Recommend JDK when missing (#115)

* Recommend JDK when missing

* Remove unused import

* Complete logic to search for JDK

Author: akaroml

.vscode/extensions.json

@@ -2,6 +2,5 @@
 	// See http://go.microsoft.com/fwlink/?LinkId=827846
 	// for the documentation about the extensions.json format
 	"recommendations": [
-		"eg2.tslint"
 	]
 }

package-lock.json

@@ -60,16 +60,22 @@
     "test": "npm run compile && node ./node_modules/vscode/bin/test"
   },
   "devDependencies": {
+    "@types/expand-tilde": "^2.0.0",
+    "@types/find-java-home": "^0.2.0",
     "@types/jquery": "^3.3.24",
     "@types/node": "^8.10.40",
+    "@types/path-exists": "^3.0.0",
     "@types/semver": "^5.5.0",
     "autoprefixer": "^8.5.1",
     "bootstrap": "^4.3.1",
     "css-loader": "^0.28.11",
+    "expand-tilde": "^2.0.2",
+    "find-java-home": "^0.2.0",
     "html-webpack-inline-source-plugin": "0.0.10",
     "html-webpack-plugin": "^3.2.0",
     "jquery": "^3.3.1",
     "node-sass": "^4.11.0",
+    "path-exists": "^3.0.0",
     "popper.js": "^1.14.7",
     "postcss-loader": "^2.1.5",
     "sass-loader": "^7.0.1",

package.json

@@ -9,6 +9,7 @@ import { initialize as initCommands } from "./commands";
 import { initialize as initRecommendations } from "./recommendation";
 import { initialize as initMisc, showReleaseNotesOnStart } from "./misc";
 import { showOverviewPageOnActivation, OverviewViewSerializer } from './overview';
+import { validateJavaRuntime } from "./java-runtime";
 
 export async function activate(context: vscode.ExtensionContext) {
   initializeTelemetry(context);
@@ -25,6 +26,10 @@ async function initializeExtension(operationId: string, context: vscode.Extensio
 
   await showOverviewPageOnActivation(context);
   await showReleaseNotesOnStart(context);
+
+  if (!await validateJavaRuntime()) {
+    vscode.commands.executeCommand("java.overview");
+  }
 }
 
 function initializeTelemetry(context: vscode.ExtensionContext) {

src/extension.ts

@@ -0,0 +1,79 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+import * as vscode from "vscode";
+import * as cp from "child_process";
+import * as path from "path";
+import * as expandTilde from "expand-tilde";
+import * as pathExists from "path-exists";
+import findJavaHome = require("find-java-home");
+
+const isWindows = process.platform.indexOf("win") === 0;
+const JAVAC_FILENAME = path.join("bin", "javac" + (isWindows ? ".exe" : "")) ;
+const JAVA_FILENAME = path.join("bin", "java" + (isWindows ? ".exe" : ""));
+
+async function getJavaVersion(javaHome: string | undefined): Promise<number> {
+  if (!javaHome) {
+    return Promise.resolve(0);
+  }
+
+  return new Promise<number>((resolve, reject) => {
+    cp.execFile(path.resolve(javaHome, JAVA_FILENAME),["-version"], {}, (err, stdout, stderr) => {
+      const regex = /version "(\d+)\.(\d+).*"/g;
+      const match = regex.exec(stderr);
+      if (!match) {
+        resolve(0);
+        return;
+      }
+
+      let major = parseInt(match[1]), minor = parseInt(match[2]);
+      if (major === 1) {
+        resolve(minor);
+      }
+
+      resolve(major);
+    });
+  });
+}
+
+async function findPossibleJdkInstallations(): Promise<{[location : string] : string | undefined}> {
+  return new Promise((resolve, reject) => {
+    const javaHomeEntries: {[location : string] : string | undefined} = {
+      "java.home": vscode.workspace.getConfiguration().get("java.home", undefined),
+      "JDK_HOME": process.env["JDK_HOME"],
+      "JAVA_HOME": process.env["JAVA_HOME"],
+      "java.other": undefined
+    };
+
+    findJavaHome({allowJre: false}, (err, home) => {
+      if (!err) {
+        javaHomeEntries.other = home;
+      }
+
+      resolve(javaHomeEntries);
+    });
+  });
+}
+
+async function validateJdkInstallation(javaHome: string | undefined) {
+  if (!javaHome) {
+    return false;
+  }
+
+  javaHome = expandTilde(javaHome);
+  return await pathExists(path.resolve(javaHome, JAVAC_FILENAME));
+}
+
+export async function validateJavaRuntime() {
+  const jdkEntries = await findPossibleJdkInstallations();
+  for (const key in jdkEntries) {
+    if (jdkEntries.hasOwnProperty(key)) {
+      const entry = jdkEntries[key];
+      if (await validateJdkInstallation(entry) && await getJavaVersion(entry) >= 8) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}