import-js-from-browserfs.js

/*
This serivec-worker is proxy to browserfs on fetch/import

Example.

// write via browserfs
fs.writeFile('/dir/a.js', 'console.log("xxx")')

// import via service-worker
import('/fs/dir/a.js');

*/

importScripts("/assets/browserfs.min.js")

let _fs = null
const ensureFS = () =>
  new Promise((resolve, reject) => {
    if (_fs != null) {
      resolve(fs)
      return
    }
    BrowserFS.install(self)
    BrowserFS.configure(
      {
        fs: "IndexedDB",
        options: {}
      },
      err => {
        if (err) {
          reject(err)
        } else {
          _fs = BrowserFS.BFSRequire("fs")
          resolve(_fs)
        }
      }
    )
  })

ensureFS()

const FS_PREFIX = "/fs/"
self.addEventListener("fetch", event => {
  const parsedUrl = new URL(event.request.url)
  const withFS = parsedUrl.pathname.startsWith(FS_PREFIX)

  if (withFS) {
    const filepath = parsedUrl.pathname.replace(FS_PREFIX, "/")
    event.respondWith(
      ensureFS().then(fs => {
        return new Promise((resolve, reject) => {
          fs.readFile(filepath, (err, ret) => {
            if (err) {
              console.error(err)
              return reject(err)
            }
            const content = ret.toString()
            const res = new Response(content, {
              mode: "no-cors",
              headers: { "Content-Type": "text/javascript" }
            })
            resolve(res)
          })
        })
      })
    )
  }
})

self.addEventListener("install", e => e.waitUntil(self.skipWaiting()))
self.addEventListener("activate", e => e.waitUntil(self.clients.claim()))