src/goEnvironmentStatus.ts - vscode-go - Git at Google

 /*---------------------------------------------------------
  * Copyright 2020 The Go Authors. All rights reserved.
  * Licensed under the MIT License. See LICENSE in the project root for license information.
  *--------------------------------------------------------*/

 'use strict';

 import cp = require('child_process');
 import fs = require('fs');
 import moment = require('moment');
 import os = require('os');
 import path = require('path');
 import { promisify } from 'util';
 import vscode = require('vscode');
 import WebRequest = require('web-request');
 import { toolInstallationEnvironment } from './goEnv';
 import { logVerbose } from './goLogging';
 import { addGoStatus, goEnvStatusbarItem, outputChannel, removeGoStatus } from './goStatus';
 import { getFromGlobalState, getFromWorkspaceState, updateGlobalState, updateWorkspaceState } from './stateUtils';
 import {
 	getBinPath, getCheckForToolsUpdatesConfig, getGoConfig, getGoVersion,
 	getTempFilePath, GoVersion, rmdirRecursive } from './util';
 import {
 	correctBinname,
 	executableFileExists,
 	fixDriveCasingInWindows,
 	getBinPathFromEnvVar,
 	getCurrentGoRoot,
 	pathExists
 } from './utils/pathUtils';

 export class GoEnvironmentOption {
 	public static fromQuickPickItem({ description, label }: vscode.QuickPickItem): GoEnvironmentOption {
 		return new GoEnvironmentOption(description, label);
 	}

 	constructor(public binpath: string, public label: string) {}

 	public toQuickPickItem(): vscode.QuickPickItem {
 		return {
 			label: this.label,
 			description: this.binpath,
 		};
 	}
 }

 export let terminalCreationListener: vscode.Disposable;

 let environmentVariableCollection: vscode.EnvironmentVariableCollection;
 export function setEnvironmentVariableCollection(env: vscode.EnvironmentVariableCollection) {
 	environmentVariableCollection = env;
 }

 // QuickPickItem names for chooseGoEnvironment menu.
 const CLEAR_SELECTION = '$(clear-all) Clear selection';
 const CHOOSE_FROM_FILE_BROWSER = '$(folder) Choose from file browser';

 /**
  * Present a command palette menu to the user to select their go binary
  */
 export async function chooseGoEnvironment() {
 	if (!goEnvStatusbarItem) {
 		return;
 	}

 	// if there is no workspace, show GOROOT with message
 	if (!vscode.workspace.name) {
 		vscode.window.showInformationMessage(`GOROOT: ${getCurrentGoRoot()}. Switching Go version is not yet supported in single-file mode.`);
 		return;
 	}

 	// fetch default go and uninstalled go versions
 	let defaultOption: GoEnvironmentOption;
 	let uninstalledOptions: GoEnvironmentOption[];
 	let goSDKOptions: GoEnvironmentOption[];
 	try {
 		[defaultOption, uninstalledOptions, goSDKOptions] = await Promise.all([
 			getDefaultGoOption(),
 			fetchDownloadableGoVersions(),
 			getSDKGoOptions()
 		]);
 	} catch (e) {
 		vscode.window.showErrorMessage(e.message);
 		return;
 	}

 	// create quick pick items
 	const uninstalledQuickPicks = uninstalledOptions.map((op) => op.toQuickPickItem());
 	const defaultQuickPick = defaultOption ? [ defaultOption.toQuickPickItem() ] : [];
 	const goSDKQuickPicks = goSDKOptions.map((op) => op.toQuickPickItem());

 	// dedup options by eliminating duplicate paths (description)
 	const clearOption: vscode.QuickPickItem = { label: CLEAR_SELECTION };
 	const filePickerOption: vscode.QuickPickItem = {
 		label: CHOOSE_FROM_FILE_BROWSER,
 		description: 'Select the go binary to use',
 	};
 	// TODO(hyangah): Add separators after clearOption if github.com/microsoft/vscode#74967 is resolved.
 	const options = [filePickerOption, clearOption, ...defaultQuickPick, ...goSDKQuickPicks, ...uninstalledQuickPicks]
 		.reduce((opts, nextOption) => {
 			if (opts.find((op) => op.description === nextOption.description || op.label === nextOption.label)) {
 				return opts;
 			}
 			return [...opts, nextOption];
 		}, [] as vscode.QuickPickItem[]);

 	// get user's selection, return if none was made
 	const selection = await vscode.window.showQuickPick<vscode.QuickPickItem>(options);
 	if (!selection) {
 		return;
 	}

 	// update currently selected go
 	try {
 		await setSelectedGo(GoEnvironmentOption.fromQuickPickItem(selection));
 	} catch (e) {
 		vscode.window.showErrorMessage(e.message);
 	}
 }

 /**
  * update the selected go path and label in the workspace state
  */
 export async function setSelectedGo(goOption: GoEnvironmentOption, promptReload = true): Promise<boolean> {
 	if (!goOption) {
 		return false;
 	}

