contract.py

from web3 import Web3, HTTPProvider
from web3.middleware import geth_poa_middleware

NET = 'rinkeby'
INFURA_API_KEY = ''
ETHERSCAN_API_KEY = ''

import requests


w3 = Web3(HTTPProvider('https://{}.infura.io/{}/'.format(
                       NET,
                       INFURA_API_KEY),
                       request_kwargs={'timeout': 60}))

w3.middleware_stack.inject(geth_poa_middleware, layer=0)


def get_abi_from_contract_address(address):
    assert type(address) is str, (
        'address must have a type str'
    )
    assert address[:2] == '0x', (
        'First two symbols of address must be 0x'
    )
    address = w3.toChecksumAddress(address)
    response = requests.get(
        'https://api{}.etherscan.io/api?module=contract&action=getabi&address={}&apikey={}'.format(
            '-rinkeby' if NET == 'rinkeby' else '',
            address,
            ETHERSCAN_API_KEY
        )
    )
    json_response = response.json()
    result = json_response['result']
    #assert result[0] == '[' and result[-1] == ']', (
    #    'ABI must have a type list'
    #)
    return result


def check_contract_functions(contract):
    list_of_functions = ['name', 'totalSupply', 'decimals', 'balanceOf',
                         'symbol']
    for function in list_of_functions:
        functions = contract.find_functions_by_name(function)
        if not functions:
            raise AssertionError('{} not found in contract'.format(function))


def get_contract(contract_address):
    assert type(contract_address) is str, (
        'contract address must have a type str'
    )
    assert contract_address[:2] == '0x', (
        'First two symbols of cotract address must be 0x'
    )
    contract_address = w3.toChecksumAddress(contract_address)
    abi = get_abi_from_contract_address(contract_address)
    contract = w3.eth.contract(address=contract_address, abi=abi)
    check_contract_functions(contract)
    return contract


def get_token_balance_with_decimals(balance, decimal):
    return balance / 10**decimal


def get_balance_from_contract(address, contract_address):
    contract_address = w3.toChecksumAddress(contract_address)
    result = w3.eth.call({
        'to': contract_address,
        'data': '0x70a08231000000000000000000000000' + address[2:],
    })
    balance = int(result.hex(), 16)
    return balance


def get_internal_contract_transaction(contract_address):
    url = 'https://api{}.etherscan.io/api?module=account&action=tokentx&contractaddress={}&offset=1000000&sort=asc&apikey={}'.format(
        '-rinkeby' if settings.NET == 'rinkeby' else '',
        contract_address,
        ETHERSCAN_API_KEY
    )
    response = requests.get(url)
    json_response = response.json()
    result = json_response['result']
    return result


def get_current_supply(address):
    transactions = get_internal_contract_transaction(address)
    return sum([int(tx['value']) for tx in transactions])