feat: Provide code actions to configure classpath (#684)

Author: jdneo

src/extension.ts

@@ -17,6 +17,7 @@ import { JavaExtGuideViewSerializer } from "./ext-guide";
 import { ClassPathConfigurationViewSerializer } from "./classpath/classpathConfigurationView";
 import { initFormatterSettingsEditorProvider } from "./formatter-settings";
 import { initRemoteProfileProvider } from "./formatter-settings/RemoteProfileProvider";
+import { CodeActionProvider } from "./providers/CodeActionProvider";
 
 export async function activate(context: vscode.ExtensionContext) {
   syncState(context);
@@ -33,6 +34,8 @@ async function initializeExtension(_operationId: string, context: vscode.Extensi
   initCommands(context);
   initRecommendations(context);
 
+  context.subscriptions.push(vscode.languages.registerCodeActionsProvider({scheme: "file", language: "java", pattern: "**/*.java"}, new CodeActionProvider()));
+
   // webview serializers to restore pages
   context.subscriptions.push(vscode.window.registerWebviewPanelSerializer("java.extGuide", new JavaExtGuideViewSerializer()));
   context.subscriptions.push(vscode.window.registerWebviewPanelSerializer("java.overview", new OverviewViewSerializer()));

src/providers/CodeActionProvider.ts

@@ -0,0 +1,30 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+import * as vscode from "vscode";
+
+// See: https://github.com/eclipse/eclipse.jdt.ls/blob/f0b68a8251b4971cac58eddc731227b66493ffc9/org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/handlers/BaseDiagnosticsHandler.java#L48
+const NOT_ON_CLASSPATH: string = "32";
+export class CodeActionProvider implements vscode.CodeActionProvider {
+    provideCodeActions(_document: vscode.TextDocument, _range: vscode.Range | vscode.Selection, context: vscode.CodeActionContext): vscode.CodeAction[] {
+        const classPathDiagnostics: vscode.Diagnostic[] = [];
+        for (const diagnostic of context.diagnostics) {
+            if (diagnostic.source === "Java" && diagnostic.code === NOT_ON_CLASSPATH) {
+                classPathDiagnostics.push(diagnostic);
+            }
+        }
+
+        if (classPathDiagnostics.length === 0) {
+            return [];
+        }
+
+        const codeAction: vscode.CodeAction = new vscode.CodeAction("Configure classpath");
+        codeAction.diagnostics = classPathDiagnostics;
+        codeAction.command = {
+            title: "Configure classpath",
+            command: "java.classpathConfiguration"
+        };
+        codeAction.kind = vscode.CodeActionKind.QuickFix;
+        return [codeAction];
+    }
+}