 	// if the selected go version is not installed, install it
 	if (goOption.binpath?.startsWith('go get')) {
 		// start a loading indicator
 		await downloadGo(goOption);
 	} else if (goOption.label === CLEAR_SELECTION) {
 		if (!getSelectedGo()) {
 			return false;  // do nothing.
 		}
 		await updateWorkspaceState('selectedGo', undefined);
 	} else if (goOption.label === CHOOSE_FROM_FILE_BROWSER) {
 		const currentGOROOT = getCurrentGoRoot();
 		const defaultUri = currentGOROOT ? vscode.Uri.file(path.join(currentGOROOT, 'bin')) : undefined;

 		const newGoUris = await vscode.window.showOpenDialog({
 			canSelectFiles: true,
 			canSelectFolders: false,
 			canSelectMany: false,
 			defaultUri,
 		});
 		if (!newGoUris || newGoUris.length !== 1) {
 			return false;
 		}
 		const newGoBin = fixDriveCasingInWindows(newGoUris[0].fsPath);
 		const oldGoBin = fixDriveCasingInWindows(path.join(defaultUri.fsPath, correctBinname('go')));

 		if (newGoBin === oldGoBin) {
 			return false;
 		}
 		if (!executableFileExists(newGoBin)) {
 			vscode.window.showErrorMessage(`${newGoBin} is not an executable`);
 			return false;
 		}
 		const newGo = await getGoVersion(newGoBin);
 		if (!newGo || !newGo.isValid() ) {
 			vscode.window.showErrorMessage(`failed to get "${newGoBin} version", invalid Go binary`);
 			return false;
 		}
 		await updateWorkspaceState('selectedGo', new GoEnvironmentOption(newGo.binaryPath, formatGoVersion(newGo)));
 	} else {
 		// check that the given binary is not already at the beginning of the PATH
 		const go = await getGoVersion();
 		if (!!go && (go.binaryPath === goOption.binpath || 'Go ' + go.format() === goOption.label)) {
 			return false;
 		}
 		await updateWorkspaceState('selectedGo', goOption);
 	}
 	// prompt the user to reload the window.
 	// promptReload defaults to true and should only be false for tests.
 	if (promptReload) {
 		const choice = await vscode.window.showInformationMessage('Please reload the window to finish applying Go version changes.', 'Reload Window');
 		if (choice === 'Reload Window') {
 			await vscode.commands.executeCommand('workbench.action.reloadWindow');
 		}
 	}
 	goEnvStatusbarItem.text = 'Go: reload required';
 	goEnvStatusbarItem.command = 'workbench.action.reloadWindow';

 	return true;
 }

 // downloadGo downloads the specified go version available in dl.golang.org.
 async function downloadGo(goOption: GoEnvironmentOption) {
 	const execFile = promisify(cp.execFile);
 	await vscode.window.withProgress({
 		title: `Downloading ${goOption.label}`,
 		location: vscode.ProgressLocation.Notification,
 	}, async () => {
 		outputChannel.show();
 		outputChannel.clear();

 		outputChannel.appendLine('Finding Go executable for downloading');
 		const goExecutable = getBinPath('go');
 		if (!goExecutable) {
 			outputChannel.appendLine('Could not find Go executable.');
 			throw new Error('Could not find Go tool.');
 		}

 		// TODO(bcloud) dedup repeated logic below which comes from
 		// https://github.com/golang/vscode-go/blob/bc23fa854192d04200c8e4f74dca18d2c3021b46/src/goInstallTools.ts#L184
 		// Install tools in a temporary directory, to avoid altering go.mod files.
 		const mkdtemp = promisify(fs.mkdtemp);
 		const toolsTmpDir = await mkdtemp(getTempFilePath('go-tools-'));
 		let tmpGoModFile: string;

 		// Write a temporary go.mod file to avoid version conflicts.
 		tmpGoModFile = path.join(toolsTmpDir, 'go.mod');
 		const writeFile = promisify(fs.writeFile);
 		await writeFile(tmpGoModFile, 'module tools');

 		// use the current go executable to download the new version
 		const env = {
 			...toolInstallationEnvironment(),
 			GO111MODULE: 'on',
 		};
 		const [, ...args] = goOption.binpath.split(' ');
 		outputChannel.appendLine(`Running ${goExecutable} ${args.join(' ')}`);
 		try {
 			await execFile(goExecutable, args, {
 				env,
 				cwd: toolsTmpDir,
 			});
 		} catch (getErr) {
 			outputChannel.appendLine(`Error finding Go: ${getErr}`);
 			throw new Error('Could not find Go version.');
 		}

 		// run `goX.X download`
 		const newExecutableName = args[1].split('/')[2];
 		const goXExecutable = getBinPath(newExecutableName);
 		outputChannel.appendLine(`Running: ${goXExecutable} download`);
 		try {
 			await execFile(goXExecutable, ['download'], { env, cwd: toolsTmpDir });
 		} catch (downloadErr) {
 			outputChannel.appendLine(`Error finishing installation: ${downloadErr}`);
 			throw new Error('Could not download Go version.');
 		}

 		outputChannel.appendLine('Finding newly downloaded Go');
 		const sdkPath = path.join(os.homedir(), 'sdk');
 		if (!await pathExists(sdkPath)) {
 			outputChannel.appendLine(`SDK path does not exist: ${sdkPath}`);
 			throw new Error(`SDK path does not exist: ${sdkPath}`);
 		}

 		const readdir = promisify(fs.readdir);
 		const subdirs = await readdir(sdkPath);
 		const dir = subdirs.find((subdir) => subdir === newExecutableName);
 		if (!dir) {
 			outputChannel.appendLine('Could not find newly downloaded Go');
 			throw new Error('Could not install Go version.');
 		}

 		const binpath = path.join(sdkPath, dir, 'bin', correctBinname('go'));
 		const newOption = new GoEnvironmentOption(binpath, goOption.label);
 		await updateWorkspaceState('selectedGo', newOption);

 		// remove tmp directories
 		outputChannel.appendLine('Cleaning up...');
 		rmdirRecursive(toolsTmpDir);
 		outputChannel.appendLine('Success!');
 	});
 }

