[scraper] rework scraper scheduling and added seeders updating

scraper/scheduler/scraper.js

@@ -0,0 +1,25 @@
+const scrapers = require('./scrapers');
+const { delay, sequence } = require('../lib/promises')
+
+function scheduleScraping() {
+  return scrapers.forEach(provider => _continuousScrape(provider))
+}
+
+function scrapeAll() {
+  return sequence(scrapers.map(provider => () => _singleScrape(provider)))
+}
+
+async function _continuousScrape(provider) {
+  return _singleScrape(provider)
+      .then(() => delay(provider.scrapeInterval))
+      .then(() => _continuousScrape(provider))
+}
+
+async function _singleScrape(provider) {
+  return provider.scraper.scrape().catch(error => {
+    console.warn(`Failed ${provider.name} scraping due: `, error);
+    return Promise.resolve()
+  })
+}
+
+module.exports = { scheduleScraping, scrapeAll }