// bankai start — the dev server: Vite middleware mode for the module
// graph and HMR, per-request streaming SSR of the same entry through
// vite.ssrLoadModule so server code shares Vite's transforms and cache.

import { createServer } from 'node:http'

import bankaiPlugin, { findCss, CLIENT_URL } from './plugin.js'
import { resolveApp } from './app.js'
import { documentHead, documentTail } from './document.js'

export default async function dev ({ entry, port = 8080, title = 'choo' }) {
  const { createServer: createViteServer } = await import('vite')
  const css = await findCss(entry) // style.css convention; restart to add it

  const vite = await createViteServer({
    appType: 'custom',
    server: { middlewareMode: true },
    plugins: [bankaiPlugin(entry, { css })],
    css: { lightningcss: { errorRecovery: true } },
    logLevel: 'warn'
  })

  const server = createServer((req, res) => {
    vite.middlewares(req, res, async () => {
      // not an asset Vite knows: this is a page navigation — SSR it
      try {
        const mod = await vite.ssrLoadModule(entry)
        const app = resolveApp(mod, entry)
        const state = {}

        // Read the first chunk before writing the head: by then stores
        // have run and the view has rendered up to its first async hole,
        // so DOMTitleChange emits have landed in state.title.
        const reader = app.toStream(req.url, state).getReader()
        const first = await reader.read()

        res.writeHead(200, { 'content-type': 'text/html; charset=utf-8' })
        res.write(documentHead({
          title: state.title || title,
          scripts: ['/@vite/client', CLIENT_URL]
        }))
        if (!first.done) res.write(first.value)
        for (;;) {
          const { done, value } = await reader.read()
          if (done) break
          res.write(value)
        }
        res.end(documentTail(state))
      } catch (err) {
        vite.ssrFixStacktrace(err)
        console.error(err)
        if (!res.headersSent) res.writeHead(500, { 'content-type': 'text/plain' })
        res.end('bankai dev error:\n\n' + (err.stack || err.message))
      }
    })
  })

  await new Promise((resolve) => server.listen(port, resolve))
  return {
    server,
    vite,
    port: server.address().port,
    origin: `http://localhost:${server.address().port}`,
    close: async () => {
      await vite.close()
      await new Promise((resolve) => server.close(resolve))
    }
  }
}