 // PATH value cached before addGoRuntimeBaseToPath modified.
 let defaultPathEnv = '';

 function pathEnvVarName(): string|undefined {
 	if (process.env.hasOwnProperty('PATH')) {
 		return 'PATH';
 	} else if (process.platform === 'win32' && process.env.hasOwnProperty('Path')) {
 		return 'Path';
 	} else {
 		return;
 	}
 }

 // addGoRuntimeBaseToPATH adds the given path to the front of the PATH environment variable.
 // It removes duplicates.
 // TODO: can we avoid changing PATH but utilize toolExecutionEnv?
 export function addGoRuntimeBaseToPATH(newGoRuntimeBase: string) {
 	if (!newGoRuntimeBase) {
 		return;
 	}
 	const pathEnvVar = pathEnvVarName();
 	if (!pathEnvVar) {
 		logVerbose(`couldn't find PATH property in process.env`);
 		return;
 	}

 	if (!defaultPathEnv) {  // cache the default value
 		defaultPathEnv = <string>process.env[pathEnvVar];
 	}

 	logVerbose(`addGoRuntimeBase(${newGoRuntimeBase}) when PATH=${defaultPathEnv}`);

 	// calling this multiple times will override the previous value.
 	// environmentVariableCollection.clear();
 	if (process.platform !== 'darwin') {
 		environmentVariableCollection?.prepend(pathEnvVar, newGoRuntimeBase + path.delimiter);
 	} else {
 		// When '-l' or '--login' flags are set, the terminal will invoke a login
 		// shell again and the paths from the user's login shell will be prepended
 		// again in front of the path mutated by environmentVariableCollection API.
 		// That causes the mutated path to be ignored which we don't want.
 		// So, let's not use the API if those flags are set, but go with the old way
 		// -- i.e. send the export shell command.
 		// See the open issue and the discussion here:
 		// https://github.com/microsoft/vscode/issues/99878#issuecomment-642808852
 		const terminalShellArgs = <string[]>(
 		vscode.workspace.getConfiguration('terminal.integrated.shellArgs').get('osx') || []);
 		if (terminalShellArgs.includes('-l') || terminalShellArgs.includes('--login')) {
 			for (const term of vscode.window.terminals) {
 				updateIntegratedTerminal(term);
 			}
 			if (!terminalCreationListener) {
 				terminalCreationListener = vscode.window.onDidOpenTerminal(updateIntegratedTerminal);
 			}
 		} else {
 			environmentVariableCollection?.prepend(pathEnvVar, newGoRuntimeBase + path.delimiter);
 		}
 	}

 	let pathVars = defaultPathEnv.split(path.delimiter);
 	pathVars = pathVars.filter((p) => p !== newGoRuntimeBase);
 	pathVars.unshift(newGoRuntimeBase);
 	process.env[pathEnvVar] = pathVars.join(path.delimiter);
 }

 // Clear terminal PATH environment modification previously installed
 // using addGoRuntimeBaseToPATH.
 // In particular, changes to vscode.EnvironmentVariableCollection persist across
 // vscode sessions, so when we decide not to mutate PATH, we need to clear
 // the preexisting changes.
 export function clearGoRuntimeBaseFromPATH() {
 	if (terminalCreationListener) {
 		const l = terminalCreationListener;
 		terminalCreationListener = undefined;
 		l.dispose();
 	}
 	const pathEnvVar = pathEnvVarName();
 	if (!pathEnvVar) {
 		logVerbose(`couldn't find PATH property in process.env`);
 		return;
 	}
 	environmentVariableCollection?.delete(pathEnvVar);
 }

 /**
  * update the PATH variable in the given terminal to default to the currently selected Go
  */
 export async function updateIntegratedTerminal(terminal: vscode.Terminal): Promise<void> {
 	if (!terminal) { return; }
 	const gorootBin = path.join(getCurrentGoRoot(), 'bin');
 	const defaultGoRuntime = getBinPathFromEnvVar('go', defaultPathEnv, false);
 	if (defaultGoRuntime && gorootBin === path.dirname(defaultGoRuntime)) {
 		return;
 	}

 	// append the goroot to the beginning of the PATH so it takes precedence
 	// TODO: add support for more terminal names
 	// this assumes all non-windows shells are bash-like.
 	if (terminal.name.toLowerCase() === 'cmd') {
 		terminal.sendText(`set PATH=${gorootBin};%Path%`, true);
 		terminal.sendText('cls');
 	} else if (['powershell', 'pwsh'].includes(terminal.name.toLowerCase())) {
 		terminal.sendText(`$env:Path="${gorootBin};$env:Path"`, true);
 		terminal.sendText('clear');
 	} else if (terminal.name.toLowerCase() === 'fish') {
 		terminal.sendText(`set -gx PATH ${gorootBin} $PATH`);
 		terminal.sendText('clear');
 	} else if (['bash', 'sh', 'zsh', 'ksh'].includes(terminal.name.toLowerCase())) {
 		terminal.sendText(`export PATH=${gorootBin}:$PATH`, true);
 		terminal.sendText('clear');
 	}
 }

 /**
  * retreive the current selected Go from the workspace state
  */
 export function getSelectedGo(): GoEnvironmentOption {
 	return getFromWorkspaceState('selectedGo');
 }

