// panel-auth — password gate for the DSH web panel.
//
// A web-profile host plugin. It wraps the panel's node:http server
// (the `webServer` service) and requires one of, on EVERY request and
// WebSocket upgrade:
//   1. a valid signed session cookie (dsh_panel), issued at login, or
//   2. a valid HTTP Basic credential from `config.users`.
//
// Browsers get a self-contained login page instead of the native Basic
// dialog; API clients keep the classic 401 + WWW-Authenticate contract.
// Login activity (success, failure, logout, rejected requests) is written
// to a structured JSONL audit file.
//
// Fail-open by design: with no users or no secret configured the guard
// passes everything through, so a broken config can never lock the panel
// out. Config is re-read on every request, so password changes applied to
// the row (HMR or restart) take effect without remounting the plugin.
//
// Row shape (profile cordis.patch.yml):
//   - insert:
//       - id: panel-auth
//         name: './panel-auth/index.js'
//         inject: [webServer]
//         config:
//           realm: 'DSH Panel'
//           secret: '<32+ chars of random text, keep private>'
//           cookieName: dsh_panel
//           cookieTtlSeconds: 2592000
//           auditLogPath: '/root/.dsh/panel-auth-audit.jsonl'   # optional
//           loginPath: '/panel-auth/login'                        # optional
//           logoutPath: '/panel-auth/logout'                      # optional
//           users:
//             - username: admin
//               passwordHash: '<output of: node panel-auth/hash.js admin <password>>'
import { appendFileSync, renameSync, statSync } from 'node:fs'
import { homedir } from 'node:os'
import { resolve } from 'node:path'
import { verifyPassword, signSession, verifySession } from './crypto.js'

const DEFAULTS = {
  realm: 'DSH Panel',
  cookieName: 'dsh_panel',
  cookieTtlSeconds: 60 * 60 * 24 * 30, // 30 days
  loginPath: '/panel-auth/login',
  logoutPath: '/panel-auth/logout',
  auditMaxBytes: 5 * 1024 * 1024,
}

// ── audit log ────────────────────────────────────────────────────────────────

export function createAuditWriter(filePath) {
  function rotateIfNeeded() {
    try {
      if (statSync(filePath).size > DEFAULTS.auditMaxBytes) renameSync(filePath, `${filePath}.1`)
    } catch {
      /* first write or concurrent rotation — ignore */
    }
  }
  return {
    path: filePath,
    write(entry) {
      try {
        appendFileSync(filePath, JSON.stringify({ ts: new Date().toISOString(), ...entry }) + '\n', { mode: 0o600 })
        rotateIfNeeded()
      } catch (error) {
        console.error('[panel-auth] audit write failed:', error && error.message ? error.message : error)
      }
    },
  }
}

export function defaultAuditPath() {
  const home = process.env.DSH_HOME || resolve(homedir(), '.dsh')
  return resolve(home, 'panel-auth-audit.jsonl')
}

// ── guard ────────────────────────────────────────────────────────────────────

export function createGuard({ getConfig, logger }) {
  function current() {
    const cfg = getConfig() ?? {}
    const users = Array.isArray(cfg.users)
      ? cfg.users.filter((u) => u && typeof u.username === 'string' && typeof u.passwordHash === 'string')
      : []
    const secret = typeof cfg.secret === 'string' ? cfg.secret : ''
    const cookieTtl = Number.isFinite(cfg.cookieTtlSeconds) && cfg.cookieTtlSeconds > 0 ? cfg.cookieTtlSeconds : DEFAULTS.cookieTtlSeconds
    return {
      users,
      secret,
      enabled: users.length > 0 && secret.length >= 16,
      realm: typeof cfg.realm === 'string' && cfg.realm.length > 0 ? cfg.realm : DEFAULTS.realm,
      cookieName: typeof cfg.cookieName === 'string' && cfg.cookieName.length > 0 ? cfg.cookieName : DEFAULTS.cookieName,
      ttl: cookieTtl,
    }
  }

