gridsome/lib/server/middlewares/assets.js

A JAMstack framework for building blazing fast websites with Vue.js

const path = require('path')
const fs = require('fs-extra')
const { mapValues } = require('lodash')
const { createWorker } = require('../../workers')
const { SUPPORTED_IMAGE_TYPES } = require('../../utils/constants')

module.exports = ({ context, config, assets }) => {
  const worker = createWorker('image-processor')

  return async (req, res, next) => {
    const relPath = req.params[1].replace(/(%2e|\.){2}/g, '')
    const filePath = path.join(context, relPath)

    if (
      !filePath.startsWith(context) ||
      !fs.existsSync(filePath)
    ) {
      return res.sendStatus(404)
    }

    const { ext } = path.parse(filePath)
    const { key, ...options } = mapValues(req.query, value => {
      return decodeURIComponent(value)
    })

    const asset = assets.get(key || req.url)

    if (!asset) return res.sendStatus(404)

    const serveFile = async file => {
      const buffer = await fs.readFile(file)

      if (process.env.NODE_ENV === 'development') {
        res.header('Cache-Control', 'private, no-cache, no-store, must-revalidate')
        res.header('Pragma', 'no-cache')
        res.header('Expires', '-1')
      }

      res.header('Accept-Ranges', 'bytes')
      res.contentType(ext)
      res.end(buffer)
    }

    try {
      if (SUPPORTED_IMAGE_TYPES.includes(ext.toLowerCase())) {
        const imageOptions = assets.images.createImageOptions(options)
        const filename = assets.images.createFileName(filePath, imageOptions, asset.hash)
        const destPath = path.join(config.imageCacheDir, filename)

        if (!fs.existsSync(destPath)) {
          await worker.processImage({
            imagesConfig: config.images,
            width: asset.width,
            height: asset.height,
            filePath,
            destPath,
            options
          })
        }

        serveFile(destPath)
      } else {
        serveFile(filePath)
      }
    } catch (err) {
      next(err)
    }
  }
}