 /**
  * return reference to the statusbar item
  */
 export function getGoEnvironmentStatusbarItem(): vscode.StatusBarItem {
 	return goEnvStatusbarItem;
 }

 export function formatGoVersion(version?: GoVersion): string {
 	if (!version || !version.isValid()) {
 		return `Go (unknown)`;
 	}
 	const versionStr = version.format(true);
 	const versionWords = versionStr.split(' ');
 	if (versionWords.length > 1 && versionWords[0] === 'devel') {
 		// Go devel +hash
 		return `Go ${versionWords[1]}`;
 	} else {
 		return `Go ${versionWords[0]}`;
 	}
 }

 async function getSDKGoOptions(): Promise<GoEnvironmentOption[]> {
 	// get list of Go versions
 	const sdkPath = path.join(os.homedir(), 'sdk');

 	if (!await pathExists(sdkPath)) {
 		return [];
 	}
 	const readdir = promisify(fs.readdir);
 	const subdirs = await readdir(sdkPath);
 	// the dir happens to be the version, which will be used as the label
 	// the path is assembled and used as the description
 	return subdirs.map((dir: string) =>
 		new GoEnvironmentOption(
 			path.join(sdkPath, dir, 'bin', correctBinname('go')),
 			dir.replace('go', 'Go '),
 		)
 	);
 }

 export async function getDefaultGoOption(): Promise<GoEnvironmentOption|undefined> {
 	// make goroot default to go.goroot
 	const goroot = getCurrentGoRoot();
 	if (!goroot) {
 		return undefined;
 	}

 	// set Go version and command
 	const version = await getGoVersion();
 	return new GoEnvironmentOption(
 		path.join(goroot, 'bin', correctBinname('go')),
 		formatGoVersion(version),
 	);
 }

 /**
  * make a web request to get versions of Go
  */
 interface GoVersionWebResult {
 	version: string;
 	stable: boolean;
 	files: {
 		filename: string;
 		os: string;
 		arch: string;
 		version: string;
 		sha256: string;
 		size: number;
 		kind: string;
 	}[];
 }
 async function fetchDownloadableGoVersions(): Promise<GoEnvironmentOption[]> {
 	// fetch information about what Go versions are available to install
 	let webResults;
 	try {
 		webResults = await WebRequest.json<GoVersionWebResult[]>('https://golang.org/dl/?mode=json');
 	} catch (error) {
 		return [];
 	}

 	if (!webResults) {
 		return [];
 	}
 	// turn the web result into GoEnvironmentOption model
 	return webResults.reduce((opts, result: GoVersionWebResult) => {
 		// TODO: allow downloading from different sites
 		const dlPath = `go get golang.org/dl/${result.version}`;
 		const label = result.version.replace('go', 'Go ');
 		return [...opts, new GoEnvironmentOption(dlPath, label)];
 	}, []);
 }

 export const latestGoVersionKey = 'latestGoVersions';
 const oneday = 60 * 60 * 24 * 1000; // 24 hours in milliseconds

 export async function getLatestGoVersions(): Promise<GoEnvironmentOption[]> {
 	const timeout = oneday;
 	const now = moment.now();

 	let results: GoEnvironmentOption[];

 	// Check if we can use cached results
 	const cachedResults = getFromGlobalState(latestGoVersionKey);
 	if (cachedResults && now - cachedResults.timestamp < timeout) {
 		results = cachedResults.goVersions;
 	} else {
 		// fetch the latest supported Go versions
 		try {
 			// fetch the latest Go versions and cache the results
 			results = await fetchDownloadableGoVersions();
 			await updateGlobalState(latestGoVersionKey, {
 				timestamp: now,
 				goVersions: results,
 			});
 		} catch (e) {
 			// hardcode the latest versions of Go in case golang.dl is unavailable
 			results = [
 				new GoEnvironmentOption('go get golang.org/dl/go1.15', 'Go 1.15'),
 				new GoEnvironmentOption('go get golang.org/dl/go1.14.7', 'Go 1.14.7'),
 			];
 		}
 	}

 	return results;
 }

 const dismissedGoVersionUpdatesKey = 'dismissedGoVersionUpdates';

 export async function offerToInstallLatestGoVersion() {
 	const goConfig = getGoConfig();
 	const checkForUpdate = getCheckForToolsUpdatesConfig(goConfig);
 	if (checkForUpdate === 'off' || checkForUpdate === 'local') {  // 'proxy' or misconfiguration..
 		return;
 	}

 	let options = await getLatestGoVersions();

 	// filter out Go versions the user has already dismissed
 	let dismissedOptions: GoEnvironmentOption[];
 	dismissedOptions = await getFromGlobalState(dismissedGoVersionUpdatesKey);
 	if (!!dismissedOptions) {
 		options = options.filter((version) => !dismissedOptions.find((x) => x.label === version.label));
 	}

 	// compare to current go version.
 	const currentVersion = await getGoVersion();
 	if (!!currentVersion) {
 		options = options.filter((version) => currentVersion.lt(version.label));
 	}

 	// notify user that there is a newer version of Go available
 	if (options.length > 0) {
 		addGoStatus('Go Update Available', 'go.promptforgoinstall', 'A newer version of Go is available');
 		vscode.commands.registerCommand('go.promptforgoinstall', () => {
 			const download = {
 				title: 'Download',
 				async command() {
 					await vscode.env.openExternal(vscode.Uri.parse(`https://golang.org/dl/`));
 				}
 			};

 			const neverAgain = {
 				title: `Don't Show Again`,
 				async command() {
 					// mark these versions as seen
 					dismissedOptions = await getFromGlobalState(dismissedGoVersionUpdatesKey);
 					if (!dismissedOptions) {
 						dismissedOptions = [];
 					}
 					options.forEach((version) => {
 						dismissedOptions.push(version);
 					});
 					await updateGlobalState(dismissedGoVersionUpdatesKey, dismissedOptions);
 				}
 			};

 			let versionsText: string;
 			if (options.length > 1) {
 				versionsText = `${options.map((x) => x.label)
 					.reduce((prev, next) => {
 						return prev + ' and ' + next;
 					})} are available`;
 			} else {
 				versionsText = `${options[0].label} is available`;
 			}

 			vscode.window
 				.showInformationMessage(
 					`${versionsText}. You are currently using ${formatGoVersion(currentVersion)}.`,
 					download,
 					neverAgain
 				)
 				.then((selection) => {
 					removeGoStatus();
 					selection.command();
 				});
 		});
 	}
 }
	/*---------------------------------------------------------
	* Copyright 2020 The Go Authors. All rights reserved.
	* Licensed under the MIT License. See LICENSE in the project root for license information.
	--------------------------------------------------------/