  function basicUser(req, cfg) {
    const header = req.headers.authorization
    if (typeof header !== 'string' || !header.startsWith('Basic ')) return null
    let decoded
    try {
      decoded = Buffer.from(header.slice(6).trim(), 'base64').toString('utf8')
    } catch {
      return null
    }
    const colon = decoded.indexOf(':')
    if (colon <= 0) return null
    const username = decoded.slice(0, colon)
    const password = decoded.slice(colon + 1)
    const found = cfg.users.find((u) => u.username === username)
    if (found === undefined) return null
    return verifyPassword(password, found.passwordHash) ? username : null
  }

  function cookieUser(req, cfg) {
    const header = req.headers.cookie
    if (typeof header !== 'string') return null
    for (const part of header.split(';')) {
      const eq = part.indexOf('=')
      if (eq <= 0) continue
      const name = part.slice(0, eq).trim()
      if (name !== cfg.cookieName) continue
      const value = part.slice(eq + 1).trim()
      const username = verifySession(cfg.secret, value, Math.floor(Date.now() / 1000))
      if (username !== null && cfg.users.some((u) => u.username === username)) return username
      return null
    }
    return null
  }

  /**
   * Identify the caller.
   * - { open: true } → config disabled, pass everything through (fail-open)
   * - { username, via } → accepted ('cookie' or 'basic')
   * - null → anonymous, challenge
   */
  function authenticate(req) {
    const cfg = current()
    if (!cfg.enabled) return { open: true }
    const cookieIdentity = cookieUser(req, cfg)
    if (cookieIdentity !== null) return { username: cookieIdentity, via: 'cookie' }
    const basicIdentity = basicUser(req, cfg)
    if (basicIdentity !== null) return { username: basicIdentity, via: 'basic' }
    return null
  }

  function checkCredentials(username, password) {
    const cfg = current()
    if (!cfg.enabled) return false
    const found = cfg.users.find((u) => u.username === username)
    if (found === undefined) return false
    return verifyPassword(password, found.passwordHash)
  }

  function issueCookieValue(username) {
    const cfg = current()
    return signSession(cfg.secret, username, Math.floor(Date.now() / 1000) + cfg.ttl)
  }

  function cookieSettings() {
    const cfg = current()
    return { name: cfg.cookieName, ttl: cfg.ttl }
  }

  function realm() {
    return current().realm
  }

  return { authenticate, checkCredentials, issueCookieValue, cookieSettings, realm }
}

// ── login page ───────────────────────────────────────────────────────────────

export function escapeHtml(value) {
  return String(value)
    .replaceAll('&', '&amp;')
    .replaceAll('<', '&lt;')
    .replaceAll('>', '&gt;')
    .replaceAll('"', '&quot;')
    .replaceAll("'", '&#39;')
}

