updating to use tpb cached torrent files

lib/cache.js

@@ -1,19 +1,45 @@
+
 const cacheManager = require('cache-manager');
+const mangodbStore = require('cache-manager-mongodb');
 
 const GLOBAL_KEY_PREFIX = 'stremio-torrentio';
 const IMDB_ID_PREFIX = `${GLOBAL_KEY_PREFIX}|imdb_id`;
 const METADATA_PREFIX = `${GLOBAL_KEY_PREFIX}|metadata`;
+const TORRENT_FILES_KEY_PREFIX = `stremio-tpb|files`;
 
 const GLOBAL_TTL = process.env.METADATA_TTL || 7 * 24 * 60 * 60; // 7 days
 
+const MONGO_URI = process.env.MONGODB_URI;
 
 const cache = initiateCache();
 
 function initiateCache() {
-  return cacheManager.caching({
-    store: 'memory',
-    ttl: GLOBAL_TTL
-  });
+  if (MONGO_URI) {
+    return cacheManager.caching({
+      store: mangodbStore,
+      uri: MONGO_URI,
+      options: {
+        collection: 'cacheManager',
+      },
+      ttl: GLOBAL_TTL,
+      ignoreCacheErrors: true
+    });
+  } else {
+    return cacheManager.caching({
+      store: 'memory',
+      ttl: GLOBAL_TTL
+    });
+  }
+}
+
+function retrieveTorrentFiles(infoHash) {
+  return cache.get(`${TORRENT_FILES_KEY_PREFIX}:${infoHash}`)
+      .then((results) => {
+        if (!results) {
+          throw new Error('No cached files found');
+        }
+        return results;
+      });
 }
 
 function cacheWrap(key, method, options) {
@@ -28,5 +54,5 @@ function cacheWrapMetadata(id, method) {
   return cacheWrap(`${METADATA_PREFIX}:${id}`, method, { ttl: GLOBAL_TTL });
 }
 
-module.exports = { cacheWrapImdbId, cacheWrapMetadata };
+module.exports = { cacheWrapImdbId, cacheWrapMetadata, retrieveTorrentFiles };