# -*- coding: utf-8 -*-
# Author: Petr Dlouhy <petr.dlouhy@auto-mat.cz>
#
# Copyright (C) 2015 o.s. Auto*Mat
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

from django.utils.translation import ungettext
from django.contrib.auth import get_permission_codename
from django.utils.translation import ugettext as _
from django.template.response import SimpleTemplateResponse, TemplateResponse
from django.utils.encoding import force_text, python_2_unicode_compatible
from django.contrib.admin import widgets, helpers
from django.views.decorators.csrf import csrf_protect
from django.utils.decorators import method_decorator
csrf_protect_m = method_decorator(csrf_protect)

class ViewPermissionMixin(object):
    def get_readonly_fields(self, request, obj=None):
        if request.user.is_superuser:
            return self.readonly_fields

        if self.declared_fieldsets:
            return flatten_fieldsets(self.declared_fieldsets)
        else:
            return list(set(
                [field.name for field in self.opts.local_fields] +
                [field.name for field in self.opts.local_many_to_many]
            ))
    
    def has_view_permission(self, request, obj=None):
        opts = self.opts
        codename = get_permission_codename('view', opts)
        return request.user.has_perm("%s.%s" % (opts.app_label, codename))

    def get_actions(self, request):
        if self.has_change_permission(request) and self.has_delete_permission(request):
            return super(ViewPermissionMixin, self).get_actions(request)
        return []

    @csrf_protect_m
    def changelist_view(self, request, extra_context=None):
        """
        The 'change list' admin view for this model.

        This is copy of code from core Django, the only change is, that view permissions are needed to see the list (instead of change permissions).
        """
        from django.contrib.admin.views.main import ERROR_FLAG
        opts = self.model._meta
        app_label = opts.app_label
        if not self.has_view_permission(request, None):
            raise PermissionDenied

        list_display = self.get_list_display(request)
        list_display_links = self.get_list_display_links(request, list_display)
        list_filter = self.get_list_filter(request)
        search_fields = self.get_search_fields(request)

        # Check actions to see if any are available on this changelist
        actions = self.get_actions(request)
        if actions:
            # Add the action checkboxes if there are any actions available.
            list_display = ['action_checkbox'] + list(list_display)

        ChangeList = self.get_changelist(request)
        try:
            cl = ChangeList(request, self.model, list_display,
                list_display_links, list_filter, self.date_hierarchy,
                search_fields, self.list_select_related, self.list_per_page,
                self.list_max_show_all, self.list_editable, self)

        except IncorrectLookupParameters:
            # Wacky lookup parameters were given, so redirect to the main
            # changelist page, without parameters, and pass an 'invalid=1'
            # parameter via the query string. If wacky parameters were given
            # and the 'invalid=1' parameter was already in the query string,
            # something is screwed up with the database, so display an error
            # page.
            if ERROR_FLAG in request.GET.keys():
                return SimpleTemplateResponse('admin/invalid_setup.html', {
                    'title': _('Database error'),
                })
            return HttpResponseRedirect(request.path + '?' + ERROR_FLAG + '=1')

        # If the request was POSTed, this might be a bulk action or a bulk
        # edit. Try to look up an action or confirmation first, but if this
        # isn't an action the POST will fall through to the bulk edit check,
        # below.
        action_failed = False
        selected = request.POST.getlist(helpers.ACTION_CHECKBOX_NAME)

        # Actions with no confirmation
        if (actions and request.method == 'POST' and
                'index' in request.POST and '_save' not in request.POST):
            if selected:
                response = self.response_action(request, queryset=cl.get_queryset(request))
                if response:
                    return response
                else:
                    action_failed = True
            else:
                msg = _("Items must be selected in order to perform "
                        "actions on them. No items have been changed.")
                self.message_user(request, msg, messages.WARNING)
                action_failed = True

        # Actions with confirmation
        if (actions and request.method == 'POST' and
                helpers.ACTION_CHECKBOX_NAME in request.POST and
                'index' not in request.POST and '_save' not in request.POST):
            if selected:
                response = self.response_action(request, queryset=cl.get_queryset(request))
                if response:
                    return response
                else:
                    action_failed = True

        # If we're allowing changelist editing, we need to construct a formset
        # for the changelist given all the fields to be edited. Then we'll
        # use the formset to validate/process POSTed data.
        formset = cl.formset = None

        # Handle POSTed bulk-edit data.
        if (request.method == "POST" and cl.list_editable and
                '_save' in request.POST and not action_failed):
            FormSet = self.get_changelist_formset(request)
            formset = cl.formset = FormSet(request.POST, request.FILES, queryset=cl.result_list)
            if formset.is_valid():
                changecount = 0
                for form in formset.forms:
                    if form.has_changed():
                        obj = self.save_form(request, form, change=True)
                        self.save_model(request, obj, form, change=True)
                        self.save_related(request, form, formsets=[], change=True)
                        change_msg = self.construct_change_message(request, form, None)
                        self.log_change(request, obj, change_msg)
                        changecount += 1

                if changecount:
                    if changecount == 1:
                        name = force_text(opts.verbose_name)
                    else:
                        name = force_text(opts.verbose_name_plural)
                    msg = ungettext("%(count)s %(name)s was changed successfully.",
                                    "%(count)s %(name)s were changed successfully.",
                                    changecount) % {'count': changecount,
                                                    'name': name,
                                                    'obj': force_text(obj)}
                    self.message_user(request, msg, messages.SUCCESS)

                return HttpResponseRedirect(request.get_full_path())

        # Handle GET -- construct a formset for display.
        elif cl.list_editable:
            FormSet = self.get_changelist_formset(request)
            formset = cl.formset = FormSet(queryset=cl.result_list)

        # Build the list of media to be used by the formset.
        if formset:
            media = self.media + formset.media
        else:
            media = self.media

        # Build the action form and populate it with available actions.
        if actions:
            action_form = self.action_form(auto_id=None)
            action_form.fields['action'].choices = self.get_action_choices(request)
        else:
            action_form = None

        selection_note_all = ungettext('%(total_count)s selected',
            'All %(total_count)s selected', cl.result_count)

        context = dict(
            self.admin_site.each_context(),
            module_name=force_text(opts.verbose_name_plural),
            selection_note=_('0 of %(cnt)s selected') % {'cnt': len(cl.result_list)},
            selection_note_all=selection_note_all % {'total_count': cl.result_count},
            title=cl.title,
            is_popup=cl.is_popup,
            to_field=cl.to_field,
            cl=cl,
            media=media,
            has_add_permission=self.has_add_permission(request),
            opts=cl.opts,
            action_form=action_form,
            actions_on_top=self.actions_on_top,
            actions_on_bottom=self.actions_on_bottom,
            actions_selection_counter=self.actions_selection_counter,
            preserved_filters=self.get_preserved_filters(request),
        )
        context.update(extra_context or {})

        return TemplateResponse(request, self.change_list_template or [
            'admin/%s/%s/change_list.html' % (app_label, opts.model_name),
            'admin/%s/change_list.html' % app_label,
            'admin/change_list.html'
        ], context, current_app=self.admin_site.name)

