// Production server for the Docker Space. No dependencies.
//
//   /        -> static dashboard from dist/
//   /data/*  -> benchmark files from DATA_DIR (bucket volume, default ./data)
//
// /data/index.json is generated ON THE FLY by scanning DATA_DIR, so new
// .jsonl files dropped into the bucket are discovered immediately — no
// manifest regeneration, no rebuild.
import { createServer } from 'node:http'
import { createReadStream, existsSync, readdirSync, statSync } from 'node:fs'
import { extname, join, normalize, resolve, sep } from 'node:path'
import { fileURLToPath } from 'node:url'

const root = resolve(fileURLToPath(new URL('.', import.meta.url)))
const distDir = join(root, 'dist')
const dataDir = resolve(process.env.DATA_DIR ?? join(root, 'data'))
const port = Number(process.env.PORT ?? 7860)

const MIME = {
  '.html': 'text/html; charset=utf-8',
  '.js': 'text/javascript',
  '.css': 'text/css',
  '.json': 'application/json',
  '.jsonl': 'application/x-ndjson',
  '.svg': 'image/svg+xml',
  '.png': 'image/png',
  '.ico': 'image/x-icon',
  '.woff2': 'font/woff2',
  '.map': 'application/json',
}

function sendFile(res, file, cacheControl) {
  const stream = createReadStream(file)
  stream.on('data', (chunk) => {
    res.bytesSent = (res.bytesSent ?? 0) + chunk.length
  })
  stream.on('error', (err) => {
    // Never let a stream error crash the server (it would take down the Space).
    console.error(`[server] failed to read ${file}:`, err.message)
    if (!res.headersSent) res.writeHead(500)
    res.end()
  })
  res.writeHead(200, {
    'Content-Type': MIME[extname(file)] ?? 'application/octet-stream',
    'Cache-Control': cacheControl,
  })
  stream.pipe(res)
}

/** Join rel onto base, refusing path traversal outside base. */
function safeJoin(base, rel) {
  const file = normalize(join(base, rel))
  return file === base || file.startsWith(base + sep) ? file : null
}

/** Recursively collect .jsonl paths under dir, prefixed with prefix. */
function collectJsonl(dir, prefix, out) {
  for (const entry of readdirSync(dir).sort()) {
    const full = join(dir, entry)
    if (statSync(full).isDirectory()) collectJsonl(full, `${prefix}${entry}/`, out)
    else if (entry.endsWith('.jsonl')) out.push(`${prefix}${entry}`)
  }
  return out
}

/**
 * Scan DATA_DIR and build the categories manifest. Category directories are
 * walked recursively to support the partitioned layout
 * (<category>/<host>/<date>/<name>.jsonl) alongside legacy flat files.
 */
function buildManifest() {
  const categories = {}
  if (existsSync(dataDir)) {
    for (const entry of readdirSync(dataDir).sort()) {
      const full = join(dataDir, entry)
      if (statSync(full).isDirectory()) {
        const files = collectJsonl(full, `${entry}/`, [])
        if (files.length > 0) categories[entry] = files
      } else if (entry.endsWith('.jsonl')) {
        ;(categories.models ??= []).push(entry)
      }
    }
  }
  return { categories }
}

createServer((req, res) => {
  const start = Date.now()
  res.on('finish', () => {
    console.log(
      `[http] ${req.method} ${req.url} -> ${res.statusCode} ${res.bytesSent ?? 0}B (${Date.now() - start}ms)`
    )
  })

  try {
    handle(req, res)
  } catch (err) {
    // Never crash the process on a single bad request.
    console.error('[server] handler error:', err)
    if (!res.headersSent) res.writeHead(500)
    res.end('internal error')
  }
}).listen(port, '0.0.0.0', () => {
  console.log(`dashboard: http://0.0.0.0:${port}  (dist=${distDir}, data=${dataDir})`)
})

function handle(req, res) {
  const url = new URL(req.url ?? '/', `http://${req.headers.host ?? 'localhost'}`)
  const path = decodeURIComponent(url.pathname)

  // Dynamic manifest — always reflects the current bucket contents.
  if (path === '/data/index.json') {
    res.writeHead(200, { 'Content-Type': 'application/json', 'Cache-Control': 'no-store' })
    res.end(JSON.stringify(buildManifest()))
    return
  }

  // Benchmark data files (never cached: results are appended over time).
  if (path.startsWith('/data/')) {
    const file = safeJoin(dataDir, path.slice('/data/'.length))
    if (file && existsSync(file) && statSync(file).isFile()) {
      sendFile(res, file, 'no-store')
    } else {
      res.writeHead(404)
      res.end('not found')
    }
    return
  }

  // Static dashboard, SPA fallback to index.html.
  let file = safeJoin(distDir, path === '/' ? 'index.html' : path.slice(1))
  if (!file || !existsSync(file) || !statSync(file).isFile()) {
    file = join(distDir, 'index.html')
  }
  sendFile(res, file, file.includes(`${sep}assets${sep}`) ? 'public, max-age=31536000, immutable' : 'no-cache')
}