refactor the installer logic

lib/install/installer.js

@@ -6,45 +6,35 @@ const { URL } = require('url')
 const path = require('path')
 const nm = require('../utils/nm')
 const bin = require('./bin')
+const registry = require('./installer/registry')
 
 const installer = (dep, deps, base, resolve, reject) => {
   mkdirp.sync(nm)
   mkdirp.sync(path.join(nm, '.bin'))
+
   const target = (base.length === 0)
     ? path.join(nm, dep)
     : path.join(nm, base.join('/'), 'node_modules', dep)
-  const url = new URL(deps[dep].tarball)
   mkdirp.sync(target)
 
-  https.get({
-    host: url.host,
-    path: url.pathname,
-    headers: npmrc.userAgent
-  }, (res) => {
-    res.pipe(
-      tar.extract({
-        cwd: target,
-        sync: true,
-        strip: 1
-      })
-    )
-    res.on('end', () => {
-      global.dependenciesCount += 1
-      bin(dep, target)
-      if (!deps[dep].dependencies) return resolve()
-      const tasks = Object.keys(deps[dep].dependencies).map((item) => {
-        const list = deps[dep].dependencies
-        let keys = [].concat(base, dep)
-        if (keys.length > 1) keys.splice(-1, 0, 'node_modules')
-        return new Promise((resolve, reject) => {
-          installer(item, list, keys, resolve, reject)
-        })
-      })
-      Promise.all(tasks).then(() => {
-        resolve()
+  const pkg = deps[dep]
+  let fetch = registry(pkg, target)
+  fetch.then(() => {
+    global.dependenciesCount += 1
+    bin(dep, target)
+    if (!pkg.dependencies) return resolve()
+    const tasks = Object.keys(pkg.dependencies).map((item) => {
+      const list = pkg.dependencies
+      let keys = [].concat(base, dep)
+      if (keys.length > 1) keys.splice(-1, 0, 'node_modules')
+      return new Promise((resolve, reject) => {
+        installer(item, list, keys, resolve, reject)
       })
     })
-  }).on('error', reject)
+    Promise.all(tasks).then(() => {
+      resolve()
+    })
+  })
 }
 
 module.exports = (deps) => {

lib/install/installer/registry.js

@@ -0,0 +1,30 @@
+const https = require('https')
+const mkdirp = require('mkdirp')
+const tar = require('tar')
+const { URL } = require('url')
+const path = require('path')
+const npmrc = require('../../utils/npmrc')
+const nm = require('../../utils/nm')
+const bin = require('../bin')
+
+module.exports = (pkg, cwd) => {
+  const url = new URL(pkg.tarball)
+  return new Promise((resolve, reject) => {
+    https.get({
+      host: url.host,
+      path: url.pathname,
+      headers: npmrc.userAgent
+    }, (res) => {
+      res.pipe(
+        tar.extract({
+          cwd: cwd,
+          sync: true,
+          strip: 1
+        })
+      )
+      res.on('end', () => {
+        resolve()
+      })
+    }).on('error', reject)
+  })
+}