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const ObservableStore = require('obs-store')
const extend = require('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<void>}
*/
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)
}
}
module.exports = CachedBalancesController
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