All: Add support for application plugins (#3257)

ReactNativeClient/lib/services/plugins/api/JoplinPlugins.ts

@@ -0,0 +1,51 @@
+import Plugin from '../Plugin';
+import Logger from 'lib/Logger';
+import { Script } from './types';
+
+/**
+ * This class provides access to plugin-related features.
+ */
+export default class JoplinPlugins {
+
+	private logger: Logger;
+	private plugin: Plugin;
+
+	constructor(logger:Logger, plugin:Plugin) {
+		this.logger = logger;
+		this.plugin = plugin;
+	}
+
+	/**
+	 * Registers a new plugin. This is the entry point when creating a plugin. You should pass a simple object with an `onStart` method to it.
+	 * That `onStart` method will be executed as soon as the plugin is loaded.
+	 *
+	 * ```typescript
+	 * joplin.plugins.register({
+	 *     onStart: async function() {
+	 *         // Run your plugin code here
+	 *     }
+	 * });
+	 * ```
+	 */
+	async register(script: Script) {
+		if (script.onStart) {
+			const startTime = Date.now();
+
+			this.logger.info(`Starting plugin: ${this.plugin.id}`);
+
+			// We don't use `await` when calling onStart because the plugin might be awaiting
+			// in that call too (for example, when opening a dialog on startup) so we don't
+			// want to get stuck here.
+			script.onStart({}).catch((error:any) => {
+				// For some reason, error thrown from the executed script do not have the type "Error"
+				// but are instead plain object. So recreate the Error object here so that it can
+				// be handled correctly by loggers, etc.
+				const newError:Error = new Error(error.message);
+				newError.stack = error.stack;
+				this.logger.error(`In plugin ${this.plugin.id}:`, newError);
+			}).then(() => {
+				this.logger.info(`Finished running onStart handler: ${this.plugin.id} (Took ${Date.now() - startTime}ms)`);
+			});
+		}
+	}
+}