from __future__ import unicode_literals

from django.conf import settings
from django.core.exceptions import PermissionDenied
from django.core.urlresolvers import reverse
from django.http import HttpResponseRedirect
from django.shortcuts import get_object_or_404

from acls.models import AccessControlList
from permissions import Permission


class ExtraContextMixin(object):
    extra_context = {}

    def get_extra_context(self):
        return self.extra_context

    def get_context_data(self, **kwargs):
        context = super(ExtraContextMixin, self).get_context_data(**kwargs)
        context.update(self.get_extra_context())
        return context


class MultipleInstanceActionMixin(object):
    model = None

    def post(self, request, *args, **kwargs):
        for pk in request.GET.get('id_list', '').split(','):
            document = get_object_or_404(self.model, pk=pk)
            try:
                self.object_action(request=request, instance=document)
            except PermissionDenied:
                pass

        return HttpResponseRedirect(self.get_success_url())


class ObjectListPermissionFilterMixin(object):
    object_permission = None

    def get_queryset(self):
        queryset = super(ObjectListPermissionFilterMixin, self).get_queryset()

        if self.object_permission:
            try:
                # Check to see if the user has the permissions globally
                Permission.check_permissions(
                    self.request.user, (self.object_permission,)
                )
            except PermissionDenied:
                # No global permission, filter ther queryset per object +
                # permission
                return AccessControlList.objects.filter_by_access(
                    self.object_permission, self.request.user, queryset
                )
            else:
                # Has the permission globally, return all results
                return queryset
        else:
            return queryset


class ObjectPermissionCheckMixin(object):
    object_permission = None

    def get_permission_object(self):
        return self.get_object()

    def dispatch(self, request, *args, **kwargs):

        if self.object_permission:
            try:
                Permission.check_permissions(
                    request.user, (self.object_permission,)
                )
            except PermissionDenied:
                AccessControlList.objects.check_access(
                    self.object_permission, request.user,
                    self.get_permission_object()
                )

        return super(
            ObjectPermissionCheckMixin, self
        ).dispatch(request, *args, **kwargs)


class RedirectionMixin(object):
    post_action_redirect = None
    action_cancel_redirect = None

    def get_post_action_redirect(self):
        return self.post_action_redirect

    def get_action_cancel_redirect(self):
        return self.action_cancel_redirect

    def dispatch(self, request, *args, **kwargs):
        post_action_redirect = self.get_post_action_redirect()
        action_cancel_redirect = self.get_action_cancel_redirect()

        self.next_url = self.request.POST.get(
            'next', self.request.GET.get(
                'next', post_action_redirect if post_action_redirect else self.request.META.get(
                    'HTTP_REFERER', reverse(settings.LOGIN_REDIRECT_URL)
                )
            )
        )
        self.previous_url = self.request.POST.get(
            'previous', self.request.GET.get(
                'previous', action_cancel_redirect if action_cancel_redirect else self.request.META.get(
                    'HTTP_REFERER', reverse(settings.LOGIN_REDIRECT_URL)
                )
            )
        )

        return super(
            RedirectionMixin, self
        ).dispatch(request, *args, **kwargs)

    def get_context_data(self, **kwargs):
        context = super(RedirectionMixin, self).get_context_data(**kwargs)
        context.update(
            {
                'next': self.next_url,
                'previous': self.previous_url
            }
        )

        return context

    def get_success_url(self):
        return self.next_url or self.previous_url


class ViewPermissionCheckMixin(object):
    view_permission = None

    def dispatch(self, request, *args, **kwargs):
        if self.view_permission:
            Permission.check_permissions(
                self.request.user, (self.view_permission,)
            )

        return super(
            ViewPermissionCheckMixin, self
        ).dispatch(request, *args, **kwargs)