cic-stack/apps/cic-ussd/cic_ussd/balance.py

# standard imports
import json
import logging
from typing import Union

# third-party imports
import celery
from cic_eth.api import Api

# local imports
from cic_ussd.error import CachedDataNotFoundError
from cic_ussd.redis import create_cached_data_key, get_cached_data
from cic_ussd.conversions import from_wei

logg = logging.getLogger()


class BalanceManager:

    def __init__(self, address: str, chain_str: str, token_symbol: str):
        """
        :param address: Ethereum address of account whose balance is being queried
        :type address: str, 0x-hex
        :param chain_str: The chain name and network id.
        :type chain_str: str
        :param token_symbol: ERC20 token symbol of whose balance is being queried
        :type token_symbol: str
        """
        self.address = address
        self.chain_str = chain_str
        self.token_symbol = token_symbol

    def get_balances(self, asynchronous: bool = False) -> Union[celery.Task, dict]:
        """
        This function queries cic-eth for an account's balances, It provides a means to receive the balance either
        asynchronously or synchronously depending on the provided value for teh asynchronous parameter. It returns a
        dictionary containing network, outgoing and incoming balances.
        :param asynchronous: Boolean value checking whether to return balances asynchronously
        :type asynchronous: bool
        :return:
        :rtype:
        """
        if asynchronous:
            cic_eth_api = Api(
                chain_str=self.chain_str,
                callback_queue='cic-ussd',
                callback_task='cic_ussd.tasks.callback_handler.process_balances_callback',
                callback_param=''
            )
            cic_eth_api.balance(address=self.address, token_symbol=self.token_symbol)
        else:
            cic_eth_api = Api(chain_str=self.chain_str)
            balance_request_task = cic_eth_api.balance(
                address=self.address,
                token_symbol=self.token_symbol)
            return balance_request_task.get()[0]


def compute_operational_balance(balances: dict) -> float:
    """This function calculates the right balance given incoming and outgoing
    :param balances:
    :type balances:
    :return:
    :rtype:
    """
    incoming_balance = balances.get('balance_incoming')
    outgoing_balance = balances.get('balance_outgoing')
    network_balance = balances.get('balance_network')

    operational_balance = (network_balance + incoming_balance) - outgoing_balance
    return from_wei(value=operational_balance)


def get_cached_operational_balance(blockchain_address: str):
    """
    :param blockchain_address:
    :type blockchain_address:
    :return:
    :rtype:
    """
    key = create_cached_data_key(
        identifier=bytes.fromhex(blockchain_address[2:]),
        salt=':cic.balances_data'
    )
    cached_balance = get_cached_data(key=key)
    if cached_balance:
        operational_balance = compute_operational_balance(balances=json.loads(cached_balance))
        return operational_balance
    else:
        raise CachedDataNotFoundError('Cached operational balance not found.')