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 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 { outputChannel } from './goStatus';
 import { getFromWorkspaceState, updateWorkspaceState } from './stateUtils';
 import { getBinPath, getGoVersion, getTempFilePath, rmdirRecursive } from './util';
 import { correctBinname, getBinPathFromEnvVar, getCurrentGoRoot, pathExists } from './utils/goPath';

 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,
 		};
 	}
 }

 // statusbar item for switching the Go environment
 let goEnvStatusbarItem: vscode.StatusBarItem;
 let terminalCreationListener: vscode.Disposable;
 let terminalPATH: string;

 /**
  * Initialize the status bar item with current Go binary
  */
 export async function initGoStatusBar(cachePath: string) {
 	if (!goEnvStatusbarItem) {
 		goEnvStatusbarItem = vscode.window.createStatusBarItem(vscode.StatusBarAlignment.Left, 50);
 	}
 	// cache the PATH on first initialization
 	// this will be the path that new integrated terminals have
 	if (!terminalPATH) {
 		terminalPATH = cachePath;
 	}

 	// set Go version and command
 	const version = await getGoVersion();
 	const goOption = new GoEnvironmentOption(version.binaryPath, formatGoVersion(version.format()));

 	// ensure terminals use the correct Go version
 	if (!terminalCreationListener) {
 		updateIntegratedTerminal(vscode.window.activeTerminal);
 		terminalCreationListener = vscode.window.onDidOpenTerminal(updateIntegratedTerminal);
 	}

 	hideGoStatusBar();
 	goEnvStatusbarItem.text = goOption.label;
 	goEnvStatusbarItem.command = 'go.environment.choose';
 	showGoStatusBar();
 }

 /**
  * disable the Go environment status bar item
  */
 export function disposeGoStatusBar() {
 	if (!!goEnvStatusbarItem) {
 		goEnvStatusbarItem.dispose();
 	}
 	if (!!terminalCreationListener) {
 		terminalCreationListener.dispose();
 	}
 }

 /**
  * Show the Go Environment statusbar item on the statusbar
  */
 export function showGoStatusBar() {
 	if (!!goEnvStatusbarItem) {
 		goEnvStatusbarItem.show();
 	}
 }

 /**
  * Hide the Go Environment statusbar item from the statusbar
  */
 export function hideGoStatusBar() {
 	if (!!goEnvStatusbarItem) {
 		goEnvStatusbarItem.hide();
 	}
 }

 /**
  * 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.toQuickPickItem();
 	const goSDKQuickPicks = goSDKOptions.map((op) => op.toQuickPickItem());

 	// dedup options by eliminating duplicate paths (description)
 	const clearOption: vscode.QuickPickItem = { label: 'Clear selection' };
 	const options = [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));
 		vscode.window.showInformationMessage(`Switched to ${selection.label}`);
 	} 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) {
 	if (!goOption) {
 		return;
 	}
 	const execFile = promisify(cp.execFile);
 	// if the selected go version is not installed, install it
 	if (goOption.binpath?.startsWith('go get')) {
 		// start a loading indicator
 		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 });
 			} 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(process.env.HOME, '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);
 			goEnvStatusbarItem.text = goOption.label;

 			// remove tmp directories
 			outputChannel.appendLine('Cleaning up...');
 			rmdirRecursive(toolsTmpDir);
 			outputChannel.appendLine('Success!');
 		});
 	} else if (goOption.label === 'Clear selection') {
 		updateWorkspaceState('selectedGo', undefined);
 	} else {
 		// check that the given binary is not already at the beginning of the PATH
 		const go = await getGoVersion();
 		if (go.binaryPath === goOption.binpath) {
 			return;
 		}

 		await updateWorkspaceState('selectedGo', goOption);
 		goEnvStatusbarItem.text = goOption.label;
 	}
 	// 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 changes.', 'Reload Window');
 		if (choice === 'Reload Window') {
 			await vscode.commands.executeCommand('workbench.action.reloadWindow');
 		}
 	}
 }

 /**
  * update the PATH variable in the given terminal to default to the currently selected Go
  */
 export async function updateIntegratedTerminal(terminal: vscode.Terminal) {
 	if (!terminal) { return; }
 	const gorootBin = path.join(getCurrentGoRoot(), 'bin');
 	const defaultGoRuntimeBin = path.dirname(getBinPathFromEnvVar('go', terminalPATH, false));
 	if (gorootBin === defaultGoRuntimeBin) {
 		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: string): string {
 	const versionWords = version.split(' ');
 	if (versionWords[0] === 'devel') {
 		// Go devel +hash
 		return `Go ${versionWords[0]} ${versionWords[4]}`;
 	} else if (versionWords.length > 0) {
 		// some other version format
 		return `Go ${version.substr(0, 8)}`;
 	} else {
 		// default semantic version format
 		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', 'go'),
 			dir.replace('go', 'Go '),
 		)
 	);
 }

 export async function getDefaultGoOption(): Promise<GoEnvironmentOption> {
 	// make goroot default to go.goroot
 	const goroot = getCurrentGoRoot();
 	if (!goroot) {
 		throw new Error('No Go command could be found.');
 	}