export function renderLoginPage({ realm, next = '/', error = '', loginPath = DEFAULTS.loginPath }) {
  const safeNext = escapeHtml(next)
  const safeError = escapeHtml(error)
  const safeRealm = escapeHtml(realm)
  const safeAction = escapeHtml(loginPath)
  return `<!doctype html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta http-equiv="Content-Security-Policy" content="default-src 'none'; style-src 'unsafe-inline'; img-src data:; form-action 'self'; base-uri 'none'">
<meta name="referrer" content="no-referrer">
<title>${safeRealm} · 登录</title>
<link rel="icon" href="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 32 32'%3E%3Crect width='32' height='32' rx='8' fill='%236d8dff'/%3E%3Cpath d='M16 8a5 5 0 0 0-5 5v3h-2a2 2 0 0 0-2 2v8a2 2 0 0 0 2 2h14a2 2 0 0 0 2-2v-8a2 2 0 0 0-2-2h-2v-3a5 5 0 0 0-5-5Zm-3 8v-3a3 3 0 1 1 6 0v3h-6Z' fill='white'/%3E%3C/svg%3E">
<style>
  :root {
    --accent: #6d8dff;
    --accent-2: #8b5cf6;
    --danger: #f87171;
    --text: #e8eaf2;
    --text-dim: #9aa1b5;
    --field-bg: rgba(255, 255, 255, 0.06);
    --field-border: rgba(255, 255, 255, 0.12);
    --card-bg: rgba(22, 26, 40, 0.82);
    --card-border: rgba(255, 255, 255, 0.1);
  }
  * { box-sizing: border-box; margin: 0; padding: 0; }
  html, body { height: 100%; }
  body {
    font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
    color: var(--text);
    display: grid;
    place-items: center;
    min-height: 100%;
    padding: 24px;
    background:
      radial-gradient(1200px 600px at 15% -10%, rgba(109, 141, 255, 0.28), transparent 60%),
      radial-gradient(1000px 700px at 110% 15%, rgba(139, 92, 246, 0.22), transparent 55%),
      radial-gradient(900px 900px at 50% 120%, rgba(45, 55, 90, 0.9), transparent 60%),
      #0d1020;
    background-attachment: fixed;
    animation: bg-breathe 14s ease-in-out infinite alternate;
  }
  @keyframes bg-breathe {
    from { filter: saturate(1); }
    to { filter: saturate(1.25); }
  }
  .card {
    width: min(400px, 100%);
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 18px;
    padding: 40px 36px 30px;
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    box-shadow: 0 24px 60px rgba(0, 0, 0, 0.45), 0 0 0 1px rgba(109, 141, 255, 0.06) inset;
    animation: card-in 0.5s cubic-bezier(0.22, 1, 0.36, 1) both;
  }
  @keyframes card-in {
    from { opacity: 0; transform: translateY(14px) scale(0.985); }
    to { opacity: 1; transform: none; }
  }
  .logo {
    width: 60px; height: 60px;
    margin: 0 auto 18px;
    border-radius: 17px;
    display: grid; place-items: center;
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    box-shadow: 0 10px 26px rgba(109, 141, 255, 0.35);
  }
  .logo svg { width: 30px; height: 30px; }
  h1 {
    font-size: 24px; font-weight: 650; text-align: center; letter-spacing: 0.02em;
  }
  .subtitle {
    text-align: center; color: var(--text-dim);
    font-size: 13.5px; margin: 8px 0 26px;
  }
  .error {
    display: flex; align-items: center; gap: 8px;
    background: rgba(248, 113, 113, 0.1);
    border: 1px solid rgba(248, 113, 113, 0.35);
    color: var(--danger);
    border-radius: 10px;
    padding: 10px 12px;
    font-size: 13.5px;
    margin-bottom: 18px;
    animation: card-in 0.3s ease both;
  }
  .error svg { flex: none; width: 16px; height: 16px; }
  label {
    display: block;
    font-size: 12px; color: var(--text-dim);
    letter-spacing: 0.06em; text-transform: uppercase;
    margin: 0 0 6px 2px;
  }
  .field { margin-bottom: 16px; }
  input {
    width: 100%;
    background: var(--field-bg);
    border: 1px solid var(--field-border);
    border-radius: 11px;
    color: var(--text);
    font-size: 15px;
    padding: 12px 14px;
    outline: none;
    transition: border-color 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
  }
  input::placeholder { color: #5a6178; }
  input:hover { border-color: rgba(255, 255, 255, 0.22); }
  input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(109, 141, 255, 0.22);
    background: rgba(255, 255, 255, 0.08);
  }
  button {
    width: 100%;
    margin-top: 8px;
    padding: 12px 0;
    font-size: 15px; font-weight: 600; color: #fff;
    border: none; border-radius: 11px; cursor: pointer;
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    box-shadow: 0 8px 22px rgba(109, 141, 255, 0.32);
    transition: transform 0.15s ease, box-shadow 0.15s ease, filter 0.15s ease;
  }
  button:hover { transform: translateY(-1px); filter: brightness(1.08); box-shadow: 0 12px 26px rgba(109, 141, 255, 0.4); }
  button:active { transform: translateY(0); filter: brightness(0.96); }
  .foot {
    margin-top: 22px; text-align: center;
    font-size: 12px; color: #565d73; line-height: 1.7;
  }
  @media (prefers-reduced-motion: reduce) {
    * { animation: none !important; transition: none !important; }
  }
</style>
</head>
<body>
  <form class="card" method="post" action="${safeAction}" autocomplete="off">
    <div class="logo" aria-hidden="true">
      <svg viewBox="0 0 24 24" fill="none">
        <rect x="4" y="10" width="16" height="10" rx="2.5" stroke="white" stroke-width="1.8"/>
        <path d="M8 10V7a4 4 0 0 1 8 0v3" stroke="white" stroke-width="1.8" stroke-linecap="round"/>
        <circle cx="12" cy="15" r="1.6" fill="white"/>
      </svg>
    </div>
    <h1>${safeRealm}</h1>
    <p class="subtitle">登录以继续 · Sign in to continue</p>
    ${safeError ? `<div class="error" role="alert">
      <svg viewBox="0 0 24 24" fill="none"><circle cx="12" cy="12" r="9" stroke="currentColor" stroke-width="1.8"/><path d="M12 7.5v5.5" stroke="currentColor" stroke-width="1.8" stroke-linecap="round"/><circle cx="12" cy="16.6" r="1.2" fill="currentColor"/></svg>
      <span>${safeError}</span>
    </div>` : ''}
    <div class="field">
      <label for="username">用户名</label>
      <input id="username" name="username" type="text" placeholder="admin" required autofocus>
    </div>
    <div class="field">
      <label for="password">密码</label>
      <input id="password" name="password" type="password" placeholder="••••••••" required>
    </div>
    <input type="hidden" name="next" value="${safeNext}">
    <button type="submit">登 录</button>
    <p class="foot">登录活动将被记录<br>Protected by panel-auth</p>
  </form>
</body>
</html>`
}

