api.js

import moment from 'moment';
import * as Expo from 'expo';
import uuid from 'uuid-random';
import Constants from 'expo-constants';

const api = Constants.manifest.packagerOpts.dev
    ? Constants.manifest.debuggerHost.split(':').shift().concat(':3000')
    : 'productionurl.com'

const url = `http://${api}/events`;

export function getEvents() {
    return fetch(url)
        .then(response => response.json())
        .then(events => events.map(e => ({ ...e, date: new Date(e.date)})));
}

export function saveEvent({ title, date }) {
    return fetch(url, {
        method: 'POST',
        body: JSON.stringify({
            title,
            date,
            id: uuid(),
        }),
        headers: new Headers({
            'Content-Type': 'application/json',
        })
    })
    
    .then(res => res.json())
    .catch(err => console.error(err));
}

export function formatDate(dateString) {
    const parsed = moment(new Date(dateString));

    if (!parsed.isValid()) {
        return dateString
    }

    return parsed.format('D MMM YYYY');
}

export function formatDateTime(dateString) {
    const parsed = moment(new Date(dateString));

    if (!parsed.isValid()) {
        return dateString
    }

    return parsed.format('H A on D MMM YYYY');
}

export function getCountDownParts(eventDate) {
    const duration = moment.duration(moment(new Date(eventDate)).diff(new Date()));
    return {
        days: parseInt(duration.as('days')),
        hours: duration.get('hours'),
        minutes: duration.get('minutes'),
        seconds: duration.get('seconds'),
    };
}