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

 /**
  * 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
 	const webResults = await WebRequest.json<GoVersionWebResult[]>('https://golang.org/dl/?mode=json');
 	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)];
 	}, []);
 }
	/*---------------------------------------------------------
	* 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 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 { outputChannel } from './goStatus';
	import { getFromWorkspaceState, updateWorkspaceState } from './stateUtils';
	import { getBinPath, getGoVersion, getTempFilePath, rmdirRecursive } from './util';
	import { correctBinname, getBinPathFromEnvVar, getCurrentGoRoot, pathExists } from './utils/goPath';

	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,
	};
	}
	}

	// statusbar item for switching the Go environment
	let goEnvStatusbarItem: vscode.StatusBarItem;
	let terminalCreationListener: vscode.Disposable;
	let terminalPATH: string;

	/**
	* Initialize the status bar item with current Go binary
	*/
	export async function initGoStatusBar(cachePath: string) {
	if (!goEnvStatusbarItem) {
	goEnvStatusbarItem = vscode.window.createStatusBarItem(vscode.StatusBarAlignment.Left, 50);
	}
	// cache the PATH on first initialization
	// this will be the path that new integrated terminals have
	if (!terminalPATH) {
	terminalPATH = cachePath;
	}

	// set Go version and command
	const version = await getGoVersion();
	const goOption = new GoEnvironmentOption(version.binaryPath, formatGoVersion(version.format()));

	// ensure terminals use the correct Go version
	if (!terminalCreationListener) {
	updateIntegratedTerminal(vscode.window.activeTerminal);
	terminalCreationListener = vscode.window.onDidOpenTerminal(updateIntegratedTerminal);
	}

	hideGoStatusBar();
	goEnvStatusbarItem.text = goOption.label;
	goEnvStatusbarItem.command = 'go.environment.choose';
	showGoStatusBar();
	}

	/**
	* disable the Go environment status bar item
	*/
	export function disposeGoStatusBar() {
	if (!!goEnvStatusbarItem) {
	goEnvStatusbarItem.dispose();
	}
	if (!!terminalCreationListener) {
	terminalCreationListener.dispose();
	}
	}

	/**
	* Show the Go Environment statusbar item on the statusbar
	*/
	export function showGoStatusBar() {
	if (!!goEnvStatusbarItem) {
	goEnvStatusbarItem.show();
	}
	}

	/**
	* Hide the Go Environment statusbar item from the statusbar
	*/
	export function hideGoStatusBar() {
	if (!!goEnvStatusbarItem) {
	goEnvStatusbarItem.hide();
	}
	}

	/**
	* 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.toQuickPickItem();
	const goSDKQuickPicks = goSDKOptions.map((op) => op.toQuickPickItem());

	// dedup options by eliminating duplicate paths (description)
	const clearOption: vscode.QuickPickItem = { label: 'Clear selection' };
	const options = [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));
	vscode.window.showInformationMessage(`Switched to ${selection.label}`);
	} 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) {
	if (!goOption) {
	return;
	}
	const execFile = promisify(cp.execFile);
	// if the selected go version is not installed, install it
	if (goOption.binpath?.startsWith('go get')) {
	// start a loading indicator
	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 });
	} 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(process.env.HOME, '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);
	goEnvStatusbarItem.text = goOption.label;

	// remove tmp directories
	outputChannel.appendLine('Cleaning up...');
	rmdirRecursive(toolsTmpDir);
	outputChannel.appendLine('Success!');
	});
	} else if (goOption.label === 'Clear selection') {
	updateWorkspaceState('selectedGo', undefined);
	} else {
	// check that the given binary is not already at the beginning of the PATH
	const go = await getGoVersion();
	if (go.binaryPath === goOption.binpath) {
	return;
	}

	await updateWorkspaceState('selectedGo', goOption);
	goEnvStatusbarItem.text = goOption.label;
	}
	// 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 changes.', 'Reload Window');
	if (choice === 'Reload Window') {
	await vscode.commands.executeCommand('workbench.action.reloadWindow');
	}
	}
	}

	/**
	* update the PATH variable in the given terminal to default to the currently selected Go
	*/
	export async function updateIntegratedTerminal(terminal: vscode.Terminal) {
	if (!terminal) { return; }
	const gorootBin = path.join(getCurrentGoRoot(), 'bin');
	const defaultGoRuntimeBin = path.dirname(getBinPathFromEnvVar('go', terminalPATH, false));
	if (gorootBin === defaultGoRuntimeBin) {
	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: string): string {
	const versionWords = version.split(' ');
	if (versionWords[0] === 'devel') {
	// Go devel +hash
	return `Go ${versionWords[0]} ${versionWords[4]}`;
	} else if (versionWords.length > 0) {
	// some other version format
	return `Go ${version.substr(0, 8)}`;
	} else {
	// default semantic version format
	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', 'go'),
	dir.replace('go', 'Go '),
	)
	);
	}

	export async function getDefaultGoOption(): Promise<GoEnvironmentOption> {
	// make goroot default to go.goroot
	const goroot = getCurrentGoRoot();
	if (!goroot) {
	throw new Error('No Go command could be found.');
	}

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

	/**
	* 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
	const webResults = await WebRequest.json<GoVersionWebResult[]>('https://golang.org/dl/?mode=json');
	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)];
	}, []);
	}