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83 lines
2.4 KiB
83 lines
2.4 KiB
const ObservableStore = require('obs-store')
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const extend = require('xtend')
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/**
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* @typedef {Object} CachedBalancesOptions
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* @property {Object} accountTracker An {@code AccountTracker} reference
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* @property {Function} getNetwork A function to get the current network
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* @property {Object} initState The initial controller state
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*/
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/**
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* Background controller responsible for maintaining
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* a cache of account balances in local storage
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*/
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class CachedBalancesController {
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/**
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* Creates a new controller instance
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*
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* @param {CachedBalancesOptions} [opts] Controller configuration parameters
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*/
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constructor (opts = {}) {
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const { accountTracker, getNetwork } = opts
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this.accountTracker = accountTracker
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this.getNetwork = getNetwork
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const initState = extend({
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cachedBalances: {},
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}, opts.initState)
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this.store = new ObservableStore(initState)
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this._registerUpdates()
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}
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/**
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* Updates the cachedBalances property for the current network. Cached balances will be updated to those in the passed accounts
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* if balances in the passed accounts are truthy.
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*
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* @param {Object} obj The the recently updated accounts object for the current network
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* @returns {Promise<void>}
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*/
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async updateCachedBalances ({ accounts }) {
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const network = await this.getNetwork()
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const balancesToCache = await this._generateBalancesToCache(accounts, network)
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this.store.updateState({
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cachedBalances: balancesToCache,
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})
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}
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_generateBalancesToCache (newAccounts, currentNetwork) {
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const { cachedBalances } = this.store.getState()
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const currentNetworkBalancesToCache = { ...cachedBalances[currentNetwork] }
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Object.keys(newAccounts).forEach(accountID => {
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const account = newAccounts[accountID]
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if (account.balance) {
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currentNetworkBalancesToCache[accountID] = account.balance
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}
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})
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const balancesToCache = {
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...cachedBalances,
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[currentNetwork]: currentNetworkBalancesToCache,
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}
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return balancesToCache
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}
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/**
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* Sets up listeners and subscriptions which should trigger an update of cached balances. These updates will
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* happen when the current account changes. Which happens on block updates, as well as on network and account
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* selections.
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*
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* @private
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*
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*/
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_registerUpdates () {
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const update = this.updateCachedBalances.bind(this)
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this.accountTracker.store.subscribe(update)
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}
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}
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module.exports = CachedBalancesController
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