	'use strict';

	import cp = require('child_process');
	import fs = require('fs');
	import moment = require('moment');
	import os = require('os');
	import path = require('path');
	import { promisify } from 'util';
	import vscode = require('vscode');
	import WebRequest = require('web-request');
	import { toolInstallationEnvironment } from './goEnv';
	import { logVerbose } from './goLogging';
	import { addGoStatus, goEnvStatusbarItem, outputChannel, removeGoStatus } from './goStatus';
	import { getFromGlobalState, getFromWorkspaceState, updateGlobalState, updateWorkspaceState } from './stateUtils';
	import {
	getBinPath, getCheckForToolsUpdatesConfig, getGoConfig, getGoVersion,
	getTempFilePath, GoVersion, rmdirRecursive } from './util';
	import {
	correctBinname,
	executableFileExists,
	fixDriveCasingInWindows,
	getBinPathFromEnvVar,
	getCurrentGoRoot,
	pathExists
	} from './utils/pathUtils';

	export class GoEnvironmentOption {
	public static fromQuickPickItem({ description, label }: vscode.QuickPickItem): GoEnvironmentOption {
	return new GoEnvironmentOption(description, label);
	}

	constructor(public binpath: string, public label: string) {}

	public toQuickPickItem(): vscode.QuickPickItem {
	return {
	label: this.label,
	description: this.binpath,
	};
	}
	}

	export let terminalCreationListener: vscode.Disposable;

	let environmentVariableCollection: vscode.EnvironmentVariableCollection;
	export function setEnvironmentVariableCollection(env: vscode.EnvironmentVariableCollection) {
	environmentVariableCollection = env;
	}

	// QuickPickItem names for chooseGoEnvironment menu.
	const CLEAR_SELECTION = '$(clear-all) Clear selection';
	const CHOOSE_FROM_FILE_BROWSER = '$(folder) Choose from file browser';

	/**
	* Present a command palette menu to the user to select their go binary
	*/
	export async function chooseGoEnvironment() {
	if (!goEnvStatusbarItem) {
	return;
	}

	// if there is no workspace, show GOROOT with message
	if (!vscode.workspace.name) {
	vscode.window.showInformationMessage(`GOROOT: ${getCurrentGoRoot()}. Switching Go version is not yet supported in single-file mode.`);
	return;
	}

	// fetch default go and uninstalled go versions
	let defaultOption: GoEnvironmentOption;
	let uninstalledOptions: GoEnvironmentOption[];
	let goSDKOptions: GoEnvironmentOption[];
	try {
	[defaultOption, uninstalledOptions, goSDKOptions] = await Promise.all([
	getDefaultGoOption(),
	fetchDownloadableGoVersions(),
	getSDKGoOptions()
	]);
	} catch (e) {
	vscode.window.showErrorMessage(e.message);
	return;
	}

	// create quick pick items
	const uninstalledQuickPicks = uninstalledOptions.map((op) => op.toQuickPickItem());
	const defaultQuickPick = defaultOption ? [ defaultOption.toQuickPickItem() ] : [];
	const goSDKQuickPicks = goSDKOptions.map((op) => op.toQuickPickItem());

	// dedup options by eliminating duplicate paths (description)
	const clearOption: vscode.QuickPickItem = { label: CLEAR_SELECTION };
	const filePickerOption: vscode.QuickPickItem = {
	label: CHOOSE_FROM_FILE_BROWSER,
	description: 'Select the go binary to use',
	};
	// TODO(hyangah): Add separators after clearOption if github.com/microsoft/vscode#74967 is resolved.
	const options = [filePickerOption, clearOption, ...defaultQuickPick, ...goSDKQuickPicks, ...uninstalledQuickPicks]
	.reduce((opts, nextOption) => {
	if (opts.find((op) => op.description === nextOption.description \|\| op.label === nextOption.label)) {
	return opts;
	}
	return [...opts, nextOption];
	}, [] as vscode.QuickPickItem[]);

	// get user's selection, return if none was made
	const selection = await vscode.window.showQuickPick<vscode.QuickPickItem>(options);
	if (!selection) {
	return;
	}

	// update currently selected go
	try {
	await setSelectedGo(GoEnvironmentOption.fromQuickPickItem(selection));
	} catch (e) {
	vscode.window.showErrorMessage(e.message);
	}
	}

	/**
	* update the selected go path and label in the workspace state
	*/
	export async function setSelectedGo(goOption: GoEnvironmentOption, promptReload = true): Promise<boolean> {
	if (!goOption) {
	return false;
	}

