/*---------------------------------------------------------
 * Copyright (C) Microsoft Corporation. All rights reserved.
 * Modification copyright 2020 The Go Authors. All rights reserved.
 * Licensed under the MIT License. See LICENSE in the project root for license information.
 *--------------------------------------------------------*/

'use strict';

/**
 * This file is loaded by both the extension and debug adapter, so it cannot import 'vscode'
 */
import fs = require('fs');
import os = require('os');
import path = require('path');
import { promisify } from 'util';

let binPathCache: { [bin: string]: string } = {};

export const envPath = process.env['PATH'] || (process.platform === 'win32' ? process.env['Path'] : null);

// find the tool's path from the given PATH env var, or null if the tool is not found.
export function getBinPathFromEnvVar(toolName: string, envVarValue: string, appendBinToPath: boolean): string|null {
	toolName = correctBinname(toolName);
	if (envVarValue) {
		const paths = envVarValue.split(path.delimiter);
		for (const p of paths) {
			const binpath = path.join(p, appendBinToPath ? 'bin' : '', toolName);
			if (executableFileExists(binpath)) {
				return binpath;
			}
		}
	}
	return null;
}

export function getBinPathWithPreferredGopathGoroot(
	toolName: string,
	preferredGopaths: string[],
	preferredGoroot?: string,
	alternateTool?: string,
	useCache = true
): string {
	const r = getBinPathWithPreferredGopathGorootWithExplanation(
		toolName, preferredGopaths, preferredGoroot, alternateTool, useCache);
	return r.binPath;
}

// Is same as getBinPathWithPreferredGopathGoroot, but returns why the
// returned path was chosen.
export function getBinPathWithPreferredGopathGorootWithExplanation(
	toolName: string,
	preferredGopaths: string[],
	preferredGoroot?: string,
	alternateTool?: string,
	useCache = true,
): {binPath: string, why?: string} {
	if (alternateTool && path.isAbsolute(alternateTool) && executableFileExists(alternateTool)) {
		binPathCache[toolName] = alternateTool;
		return {binPath: alternateTool, why: 'alternateTool'};
	}

	// FIXIT: this cache needs to be invalidated when go.goroot or go.alternateTool is changed.
	if (useCache && binPathCache[toolName]) {
		return {binPath: binPathCache[toolName], why: 'cached'};
	}

	const binname = alternateTool && !path.isAbsolute(alternateTool) ? alternateTool : toolName;
	const found = (why: string) => binname === toolName ? why : 'alternateTool';
	const pathFromGoBin = getBinPathFromEnvVar(binname, process.env['GOBIN'], false);
	if (pathFromGoBin) {
		binPathCache[toolName] = pathFromGoBin;
		return {binPath: pathFromGoBin, why: binname === toolName ? 'gobin' : 'alternateTool'};
	}

	for (const preferred of preferredGopaths) {
		if (typeof preferred === 'string') {
			// Search in the preferred GOPATH workspace's bin folder
			const pathFrompreferredGoPath = getBinPathFromEnvVar(binname, preferred, true);
			if (pathFrompreferredGoPath) {
				binPathCache[toolName] = pathFrompreferredGoPath;
				return {binPath: pathFrompreferredGoPath, why: found('gopath')};
			}
		}
	}

	// Check GOROOT (go, gofmt, godoc would be found here)
	const pathFromGoRoot = getBinPathFromEnvVar(binname, preferredGoroot || getCurrentGoRoot(), true);
	if (pathFromGoRoot) {
		binPathCache[toolName] = pathFromGoRoot;
		return {binPath: pathFromGoRoot, why: found('goroot')};
	}

	// Finally search PATH parts
	const pathFromPath = getBinPathFromEnvVar(binname, envPath, false);
	if (pathFromPath) {
		binPathCache[toolName] = pathFromPath;
		return {binPath: pathFromPath, why: found('path')};
	}

	// Check default path for go
	if (toolName === 'go') {
		const defaultPathForGo = process.platform === 'win32' ? 'C:\\Go\\bin\\go.exe' : '/usr/local/go/bin/go';
		if (executableFileExists(defaultPathForGo)) {
			binPathCache[toolName] = defaultPathForGo;
			return {binPath: defaultPathForGo, why: 'default'};
		}
		return {binPath: ''};
	}

	// Else return the binary name directly (this will likely always fail downstream)
	return {binPath: toolName};
}

