import { Observable } from 'rx';

import debug from 'debug';

import { reportError } from '../middlewares/error-reporter';

import InMemoryCache from '../utils/in-memory-cache';

const log = debug('fcc:boot:donate');

const fiveMinutes = 1000 * 60 * 5;

export default function(Donation) {

let activeDonationUpdateInterval = null;

const activeDonationCountCacheTTL = fiveMinutes;

const activeDonationCountCache = InMemoryCache(0, reportError);

const activeDonationsQuery$ = () =>

Donation.find$({

// eslint-disable-next-line no-undefined

where: { endDate: undefined }

}).map(instances => instances.length);

function cleanUp() {

if (activeDonationUpdateInterval) {

clearInterval(activeDonationUpdateInterval);

}

return;

}

process.on('exit', cleanUp);

Donation.on('dataSourceAttached', () => {

Donation.find$ = Observable.fromNodeCallback(Donation.find.bind(Donation));

Donation.findOne$ = Observable.fromNodeCallback(

Donation.findOne.bind(Donation)

);

seedTheCache()

.then(setupCacheUpdateInterval)

.catch(err => {

const errMsg = `Error caught seeding the cache: ${err.message}`;

err.message = errMsg;

reportError(err);

});

});

function seedTheCache() {

return new Promise((resolve, reject) =>

Observable.defer(activeDonationsQuery$).subscribe(count => {

log('activeDonator count: %d', count);

activeDonationCountCache.update(() => count);

return resolve();

}, reject)

);

}

function setupCacheUpdateInterval() {

activeDonationUpdateInterval = setInterval(

() =>

Observable.defer(activeDonationsQuery$).subscribe(

count => {

log('activeDonator count: %d', count);

return activeDonationCountCache.update(() => count);

},

err => {

const errMsg = `Error caught updating the cache: ${err.message}`;

err.message = errMsg;

reportError(err);

}

),

activeDonationCountCacheTTL

);

return null;

}

function getCurrentActiveDonationCount$() {

return Observable.of(activeDonationCountCache.get());

}

Donation.getCurrentActiveDonationCount$ = getCurrentActiveDonationCount$;

}