	// if the selected go version is not installed, install it
	if (goOption.binpath?.startsWith('go get')) {
	// start a loading indicator
	await downloadGo(goOption);
	} else if (goOption.label === CLEAR_SELECTION) {
	if (!getSelectedGo()) {
	return false; // do nothing.
	}
	await updateWorkspaceState('selectedGo', undefined);
	} else if (goOption.label === CHOOSE_FROM_FILE_BROWSER) {
	const currentGOROOT = getCurrentGoRoot();
	const defaultUri = currentGOROOT ? vscode.Uri.file(path.join(currentGOROOT, 'bin')) : undefined;

	const newGoUris = await vscode.window.showOpenDialog({
	canSelectFiles: true,
	canSelectFolders: false,
	canSelectMany: false,
	defaultUri,
	});
	if (!newGoUris \|\| newGoUris.length !== 1) {
	return false;
	}
	const newGoBin = fixDriveCasingInWindows(newGoUris[0].fsPath);
	const oldGoBin = fixDriveCasingInWindows(path.join(defaultUri.fsPath, correctBinname('go')));

	if (newGoBin === oldGoBin) {
	return false;
	}
	if (!executableFileExists(newGoBin)) {
	vscode.window.showErrorMessage(`${newGoBin} is not an executable`);
	return false;
	}
	const newGo = await getGoVersion(newGoBin);
	if (!newGo \|\| !newGo.isValid() ) {
	vscode.window.showErrorMessage(`failed to get "${newGoBin} version", invalid Go binary`);
	return false;
	}
	await updateWorkspaceState('selectedGo', new GoEnvironmentOption(newGo.binaryPath, formatGoVersion(newGo)));
	} else {
	// check that the given binary is not already at the beginning of the PATH
	const go = await getGoVersion();
	if (!!go && (go.binaryPath === goOption.binpath \|\| 'Go ' + go.format() === goOption.label)) {
	return false;
	}
	await updateWorkspaceState('selectedGo', goOption);
	}
	// prompt the user to reload the window.
	// promptReload defaults to true and should only be false for tests.
	if (promptReload) {
	const choice = await vscode.window.showInformationMessage('Please reload the window to finish applying Go version changes.', 'Reload Window');
	if (choice === 'Reload Window') {
	await vscode.commands.executeCommand('workbench.action.reloadWindow');
	}
	}
	goEnvStatusbarItem.text = 'Go: reload required';
	goEnvStatusbarItem.command = 'workbench.action.reloadWindow';

	return true;
	}

	// downloadGo downloads the specified go version available in dl.golang.org.
	async function downloadGo(goOption: GoEnvironmentOption) {
	const execFile = promisify(cp.execFile);
	await vscode.window.withProgress({
	title: `Downloading ${goOption.label}`,
	location: vscode.ProgressLocation.Notification,
	}, async () => {
	outputChannel.show();
	outputChannel.clear();

	outputChannel.appendLine('Finding Go executable for downloading');
	const goExecutable = getBinPath('go');
	if (!goExecutable) {
	outputChannel.appendLine('Could not find Go executable.');
	throw new Error('Could not find Go tool.');
	}

	// TODO(bcloud) dedup repeated logic below which comes from
	// https://github.com/golang/vscode-go/blob/bc23fa854192d04200c8e4f74dca18d2c3021b46/src/goInstallTools.ts#L184
	// Install tools in a temporary directory, to avoid altering go.mod files.
	const mkdtemp = promisify(fs.mkdtemp);
	const toolsTmpDir = await mkdtemp(getTempFilePath('go-tools-'));
	let tmpGoModFile: string;

	// Write a temporary go.mod file to avoid version conflicts.
	tmpGoModFile = path.join(toolsTmpDir, 'go.mod');
	const writeFile = promisify(fs.writeFile);
	await writeFile(tmpGoModFile, 'module tools');

	// use the current go executable to download the new version
	const env = {
	...toolInstallationEnvironment(),
	GO111MODULE: 'on',
	};
	const [, ...args] = goOption.binpath.split(' ');
	outputChannel.appendLine(`Running ${goExecutable} ${args.join(' ')}`);
	try {
	await execFile(goExecutable, args, {
	env,
	cwd: toolsTmpDir,
	});
	} catch (getErr) {
	outputChannel.appendLine(`Error finding Go: ${getErr}`);
	throw new Error('Could not find Go version.');
	}

	// run `goX.X download`
	const newExecutableName = args[1].split('/')[2];
	const goXExecutable = getBinPath(newExecutableName);
	outputChannel.appendLine(`Running: ${goXExecutable} download`);
	try {
	await execFile(goXExecutable, ['download'], { env, cwd: toolsTmpDir });
	} catch (downloadErr) {
	outputChannel.appendLine(`Error finishing installation: ${downloadErr}`);
	throw new Error('Could not download Go version.');
	}

	outputChannel.appendLine('Finding newly downloaded Go');
	const sdkPath = path.join(os.homedir(), 'sdk');
	if (!await pathExists(sdkPath)) {
	outputChannel.appendLine(`SDK path does not exist: ${sdkPath}`);
	throw new Error(`SDK path does not exist: ${sdkPath}`);
	}

	const readdir = promisify(fs.readdir);
	const subdirs = await readdir(sdkPath);
	const dir = subdirs.find((subdir) => subdir === newExecutableName);
	if (!dir) {
	outputChannel.appendLine('Could not find newly downloaded Go');
	throw new Error('Could not install Go version.');
	}

	const binpath = path.join(sdkPath, dir, 'bin', correctBinname('go'));
	const newOption = new GoEnvironmentOption(binpath, goOption.label);
	await updateWorkspaceState('selectedGo', newOption);

	// remove tmp directories
	outputChannel.appendLine('Cleaning up...');
	rmdirRecursive(toolsTmpDir);
	outputChannel.appendLine('Success!');
	});
	}

