Add code from express-unpkg repo

server/middleware/MetadataUtils.js

@@ -0,0 +1,51 @@
+const fs = require('fs')
+const { join: joinPaths } = require('path')
+const { getContentType, getStats, getFileType } = require('./FileUtils')
+
+const getEntries = (baseDir, path, maximumDepth) =>
+  new Promise((resolve, reject) => {
+    fs.readdir(joinPaths(baseDir, path), (error, files) => {
+      if (error) {
+        reject(error)
+      } else {
+        resolve(
+          Promise.all(
+            files.map(f => getStats(joinPaths(baseDir, path, f)))
+          ).then(
+            statsArray => Promise.all(statsArray.map(
+              (stats, index) => getMetadata(baseDir, joinPaths(path, files[index]), stats, maximumDepth - 1)
+            ))
+          )
+        )
+      }
+    })
+  })
+
+const formatTime = (time) =>
+  new Date(time).toISOString()
+
+const getMetadata = (baseDir, path, stats, maximumDepth) => {
+  const metadata = {
+    path,
+    lastModified: formatTime(stats.mtime),
+    contentType: getContentType(path),
+    size: stats.size,
+    type: getFileType(stats)
+  }
+
+  if (!stats.isDirectory() || maximumDepth === 0)
+    return Promise.resolve(metadata)
+
+  return getEntries(baseDir, path, maximumDepth).then(files => {
+    metadata.files = files
+    return metadata
+  })
+}
+
+const generateMetadata = (baseDir, path, stats, maximumDepth, callback) =>
+  getMetadata(baseDir, path, stats, maximumDepth)
+    .then(metadata => callback(null, metadata), callback)
+
+module.exports = {
+  generateMetadata
+}