feat load existing agent (#9)

README.md

@@ -30,7 +30,7 @@ You can use ClippyJS directly in the browser using CDN:
 Install and import an agent:
 
 ```js
-import { initAgent } from "clippyjs";
+import { initAgent, loadExistingAgent } from "clippyjs";
 import { Clippy } from "clippyjs/agents";
 
 // Load and show the agent
@@ -106,6 +106,9 @@ agent.resume();
 
 // Remove the agent from the DOM
 agent.dispose();
+
+// Recover a previously created agent instance
+const sameAgent = loadExistingAgent(agent._el);
 ```
 
 ## Text-to-Speech

src/agent.ts

@@ -2,6 +2,9 @@ import Queue from "./queue.ts";
 import Animator from "./animator.ts";
 import Balloon from "./balloon.ts";
 
+const agentRegistry = new WeakMap<HTMLElement, Agent>();
+const activeAgents = new Set<Agent>();
+
 export interface AgentLoaders {
   agent: () => Promise<{ default: any }>;
   sound: () => Promise<{ default: any }>;
@@ -49,6 +52,8 @@ export default class Agent {
     });
 
     document.body.appendChild(this._el);
+    agentRegistry.set(this._el, this);
+    activeAgents.add(this);
 
     this._animator = new Animator(this._el, mapUrl, data, sounds);
     this._balloon = new Balloon(this._el);
@@ -700,6 +705,8 @@ export default class Agent {
     this._animator.dispose();
     this._balloon.dispose();
     this._queue.dispose();
+    activeAgents.delete(this);
+    agentRegistry.delete(this._el);
     this._el.remove();
   }
 
@@ -729,6 +736,21 @@ export async function initAgent(loaders: AgentLoaders): Promise<Agent> {
   return new Agent(map, data, sounds);
 }
 
+export function loadExistingAgent(element?: HTMLElement | null): Agent | undefined {
+  if (!element) {
+    return activeAgents.values().next().value;
+  }
+
+  let current: HTMLElement | null = element;
+  while (current) {
+    const agent = agentRegistry.get(current);
+    if (agent) {
+      return agent;
+    }
+    current = current.parentElement;
+  }
+}
+
 async function _loadSounds(loaders: AgentLoaders): Promise<Record<string, string>> {
   const audio = document.createElement("audio");
   const canPlayMp3 = !!audio.canPlayType && audio.canPlayType("audio/mp3") !== "";

src/index.ts

@@ -1 +1 @@
-export { initAgent } from "./agent.ts";
+export { initAgent, loadExistingAgent } from "./agent.ts";