import base64
import json
import logging
import traceback
import zlib

from decimal import Decimal

# DecimalEncoder is a helper class to convert a DynamoDB item to JSON.
# Ref: https://stackoverflow.com/questions/40033189/using-boto3-in-python-to-acquire-results-from-dynamodb-and-parse-into-a-usable-v


class DecimalEncoder(json.JSONEncoder):
    def default(self, o):
        if isinstance(o, Decimal):  # <---resolving decimals
            try:
                if o == o.to_integral_value():  # integers
                    return int(o)
                else:  # floats
                    # d = float(o)
                    # return string if precision lost
                    # if 'e' in str(d):
                    #     return format(o, "f")
                    # else:
                    #     return d
                    return float(o)
            except Exception as e:
                logging.getLogger().warning(
                    "Error encoding Decimal value to number.")
                # logging.getLogger().warning(json.dumps(traceback.format_exception(
                #     type(e), e, e.__traceback__)))
                # return format(o, "f")
                raise e
        if isinstance(o, set):  # <---resolving sets as lists
            return list(o)
        return super(DecimalEncoder, self).default(o)


def encode_obj(input):
    if not input:
        return None

    return base64.b64encode(
        zlib.compress(
            json.dumps(input, cls=DecimalEncoder).encode('utf8')
        )
    ).decode('utf8')


def decode_obj(input):
    if not input:
        return None

    return json.loads(
        zlib.decompress(
            base64.b64decode(input)
        ).decode('utf8')
    )