52 lines
1.4 KiB
JavaScript
52 lines
1.4 KiB
JavaScript
const BN = require('ethereumjs-util').BN
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const normalize = require('eth-sig-util').normalize
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class PendingBalanceCalculator {
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// Must be initialized with two functions:
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// getBalance => Returns a promise of a BN of the current balance in Wei
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// getPendingTransactions => Returns an array of TxMeta Objects,
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// which have txParams properties, which include value, gasPrice, and gas,
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// all in a base=16 hex format.
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constructor ({ getBalance, getPendingTransactions }) {
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this.getPendingTransactions = getPendingTransactions
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this.getNetworkBalance = getBalance
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}
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async getBalance () {
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const results = await Promise.all([
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this.getNetworkBalance(),
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this.getPendingTransactions(),
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])
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const [ balance, pending ] = results
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if (!balance) return undefined
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const pendingValue = pending.reduce((total, tx) => {
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return total.add(this.calculateMaxCost(tx))
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}, new BN(0))
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return `0x${balance.sub(pendingValue).toString(16)}`
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}
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calculateMaxCost (tx) {
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const txValue = tx.txParams.value
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const value = this.hexToBn(txValue)
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const gasPrice = this.hexToBn(tx.txParams.gasPrice)
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const gas = tx.txParams.gas
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const gasLimit = tx.txParams.gasLimit
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const gasLimitBn = this.hexToBn(gas || gasLimit)
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const gasCost = gasPrice.mul(gasLimitBn)
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return value.add(gasCost)
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}
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hexToBn (hex) {
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return new BN(normalize(hex).substring(2), 16)
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}
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}
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module.exports = PendingBalanceCalculator
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