolute_url method of the model.")

    def get_url_name_args(self):
        """
        Returns the arguments for the url name. Default is an empty list.
        """
        if self.url_name_args is not None:
            return self.url_name_args
        return []


class QuestionMixin(object):
    """
    Mixin for questions to the requesting user.

    The initial value of url_name_args is None, but the default given by
    the used get_url_name_args method is [self.object.pk] if it exist, else
    an empty list. Set url_name_args to an empty list, if you use an url
    name which does not need any arguments.
    """
    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"))]
    question_url_name = None
    success_url_name = None
    url_name_args = None

    def get_redirect_url(self, **kwargs):
        # TODO: raise error when question_url_name/success_url_name is not present
        if self.request.method == 'GET':
            return reverse(self.question_url_name, args=self.get_question_url_name_args())
        else:
            return reverse(self.success_url_name, args=self.get_success_url_name_args())

    def get_question_url_name_args(self):
        return self.get_url_name_args()

    def get_success_url_name_args(self):
        return self.get_url_name_args()

    def get_url_name_args(self):
        """
        Returns the arguments for the url name. Default is an empty list
        or [self.object.pk] if this exist.
        """
        if self.url_name_args is not None:
            return self.url_name_args
        try:
            return [self.object.pk]
        except AttributeError:
            return []

    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([
            '<button type="submit" class="btn btn-mini" name="%s">%s</button>' % (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):
    """
    View to redirect to another url.

    The initial value of url_name_args is None, but the default given by
    the used get_url_name_args method is [self.object.pk] if it exist, else
    an empty list. Set url_name_args to an empty list, if you use an url
    name which does not need any arguments.
    """
    permanent = False
    allow_ajax = False
    url_name = None
    url_name_args = None

    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):
        if self.url_name is not None:
            return reverse(self.url_name, args=self.get_url_name_args())
        else:
            return super(RedirectView, self).get_redirect_url(**kwargs)

    def get_url_name_args(self):
        """
        Returns the arguments for the url name. Default is an empty list
        or [self.object.pk] if this exist.
        """
        if self.url_name_args is not None:
            return self.url_name_args
        try:
            return [self.object.pk]
        except AttributeError:
            return []


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):
    success_message = None

    def form_invalid(self, form):
        messages.error(self.request, _('Please check the form for errors.'))
        return super(UpdateView, self).form_invalid(form)

    def form_valid(self, form):
        value = super(UpdateView, self).form_valid(form)
        messages.success(self.request, self.get_success_message())
        return value

    def get_success_message(self):
        if self.success_message is None:
            message = _('%s was successfully modified.') % html_strong(self.object)
        else:
            message = self.success_message
        return message


class CreateView(PermissionMixin, UrlMixin, ExtraContextMixin,
                 ModelFormMixin, _CreateView):
    success_message = None

    def form_invalid(self, form):
        messages.error(self.request, _('Please check the form for errors.'))
        return super(CreateView, self).form_invalid(form)

    def form_valid(self, form):
        value = super(CreateView, self).form_valid(form)
        messages.success(self.request, self.get_success_message())
        return value

    def get_success_message(self):
        if self.success_message is None:
            message = _('%s was successfully created.') % html_strong(self.object)
        else:
            message = self.success_message
        return message


class DeleteView(SingleObjectMixin, QuestionMixin, RedirectView):
    question_url_name = None
    success_url_name = None

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

    def get_redirect_url(self, **kwargs):
        if self.question_url_name is None and (self.request.method == 'GET' or
                                               self.get_answer() == 'no'):
            return self.object.get_absolute_url()
        else:
            return super(DeleteView, self).get_redirect_url(**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)

    def get_url_name_args(self):
        return []


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):
    """
    Receiver to the template_manipulation signal. Collects from the file
    views.py in all apps the tabs setup by the function register_tab.
    Inserts the tab objects and also the extra_stylefiles to the context.
    """
    tabs = []
    if 'extra_stylefiles' in context:
        extra_stylefiles = context['extra_stylefiles']
    else:
        extra_stylefiles = []
    # TODO: Do not go over the filesystem by any request
    for app in settings.INSTALLED_APPS:
        try:
            mod = import_module(app + '.views')
            tab = mod.register_tab(request)
            tabs.append(tab)
            if tab.stylefile:
                extra_stylefiles.append(tab.stylefile)
        except (ImportError, AttributeError):
            continue
    context.update({
        'tabs': tabs,
        'extra_stylefiles': extra_stylefiles})