import express from 'express'
import fs from 'node:fs'
import http from 'node:http'
import path from 'node:path'
import { fileURLToPath } from 'node:url'
import { WebSocketServer } from 'ws'
import { initStore, DATA_DIR, UPLOADS_DIR, getRegistry, canAccessDoc, docByShareToken, uploadProject } from './store.js'
import { registerAuthRoutes, resolveUser, resolveShare, shareCookie, OAUTH_ENABLED, HOST, bootPayload } from './auth.js'
import { apiRouter } from './api.js'
import { hocuspocus } from './collab.js'
import { stopDefaultAgents } from './default-agent.js'

initStore()

const __dirname = path.dirname(fileURLToPath(import.meta.url))
const PUBLIC_DIR = path.join(__dirname, '..', 'public')
const PORT = Number(process.env.PORT || 3000)

const app = express()
app.set('trust proxy', true)
app.use(resolveUser())
app.use(resolveShare)
// A share link is a bearer credential and documents link outwards; never let a
// URL from this app travel in a Referer header to another origin.
app.use((req, res, next) => {
  res.set('Referrer-Policy', 'no-referrer')
  next()
})

app.get('/healthz', (req, res) => res.json({ ok: true, oauth: OAUTH_ENABLED }))
registerAuthRoutes(app)
app.use('/api', apiRouter())

// The HTML shell must never be cached: it carries the ?v=<buildId> asset URLs,
// and a stale shell means a stale bundle, which the collab build-check then
// rejects — a tab that looks fine but silently saves nothing. The bundles
// themselves are versioned, so they can be cached hard.
// The shells are tiny; keep them in memory but re-read when a build replaces
// them, so a rebuild without a restart cannot serve yesterday's asset URLs.
const shells = new Map()
const shell = name => {
  const file = path.join(PUBLIC_DIR, name)
  const stamp = fs.statSync(file).mtimeMs
  const hit = shells.get(name)
  if (hit?.stamp === stamp) return hit.body
  const body = fs.readFileSync(file, 'utf8')
  shells.set(name, { stamp, body })
  return body
}
const escapeHtml = s =>
  String(s).replace(/[&<>"']/g, c => ({ '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' })[c])

// The header would otherwise show "…" for the whole load. The title is already
// in the registry, so the shell can carry it — but only to someone who is
// allowed to see the project, or the placeholder leaks private titles.
// header = project name; tab = "page · project" (matching the client's painter)
const titleFor = (req, id, slug) => {
  if (!id) return null
  if (!canAccessDoc(id, req.user?.username) && req.share?.docId !== id) return null
  const meta = getRegistry()[id]
  if (!meta) return null
  const project = meta.title || null
  const page = slug === '_structure' ? 'Structure' : slug && slug !== 'home' ? meta.pages?.[slug]?.title || null : null
  if (!project && !page) return null
  return { header: project || page, tab: page && project ? `${page} · ${project}` : page || project }
}

const sendShell = name => (req, res) => {
  const json = JSON.stringify(bootPayload(req)).replace(/</g, '\\u003c')
  let body = shell(name).replace('<!--boot-->', `<script>window.__BOOT=${json}</script>`)
  const title = titleFor(req, req.params.id, req.params.slug)
  if (title) {
    body = body
      .replace('<span id="doc-title">…</span>', `<span id="doc-title">${escapeHtml(title.header)}</span>`)
      .replace('<title>Document</title>', `<title>${escapeHtml(title.tab)}</title>`)
  }
  res.set('Cache-Control', 'no-cache, must-revalidate')
  res.type('html').send(body)
}
const sendDoc = sendShell('doc.html')

// No index page: / means "the document I was last in". A signed-out visitor gets
// the shell and its sign-in overlay; a signed-in one is sent to their most recent
// document, and only sees the shell bare if they have none to send them to. The
// redirect keeps GET / free of side effects — creating a document is a POST the
// switcher makes, not something a page load does behind you.
app.get('/', (req, res, next) => {
  if (!req.user) return sendDoc(req, res, next)
  const registry = getRegistry()
  const mine = Object.entries(registry)
    .filter(([id]) => canAccessDoc(id, req.user.username))
    .sort((a, b) => (b[1].updatedAt || 0) - (a[1].updatedAt || 0))
  if (mine.length) return res.redirect(302, `/d/${mine[0][0]}`)
  sendDoc(req, res, next)
})

// Bundles are immutable per build id, so a client that asks for ?v=<id> can keep
// the answer forever — that is what makes a second visit cost no bytes at all.
app.use((req, res, next) => {
  if (req.query.v) res.set('Cache-Control', 'public, max-age=31536000, immutable')
  next()
})

