import json
from collections import OrderedDict
from tastypie.serializers import Serializer
from tastypie import fields
from tastypie.resources import Resource
from django.core.serializers.json import DjangoJSONEncoder

class OrderedSerializer(Serializer):
    def to_json(self, data, options=None):
        options = options or {}

        data = self.to_simple(data, options)
        return json.dumps(data, cls=DjangoJSONEncoder, sort_keys=False)

    def to_simple(self, data, options):
        if isinstance(data, Bundle):
            return OrderedDict((key, self.to_simple(val, options)) for (key, val) in data.data.items())
        return super(OrderedSerializer, self).to_simple( data, options)
        

class SomeResource(Resource):
    first_name = fields.fields.CharField(attribute='first_name',)
    last_name = fields.fields.CharField(attribute='last_name',)
    class Meta:
        resource_name = 'someresource'
        serializer = OrderedSerializer()
        field_order = ['first_name','last_name']

    def full_dehydrate(self, bundle, for_list=False):
        """
        Given a bundle with an object instance, extract the information from it
        to populate the resource.
        """
        use_in = ['all', 'list' if for_list else 'detail']
        """
        Convert bundle data to OrderedDict
        """
        bundle.data = OrderedDict(bundle.data)
        # Dehydrate each field.
        items = self.fields.items()
        ## make data ordered
        for field in self._meta.field_order:
            for field_name, field_object in items:
                if field_name == field:
        ## 
                    # If it's not for use in this mode, skip
                    field_use_in = getattr(field_object, 'use_in', 'all')
                    if callable(field_use_in):
                        if not field_use_in(bundle):
                            continue
                    else:
                        if field_use_in not in use_in:
                            continue

                    # A touch leaky but it makes URI resolution work.
                    if getattr(field_object, 'dehydrated_type', None) == 'related':
                        field_object.api_name = self._meta.api_name
                        field_object.resource_name = self._meta.resource_name

                    bundle.data[field_name] = field_object.dehydrate(bundle, for_list=for_list)

                    # Check for an optional method to do further dehydration.
                    method = getattr(self, "dehydrate_%s" % field_name, None)

                    if method:
                        bundle.data[field_name] = method(bundle)

        bundle = self.dehydrate(bundle)
        return bundle