from django.contrib import messages
from django.core.paginator import Paginator, EmptyPage
from django.shortcuts import redirect
from django.views.generic import View
from misago.core.exceptions import ExplicitFirstPage
from misago.admin import site
from misago.admin.views import render


class AdminBaseMixin(object):
    """
    Admin mixin abstraciton used for configuring admin CRUD views.

    Takes following attributes:

    Model = Model instance
    message_404 = string used in "requested item not found" messages
    root_link = name of link leading to root action (eg. list of all items
    template_dir = directory with templates
    """
    Model = None
    message_404 = None
    root_link = None
    template_dir = None

    def get_model(self):
        return self.Model


class AdminView(View):
    def final_template(self):
        return '%s/%s' % (self.template_dir, self.template)

    def get_target(self, target):
        Model = self.get_model()
        return Model.objects.get(id=target)

    def _get_target(self, request, kwargs):
        """
        get_target is called by view to fetch item from DB
        """
        Model = self.get_model()

        try:
            return self.get_target(target)
        except Model.DoesNotExist:
            messages.error(request, self.message_404)
            return redirect(self.root_link)

    def render(self, request, context=None):
        context = context or {}

        context['root_link'] = self.root_link

        return render(request, self.final_template(), context)


class ItemsList(AdminView):
    template = 'list.html'

    items_per_page = 0

    def get_queryset(self):
        return self.get_model().objects.all()

    def paginate_items(self, context, page):
        try:
            page = int(page)
            if page == 1:
                raise ExplicitFirstPage()
            elif page == 0:
                page = 1
        except ValueError:
            page_no = 1

        context['paginator'] = Paginator(context['items'],
                                         self.items_per_page,
                                         allow_empty_first_page=True)
        context['page'] = context['paginator'].page(page)
        context['items'] = context['page'].object_list

    def filter_items(self, request, context):
        pass

    def dispatch(self, request, *args, **kwargs):
        context = {
            'items': self.get_queryset(),
            'paginator': None,
            'page': None,
        }

        if self.items_per_page:
            self.paginate_items(context, kwargs.get('page', 0))

        return self.render(request, context)


class FormView(AdminView):
    template = 'form.html'

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


class ButtonView(AdminView):
    def get(self, request, *args, **kwargs):
        pass

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