Implemented external API

This commit provides an external API that can be used by other
extensions to communicate with the base trace extension. The
current API provides a way to retrieve the active experiment as well as
fire events and register callbacks. This is the initial API and will be
further expanded in future commits.

Fixes #140

Signed-off-by: Neel Gondalia <ngondalia@blackberry.com>

Author: ngondalia

vscode-trace-extension/src/extension.ts

@@ -8,10 +8,13 @@ import { fileHandler, openOverviewHandler, resetZoomHandler, keyboardShortcutsHa
 import { TraceServerConnectionStatusService } from './utils/trace-server-status';
 import { updateTspClient } from './utils/tspClient';
 import { TraceExtensionLogger } from './utils/trace-extension-logger';
+import { ExternalAPI, traceExtensionAPI} from './external-api/external-api';
+import { TraceExtensionEventManager } from './utils/trace-extension-event-manager';
 
 export let traceLogger: TraceExtensionLogger;
+export const traceExtensionEventManager: TraceExtensionEventManager = new TraceExtensionEventManager();
 
-export function activate(context: vscode.ExtensionContext): void {
+export function activate(context: vscode.ExtensionContext): ExternalAPI {
     traceLogger = new TraceExtensionLogger('Trace Extension');
 
     const serverStatusBarItemPriority = 1;
@@ -69,6 +72,8 @@ export function activate(context: vscode.ExtensionContext): void {
     context.subscriptions.push(vscode.commands.registerCommand('traceViewer.shortcuts', () => {
         keyboardShortcutsHandler(context.extensionUri);
     }));
+
+    return traceExtensionAPI;
 }
 
 export function deactivate(): void {

vscode-trace-extension/src/external-api/external-api.ts

@@ -0,0 +1,43 @@
+/***************************************************************************************
+ * Copyright (c) 2023 BlackBerry Limited and others.
+ *
+ * Licensed under the MIT license. See LICENSE file in the project root for details.
+ ***************************************************************************************/
+import { Experiment } from 'tsp-typescript-client/lib/models/experiment';
+import { TraceViewerPanel } from '../trace-viewer-panel/trace-viewer-webview-panel';
+import { traceExtensionEventManager } from '../extension';
+
+export interface ExternalAPI {
+    getActiveExperiment(): Experiment | undefined,
+    fireEventEmitter(eventId: string, data: unknown): void,
+    getEventEmitterIds(): Iterable<string>
+}
+
+export const traceExtensionAPI: ExternalAPI = {
+    /**
+     * Retrieves the currently active experiement
+     *
+     * @returns Experiment if one is currently active, otherwise undefined
+     */
+    getActiveExperiment(): Experiment | undefined {
+        return TraceViewerPanel.getCurrentExperiment();
+    },
+
+    /**
+     * Fires the event emitter with the provided ID
+     *
+     * @param eventId ID of the event emitter to fire
+     * @param data event object
+     */
+    fireEventEmitter(eventId: string, data: unknown): void {
+        traceExtensionEventManager.fireEventEmitter(eventId, data);
+    },
+    /**
+     * Retrieves the list of event emitters registered with the Event Manager
+     *
+     * @returns list of event emitter IDs
+     */
+    getEventEmitterIds(): Iterable<string> {
+        return traceExtensionEventManager.getKeys();
+    }
+};

vscode-trace-extension/src/trace-explorer/opened-traces/trace-explorer-opened-traces-webview-provider.ts

@@ -8,6 +8,8 @@ import { TraceViewerPanel } from '../../trace-viewer-panel/trace-viewer-webview-
 import { TraceServerConnectionStatusService } from '../../utils/trace-server-status';
 import { getTraceServerUrl, getTspClientUrl } from '../../utils/tspClient';
 import { VSCODE_MESSAGES } from 'vscode-trace-common/lib/messages/vscode-message-manager';
+import { traceExtensionEventManager } from 'vscode-trace-extension/src/extension';
+import { SignalCallbackInterface } from '../../utils/trace-extension-event-manager';
 
 const JSONBig = JSONBigConfig({
     useNativeBigInt: true,
@@ -16,15 +18,20 @@ const JSONBig = JSONBigConfig({
 export class TraceExplorerOpenedTracesViewProvider implements vscode.WebviewViewProvider {
 
 	public static readonly viewType = 'traceExplorer.openedTracesView';
+	public static readonly eventEmitter_id_callback = this.viewType + '.register_callback';
 
 	private _view?: vscode.WebviewView;
 	private _disposables: vscode.Disposable[] = [];
 	private _selectedExperiment: Experiment | undefined;
 
