Smart Contract SDK

A simple library for building smart contract interactions. When offline, or away from a web3 wallet, smart
contract interaction is quite difficult. This is because it requires special transaction data that defines
a function call on a smart contract. This library intends to improve this experience by providing a simple interface
for common smart contract function calls. It also aims to be extensible to a wide variety of contracts.

Installing

``bash
npm i @bitgo/smart-contracts
`

Supported Chains

* eth
* trx




Example Usage

*
The basic usage enables users to specify contracts by name and build transaction data from them.



##### Ethereum example
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const cDAI = getContractsFactory('eth').getContract('Compound').instance('cDAI');
const { data, amount, address } = cDAI.methods().mint.call({ mintAmount: '1000000000' });
`




##### Tron example
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const cWbtcEth = getContractsFactory('trx').getContract('WrappedToken').instance('WBTC');
const { data, amount } = cWbtcEth.methods().transfer.call({ _to: 'TGeT2sfMYcjx3ra2HhQUvMyBcVhjBc1Lbk', _value: '100' });
`
*



Users can specify an instance of the contract protocol by address instead of name
##### Ethereum example
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const cDAI = getContractsFactory('eth').getContract('Compound').instance()
cDai.address = '0x5d3a536e4d6dbd6114cc1ead35777bab948e3643';
const { data } = cDAI.methods().mint.call({ mintAmount: '1000000000' });
`



##### Tron example
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const cDAI = getContractsFactory('trx').getContract('WrappedToken').instance()
cWbtcEth.address = 'TXpw8XeWYeTUd4quDskoUqeQPowRh4jY65';
const { data } = cWbtcEth.methods().transfer.call({ _to: 'TGeT2sfMYcjx3ra2HhQUvMyBcVhjBc1Lbk', _value: '100' };
`

*
The decoder can parse call data and output a human-readable explanation of a given contract call.



##### Ethereum example
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const decoder = getContractsFactory('eth').getDecoder();
decoder.decode(Buffer.from('a9059cbb00000000000000000000000010d4f942617a231eb1430c88fe43c8c2050437d90000000000000000000000000000000000000000000000000000000000002710', 'hex'));
{ methodId: '0xa9059cbb',
name: 'transfer',
args:
[ { name: '_to',
type: 'address',
value: '0x10d4f942617a231eb1430c88fe43c8c2050437d9' },
{ name: '_value', type: 'uint256', value: 10000 } ],
contractName: 'StandardERC20' }
`



##### Tron example
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const decoder = getContractsFactory('trx').getDecoder();
decoder.decode(Buffer.from('a9059cbb000000000000000000000000efc230e125c24de35f6290afcafa28d50b43653600000000000000000000000000000000000000000000000000000000000003e8', 'hex'));
// result
{ methodId: '0xa9059cbb',
name: 'transfer',
args:
[ { name: '_to',
type: 'address',
value: 'TXpw8XeWYeTUd4quDskoUqeQPowRh4jY65' },
{ name: '_value', type: 'uint256', value: '1000' } ],
contractName: 'StandardERC20' }
`




Integration with BitGo SDK

The output of this library is well formed as an argument to a BitGo SDK sendMany call. This makes it useful for
integration alongside the Bitgo SDK.

$3

`js
import { getContractsFactory } from '@bitgo/smart-contracts';

import { BitGo, Coin } from 'bitgo';

async function sendBitGoTx() {
const bitGo = new BitGo({ env: 'test' });
const baseCoin = bitGo.coin('eth');
const bitGoWallet = await baseCoin.wallets().get({ id: '5941ce2db42fcbc70717e5a898fd1595' });

const cDAI = getContractsFactory('eth').getContract('Compound').instance('cDAI');

const transaction = await bitGoWallet.sendMany({
recipients: cDAI.methods().mint.call({ mintAmount: '1000000000' }),
walletPassphrase: 'password'
})

}

sendBitGoTx();
`

Types

#### Contract
listContractTypes() -- get the available contract types.
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const types = getContractsFactory('eth').listContractTypes();
// response: ['Compound', 'StandardERC20']
`

listMethods() -- get the available contract methods.
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const types = getContractsFactory('eth').getContract('StandardERC20').listMethods();
// response: [{ name: 'transfer', inputs: [...], outputs: [...] }, { name: 'approve', ... }]
`

methods() -- get contract method builder objects
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const types = getContractsFactory('eth').getContract('StandardERC20').methods();
// response: { transfer: { call: }, approve: { call: } }
`

.name -- get contract name property
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const types = getContractsFactory('eth').getContract('StandardERC20').name;
// response: StandardERC20
`

.address -- set contract address property to the contract instance
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const types = getContractsFactory('eth').getContract('StandardERC20').instance();
type.address = '0x5d3a536e4d6dbd6114cc1ead35777bab948e3643';
// response: Contract intance with address set
`

instance() -- set contract instance
`js
import { getContractsFactory } from '@bitgo/smart-contracts';
const types = getContractsFactory('eth').getContract('StandardERC20').instance('DAI');
// response: Contract with DAI address set
`

Supported Protocols:

This library supports a limited number of smart contract protocols, as it maintains solidity ABIs locally.

* On ethereum chain
- Compound -- Examples
- StandardERC20 -- Examples
- MakerDAO -- Examples
* On tron chain
- WrappedToken - Examples

Adding a new ABI type


This library is quite extensible to new chains and protocols -- if there are other contract types that you would like to use,
feel free to submit a PR adding them. To do so, make the following changes:
- Add a new supported chain creating the directory chainName at the root level of the project, for example eth, trx, etc.
- Add the JSON ABI to chainName/abis directory, named [ProtocolName].json.
- Add the new contract the index.ts on chainName/abis.
- Add the ProtocolName and addresses for various instances of the protocol in chainName/config/instances.json
- For example, Compound protocol has cDAI, cUSDC, etc for eth chain.
- Add the protocol to the README above
- Add some example usages in the chainName/examples` directory