trezor-wallet/src/js/services/CoinmarketcapService.js

/* @flow */
'use strict';

import { JSONRequest, httpRequest } from '../utils/networkUtils';
import { resolveAfter } from '../utils/promiseUtils';
import { READY } from '../actions/constants/localStorage';

import type { 
    Middleware,
    MiddlewareAPI,
    MiddlewareDispatch,
    State,
    Dispatch,
    Action,
    AsyncAction,
    GetState 
} from '~/flowtype';
import type { Config, FiatValueTicker } from '../reducers/LocalStorageReducer';

export const RATE_UPDATE: 'rate__update' = 'rate__update';

export type FiatRateAction = {
    type: typeof RATE_UPDATE;
    network: string;
    rate: any;
}

const loadRateAction = (): AsyncAction => {
    return async (dispatch: Dispatch, getState: GetState): Promise<void> => {

        const config: ?Config = getState().localStorage.config;
        if (!config) return;

        try {
            config.fiatValueTickers.forEach(async (ticker: FiatValueTicker) => {
                // const rate: ?Array<any> = await JSONRequest(`${ticker.url}?convert=USD`, 'json');
                const rate: ?Array<any> = await httpRequest(`${ticker.url}?convert=USD`, 'json');
                if (rate) {
                    dispatch({
                        type: RATE_UPDATE,
                        network: ticker.network,
                        rate: rate[0]
                    });
                }
            })
        } catch (error) {
            // ignore error
        }

        await resolveAfter(50000);
    }
}

/**
 * Middleware 
 */
const CoinmarketcapService: Middleware = (api: MiddlewareAPI) => (next: MiddlewareDispatch) => (action: Action): Action => {

    next(action);

    if (action.type === READY) {
        api.dispatch( loadRateAction() );
    }

    return action;
};

export default CoinmarketcapService;