	// PATH value cached before addGoRuntimeBaseToPath modified.
	let defaultPathEnv = '';

	function pathEnvVarName(): string\|undefined {
	if (process.env.hasOwnProperty('PATH')) {
	return 'PATH';
	} else if (process.platform === 'win32' && process.env.hasOwnProperty('Path')) {
	return 'Path';
	} else {
	return;
	}
	}

	// addGoRuntimeBaseToPATH adds the given path to the front of the PATH environment variable.
	// It removes duplicates.
	// TODO: can we avoid changing PATH but utilize toolExecutionEnv?
	export function addGoRuntimeBaseToPATH(newGoRuntimeBase: string) {
	if (!newGoRuntimeBase) {
	return;
	}
	const pathEnvVar = pathEnvVarName();
	if (!pathEnvVar) {
	logVerbose(`couldn't find PATH property in process.env`);
	return;
	}

	if (!defaultPathEnv) { // cache the default value
	defaultPathEnv = <string>process.env[pathEnvVar];
	}

	logVerbose(`addGoRuntimeBase(${newGoRuntimeBase}) when PATH=${defaultPathEnv}`);

	// calling this multiple times will override the previous value.
	// environmentVariableCollection.clear();
	if (process.platform !== 'darwin') {
	environmentVariableCollection?.prepend(pathEnvVar, newGoRuntimeBase + path.delimiter);
	} else {
	// When '-l' or '--login' flags are set, the terminal will invoke a login
	// shell again and the paths from the user's login shell will be prepended
	// again in front of the path mutated by environmentVariableCollection API.
	// That causes the mutated path to be ignored which we don't want.
	// So, let's not use the API if those flags are set, but go with the old way
	// -- i.e. send the export shell command.
	// See the open issue and the discussion here:
	// https://github.com/microsoft/vscode/issues/99878#issuecomment-642808852
	const terminalShellArgs = <string[]>(
	vscode.workspace.getConfiguration('terminal.integrated.shellArgs').get('osx') \|\| []);
	if (terminalShellArgs.includes('-l') \|\| terminalShellArgs.includes('--login')) {
	for (const term of vscode.window.terminals) {
	updateIntegratedTerminal(term);
	}
	if (!terminalCreationListener) {
	terminalCreationListener = vscode.window.onDidOpenTerminal(updateIntegratedTerminal);
	}
	} else {
	environmentVariableCollection?.prepend(pathEnvVar, newGoRuntimeBase + path.delimiter);
	}
	}

	let pathVars = defaultPathEnv.split(path.delimiter);
	pathVars = pathVars.filter((p) => p !== newGoRuntimeBase);
	pathVars.unshift(newGoRuntimeBase);
	process.env[pathEnvVar] = pathVars.join(path.delimiter);
	}

	// Clear terminal PATH environment modification previously installed
	// using addGoRuntimeBaseToPATH.
	// In particular, changes to vscode.EnvironmentVariableCollection persist across
	// vscode sessions, so when we decide not to mutate PATH, we need to clear
	// the preexisting changes.
	export function clearGoRuntimeBaseFromPATH() {
	if (terminalCreationListener) {
	const l = terminalCreationListener;
	terminalCreationListener = undefined;
	l.dispose();
	}
	const pathEnvVar = pathEnvVarName();
	if (!pathEnvVar) {
	logVerbose(`couldn't find PATH property in process.env`);
	return;
	}
	environmentVariableCollection?.delete(pathEnvVar);
	}

	/**
	* update the PATH variable in the given terminal to default to the currently selected Go
	*/
	export async function updateIntegratedTerminal(terminal: vscode.Terminal): Promise<void> {
	if (!terminal) { return; }
	const gorootBin = path.join(getCurrentGoRoot(), 'bin');
	const defaultGoRuntime = getBinPathFromEnvVar('go', defaultPathEnv, false);
	if (defaultGoRuntime && gorootBin === path.dirname(defaultGoRuntime)) {
	return;
	}

	// append the goroot to the beginning of the PATH so it takes precedence
	// TODO: add support for more terminal names
	// this assumes all non-windows shells are bash-like.
	if (terminal.name.toLowerCase() === 'cmd') {
	terminal.sendText(`set PATH=${gorootBin};%Path%`, true);
	terminal.sendText('cls');
	} else if (['powershell', 'pwsh'].includes(terminal.name.toLowerCase())) {
	terminal.sendText(`$env:Path="${gorootBin};$env:Path"`, true);
	terminal.sendText('clear');
	} else if (terminal.name.toLowerCase() === 'fish') {
	terminal.sendText(`set -gx PATH ${gorootBin} $PATH`);
	terminal.sendText('clear');
	} else if (['bash', 'sh', 'zsh', 'ksh'].includes(terminal.name.toLowerCase())) {
	terminal.sendText(`export PATH=${gorootBin}:$PATH`, true);
	terminal.sendText('clear');
	}
	}

	/**
	* retreive the current selected Go from the workspace state
	*/
	export function getSelectedGo(): GoEnvironmentOption {
	return getFromWorkspaceState('selectedGo');
	}

