from rest_framework import viewsets
from rest_framework_json_api import serializers
from rest_framework_json_api.utils import get_included_resources
from rest_framework_json_api.views import AutoPrefetchMixin, RelatedMixin

basic_filter = ('exact', 'isnull')
text_filter = ('exact', 'contains', 'iexact', 'icontains', 'startswith', 'istartswith', 'endswith', 'iendswith')
date_filter = ('exact', 'gte', 'lte')
int_filter = ('exact', 'gte', 'lte')


class PreloadIncludesMixin(object):
    """
    This mixin provides a helper attributes to select or prefetch related models
    based on the include specified in the URL.

    __all__ can be used to specify a prefetch which should be done regardless of the include


    .. code:: python

        # When MyViewSet is called with ?include=author it will prefetch author and authorbio
        class MyViewSet(viewsets.ModelViewSet):
            queryset = Book.objects.all()
            prefetch_for_includes = {
                '__all__': [],
                'category.section': ['category']
            }
            select_for_includes = {
                '__all__': [],
                'author': ['author', 'author__authorbio'],
            }
    """

    def get_select_related(self, include):
        return getattr(self, 'select_for_includes', {}).get(include, None)

    def get_prefetch_related(self, include):
        return getattr(self, 'prefetch_for_includes', {}).get(include, None)

    def get_queryset(self, *args, **kwargs):
        qs = super(PreloadIncludesMixin, self).get_queryset(*args, **kwargs)

        included_resources = get_included_resources(self.request)
        for included in included_resources + ['__all__']:

            select_related = self.get_select_related(included)
            if select_related is not None:
                qs = qs.select_related(*select_related)

            prefetch_related = self.get_prefetch_related(included)
            if prefetch_related is not None:
                if not isinstance(prefetch_related, list):
                    qs = qs.prefetch_related(*prefetch_related(self))
                else:
                    qs = qs.prefetch_related(*prefetch_related)

        return qs


class ReasonableModelViewSet(AutoPrefetchMixin,
                           PreloadIncludesMixin,
                           RelatedMixin,
                           viewsets.ModelViewSet):
    http_method_names = ['get', 'post', 'patch', 'delete', 'head', 'options']


class ReasonableModelSerializer(serializers.ModelSerializer):
    """
    Reusable class to extend DJA ModelSerializer and make it more JSONAPI compatible
    """

    def get_field_names(self, declared_fields, info):
        method = self.context['request'].method

        included_rel_fields = []
        if method == 'GET':
            included_rel_fields = [qp for qp in (
                self.context['request'].query_params['include'].split(',')
                if 'include' in self.context['request'].query_params else []
            ) if qp in (self.included_serializers if hasattr(self, 'included_serializers') else [])]
        elif method == 'POST' or method == 'PATCH':
            included_rel_fields = [irel for irel in (
                self.context['request'].data.keys()
            ) if irel in (self.included_serializers if hasattr(self, 'included_serializers') else [])]

        fields = super().get_field_names(declared_fields, info)
        return fields + included_rel_fields