[badge]: Badge decoration for active debug sessions

Fixes: #8303

Decorates the debug tab-bar with active debug sessions.

Co-authored-by: Kaiyue Pan <[email protected]>
Co-authored-by: Anas Shahid <[email protected]>

Signed-off-by: Kaiyue Pan <[email protected]>
Signed-off-by: Anas Shahid <[email protected]>

packages/debug/src/browser/debug-frontend-module.ts

@@ -57,6 +57,8 @@ import { MonacoEditorService } from '@theia/monaco/lib/browser/monaco-editor-ser
 import { DebugBreakpointWidget } from './editor/debug-breakpoint-widget';
 import { DebugInlineValueDecorator } from './editor/debug-inline-value-decorator';
 import { JsonSchemaContribution } from '@theia/core/lib/browser/json-schema-store';
+import { TabBarDecorator } from '@theia/core/lib/browser/shell/tab-bar-decorator';
+import { DebugTabBarDecorator, DebugSessionManagerGetter } from './debug-tab-bar-decorator';
 
 export default new ContainerModule((bind: interfaces.Bind) => {
     bind(DebugCallStackItemTypeKey).toDynamicValue(({ container }) =>
@@ -116,4 +118,8 @@ export default new ContainerModule((bind: interfaces.Bind) => {
     bindLaunchPreferences(bind);
 
     bind(DebugWatchManager).toSelf().inSingletonScope();
+    bind(FrontendApplicationContribution).toService(DebugTabBarDecorator);
+    bind(DebugTabBarDecorator).toSelf().inSingletonScope();
+    bind(DebugSessionManagerGetter).toDynamicValue(ctx => () => ctx.container.get(DebugSessionManager)).inSingletonScope();
+    bind(TabBarDecorator).toService(DebugTabBarDecorator);
 });

packages/debug/src/browser/debug-tab-bar-decorator.ts

@@ -0,0 +1,63 @@
+/********************************************************************************
+ * Copyright (C) 2020 Ericsson and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the Eclipse
+ * Public License v. 2.0 are satisfied: GNU General Public License, version 2
+ * with the GNU Classpath Exception which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ ********************************************************************************/
+
+import { injectable, inject } from 'inversify';
+import { Emitter, Event } from '@theia/core/lib/common/event';
+import { DebugSessionManager } from './debug-session-manager';
+import { TabBarDecorator } from '@theia/core/lib/browser/shell/tab-bar-decorator';
+import { FrontendApplication, FrontendApplicationContribution, Title, Widget } from '@theia/core/lib/browser';
+import { WidgetDecoration } from '@theia/core/lib/browser/widget-decoration';
+import { DisposableCollection } from '@theia/core/lib/common';
+
+export const DebugSessionManagerGetter = Symbol.for('DebugSessionManagerGetter');
+export type DebugSessionManagerGetter = () => DebugSessionManager;
+
+@injectable()
+export class DebugTabBarDecorator implements TabBarDecorator, FrontendApplicationContribution {
+
+    readonly id = 'theia-debug-tabbar-decorator';
+    protected readonly emitter = new Emitter<void>();
+
+    protected toDispose = new DisposableCollection();
+
+    @inject(DebugSessionManagerGetter)
+    protected readonly debugSessionManager: DebugSessionManagerGetter;
+
+    onStart(app: FrontendApplication): void {
+        this.toDispose.pushAll([
+            this.debugSessionManager().onDidStartDebugSession(() => this.fireDidChangeDecorations()),
+            this.debugSessionManager().onDidStopDebugSession(() => this.fireDidChangeDecorations()),
+            this.debugSessionManager().onDidDestroyDebugSession(() => this.fireDidChangeDecorations())
+        ]);
+    }
+
+    decorate(title: Title<Widget>): WidgetDecoration.Data[] {
+        if (title.owner.id === 'debug') {
+            const sessionCount = this.debugSessionManager().sessions.length;
+            return sessionCount > 0 ? [{ badge: sessionCount }] : [];
+        } else {
+            return [];
+        }
+    }
+
+    get onDidChangeDecorations(): Event<void> {
+        return this.emitter.event;
+    }
+
+    protected fireDidChangeDecorations(): void {
+        this.emitter.fire(undefined);
+    }
+}