	/**
	* return reference to the statusbar item
	*/
	export function getGoEnvironmentStatusbarItem(): vscode.StatusBarItem {
	return goEnvStatusbarItem;
	}

	export function formatGoVersion(version?: GoVersion): string {
	if (!version \|\| !version.isValid()) {
	return `Go (unknown)`;
	}
	const versionStr = version.format(true);
	const versionWords = versionStr.split(' ');
	if (versionWords.length > 1 && versionWords[0] === 'devel') {
	// Go devel +hash
	return `Go ${versionWords[1]}`;
	} else {
	return `Go ${versionWords[0]}`;
	}
	}

	async function getSDKGoOptions(): Promise<GoEnvironmentOption[]> {
	// get list of Go versions
	const sdkPath = path.join(os.homedir(), 'sdk');

	if (!await pathExists(sdkPath)) {
	return [];
	}
	const readdir = promisify(fs.readdir);
	const subdirs = await readdir(sdkPath);
	// the dir happens to be the version, which will be used as the label
	// the path is assembled and used as the description
	return subdirs.map((dir: string) =>
	new GoEnvironmentOption(
	path.join(sdkPath, dir, 'bin', correctBinname('go')),
	dir.replace('go', 'Go '),
	)
	);
	}

	export async function getDefaultGoOption(): Promise<GoEnvironmentOption\|undefined> {
	// make goroot default to go.goroot
	const goroot = getCurrentGoRoot();
	if (!goroot) {
	return undefined;
	}

	// set Go version and command
	const version = await getGoVersion();
	return new GoEnvironmentOption(
	path.join(goroot, 'bin', correctBinname('go')),
	formatGoVersion(version),
	);
	}

	/**
	* make a web request to get versions of Go
	*/
	interface GoVersionWebResult {
	version: string;
	stable: boolean;
	files: {
	filename: string;
	os: string;
	arch: string;
	version: string;
	sha256: string;
	size: number;
	kind: string;
	}[];
	}
	async function fetchDownloadableGoVersions(): Promise<GoEnvironmentOption[]> {
	// fetch information about what Go versions are available to install
	let webResults;
	try {
	webResults = await WebRequest.json<GoVersionWebResult[]>('https://golang.org/dl/?mode=json');
	} catch (error) {
	return [];
	}

	if (!webResults) {
	return [];
	}
	// turn the web result into GoEnvironmentOption model
	return webResults.reduce((opts, result: GoVersionWebResult) => {
	// TODO: allow downloading from different sites
	const dlPath = `go get golang.org/dl/${result.version}`;
	const label = result.version.replace('go', 'Go ');
	return [...opts, new GoEnvironmentOption(dlPath, label)];
	}, []);
	}

	export const latestGoVersionKey = 'latestGoVersions';
	const oneday = 60 * 60 * 24 * 1000; // 24 hours in milliseconds

	export async function getLatestGoVersions(): Promise<GoEnvironmentOption[]> {
	const timeout = oneday;
	const now = moment.now();

	let results: GoEnvironmentOption[];

	// Check if we can use cached results
	const cachedResults = getFromGlobalState(latestGoVersionKey);
	if (cachedResults && now - cachedResults.timestamp < timeout) {
	results = cachedResults.goVersions;
	} else {
	// fetch the latest supported Go versions
	try {
	// fetch the latest Go versions and cache the results
	results = await fetchDownloadableGoVersions();
	await updateGlobalState(latestGoVersionKey, {
	timestamp: now,
	goVersions: results,
	});
	} catch (e) {
	// hardcode the latest versions of Go in case golang.dl is unavailable
	results = [
	new GoEnvironmentOption('go get golang.org/dl/go1.15', 'Go 1.15'),
	new GoEnvironmentOption('go get golang.org/dl/go1.14.7', 'Go 1.14.7'),
	];
	}
	}

	return results;
	}

	const dismissedGoVersionUpdatesKey = 'dismissedGoVersionUpdates';

	export async function offerToInstallLatestGoVersion() {
	const goConfig = getGoConfig();
	const checkForUpdate = getCheckForToolsUpdatesConfig(goConfig);
	if (checkForUpdate === 'off' \|\| checkForUpdate === 'local') { // 'proxy' or misconfiguration..
	return;
	}

	let options = await getLatestGoVersions();

	// filter out Go versions the user has already dismissed
	let dismissedOptions: GoEnvironmentOption[];
	dismissedOptions = await getFromGlobalState(dismissedGoVersionUpdatesKey);
	if (!!dismissedOptions) {
	options = options.filter((version) => !dismissedOptions.find((x) => x.label === version.label));
	}

	// compare to current go version.
	const currentVersion = await getGoVersion();
	if (!!currentVersion) {
	options = options.filter((version) => currentVersion.lt(version.label));
	}

	// notify user that there is a newer version of Go available
	if (options.length > 0) {
	addGoStatus('Go Update Available', 'go.promptforgoinstall', 'A newer version of Go is available');
	vscode.commands.registerCommand('go.promptforgoinstall', () => {
	const download = {
	title: 'Download',
	async command() {
	await vscode.env.openExternal(vscode.Uri.parse(`https://golang.org/dl/`));
	}
	};

	const neverAgain = {
	title: `Don't Show Again`,
	async command() {
	// mark these versions as seen
	dismissedOptions = await getFromGlobalState(dismissedGoVersionUpdatesKey);
	if (!dismissedOptions) {
	dismissedOptions = [];
	}
	options.forEach((version) => {
	dismissedOptions.push(version);
	});
	await updateGlobalState(dismissedGoVersionUpdatesKey, dismissedOptions);
	}
	};

	let versionsText: string;
	if (options.length > 1) {
	versionsText = `${options.map((x) => x.label)
	.reduce((prev, next) => {
	return prev + ' and ' + next;
	})} are available`;
	} else {
	versionsText = `${options[0].label} is available`;
	}

	vscode.window
	.showInformationMessage(
	`${versionsText}. You are currently using ${formatGoVersion(currentVersion)}.`,
	download,
	neverAgain
	)
	.then((selection) => {
	removeGoStatus();
	selection.command();
	});
	});
	}
	}