/*---------------------------------------------------------
 * Copyright (C) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License. See LICENSE in the project root for license information.
 *--------------------------------------------------------*/

import cp = require('child_process');
import path = require('path');
import vscode = require('vscode');
import { toolExecutionEnvironment } from './goEnv';
import { installTools } from './goInstallTools';
import { envPath, fixDriveCasingInWindows, getCurrentGoRoot } from './goPath';
import { getTool } from './goTools';
import { getFromGlobalState, updateGlobalState } from './stateUtils';
import { getBinPath, getGoConfig, getGoVersion, getModuleCache } from './util';

export let GO111MODULE: string;

async function runGoModEnv(folderPath: string): Promise<string> {
	const goExecutable = getBinPath('go');
	if (!goExecutable) {
		console.warn(
			`Failed to run "go env GOMOD" to find mod file as the "go" binary cannot be found in either GOROOT(${getCurrentGoRoot()}) or PATH(${envPath})`
		);
		return;
	}
	const env = toolExecutionEnvironment();
	GO111MODULE = env['GO111MODULE'];
	return new Promise((resolve) => {
		cp.execFile(goExecutable, ['env', 'GOMOD'], { cwd: folderPath, env }, (err, stdout) => {
			if (err) {
				console.warn(`Error when running go env GOMOD: ${err}`);
				return resolve();
			}
			const [goMod] = stdout.split('\n');
			resolve(goMod);
		});
	});
}

export function isModSupported(fileuri: vscode.Uri): Promise<boolean> {
	return getModFolderPath(fileuri).then((modPath) => !!modPath);
}

export const packagePathToGoModPathMap: { [key: string]: string } = {};

export async function getModFolderPath(fileuri: vscode.Uri): Promise<string> {
	const pkgPath = path.dirname(fileuri.fsPath);
	if (packagePathToGoModPathMap[pkgPath]) {
		return packagePathToGoModPathMap[pkgPath];
	}

	// We never would be using the path under module cache for anything
	// So, dont bother finding where exactly is the go.mod file
	const moduleCache = getModuleCache();
	if (fixDriveCasingInWindows(fileuri.fsPath).startsWith(moduleCache)) {
		return moduleCache;
	}
	const goVersion = await getGoVersion();
	if (goVersion.lt('1.11')) {
		return;
	}

	let goModEnvResult = await runGoModEnv(pkgPath);
	if (goModEnvResult) {
		logModuleUsage();
		goModEnvResult = path.dirname(goModEnvResult);
		const goConfig = getGoConfig(fileuri);

		if (goConfig['inferGopath'] === true) {
			goConfig.update('inferGopath', false, vscode.ConfigurationTarget.WorkspaceFolder);
			vscode.window.showInformationMessage(
				'The "inferGopath" setting is disabled for this workspace because Go modules are being used.'
			);
		}

		// TODO(rstambler): This will offer multiple prompts to the user, but
		// it's still better than waiting for user input. Ideally, this should
		// be combined into one prompt.
		if (goConfig['useLanguageServer'] === false) {
			const promptMsg =
				'For better performance using Go modules, you can try the experimental Go language server, gopls.';
			promptToUpdateToolForModules('gopls', promptMsg, goConfig);

			if (goConfig['formatTool'] === 'goreturns') {
				const promptMsgForFormatTool = `The goreturns tool does not support Go modules. Please update the "formatTool" setting to goimports.`;
				promptToUpdateToolForModules('switchFormatToolToGoimports', promptMsgForFormatTool, goConfig);
			}
		}
	}
	packagePathToGoModPathMap[pkgPath] = goModEnvResult;
	return goModEnvResult;
}

let moduleUsageLogged = false;
function logModuleUsage() {
	if (moduleUsageLogged) {
		return;
	}
	moduleUsageLogged = true;
}

const promptedToolsForCurrentSession = new Set<string>();
export async function promptToUpdateToolForModules(
	tool: string,
	promptMsg: string,
	goConfig?: vscode.WorkspaceConfiguration
): Promise<boolean> {
	if (promptedToolsForCurrentSession.has(tool)) {
		return false;
	}
	const promptedToolsForModules = getFromGlobalState('promptedToolsForModules', {});
	if (promptedToolsForModules[tool]) {
		return false;
	}
	const goVersion = await getGoVersion();
	const selected = await vscode.window.showInformationMessage(promptMsg, 'Update', 'Later', `Don't show again`);
	let choseToUpdate = false;
	switch (selected) {
		case 'Update':
			choseToUpdate = true;
			if (!goConfig) {
				goConfig = getGoConfig();
			}
			if (tool === 'switchFormatToolToGoimports') {
				goConfig.update('formatTool', 'goimports', vscode.ConfigurationTarget.Global);
			} else {
				await installTools([getTool(tool)], goVersion);
			}
			promptedToolsForModules[tool] = true;
			updateGlobalState('promptedToolsForModules', promptedToolsForModules);
			break;
		case `Don't show again`:
			promptedToolsForModules[tool] = true;
			updateGlobalState('promptedToolsForModules', promptedToolsForModules);
			break;
		case 'Later':
		default:
			promptedToolsForCurrentSession.add(tool);
			break;
	}
	return choseToUpdate;
}

const folderToPackageMapping: { [key: string]: string } = {};
export async function getCurrentPackage(cwd: string): Promise<string> {
	if (folderToPackageMapping[cwd]) {
		return folderToPackageMapping[cwd];
	}

	const moduleCache = getModuleCache();
	if (cwd.startsWith(moduleCache)) {
		let importPath = cwd.substr(moduleCache.length + 1);
		const matches = /@v\d+(\.\d+)?(\.\d+)?/.exec(importPath);
		if (matches) {
			importPath = importPath.substr(0, matches.index);
		}

		folderToPackageMapping[cwd] = importPath;
		return importPath;
	}

	const goRuntimePath = getBinPath('go');
	if (!goRuntimePath) {
		console.warn(
			`Failed to run "go list" to find current package as the "go" binary cannot be found in either GOROOT(${getCurrentGoRoot()}) or PATH(${envPath})`
		);
		return;
	}
	return new Promise<string>((resolve) => {
		const childProcess = cp.spawn(goRuntimePath, ['list'], { cwd, env: toolExecutionEnvironment() });
		const chunks: any[] = [];
		childProcess.stdout.on('data', (stdout) => {
			chunks.push(stdout);
		});

		childProcess.on('close', () => {
			// Ignore lines that are empty or those that have logs about updating the module cache
			const pkgs = chunks
				.join('')
				.toString()
				.split('\n')
				.filter((line) => line && line.indexOf(' ') === -1);
			if (pkgs.length !== 1) {
				resolve();
				return;
			}
			folderToPackageMapping[cwd] = pkgs[0];
			resolve(pkgs[0]);
		});
	});
}