[add] json-watcher

src/lib/watchers/wotwizard/json-watcher.ts

@@ -0,0 +1,32 @@
+import {Conf, ConfWWMeta} from "../../types/conf";
+import {urlWatcher} from '../abstract/url-watcher'
+
+function handleLateness(confHead: ConfWWMeta, data: WWMetaJson) {
+  const diff = Math.round(Date.now()/1000 - data.now)
+  if (diff >= confHead.maxLate) {
+    throw `WWMeta.json is late by ${diff}s (>= ${confHead.maxLate})`
+  }
+}
+
+export function jsonWatcher(conf: Conf) {
+
+  const URL_PATH = '/WWMeta.json'
+
+  return async (confWWMeta: ConfWWMeta) => {
+
+    return urlWatcher(conf, async (data) => {
+      handleLateness(confWWMeta, data)
+    })({
+      name: `WWMeta.json watcher ${confWWMeta.address}`,
+      address: confWWMeta.address + URL_PATH,
+      frequency: confWWMeta.frequency
+    })
+  }
+}
+
+interface WWMetaJson {
+  dossNb: number
+  block: number
+  now: number
+  computation_duration: number
+}