Quick jab at persistence in util/discord for server preferences, shou…

…ld refactor to a dao layer soon

util/discord.js

@@ -1,3 +1,31 @@
+const fs = require('fs')
+const _cacheFile = 'serverprefs.json'
+const debug = msg => console.log(`sprefs: ${msg}`)
+
+// Public constants for main bot.js process to watch for
+const LISTEN_KEY = `heylisten`
+const DEAFEN_KEY = `begonebot`
+
+// Live cache for fast access
+let serverPrefs = {}
+
+// Load old cache on init
+try {
+  serverPrefs = JSON.parse(fs.readFileSync(_cacheFile))
+} catch (error) {
+  debug(`if ENOENT this is totally ok - could not load JSON from old cache: ${error}`)
+  serverPrefs = {}
+}
+
+// Simple persistence layer
+function _savePreferences(){
+  try {
+    fs.writeFileSync(_cacheFile, JSON.stringify(serverPrefs, null, 2))
+  } catch(error) {
+    debug(`error saving cache: ${error}`)
+  }
+}
+
 // Relies on discord permission scheme: https://discord.com/developers/docs/topics/permissions
 exports.isPowerfulMember = function(discordJsMsg){
   const isAdmin = discordJsMsg.member.permissions.any(['ADMINISTRATOR', 'MANAGE_CHANNELS'])