/**
 * Returns the goroot path if it exists, otherwise returns an empty string
 */
let currentGoRoot = '';
export function getCurrentGoRoot(): string {
	return currentGoRoot || process.env['GOROOT'] || '';
}

export function setCurrentGoRoot(goroot: string) {
	currentGoRoot = goroot;
}

export function correctBinname(toolName: string) {
	if (process.platform === 'win32') {
		return toolName + '.exe';
	}
	return toolName;
}

function executableFileExists(filePath: string): boolean {
	let exists = true;
	try {
		exists = fs.statSync(filePath).isFile();
		if (exists) {
			fs.accessSync(filePath, fs.constants.F_OK | fs.constants.X_OK);
		}
	} catch (e) {
		exists = false;
	}
	return exists;
}

export function fileExists(filePath: string): boolean {
	try {
		return fs.statSync(filePath).isFile();
	} catch (e) {
		return false;
	}
}

export async function pathExists(p: string): Promise<boolean> {
	try {
		const stat = promisify(fs.stat);
		return (await stat(p)).isDirectory();
	} catch (e) {
		return false;
	}
}

export function clearCacheForTools() {
	binPathCache = {};
}

/**
 * Exapnds ~ to homedir in non-Windows platform
 */
export function resolveHomeDir(inputPath: string): string {
	if (!inputPath || !inputPath.trim()) {
		return inputPath;
	}
	return inputPath.startsWith('~') ? path.join(os.homedir(), inputPath.substr(1)) : inputPath;
}

// Walks up given folder path to return the closest ancestor that has `src` as a child
export function getInferredGopath(folderPath: string): string {
	if (!folderPath) {
		return;
	}

	const dirs = folderPath.toLowerCase().split(path.sep);

	// find src directory closest to given folder path
	const srcIdx = dirs.lastIndexOf('src');
	if (srcIdx > 0) {
		return folderPath.substr(0, dirs.slice(0, srcIdx).join(path.sep).length);
	}
}

/**
 * Returns the workspace in the given Gopath to which given directory path belongs to
 * @param gopath string Current Gopath. Can be ; or : separated (as per os) to support multiple paths
 * @param currentFileDirPath string
 */
export function getCurrentGoWorkspaceFromGOPATH(gopath: string, currentFileDirPath: string): string {
	if (!gopath) {
		return;
	}
	const workspaces: string[] = gopath.split(path.delimiter);
	let currentWorkspace = '';
	currentFileDirPath = fixDriveCasingInWindows(currentFileDirPath);

	// Find current workspace by checking if current file is
	// under any of the workspaces in $GOPATH
	for (const workspace of workspaces) {
		const possibleCurrentWorkspace = path.join(workspace, 'src');
		if (
			currentFileDirPath.startsWith(possibleCurrentWorkspace) ||
			(process.platform === 'win32' &&
				currentFileDirPath.toLowerCase().startsWith(possibleCurrentWorkspace.toLowerCase()))
		) {
			// In case of nested workspaces, (example: both /Users/me and /Users/me/src/a/b/c are in $GOPATH)
			// both parent & child workspace in the nested workspaces pair can make it inside the above if block
			// Therefore, the below check will take longer (more specific to current file) of the two
			if (possibleCurrentWorkspace.length > currentWorkspace.length) {
				currentWorkspace = currentFileDirPath.substr(0, possibleCurrentWorkspace.length);
			}
		}
	}
	return currentWorkspace;
}

// Workaround for issue in https://github.com/Microsoft/vscode/issues/9448#issuecomment-244804026
export function fixDriveCasingInWindows(pathToFix: string): string {
	return process.platform === 'win32' && pathToFix
		? pathToFix.substr(0, 1).toUpperCase() + pathToFix.substr(1)
		: pathToFix;
}

/**
 * Returns the tool name from the given path to the tool
 * @param toolPath
 */
export function getToolFromToolPath(toolPath: string): string | undefined {
	if (!toolPath) {
		return;
	}
	let tool = path.basename(toolPath);
	if (process.platform === 'win32' && tool.endsWith('.exe')) {
		tool = tool.substr(0, tool.length - 4);
	}
	return tool;
}

/**
 * Returns output with relative filepaths expanded using the provided directory
 * @param output
 * @param cwd
 */
export function expandFilePathInOutput(output: string, cwd: string): string {
	const lines = output.split('\n');
	for (let i = 0; i < lines.length; i++) {
		const matches = lines[i].match(/\s*(\S+\.go):(\d+):/);
		if (matches && matches[1] && !path.isAbsolute(matches[1])) {
			lines[i] = lines[i].replace(matches[1], path.join(cwd, matches[1]));
		}
	}
	return lines.join('\n');
}