zx/index.mjs

A tool for writing better scripts

// Copyright 2021 Google LLC
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     https://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import {existsSync} from 'fs'
import {exec} from 'child_process'
import {createInterface} from 'readline'
import {default as nodeFetch} from 'node-fetch'
import {promisify} from 'util'
import which from 'which'
import chalk from 'chalk'
import shq from 'shq'

export {chalk}

function colorize(cmd) {
  return cmd.replace(/^\w+\s/, substr => {
    return chalk.greenBright(substr)
  })
}

function substitute(arg) {
  if (arg instanceof ProcessOutput) {
    return arg.stdout.replace(/\n$/, '')
  }
  return arg.toString()
}

export function $(pieces, ...args) {
  let __from = (new Error().stack.split('at ')[2]).trim()
  let cmd = pieces[0], i = 0
  while (i < args.length) cmd += $.quote(substitute(args[i])) + pieces[++i]

  if ($.verbose) console.log('$', colorize(cmd))

  return new Promise((resolve, reject) => {
    let options = {
      windowsHide: true,
    }
    if (typeof $.shell !== 'undefined') options.shell = $.shell
    if (typeof $.cwd !== 'undefined') options.cwd = $.cwd

    let child = exec($.prefix + cmd, options)
    let stdout = '', stderr = '', combined = ''
    child.stdout.on('data', data => {
      if ($.verbose) process.stdout.write(data)
      stdout += data
      combined += data
    })
    child.stderr.on('data', data => {
      if ($.verbose) process.stderr.write(data)
      stderr += data
      combined += data
    })
    child.on('exit', code => {
      (code === 0 ? resolve : reject)(
        new ProcessOutput({code, stdout, stderr, combined, __from})
      )
    })
  })
}

$.verbose = true
try {
  $.shell = await which('bash')
  $.prefix = 'set -euo pipefail;'
} catch (e) {
  // Bash not found, no prefix.
  $.prefix = ''
}
$.quote = shq
$.cwd = undefined

export function cd(path) {
  if ($.verbose) console.log('$', colorize(`cd ${path}`))
  if (!existsSync(path)) {
    let __from = (new Error().stack.split('at ')[2]).trim()
    console.error(`cd: ${path}: No such directory`)
    console.error(`  at ${__from}`)
    process.exit(1)
  }
  $.cwd = path
}

export async function question(query, options) {
  let completer = undefined
  if (Array.isArray(options?.choices)) {
    completer = function completer(line) {
      const completions = options.choices
      const hits = completions.filter((c) => c.startsWith(line))
      return [hits.length ? hits : completions, line]
    }
  }
  const rl = createInterface({
    input: process.stdin,
    output: process.stdout,
    completer,
  })
  const question = (q) => new Promise((resolve) => rl.question(q ?? '', resolve))
  let answer = await question(query)
  rl.close()
  return answer
}

export async function fetch(url, init) {
  if ($.verbose) {
    if (typeof init !== 'undefined') {
      console.log('$', colorize(`fetch ${url}`), init)
    } else {
      console.log('$', colorize(`fetch ${url}`))
    }
  }
  return nodeFetch(url, init)
}

export const sleep = promisify(setTimeout)

export class ProcessOutput {
  #code = 0
  #stdout = ''
  #stderr = ''
  #combined = ''
  #__from = ''

  constructor({code, stdout, stderr, combined, __from}) {
    this.#code = code
    this.#stdout = stdout
    this.#stderr = stderr
    this.#combined = combined
    this.#__from = __from
  }

  toString() {
    return this.#combined
  }

  get stdout() {
    return this.#stdout
  }

  get stderr() {
    return this.#stderr
  }

  get exitCode() {
    return this.#code
  }

  get __from() {
    return this.#__from
  }
}