# TODO(niklas9):
# * should we take care of transforming between time zones in any way here ?
# * get default datetime format from settings ?
DEFAULT_DATETIME_FMT = '%Y-%m-%d %H:%M:%S'
# TODO(niklas9):
# * metaclass below just for Django < 1.9, fix a if stmt for it?
#__metaclass__ = models.SubfieldBase
description = "Unix timestamp integer to datetime object"

def get_internal_type(self):
    return 'PositiveIntegerField'

def to_python(self, val):
    if val is None or isinstance(val, datetime.datetime):
        return val
    if isinstance(val, datetime.date):
        return datetime.datetime(val.year, val.month, val.day)
        
    try:
        date_value = datetime.datetime.fromtimestamp(float(val))
        return date_value            
    except ValueError:
        # parse the following value : ('2016-10-03 19:00:00+0200'
        date_value = parse_datetime(val)
        return date_value

def get_db_prep_value(self, val, *args, **kwargs):
    if val is None:  return None
    return int(time.mktime(val.timetuple()))

def value_to_string(self, obj):
    val = self._get_val_from_obj(obj)
    return self.to_python(val).strftime(self.DEFAULT_DATETIME_FMT)

def from_db_value(self, val, expression, connection, context):
    return self.to_python(val)