feat: watch erc20 balances

src/eventSyncer.js

@@ -6,7 +6,7 @@ const equal = require('fast-deep-equal');
 const Database = require('./database.js');
 const Events = require('events');
 const Web3Eth = require('web3-eth');
-
+const toBN = require('number-to-bn');
 class EventSyncer {
 
   constructor(provider, options = {}) {
@@ -143,6 +143,8 @@ class EventSyncer {
   trackBalance(address, erc20Address) {
     const sub = new ReplaySubject();
 
+    // TODO: validate address?
+
     let callFn;
     if(!erc20Address){
       callFn = () => {
@@ -156,7 +158,19 @@ class EventSyncer {
         }]);
       };
     } else {
-      // TODO: track erc20
+      callFn = () => {
+        const fn  = this.web3.call;
+                  //  balanceOf
+        const data = "0x70a08231" + "000000000000000000000000" + erc20Address.substring(2); 
+        console.log(data);
+        fn.apply(fn, [{to: erc20Address, data}, (err, result) => {
+          if(err) {
+            sub.error(err);
+            return;
+          }
+          sub.next(toBN(result).toNumber());
+        }]);
+      };
     }
 
     callFn();

test/test5.js

@@ -0,0 +1,67 @@
+const Web3Eth = require('web3-eth');
+
+let eth = new Web3Eth("ws://localhost:8545");
+
+async function deployContract() {
+  let accounts = await eth.getAccounts();
+
+  // pragma solidity ^0.5.0;
+  // contract ERC20Token {
+  //     function balanceOf(address _owner)
+  //         external
+  //         view
+  //         returns (uint256 balance)
+  //     {
+  //         return block.number;
+  //     }
+  // }
+
+  let abi = [
+    {
+      "constant": true,
+      "inputs": [
+        {
+          "name": "_owner",
+          "type": "address"
+        }
+      ],
+      "name": "balanceOf",
+      "outputs": [
+        {
+          "name": "balance",
+          "type": "uint256"
+        }
+      ],
+      "payable": false,
+      "stateMutability": "view",
+      "type": "function"
+    }
+  ];
+
+  var contract = new eth.Contract(abi)
+  let instance = await contract.deploy({
+    data: '0x608060405234801561001057600080fd5b5060d58061001f6000396000f3fe6080604052600436106039576000357c01000000000000000000000000000000000000000000000000000000009004806370a0823114603e575b600080fd5b348015604957600080fd5b50608960048036036020811015605e57600080fd5b81019080803573ffffffffffffffffffffffffffffffffffffffff169060200190929190505050609f565b6040518082815260200191505060405180910390f35b600043905091905056fea165627a7a72305820267fb09927dce2942fe73ac7487c4f1565dae60b08aa5434a22cb1f71366bd090029',
+    arguments: []
+  }).send({
+    from: accounts[0],
+    gas: '4700000'
+  })
+  return instance
+}
+
+async function run() {
+  let accounts = await eth.getAccounts();
+  var DummyERC20Token = await deployContract()
+  console.dir(DummyERC20Token.options.address)
+
+
+  const EventSyncer = require('../src/eventSyncer.js')
+  const eventSyncer = new EventSyncer(eth.currentProvider);
+
+  await eventSyncer.init();
+  eventSyncer.trackBalance(accounts[0], DummyERC20Token.options.address).pipe().subscribe((balance) => {
+    console.log("balance is ", balance)
+  });
+}
+
+run()