inventid/opengraph-cacher

import ElasticSearch from 'elasticsearch';
import moment from "moment-timezone";
import log, {INFO, WARN} from "./log";

const config = process.env.ES_URL ? {
    index : process.env.ES_INDEX,
    type : process.env.ES_TYPE,
    url : process.env.ES_URL,
    version : process.env.ES_VERSION,
    duration : parseInt(process.env.CACHE_IN_DAYS, 10) || 28
} : null;

if (config) {
    log(INFO, `Connected to Elasticsearch ${config.version} on ${config.url} using index '${config.index}' with type '${config.type}'. Using a cache of ${config.duration} days.`);
} else {
    log(INFO, `No Elasticsearch cache configured`);
}

const es = config ? new ElasticSearch.Client({
    host : config.url,
    apiVersion : config.version
}) : null;

function isCacheExpired(date) {
    return moment(date).add(config.duration, 'days').isBefore(moment(new Date()));
}

function isCacheEntryValid(response, url) {
    if (!response._source || !response._source._scrapedAt) {
        log(WARN, `Formatting error in cache, refetching ${url}`);
        return false;
    }
    if (isCacheExpired(response._source._scrapedAt)) {
        // cache is just expired
        log(INFO, `Getting new value for '${url}' since the cache expired`);
        return false;
    }
    return true;
}

async function get(urlToFetch) {
    if (!es) {
        return null;
    }
    const encodedUrl = encodeURI(urlToFetch);
    try {
        const response = await es.get({index : config.index, type : config.type, id : encodedUrl});
        if (isCacheEntryValid(response, urlToFetch)) {
            return {
                statusCode : !response._source.err ? 200 : 404,
                response : response._source
            };
        }
    } catch (e) {
        return null;
    }
}

async function save(url, resultData) {
    if (!es) {
        return null;
    }
    const encodedUrl = encodeURI(url);

    const saveData = {...resultData, _cacheResponse : true};
    try {
        await es.index({index : config.index, type : config.type, id : encodedUrl, body : saveData});
        return true;
    } catch (err) {
        if (err) {
            log(WARN, `Could not save value to cache due to error: ${err}`);
        }
        return false;
    }
}

async function remove(url) {
    if (!es) {
        return null;
    }
    const encodedUrl = encodeURI(url);
    return await es.delete({index : config.index, type : config.type, id : encodedUrl});
}

export {save, get, remove};