implemented amplitude metrics (#1141)

app/user.js

@@ -9,6 +9,16 @@ import storage from './storage';
 
 const textEncoder = new TextEncoder();
 const textDecoder = new TextDecoder();
+const anonId = arrayToB64(crypto.getRandomValues(new Uint8Array(16)));
+
+async function hashId(id) {
+  const d = new Date();
+  const month = d.getUTCMonth();
+  const year = d.getUTCFullYear();
+  const encoded = textEncoder.encode(`${id}:${year}:${month}`);
+  const hash = await crypto.subtle.digest('SHA-256', encoded);
+  return arrayToB64(new Uint8Array(hash.slice(16)));
+}
 
 export default class User {
   constructor(storage) {
@@ -25,6 +35,14 @@ export default class User {
     this.storage.user = data;
   }
 
+  get firstAction() {
+    return this.storage.get('firstAction');
+  }
+
+  set firstAction(action) {
+    this.storage.set('firstAction', action);
+  }
+
   get avatar() {
     const defaultAvatar = assets.get('user.svg');
     if (this.info.avatarDefault) {
@@ -63,6 +81,14 @@ export default class User {
     return this.loggedIn ? LIMITS.MAX_DOWNLOADS : LIMITS.ANON.MAX_DOWNLOADS;
   }
 
+  async metricId() {
+    return this.loggedIn ? hashId(this.info.uid) : undefined;
+  }
+
+  async deviceId() {
+    return this.loggedIn ? hashId(this.storage.id) : hashId(anonId);
+  }
+
   async login(email) {
     const state = arrayToB64(crypto.getRandomValues(new Uint8Array(16)));
     storage.set('oauthState', state);