const { resolve, basename } = require('path')
const util = require('util')
const fs = require('fs')
const { unlink } = fs.promises || { unlink: util.promisify(fs.unlink) }
const Arborist = require('@npmcli/arborist')
const log = require('npmlog')

const npm = require('./npm.js')
const usageUtil = require('./utils/usage.js')
const usage = usageUtil('shrinkwrap', 'npm shrinkwrap')

const cmd = (args, cb) => shrinkwrap().then(() => cb()).catch(cb)

const shrinkwrap = async () => {
  // if has a npm-shrinkwrap.json, nothing to do
  // if has a package-lock.json, rename to npm-shrinkwrap.json
  // if has neither, load the actual tree and save that as npm-shrinkwrap.json
  // in all cases, re-cast to current lockfile version
  //
  // loadVirtual, fall back to loadActual
  // rename shrinkwrap file type, and tree.meta.save()
  if (npm.flatOptions.global) {
    const er = new Error('`npm shrinkwrap` does not work for global packages')
    er.code = 'ESHRINKWRAPGLOBAL'
    throw er
  }

  const path = npm.prefix
  const sw = resolve(path, 'npm-shrinkwrap.json')
  const arb = new Arborist({ ...npm.flatOptions, path })
  const tree = await arb.loadVirtual().catch(() => arb.loadActual())
  const { meta } = tree
  const newFile = meta.hiddenLockfile || !meta.loadedFromDisk
  const oldFilename = meta.filename
  const notSW = !newFile && basename(oldFilename) !== 'npm-shrinkwrap.json'

  meta.hiddenLockfile = false
  meta.filename = sw
  await meta.save()

  if (newFile)
    log.notice('', 'created a lockfile as npm-shrinkwrap.json')
  else if (notSW) {
    await unlink(oldFilename)
    log.notice('', 'package-lock.json has been renamed to npm-shrinkwrap.json')
  } else if (meta.originalLockfileVersion !== npm.lockfileVersion)
    log.notice('', `npm-shrinkwrap.json updated to version ${npm.lockfileVersion}`)
  else
    log.notice('', 'npm-shrinkwrap.json up to date')
}

module.exports = Object.assign(cmd, { usage })