Misago/misago/threads/views/goto.py

from math import ceil

from django.core.exceptions import PermissionDenied
from django.shortcuts import get_object_or_404, redirect
from django.utils.translation import ugettext as _
from django.views.generic import View

from misago.conf import settings

from ..permissions.threads import exclude_invisible_posts
from ..viewmodels.thread import ForumThread


class GotoView(View):
    thread = None
    read_aware=False

    def get(self, request, pk, slug, **kwargs):
        thread = self.get_thread(request, pk, slug).thread
        self.test_permissions(request, thread)

        posts_queryset = exclude_invisible_posts(request.user, thread.category, thread.post_set)

        target_post = self.get_target_post(thread, posts_queryset.order_by('id'), **kwargs)
        target_page = self.compute_post_page(target_post, posts_queryset)

        return self.get_redirect(thread, target_post, target_page)

    def get_thread(self, request, pk, slug):
        return self.thread(request, pk, slug, read_aware=self.read_aware)

    def test_permissions(self, request, thread):
        pass

    def get_target_post(self, thread, posts_queryset):
        raise NotImplementedError("goto views should define their own get_target_post method")

    def compute_post_page(self, target_post, posts_queryset):
        thread_len = posts_queryset.count()
        if thread_len <= settings.MISAGO_POSTS_PER_PAGE + settings.MISAGO_POSTS_TAIL:
            return 1 # no chance for post to be on other page than only page

        # compute total count of thread pages
        thread_pages = thread_len // settings.MISAGO_POSTS_PER_PAGE
        thread_tail = thread_len - thread_pages * settings.MISAGO_POSTS_PER_PAGE
        if thread_tail > settings.MISAGO_POSTS_TAIL:
            thread_pages += 1

        # resolve post's page
        post_offset = posts_queryset.filter(pk__lte=target_post.pk).count()
        post_page = int(ceil(float(post_offset) / settings.MISAGO_POSTS_PER_PAGE))
        if post_page > thread_pages:
            post_page = thread_pages

        return post_page

    def get_redirect(self, thread, target_post, target_page):
        thread_url = thread.thread_type.get_thread_absolute_url(thread, target_page)
        return redirect('%s#post-%s' % (thread_url, target_post.pk))


class ThreadGotoPostView(GotoView):
    thread = ForumThread

    def get_target_post(self, thread, posts_queryset, **kwargs):
        return get_object_or_404(posts_queryset, pk=kwargs['post'])


class ThreadGotoLastView(GotoView):
    thread = ForumThread

    def get_target_post(self, thread, posts_queryset, **kwargs):
        return posts_queryset.order_by('-id')[:1][0]


class ThreadGotoNewView(GotoView):
    thread = ForumThread
    read_aware = True

    def get_target_post(self, thread, posts_queryset, **kwargs):
        return posts_queryset.order_by('-id')[:1][0]

    def get_target_post(self, thread, posts_queryset, **kwargs):
        try:
            return posts_queryset.filter(posted_on__gt=thread.last_read_on).order_by('id')[:1][0]
        except IndexError:
            return posts_queryset.order_by('-id')[:1][0]


class ThreadGotoUnapprovedView(GotoView):
    thread = ForumThread

    def test_permissions(self, request, thread):
        if not thread.acl['can_approve']:
            raise PermissionDenied(
                _("You need permission to approve content to be able to go to first unapproved post."))

    def get_target_post(self, thread, posts_queryset, **kwargs):
        try:
            return posts_queryset.filter(is_unapproved=True).order_by('id')[:1][0]
        except IndexError:
            return posts_queryset.order_by('-id')[:1][0]