// ── request helpers ──────────────────────────────────────────────────────────

function clientIp(req) {
  const remote = req.socket?.remoteAddress ?? ''
  const loopback = remote === '127.0.0.1' || remote === '::1' || remote === '::ffff:127.0.0.1'
  if (loopback) {
    const forwarded = req.headers['x-forwarded-for']
    if (typeof forwarded === 'string' && forwarded.length > 0) {
      const first = forwarded.split(',')[0].trim()
      if (first.length > 0) return first
    }
  }
  return remote
}

function acceptsHtml(req) {
  const accept = req.headers.accept
  return typeof accept === 'string' && accept.includes('text/html')
}

function sanitizeNext(next) {
  if (typeof next !== 'string' || next.length === 0 || next.length > 2048) return '/'
  if (!next.startsWith('/') || next.startsWith('//')) return '/'
  return next
}

function readBody(req, maxBytes) {
  return new Promise((resolveBody) => {
    let size = 0
    const chunks = []
    let done = false
    const finish = () => {
      if (done) return
      done = true
      resolveBody(Buffer.concat(chunks).toString('utf8'))
    }
    req.on('data', (chunk) => {
      size += chunk.length
      if (size > maxBytes) {
        done = true
        resolveBody(null)
        req.destroy()
        return
      }
      chunks.push(chunk)
    })
    req.on('end', finish)
    req.on('error', finish)
  })
}

