import wagtail.api.v2.serializers as wagtail_serializers
from rest_framework.fields import SerializerMethodField

from vbv_lernwelt.course.models import CoursePage
from vbv_lernwelt.course.serializers import CourseCategorySerializer, CourseSerializer
from vbv_lernwelt.learnpath.utils import get_wagtail_type


def get_it_serializer_class(model, field_names):
    return wagtail_serializers.get_serializer_class(model, field_names=field_names, meta_fields=[], base=ItBaseSerializer)


class ItTypeField(wagtail_serializers.TypeField):
    def to_representation(self, obj):
        name = get_wagtail_type(obj)
        return name


class ItBaseSerializer(wagtail_serializers.BaseSerializer):
    type = ItTypeField(read_only=True)
    children = SerializerMethodField()
    course = SerializerMethodField()
    course_category = CourseCategorySerializer(read_only=True)

    meta_fields = []

    def __init__(self, *args, **kwargs):
        self.descendants = kwargs.pop('descendants', None)
        super().__init__(*args, **kwargs)

    def get_children(self, obj):
        if not self.descendants:
            self.descendants = [p for p in obj.get_descendants().specific()]
        children = _get_children(self.descendants, obj)
        return [c.specific.get_serializer_class()(c.specific, descendants=self.descendants).data for c in children]

    def get_course(self, obj):
        if hasattr(obj, 'course'):
            return CourseSerializer(obj.course).data
        else:
            course_parent_page = obj.get_ancestors().exact_type(CoursePage).last()
            if course_parent_page:
                return CourseSerializer(course_parent_page.specific.course).data
        return ''


def _get_descendants(pages, obj):
    return [c for c in pages if c.path.startswith(obj.path) and c.depth >= obj.depth]


def _get_children(pages, obj):
    return [c for c in pages if c.path.startswith(obj.path) and obj.depth + 1 == c.depth]