# -*- coding: utf-8 -*-

'''

Created on Nov 14, 2014

from https://gist.github.com/gsakkis/601977

to correct https://code.djangoproject.com/ticket/10227

@author: ymh

'''

from django.core.exceptions import ObjectDoesNotExist

from django.db import models

from django.db.models import fields as django_fields

def isalambda(v):

    LAMBDA = lambda:0

    return isinstance(v, type(LAMBDA)) and v.__name__ == LAMBDA.__name__

class OneToOneField(models.OneToOneField):    

    def __init__(self, *args, **kwargs):

        self.related_default = kwargs.pop('related_default', None)

        #This is BAD. Did this to avoid more work in Django 1.7 migration

        #TODO: correct this

        if self.related_default == "lambda:":

            self.related_default = lambda instance: None

        super(OneToOneField, self).__init__(*args, **kwargs)

    def contribute_to_related_class(self, cls, related):

        setattr(cls, related.get_accessor_name(),

                SingleRelatedObjectDescriptor(related, self.related_default))

    def deconstruct(self):

        name, path, args, kwargs = super(OneToOneField, self).deconstruct()

        if self.related_default is not None:

            # this is VERY dirty and works only in our application.

            #TODO: correct this...

            if isalambda(self.related_default):

                kwargs['related_default'] = "lambda:"

            else:

                kwargs['related_default'] = self.related_default

        return name, path, args, kwargs

class SingleRelatedObjectDescriptor(django_fields.related.SingleRelatedObjectDescriptor):

    def __init__(self, related, default):

        super(SingleRelatedObjectDescriptor, self).__init__(related)

        self.default = default

    def __get__(self, instance, instance_type=None):

        try:

            return super(SingleRelatedObjectDescriptor, self).__get__(instance,

                                                                      instance_type)

        except ObjectDoesNotExist:

            if self.default is None:

                raise

            value = self.default(instance)

            setattr(instance, self.cache_name, value)

            if value is not None:

                setattr(value, self.related.field.get_cache_name(), instance)

            return value