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