fetch-packument.js

'use strict'
const fetch = require('npm-registry-fetch')
const optCheck = require('pacote/lib/util/opt-check')
const BB = require('bluebird')
const LRU = require('lru-cache')
const CORGI_DOC = 'application/vnd.npm.install-v1+json; q=1.0, application/json; q=0.8, */*'
const JSON_DOC = 'application/json'

module.exports = packument

function packument (name, opts) {
  opts = optCheck(opts)
  const registry = fetch.pickRegistry(name, opts)
  const uri = registry.replace(/\/?$/, `/${name.replace(/[/]/g, '%2f')}`)
  return fetchPackument(uri, name, registry, opts)
}

function fetchPackument (uri, spec, registry, opts) {
  const mem = pickMem(opts)
  if (mem && !opts.preferOnline && mem.has(uri)) {
    return BB.resolve(mem.get(uri))
  }
  return fetch(uri, Object.assign({
    headers: {
      'pacote-req-type': 'packument',
      'pacote-pkg-id': `registry:${spec}`,
      accept: opts.fullMetadata ? JSON_DOC : CORGI_DOC
    },
    spec
  }, opts, {
    // Force integrity to null: we never check integrity hashes for manifests
    integrity: null
  })).then(res => res.json().then(packument => {
    packument._cached = decodeURIComponent(res.headers.has('x-local-cache'))
    packument._contentLength = +res.headers.get('content-length')
    // NOTE - we need to call pickMem again because proxy
    //        objects get reused!
    const mem = pickMem(opts)
    if (mem) {
      mem.set(uri, packument)
    }
    return packument
  }))
}

const MEMO = new LRU({
  length: m => m._contentLength,
  max: 200 * 1024 * 1024, // 200MB
  maxAge: 30 * 1000 // 30s
})

class ObjProxy {
  get (key) { return this.obj[key] }
  set (key, val) { this.obj[key] = val }
}

// This object is used synchronously and immediately, so
// we can safely reuse it instead of consing up new ones
const PROX = new ObjProxy()
function pickMem (opts) {
  if (!opts || !opts.memoize) {
    return MEMO
  } else if (opts.memoize.get && opts.memoize.set) {
    return opts.memoize
  } else if (typeof opts.memoize === 'object') {
    PROX.obj = opts.memoize
    return PROX
  } else {
    return null
  }
}