tools.py

from web3 import Web3, HTTPProvider

import json
import requests


def getWeb3():
    '''
    Return web3 object
    '''
    return Web3(HTTPProvider('https://mainnet.infura.io/'))


def loadContracts():
    '''
    Loads contracts from MEW git, falls back to local instance if fails
    '''
    ETH_TOKEN_URI = '''
        https://raw.githubusercontent.com/kvhnuke/etherwallet/
        mercury/app/scripts/tokens/ethTokens.json
    '''
    try:
        contracts = requests.get(ETH_TOKEN_URI).json()
    except:
        file = open('ethTokens.json', 'r')
        contracts = json.loads(file.read())
    return contracts


def decompressToken(token):
    '''
    Searches local database using known token data
    '''
    response = {}
    response['address'] = None
    response['symbol'] = None
    response['decimal'] = None

    # check if token is an address
    if len(token) == 42 and token[:2] == '0x':
        # check to see if we know the address
        for contract in loadContracts():
            if contract['address'] == token:
                response['address'] = contract['address']
                response['symbol'] = contract['symbol']
                response['decimal'] = contract['decimal']
                return response
        # lookup failed, going in raw
        response['address'] = token
    else:
        # Get contract params
        for contract in loadContracts():
            if contract['symbol'].upper() == token.upper():
                response['address'] = contract['address']
                response['symbol'] = contract['symbol']
                response['decimal'] = contract['decimal']
                return response
    return response


def makeABICall(address):
    web3 = getWeb3()
    GENERIC_ABI = '''
        [{"constant":true,"inputs":[{"name":"_owner","type":"address"}],
        "name":"balanceOf","outputs":[{"name":"","type":"uint256"}],
        "payable":false,"stateMutability":"view","type":"function"}]
    '''
    abi = json.loads(GENERIC_ABI)
    token = web3.eth.contract(address, abi=abi)
    return token


def getBalance(decimal, token, wallet):
    try:
        divisor = 10 ** decimal
        return token.call().balanceOf(wallet) / divisor
    except:
        return token.call().balanceOf(wallet)