// Serve the build's pre-compressed twin when the client takes it. Saves ~480KB
// on a cold editor load; without it express.static ships the raw bundle.
const ENCODINGS = [
  ['br', '.br'],
  ['gzip', '.gz'],
]
app.get(/\.(?:js|css)$/, (req, res, next) => {
  const name = path.basename(req.path)
  if (name !== req.path.slice(1)) return next() // only flat asset names, no traversal
  const accepted = req.headers['accept-encoding'] || ''
  for (const [token, ext] of ENCODINGS) {
    if (!new RegExp(`\\b${token}\\b`).test(accepted)) continue
    const file = path.join(PUBLIC_DIR, name + ext)
    if (!fs.existsSync(file)) continue
    res.set('Content-Encoding', token)
    res.set('Vary', 'Accept-Encoding')
    res.type(path.extname(name))
    return res.sendFile(file)
  }
  next()
})
app.use(express.static(PUBLIC_DIR, { index: false, setHeaders: (res, filePath) => {
  if (filePath.endsWith('.html')) res.set('Cache-Control', 'no-cache, must-revalidate')
  // the webfont files are content-addressed by name; a new face gets a new name
  else if (filePath.includes(`${path.sep}fonts${path.sep}`)) res.set('Cache-Control', 'public, max-age=31536000, immutable')
} }))
app.get('/d/:id', sendDoc)
app.get('/d/:id/:slug', sendDoc)

// Public share links. The token in the path is the whole credential, so it is
// exchanged for a cookie on arrival: nothing else in the app has to carry it,
// and the socket handshake and <img> requests are covered by the same grant.
// An unknown or revoked token is a 404 — it must not confirm that a project
// with that id exists.
const sendShared = (req, res) => {
  const docId = docByShareToken(req.params.token)
  if (!docId) return res.status(404).type('html').send(shell('doc.html'))
  res.setHeader('set-cookie', shareCookie(req.params.token))
  // Redirect rather than render here. The token IS the credential, and a
  // rendered page leaves it in the address bar, in history, and — because a
  // document may carry external images and links — in the Referer header sent
  // to whatever host those point at. The cookie carries the grant from here on,
  // so /d/<id> works for this visitor and for nobody else.
  const slug = req.params.slug ? `/${encodeURIComponent(req.params.slug)}` : ''
  res.redirect(302, `/d/${docId}${slug}`)
}
app.get('/p/:token', sendShared)
app.get('/p/:token/:slug', sendShared)

// uploaded images (auth required — same session cookie the <img> tags send)
app.get('/files/:name', (req, res) => {
  if (!/^[a-f0-9]{16}\.(png|jpg|gif|webp|svg)$/.test(req.params.name)) return res.status(400).end()
  // A signed-in user may fetch any upload by name, as they always could. A
  // public-link visitor is confined to the project their link opens: uploads
  // are global on disk, so without this the cookie would be a key to every
  // figure on the instance for anyone holding any link.
  if (!req.user) {
    if (!req.share) return res.status(401).end()
    if (uploadProject(req.params.name) !== req.share.docId) return res.status(404).end()
  }
  // dotfiles:'allow' — DATA_DIR may itself be a dot-directory (e.g. ./.browser-data in tests)
  res.sendFile(path.join(UPLOADS_DIR, req.params.name), { maxAge: '365d', immutable: true, dotfiles: 'allow' }, err => {
    if (err) res.status(404).end()
  })
})

const server = http.createServer(app)
const wss = new WebSocketServer({ noServer: true })

server.on('upgrade', (request, socket, head) => {
  if (!request.url?.startsWith('/collab')) {
    socket.destroy()
    return
  }
  wss.handleUpgrade(request, socket, head, ws => {
    // hocuspocus v4: the caller owns the socket events and feeds them in
    const connection = hocuspocus.handleConnection(ws, request)
    ws.on('message', data => connection.handleMessage(new Uint8Array(data)))
    ws.on('close', (code, reason) => connection.handleClose({ code, reason: reason?.toString() }))
    ws.on('error', () => connection.handleClose({ code: 1011, reason: 'socket error' }))
  })
})

server.listen(PORT, () => {
  console.log(`interactive-editor listening on :${PORT} (host: ${HOST}, oauth: ${OAUTH_ENABLED}, data: ${DATA_DIR})`)
})

// heartbeat: visible in Space logs — if it stops ticking while the app is
// unreachable, the event loop is blocked (e.g. a hung sync write on the
// bucket mount); lag > ~1s means something synchronous is hogging the loop
let hbLast = Date.now()
setInterval(() => {
  const lag = Date.now() - hbLast - 60000
  hbLast = Date.now()
  const mem = Math.round(process.memoryUsage().rss / 1e6)
  console.log(`[hb] rss=${mem}MB docs=${hocuspocus.documents?.size ?? '?'} lag=${lag}ms`)
}, 60000)

for (const signal of ['SIGTERM', 'SIGINT']) {
  process.on(signal, () => {
    stopDefaultAgents()
    try { hocuspocus.flushPendingStores() } catch {}
    setTimeout(() => process.exit(0), 500)
  })
}