fix: fix css split

Author: yibn2008

lib/index.js

@@ -1,5 +1,6 @@
 'use strict'
 
+const path = require('path')
 const split = require('css-split')
 const { RawSource } = require('webpack-sources')
 const { interpolateName } = require('loader-utils')
@@ -25,7 +26,7 @@ const strip = (str) => str.replace(/\/$/, '')
  * @param {String} input Name to be interpolated.
  * @returns {Function} Function to do the interpolating.
  */
-const nameInterpolator = (input) => ({file, content, index}) => {
+const nameInterpolator = (input) => ({ file, content, index }) => {
   const res = interpolateName({
     context: '/',
     resourcePath: `/${file}`
@@ -51,7 +52,7 @@ const normalizeImports = (input, preserve) => {
         if (preserve) {
           return nameInterpolator('[name]-split.[ext]')
         }
-        return ({file}) => file
+        return ({ file }) => file
       }
       return () => false
     default:
@@ -102,6 +103,7 @@ class FastCSSSplitWebpackPlugin {
     const input = {
       source: asset.source()
     }
+    const dirname = path.dirname(key)
     const getName = (i) => this.options.filename(Object.assign({}, asset, {
       content: input.source,
       file: key,
@@ -111,6 +113,7 @@ class FastCSSSplitWebpackPlugin {
     const chunks = split(input.source, this.options.size).map((part, i) => {
       const result = new RawSource(part.content)
       result.name = getName(i)
+      result.fullname = dirname && dirname !== '.' ? `${dirname}/${result.name}` : result.name
       return result
     })
 
@@ -136,11 +139,11 @@ class FastCSSSplitWebpackPlugin {
         }
         // Inject the new files into the chunk.
         entry.chunks.forEach((file) => {
-          assets[file.name] = file
-          chunk.files.push(file.name)
+          assets[file.fullname] = file
+          chunk.files.push(file.fullname)
         })
         const content = entry.chunks.map((file) => {
-          return `@import "${publicPath}/${file._name}";`
+          return `@import "${publicPath}/${file.name}";`
         }).join('\n')
         const imports = this.options.imports(Object.assign({}, entry, {
           content