from django.utils.translation import ugettext_lazy as _

from wagtail.wagtailadmin.forms import (
    BaseGroupCollectionMemberPermissionFormSet,
)
from wagtail.wagtailcore import hooks
from wagtail.wagtailcore.models import Collection, Page

from .utils import get_kfet_root_collection, get_kfet_root_page


def get_kfetcms_group_formview_extra():
    # Prevents querying the database too soon.
    from .forms import (
        CmsGroupForm, SnippetsCmsGroupForm, prepare_page_permissions_formset,
        prepare_collection_member_permissions_formset,
    )
    forms = []

    # Misc cms-related permissions.
    forms.append((CmsGroupForm, {'prefix': 'kfetcms'}))

    # Snippets permissions.
    forms.append((SnippetsCmsGroupForm, {'prefix': 'kfetcms-snippets'}))

    # Setup PagePermissionsFormSet for kfet root page descendants only.

    root_page = get_kfet_root_page()

    if root_page:
        pages = Page.objects.descendant_of(root_page, inclusive=True)
        forms.append(
            (prepare_page_permissions_formset(pages=pages), {})
        )

    # Setup CollectionPermissions for kfet root collection descendants only.

    root_collection = get_kfet_root_collection()

    if root_collection:
        collections = Collection.objects.descendant_of(
            root_collection, inclusive=True)

        # Retrieve forms based on CollectionMemberPermissionFormSet displayed
        # by Wagtail admin site.
        # http://docs.wagtail.io/en/stable/reference/hooks.html#register-group-permission-panel
        collectionmember_form_classes = []
        for fn in hooks.get_hooks('register_group_permission_panel'):
            form_cls = fn()
            if issubclass(
                form_cls,
                BaseGroupCollectionMemberPermissionFormSet
            ):
                collectionmember_form_classes.append(form_cls)

        # Apply choices limit.
        for form_cls in collectionmember_form_classes:
            forms.append((
                prepare_collection_member_permissions_formset(
                    form_cls, collections=collections),
                {},
            ))

    # The 'extra' definition of kfetcms.

    extra = {
        'title': _("Site"),
        'description': _(
            "Permissions liées aux pages à contenu libre."
        ),
        'form_classes': forms,
    }

    return extra