90 lines
2.6 KiB
JavaScript
90 lines
2.6 KiB
JavaScript
import { ObservableStore } from '@metamask/obs-store';
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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} getCurrentChainId A function to get the current chain id
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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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export default 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, getCurrentChainId } = opts;
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this.accountTracker = accountTracker;
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this.getCurrentChainId = getCurrentChainId;
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const initState = { cachedBalances: {}, ...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 chain. 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 chain
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* @param obj.accounts
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* @returns {Promise<void>}
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*/
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async updateCachedBalances({ accounts }) {
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const chainId = this.getCurrentChainId();
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const balancesToCache = await this._generateBalancesToCache(
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accounts,
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chainId,
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);
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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, chainId) {
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const { cachedBalances } = this.store.getState();
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const currentChainBalancesToCache = { ...cachedBalances[chainId] };
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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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currentChainBalancesToCache[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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[chainId]: currentChainBalancesToCache,
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};
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return balancesToCache;
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}
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/**
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* Removes cachedBalances
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*/
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clearCachedBalances() {
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this.store.updateState({ cachedBalances: {} });
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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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_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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