add replay functionality

server/GameLog.js

@@ -0,0 +1,25 @@
+import fs from 'fs'
+
+const DATA_DIR = './../data'
+
+const log = (gameId, ...args) => {
+  const str = JSON.stringify(args)
+  fs.appendFileSync(`${DATA_DIR}/log_${gameId}.log`, str + "\n")
+}
+
+const get = (gameId) => {
+  const all = fs.readFileSync(`${DATA_DIR}/log_${gameId}.log`, 'utf-8')
+  return all.split("\n").filter(line => !!line).map((line) => {
+    try {
+      return JSON.parse(line)
+    } catch (e) {
+      console.log(line)
+      console.log(e)
+    }
+  })
+}
+
+export default {
+  log,
+  get,
+}