Fetch crypto prices using cryptocompare api (includes retries and caching)

gsheets-crypto-price.js

// #loljavascript

var settings = {
  cacheExpiresSec: 10,
  extraParams: "&extraParams=your-id-here", // enter your id here
  retry: {
    factor: 2,
    max: 5,
    maxRetries: 5,
  },
  syms: [
    "BTC",
    "ETH",
    "LTC",
    "BCH",
    "XRP",
    "ADA",
    "VEN",
    "NEO",
    "IOT",
    "XRB"
  ]
};

function nowSeconds() {
  return Date.now() / 1000;
}

function retry(f) {
  function loop(count, delay) {
    try {
      return f();
    } catch (e) {
      console.error("Error encountered, retrying...");
      const newCount = count + 1;
      if (newCount >= settings.retry.maxRetries) {
        throw e;
      } else {
        const newDelay = Math.min(delay * settings.retry.factor, settings.retry.factor);
        return loop(newCount, newDelay);
      }
    }
  }
  return function() { return loop(0, 0.5); };
}

function cacheGetOrUpdate(key, f) {
  const cache = CacheService.getDocumentCache();
  const cached = cache.get(key)
  if (cached != null) {
    console.log("Found cached data for key: " + key);
    return JSON.parse(cached); // easiest way to encode type
  }
  const value = f();
  const valueJs = JSON.stringify(value); // encode type
  cache.put(key, valueJs, settings.cacheExpiresSec);
  return value;
}

function fetchJson(url) {
  return cacheGetOrUpdate("fetch:" + url, retry(function () {
    console.log("Fetching url " + url);
    const response = UrlFetchApp.fetch(url);
    const result = response.getContentText();
    console.log("Response: " + result);
    const js = JSON.parse(result);
    const isError = js.Response == "Error";
    if (isError) {
      console.error("Error when fetching url: " + url + ", " + js.Message);
      throw new Error(js.Message);
    }
    return js;
  }));
}

var dataEndpoint = "https://min-api.cryptocompare.com/data";

function fetchPrices(toSym) {
  const syms = settings.syms.join(",");
  const url = dataEndpoint + "/pricemulti?fsyms=" + syms + "&tsyms=" + toSym + settings.extraParams;
  return fetchJson(url)
}

function fetchPrice(sym, toSym) {
  return fetchPrices(toSym)[sym][toSym];
}

function fetchPriceHistorical(sym, toSym, durSec) {
  const ts = Math.floor(nowSeconds() - durSec);
  const url = dataEndpoint + "/pricehistorical?fsym=" + sym + "&tsyms=" + toSym + "&ts=" + ts + settings.extraParams;
  return fetchJson(url)[sym][toSym];
}

function fetchRateLimitSecond() {
  return fetchJson("https://min-api.cryptocompare.com/stats/rate/second/limit");
}

function fetchRateLimitMinute() {
  return fetchJson("https://min-api.cryptocompare.com/stats/rate/minute/limit");
}

function fetchRateLimitHour() {
  return fetchJson("https://min-api.cryptocompare.com/stats/rate/hour/limit");
}


function CRYPTOPRICE(sym, toSym) {
  return fetchPrice(sym, toSym);
}

function CRYPTOPRICEHOUR(sym, toSym) {
  return fetchPriceHistorical(sym, toSym, 60 * 60);
}

function CRYPTOPRICEDAY(sym, toSym) {
  return fetchPriceHistorical(sym, toSym, 60 * 60 * 24);
}

function CRYPTORATELIMITSECOND() {
  return JSON.stringify(fetchRateLimitSecond().CallsLeft);
}

function CRYPTORATELIMITMINUTE() {
  return JSON.stringify(fetchRateLimitMinute().CallsLeft);
}

function CRYPTORATELIMITHOUR() {
  return JSON.stringify(fetchRateLimitHour().CallsLeft);
}