Further js refactoring

app/static/js/app/extensions/user-hub.js

@@ -0,0 +1,68 @@
+nopaque.app.extensions.UserHub = class UserHub extends EventTarget {
+  #data;
+
+  constructor(app) {
+    super();
+
+    this.app = app;
+
+    this.#data = {
+      users: {},
+      promises: {}
+    };
+  }
+
+  init() {
+    this.app.users.socket.on('patch', (patch) => {this.#onPatch(patch)});
+  }
+
+  add(userId) {
+    if (!(userId in this.#data.promises)) {
+      this.#data.promises[userId] = this.#add(userId);
+    }
+
+    return this.#data.promises[userId];
+  }
+
+  async #add(userId) {
+    await this.app.users.subscribe(userId);
+    this.#data.users[userId] = await this.app.users.get(userId);
+  }
+
+  async get(userId) {
+    await this.add(userId);
+    return this.#data.users[userId];
+  }
+
+  #onPatch(patch) {
+    // Filter patch to only include operations on users that are initialized
+    const filterRegExp = new RegExp(`^/users/(${Object.keys(this.#data.users).join('|')})`);
+    const filteredPatch = patch.filter(operation => filterRegExp.test(operation.path));
+
+    // Apply patch
+    jsonpatch.applyPatch(this.#data, filteredPatch);
+
+    // Notify event listeners
+    const patchEventa = new CustomEvent('patch', {detail: filteredPatch});
+    this.dispatchEvent(patchEventa);
+
+    // Notify event listeners. Event type: "patch *"
+    const patchEvent = new CustomEvent('patch *', {detail: filteredPatch});
+    this.dispatchEvent(patchEvent);
+
+    // Group patches by user id: {<user-id>: [op, ...], ...}
+    const patches = {};
+    const matchRegExp = new RegExp(`^/users/([A-Za-z0-9]+)`);
+    for (let operation of filteredPatch) {
+      const [match, userId] = operation.path.match(matchRegExp);
+      if (!(userId in patches)) {patches[userId] = [];}
+      patches[userId].push(operation);
+    }
+
+    // Notify event listeners. Event type: "patch <user-id>"
+    for (let [userId, patch] of Object.entries(patches)) {
+      const userPatchEvent = new CustomEvent(`patch ${userId}`, {detail: patch});
+      this.dispatchEvent(userPatchEvent);
+    }
+  }
+}