from django.http import HttpResponseForbidden
from django.shortcuts import get_object_or_404, redirect
from django.utils.translation import gettext_lazy

from wagtail import hooks
from wagtail.admin import messages
from wagtail.admin.forms.collections import CollectionForm
from wagtail.admin.ui.tables import TitleColumn
from wagtail.admin.views.generic import CreateView, DeleteView, EditView, IndexView
from wagtail.models import Collection
from wagtail.permissions import collection_permission_policy


class Index(IndexView):
    permission_policy = collection_permission_policy
    model = Collection
    context_object_name = "collections"
    results_template_name = "wagtailadmin/collections/index_results.html"
    add_url_name = "wagtailadmin_collections:add"
    index_url_name = "wagtailadmin_collections:index"
    page_title = gettext_lazy("Collections")
    add_item_label = gettext_lazy("Add a collection")
    header_icon = "folder-open-1"
    columns = [
        TitleColumn(
            "name",
            label=gettext_lazy("Name"),
            url_name="wagtailadmin_collections:edit",
            id_accessor="0",
            accessor="1",
        )
    ]

    def get_queryset(self):
        return self.permission_policy.instances_user_has_any_permission_for(
            self.request.user, ["add", "change", "delete"]
        ).exclude(depth=1)

    def get_table(self, object_list):
        return super().get_table(object_list.get_indented_choices())


class Create(CreateView):
    permission_policy = collection_permission_policy
    model = Collection
    form_class = CollectionForm
    page_title = gettext_lazy("Add collection")
    success_message = gettext_lazy("Collection '%(object)s' created.")
    add_url_name = "wagtailadmin_collections:add"
    edit_url_name = "wagtailadmin_collections:edit"
    index_url_name = "wagtailadmin_collections:index"
    header_icon = "folder-open-1"
    _show_breadcrumbs = True

    def get_form(self, form_class=None):
        form = super().get_form(form_class)
        # Now filter collections offered in parent field by current user's add permissions
        collections = self.permission_policy.instances_user_has_permission_for(
            self.request.user, "add"
        )
        form.fields["parent"].queryset = collections
        return form

    def save_instance(self):
        instance = self.form.save(commit=False)
        parent = self.form.cleaned_data["parent"]
        parent.add_child(instance=instance)
        return instance


class Edit(EditView):
    permission_policy = collection_permission_policy
    model = Collection
    form_class = CollectionForm
    template_name = "wagtailadmin/collections/edit.html"
    success_message = gettext_lazy("Collection '%(object)s' updated.")
    error_message = gettext_lazy("The collection could not be saved due to errors.")
    delete_item_label = gettext_lazy("Delete collection")
    edit_url_name = "wagtailadmin_collections:edit"
    index_url_name = "wagtailadmin_collections:index"
    delete_url_name = "wagtailadmin_collections:delete"
    context_object_name = "collection"
    header_icon = "folder-open-1"
    _show_breadcrumbs = True

    def _user_may_move_collection(self, user, instance):
        """
        Is this instance used for assigning GroupCollectionPermissions to the user?
        If so, this user is not allowed do move the collection to a new part of the tree
        """
        if user.is_active and user.is_superuser:
            return True
        else:
            permissions = (
                self.permission_policy._get_user_permission_objects_for_actions(
                    user, {"add", "change", "delete"}
                )
            )
            return not {
                permission
                for permission in permissions
                if permission.collection_id == instance.pk
            }

    def get_queryset(self):
        return self.permission_policy.instances_user_has_permission_for(
            self.request.user, "change"
        ).exclude(depth=1)

    def get_form(self, form_class=None):
        form = super().get_form(form_class)
        user = self.request.user
        # if user does not have add permission anywhere, they can't move a collection
        if not self.permission_policy.user_has_permission(user, "add"):
            form.fields.pop("parent")
        # If this instance is a collection used to assign permissions for this user,
        # do not let the user move this collection.
        elif not self._user_may_move_collection(user, form.instance):
            form.fields.pop("parent")
        else:
            # Filter collections offered in parent field by current user's add permissions
            collections = self.permission_policy.instances_user_has_permission_for(
                user, "add"
            )
            form.fields["parent"].queryset = collections
            # Disable unavailable options in CollectionChoiceField select widget
            form.fields["parent"].disabled_queryset = form.instance.get_descendants(
                inclusive=True
            )

        form.initial["parent"] = form.instance.get_parent().pk
        return form

    def save_instance(self):
        instance = self.form.save()
        if "parent" in self.form.changed_data:
            instance.move(self.form.cleaned_data["parent"], "sorted-child")
        return instance


class Delete(DeleteView):
    permission_policy = collection_permission_policy
    model = Collection
    success_message = gettext_lazy("Collection '%(object)s' deleted.")
    index_url_name = "wagtailadmin_collections:index"
    edit_url_name = "wagtailadmin_collections:edit"
    delete_url_name = "wagtailadmin_collections:delete"
    page_title = gettext_lazy("Delete collection")
    confirmation_message = gettext_lazy(
        "Are you sure you want to delete this collection?"
    )
    header_icon = "folder-open-1"

    def get_queryset(self):
        return self.permission_policy.instances_user_has_permission_for(
            self.request.user, "delete"
        ).exclude(depth=1)

    def get_collection_contents(self):
        collection_contents = [
            hook(self.object)
            for hook in hooks.get_hooks("describe_collection_contents")
        ]

        # filter out any hook responses that report that the collection is empty
        # (by returning None, or a dict with 'count': 0)
        def is_nonempty(item_type):
            return item_type and item_type["count"] > 0

        return list(filter(is_nonempty, collection_contents))

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        collection_contents = self.get_collection_contents()

        if collection_contents:
            # collection is non-empty; render the 'not allowed to delete' response
            self.template_name = "wagtailadmin/collections/delete_not_empty.html"
            context["collection_contents"] = collection_contents

        return context

    def post(self, request, pk):
        self.object = get_object_or_404(self.get_queryset(), id=pk)
        collection_contents = self.get_collection_contents()

        if collection_contents:
            # collection is non-empty; refuse to delete it
            return HttpResponseForbidden()

        messages.success(request, self.get_success_message())
        self.object.delete()
        return redirect(self.index_url_name)
