@sap/cds-dk/lib/watch/vite-watch.js

Command line client and development toolkit for the SAP Cloud Application Programming Model

const cds = require('../../lib/cds')
const { pathToFileURL } = require('node:url')
const { path, stat, readdir, isdir, colors: { BOLD, RESET } } = cds.utils

let hmrPort = 24100

async function hasViteConfig(appPath) {
  for (const name of ['vite.config.js', 'vite.config.mjs', 'vite.config.ts']) {
    const file = await stat(path.join(appPath, name)).catch(e => e.code === 'ENOENT' ? null : Promise.reject(e))
    return !!file
  }
  return false
}

async function findViteApps() {
  const app = cds.env.folders.app
  const apps = []
  if (!isdir(app)) return apps
  const entries = await readdir(app)
  for (const entry of entries) {
    const appName = typeof entry === 'string' ? entry : entry.name
    if (!appName) continue
    const appPath = path.join(cds.root, app, appName)
    if (!isdir(appPath)) continue
    if (await hasViteConfig(appPath)) apps.push({ name: appName, path: appPath })
  }
  return apps
}

async function loadCreateServer(fromPath) {
  try {
      const vitePath = require.resolve('vite', { paths: [fromPath] })
      return (await import(pathToFileURL(vitePath).href)).createServer
    } catch(e) {
      if (e.code !== 'MODULE_NOT_FOUND') throw e
      /* try next path */
  }
  const relative = path.relative(cds.root, fromPath)
  throw `[cds] - Found Vite app in ${relative}, but package "vite" is not installed. Run ${BOLD}npm install vite --prefix ${relative}${RESET} to install it.`
}

cds.on('bootstrap', app => {

  let viteMiddleware = null
  app.use((req, res, next) => {
    if (viteMiddleware) return viteMiddleware(req, res, next)
    next()
  })

  cds.on('served', async () => {
    const viteApps = await findViteApps()
    if (!viteApps.length) return

    const createServer = await loadCreateServer(viteApps[0].path)

    // Build a middleware chain from all Vite servers, keyed by base path
    const viteServers = []
    const normalizeBase = base => {
      if (!base.startsWith('/')) base = `/${base}`
      return base.endsWith('/') ? base : `${base}/`
    }

    for (const viteApp of viteApps) {
      const base = normalizeBase(viteApp.name)
      const server = await createServer({ base, root: viteApp.path, server: { middlewareMode: true, hmr: { port: hmrPort++ } }})
      viteServers.push({ base, middlewares: server.middlewares })
    }

    viteMiddleware = (req, res, next) => {
      const url = req.url || ''
      const match = viteServers.find(v => url.startsWith(v.base) || url.startsWith('/@'))
      if (match) return match.middlewares(req, res, next)
      next()
    }
  })
})