// ── server wrap ──────────────────────────────────────────────────────────────

/**
 * Atomically wrap the panel's http.Server: replace its 'request' and
 * 'upgrade' listeners with an auth gate that forwards to the originals.
 * Returns a disposer that restores the exact original listeners.
 */
export function installGuard(server, guard, { audit, loginPath, logoutPath }) {
  const origRequest = server.listeners('request')
  const origUpgrade = server.listeners('upgrade')

  const challenge = (res) => {
    res.statusCode = 401
    res.setHeader('WWW-Authenticate', `Basic realm="${guard.realm()}", charset="UTF-8"`)
    res.setHeader('Content-Type', 'application/json; charset=utf-8')
    res.setHeader('Cache-Control', 'no-store')
    res.setHeader('Content-Length', String(Buffer.byteLength('{"error":"authentication required"}')))
    res.end('{"error":"authentication required"}')
  }

  const serveLogin = (req, res, error, status = 200, next = '/') => {
    const page = renderLoginPage({ realm: guard.realm(), next: sanitizeNext(next), error, loginPath })
    res.statusCode = status
    res.setHeader('Content-Type', 'text/html; charset=utf-8')
    res.setHeader('Cache-Control', 'no-store')
    res.setHeader('Content-Length', String(Buffer.byteLength(page)))
    res.end(page)
  }

  const handleLogin = async (req, res) => {
    let queryNext = '/'
    try {
      queryNext = new URL(req.url ?? '/', 'http://x').searchParams.get('next') ?? '/'
    } catch {
      /* malformed URL */
    }
    if (req.method !== 'POST') {
      serveLogin(req, res, '', 200, queryNext)
      return
    }
    // Cross-origin form posts are rejected: the login form must come from this host.
    const origin = req.headers.origin
    const host = req.headers.host
    if (typeof origin === 'string' && typeof host === 'string') {
      try {
        if (new URL(origin).host !== host) {
          audit.write({ event: 'login-fail', username: '', ip: clientIp(req), ua: req.headers['user-agent'] ?? '', reason: 'cross-origin' })
          serveLogin(req, res, '非法请求来源', 403, queryNext)
          return
        }
      } catch {
        audit.write({ event: 'login-fail', username: '', ip: clientIp(req), ua: req.headers['user-agent'] ?? '', reason: 'cross-origin' })
        serveLogin(req, res, '非法请求来源', 403, queryNext)
        return
      }
    }
    const body = await readBody(req, 8192)
    if (body === null) {
      audit.write({ event: 'login-fail', username: '', ip: clientIp(req), ua: req.headers['user-agent'] ?? '', reason: 'body-too-large' })
      serveLogin(req, res, '请求过大', 413, queryNext)
      return
    }
    const fields = new URLSearchParams(body)
    const username = fields.get('username') ?? ''
    const password = fields.get('password') ?? ''
    const next = sanitizeNext(fields.get('next') ?? queryNext)
    const ip = clientIp(req)
    const ua = req.headers['user-agent'] ?? ''
    if (!username || !password) {
      audit.write({ event: 'login-fail', username, ip, ua, reason: 'missing-fields' })
      serveLogin(req, res, '请输入用户名和密码', 403, next)
      return
    }
    if (guard.checkCredentials(username, password)) {
      const value = guard.issueCookieValue(username)
      const settings = guard.cookieSettings()
      audit.write({ event: 'login-ok', username, ip, ua })
      res.statusCode = 303
      res.setHeader('Set-Cookie', `${settings.name}=${value}; Path=/; HttpOnly; SameSite=Lax; Max-Age=${settings.ttl}`)
      res.setHeader('Location', next)
      res.setHeader('Content-Length', '0')
      res.end()
      return
    }
    audit.write({ event: 'login-fail', username, ip, ua, reason: 'bad-credentials' })
    serveLogin(req, res, '用户名或密码错误', 403, next)
  }

  const handleLogout = (req, res) => {
    const settings = guard.cookieSettings()
    audit.write({ event: 'logout', username: '', ip: clientIp(req), ua: req.headers['user-agent'] ?? '' })
    res.statusCode = 303
    res.setHeader('Set-Cookie', `${settings.name}=; Path=/; HttpOnly; SameSite=Lax; Max-Age=0`)
    res.setHeader('Location', loginPath)
    res.setHeader('Content-Length', '0')
    res.end()
  }

