"""
Serialize data to/from JSON
"""

import datetime
import decimal
from StringIO import StringIO

from django.core.serializers.base import DeserializationError
from django.core.serializers.python import Serializer as PythonSerializer
from django.core.serializers.python import Deserializer as PythonDeserializer
from django.utils import simplejson
from django.utils.timezone import is_aware

class Serializer(PythonSerializer):
    """
    Convert a queryset to JSON.
    """
    internal_use_only = False

    def end_serialization(self):
        if simplejson.__version__.split('.') >= ['2', '1', '3']:
            # Use JS strings to represent Python Decimal instances (ticket #16850)
            self.options.update({'use_decimal': False})
        simplejson.dump(self.objects, self.stream, cls=DjangoJSONEncoder, **self.options)

    def getvalue(self):
        if callable(getattr(self.stream, 'getvalue', None)):
            return self.stream.getvalue()


def Deserializer(stream_or_string, **options):
    """
    Deserialize a stream or string of JSON data.
    """
    if isinstance(stream_or_string, basestring):
        stream = StringIO(stream_or_string)
    else:
        stream = stream_or_string
    try:
        for obj in PythonDeserializer(simplejson.load(stream), **options):
            yield obj
    except GeneratorExit:
        raise
    except Exception, e:
        # Map to deserializer error
        raise DeserializationError(e)


class DjangoJSONEncoder(simplejson.JSONEncoder):
    """
    JSONEncoder subclass that knows how to encode date/time and decimal types.
    """
    def default(self, o):
        # See "Date Time String Format" in the ECMA-262 specification.
        if isinstance(o, datetime.datetime):
            r = o.isoformat()
            if o.microsecond:
                r = r[:23] + r[26:]
            if r.endswith('+00:00'):
                r = r[:-6] + 'Z'
            return r
        elif isinstance(o, datetime.date):
            return o.isoformat()
        elif isinstance(o, datetime.time):
            if is_aware(o):
                raise ValueError("JSON can't represent timezone-aware times.")
            r = o.isoformat()
            if o.microsecond:
                r = r[:12]
            return r
        elif isinstance(o, decimal.Decimal):
            return str(o)
        else:
            return super(DjangoJSONEncoder, self).default(o)

# Older, deprecated class name (for backwards compatibility purposes).
DateTimeAwareJSONEncoder = DjangoJSONEncoder