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const Web3 = require('web3')
const contracts = require('eth-contract-metadata')
const { warn } = require('loglevel')
const { MAINNET } = require('./network/enums')
// By default, poll every 3 minutes
const DEFAULT_INTERVAL = 180 * 1000
const ERC20_ABI = [{'constant': true, 'inputs': [{'name': '_owner', 'type': 'address'}], 'name': 'balanceOf', 'outputs': [{'name': 'balance', 'type': 'uint256'}], 'payable': false, 'type': 'function'}]
/**
* A controller that polls for token exchange
* rates based on a user's current token list
*/
class DetectTokensController {
/**
* Creates a DetectTokensController
*
* @param {Object} [config] - Options to configure controller
*/
constructor ({ interval = DEFAULT_INTERVAL, preferences, network, keyringMemStore } = {}) {
this.preferences = preferences
this.interval = interval
this.network = network
this.keyringMemStore = keyringMemStore
}
/**
* For each token in eth-contract-metada, find check selectedAddress balance.
*
*/
async detectNewTokens () {
if (!this.isActive) { return }
if (this._network.store.getState().provider.type !== MAINNET) { return }
this.web3.setProvider(this._network._provider)
for (const contractAddress in contracts) {
if (contracts[contractAddress].erc20 && !(this.tokenAddresses.includes(contractAddress.toLowerCase()))) {
this.detectTokenBalance(contractAddress)
}
}
}
/**
* Find if selectedAddress has tokens with contract in contractAddress.
*
* @param {string} contractAddress Hex address of the token contract to explore.
* @returns {boolean} If balance is detected, token is added.
*
*/
async detectTokenBalance (contractAddress) {
const ethContract = this.web3.eth.contract(ERC20_ABI).at(contractAddress)
ethContract.balanceOf(this.selectedAddress, (error, result) => {
if (!error) {
if (!result.isZero()) {
this._preferences.addToken(contractAddress, contracts[contractAddress].symbol, contracts[contractAddress].decimals)
}
} else {
warn(`MetaMask - DetectTokensController balance fetch failed for ${contractAddress}.`, error)
}
})
}
/**
* Restart token detection polling period and call detectNewTokens
* in case of address change or user session initialization.
*
*/
restartTokenDetection () {
if (!(this.isActive && this.selectedAddress)) { return }
this.detectNewTokens()
this.interval = DEFAULT_INTERVAL
}
/**
* @type {Number}
*/
set interval (interval) {
this._handle && clearInterval(this._handle)
if (!interval) { return }
this._handle = setInterval(() => { this.detectNewTokens() }, interval)
}
/**
* In setter when selectedAddress is changed, detectNewTokens and restart polling
* @type {Object}
*/
set preferences (preferences) {
if (!preferences) { return }
this._preferences = preferences
preferences.store.subscribe(({ tokens = [] }) => { this.tokenAddresses = tokens.map((obj) => { return obj.address }) })
preferences.store.subscribe(({ selectedAddress }) => {
if (this.selectedAddress !== selectedAddress) {
this.selectedAddress = selectedAddress
this.restartTokenDetection()
}
})
}
/**
* @type {Object}
*/
set network (network) {
if (!network) { return }
this._network = network
this.web3 = new Web3(network._provider)
}
/**
* In setter when isUnlocked is updated to true, detectNewTokens and restart polling
* @type {Object}
*/
set keyringMemStore (keyringMemStore) {
if (!keyringMemStore) { return }
this._keyringMemStore = keyringMemStore
this._keyringMemStore.subscribe(({ isUnlocked }) => {
if (this.isUnlocked !== isUnlocked) {
this.isUnlocked = isUnlocked
if (isUnlocked) { this.restartTokenDetection() }
}
})
}
/**
* Internal isActive state
* @type {Object}
*/
get isActive () {
return this.isOpen && this.isUnlocked
}
}
module.exports = DetectTokensController
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