-   	constructor(
+	constructor(
 		private readonly _extensionUri: vscode.Uri,
 		private readonly _statusService: TraceServerConnectionStatusService,
-	) {}
+	) {
+	    traceExtensionEventManager.registerEventEmitter(TraceExplorerOpenedTracesViewProvider.eventEmitter_id_callback);
+	    traceExtensionEventManager.onEvent(TraceExplorerOpenedTracesViewProvider.eventEmitter_id_callback,
+	        (data: unknown) => {this.registerCallbackForSignal(data as SignalCallbackInterface);});
+	}
 
 	private _onOpenedTracesWidgetActivated = (experiment: Experiment): void => this.doHandleTracesWidgetActivatedSignal(experiment);
 	private _onOpenedTracesChanged = (payload: OpenedTracesUpdatedSignalPayload): void => this.doHandleOpenedTracesChangedSignal(payload);
@@ -52,6 +59,16 @@ export class TraceExplorerOpenedTracesViewProvider implements vscode.WebviewView
 	    }
 	}
 
+	protected registerCallbackForSignal(data: SignalCallbackInterface): void {
+		this._view?.webview.onDidReceiveMessage(message => {
+		    switch (message.command) {
+		    case data.signal: {
+		        data.callback(message);
+		    }
+		    }
+		});
+	}
+
 	protected doHandleExperimentSelectedSignal(experiment: Experiment | undefined): void {
 	    if (this._view) {
 	        this._selectedExperiment = experiment;

vscode-trace-extension/src/trace-viewer-panel/trace-viewer-webview-panel.ts

@@ -78,6 +78,10 @@ export class TraceViewerPanel {
 		TraceViewerPanel.currentPanel?.resetZoom();
 	}
 
+	public static getCurrentExperiment(): Experiment | undefined {
+	    return TraceViewerPanel.currentPanel?._experiment;
+	}
+
 	private static async saveTraceCsv(csvData: string, defaultFileName: string) {
 	    const saveDialogOptions = {
 	        defaultUri: vscode.workspace.workspaceFolders

vscode-trace-extension/src/utils/trace-extension-event-manager.ts

@@ -0,0 +1,69 @@
+/***************************************************************************************
+ * Copyright (c) 2023 BlackBerry Limited and others.
+ *
+ * Licensed under the MIT license. See LICENSE file in the project root for details.
+ ***************************************************************************************/
+import * as vscode from 'vscode';
+
+export interface SignalCallbackInterface {
+    signal: string,
+    callback: (data: unknown) => void
+}
+
+/**
+ *  Manages the events for the trace extension
+ */
+export class TraceExtensionEventManager {
+    private eventEmitterMap: Map<string, vscode.EventEmitter<unknown>>;
+    constructor() {
+        this.eventEmitterMap = new Map<string, vscode.EventEmitter<unknown>>();
+    }
+
+    /**
+     * Get the event emitter registered based on Id
+     *
+     * @param id event emitter Id
+     * @returns event emitter for the given id if exists, otherwise undefined
+     */
+    getEventEmitter(id: string): vscode.EventEmitter<unknown> | undefined {
+        return this.eventEmitterMap.get(id);
+    }
+
+    /**
+     * Register an event emitter with the provided Id
+     *
+     * @param id event emitter Id
+     */
+    registerEventEmitter(id: string): void {
+        this.eventEmitterMap.set(id, new vscode.EventEmitter<unknown>());
+    }
+
+    /**
+     * Fire the event emitter with the provided Id
+     *
+     * @param id event emitter Id
+     * @param data event object
+     */
+    fireEventEmitter(id: string, data: unknown): void {
+        this.getEventEmitter(id)?.fire(data);
+    }
+
+    /**
+     * Retrieves an iterable event emitter Ids
+     *
+     * @returns Iterable Event Ids
+     */
+    getKeys(): Iterable<string> {
+        return this.eventEmitterMap.keys();
+    }
+
+    /**
+     * Attaches a listener for an event based on the event emitter id
+     *
+     * @param id event emitter Id
+     * @param callback function to call when the event is triggered
+     */
+    onEvent(id: string, callback: (data: unknown) => void): void {
+        this.getEventEmitter(id)?.event(callback);
+    }
+}