NodeJS Plugin Runtime (#53)

plugin-runtime/src/PluginManager.ts

@@ -0,0 +1,61 @@
+import { existsSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import path from 'node:path';
+import { getAsset } from 'node:sea';
+import { PluginHandle } from './PluginHandle';
+import { loadPlugins, PluginInfo } from './plugins';
+
+export class PluginManager {
+  #handles: PluginHandle[] | null = null;
+  static #instance: PluginManager | null = null;
+  static #workerPath = path.join(tmpdir(), `index.${Math.random()}.worker.js`);
+
+  public static instance(): PluginManager {
+    if (PluginManager.#instance == null) {
+      PluginManager.#instance = new PluginManager();
+      PluginManager.#instance.plugins(); // Trigger workers to boot, as it takes a few seconds
+    }
+    return PluginManager.#instance;
+  }
+
+  async plugins(): Promise<PluginHandle[]> {
+    await this.#ensureWorkerForSea();
+    this.#handles = this.#handles ?? loadPlugins(PluginManager.#workerPath);
+    return this.#handles;
+  }
+
+  /**
+   * Copy worker JS asset to filesystem if we're in single-executable-application (SEA)
+   * @private
+   */
+  async #ensureWorkerForSea() {
+    if (existsSync(PluginManager.#workerPath)) return;
+
+    console.log('Writing worker file to', PluginManager.#workerPath);
+    writeFileSync(PluginManager.#workerPath, getAsset('worker', 'utf8'));
+  }
+
+  async #pluginsWithInfo(): Promise<{ plugin: PluginHandle; info: PluginInfo }[]> {
+    const plugins = await this.plugins();
+    return Promise.all(plugins.map(async (plugin) => ({ plugin, info: await plugin.getInfo() })));
+  }
+
+  async pluginsWith(capability: PluginInfo['capabilities'][0]): Promise<PluginHandle[]> {
+    return (await this.#pluginsWithInfo())
+      .filter((v) => v.info.capabilities.includes(capability))
+      .map((v) => v.plugin);
+  }
+
+  async plugin(name: string): Promise<PluginHandle | null> {
+    return (await this.#pluginsWithInfo()).find((v) => v.info.name === name)?.plugin ?? null;
+  }
+
+  async pluginOrThrow(name: string): Promise<PluginHandle> {
+    const plugin = await this.plugin(name);
+    if (plugin == null) {
+      throw new Error(`Failed to find plugin by ${name}`);
+    }
+
+    return plugin;
+  }
+}