  const onRequest = (req, res) => {
    let pathname = '/'
    try {
      pathname = new URL(req.url ?? '/', 'http://x').pathname
    } catch {
      /* malformed URL → treat as anonymous */
    }
    if (pathname === loginPath) {
      handleLogin(req, res)
      return
    }
    if (pathname === logoutPath) {
      handleLogout(req, res)
      return
    }
    const who = guard.authenticate(req)
    if (who === null) {
      if (acceptsHtml(req)) {
        audit.write({ event: 'challenge', username: '', ip: clientIp(req), ua: req.headers['user-agent'] ?? '', path: pathname })
        serveLogin(req, res, '', 200, req.url ?? '/')
        return
      }
      audit.write({ event: 'reject', username: '', ip: clientIp(req), ua: req.headers['user-agent'] ?? '', method: req.method ?? '', path: pathname })
      challenge(res)
      return
    }
    if (!who.open && who.via === 'basic') {
      const value = guard.issueCookieValue(who.username)
      const settings = guard.cookieSettings()
      const existing = res.getHeader('Set-Cookie')
      const cookieHeader = `${settings.name}=${value}; Path=/; HttpOnly; SameSite=Lax; Max-Age=${settings.ttl}`
      res.setHeader('Set-Cookie', existing === undefined ? cookieHeader : [].concat(existing, cookieHeader))
    }
    for (const fn of origRequest) fn(req, res)
  }

  const onUpgrade = (req, socket, head) => {
    let pathname = '/'
    try {
      pathname = new URL(req.url ?? '/', 'http://x').pathname
    } catch {
      /* malformed URL → reject */
    }
    if (pathname === loginPath || pathname === logoutPath) {
      socket.end('HTTP/1.1 405 Method Not Allowed\r\nConnection: close\r\nContent-Length: 0\r\n\r\n')
      socket.destroy()
      return
    }
    const who = guard.authenticate(req)
    if (who === null) {
      audit.write({ event: 'reject', username: '', ip: clientIp(req), ua: req.headers['user-agent'] ?? '', method: 'UPGRADE', path: pathname })
      socket.end('HTTP/1.1 401 Unauthorized\r\nConnection: close\r\nContent-Length: 0\r\n\r\n')
      socket.destroy()
      return
    }
    for (const fn of origUpgrade) fn(req, socket, head)
  }

  server.removeAllListeners('request')
  server.removeAllListeners('upgrade')
  server.on('request', onRequest)
  server.on('upgrade', onUpgrade)

  return () => {
    server.removeListener('request', onRequest)
    server.removeListener('upgrade', onUpgrade)
    for (const fn of origRequest) server.on('request', fn)
    for (const fn of origUpgrade) server.on('upgrade', fn)
  }
}

// ── plugin ───────────────────────────────────────────────────────────────────

export default function panelAuth(ctx, config) {
  const cfg = config ?? {}
  const guard = createGuard({ getConfig: () => cfg, logger: null })
  const auditPath = typeof cfg.auditLogPath === 'string' && cfg.auditLogPath.length > 0 ? cfg.auditLogPath : defaultAuditPath()
  const audit = createAuditWriter(auditPath)
  const loginPath = typeof cfg.loginPath === 'string' && cfg.loginPath.length > 0 ? cfg.loginPath : DEFAULTS.loginPath
  const logoutPath = typeof cfg.logoutPath === 'string' && cfg.logoutPath.length > 0 ? cfg.logoutPath : DEFAULTS.logoutPath
  console.log('[panel-auth] audit log: ' + auditPath)
  let disposer
  let timer
  let stopped = false
  ctx.effect(() => () => {
    stopped = true
    if (timer !== undefined) clearInterval(timer)
    if (disposer !== undefined) disposer()
  })
  const tryWrap = () => {
    const server = ctx.webServer.server
    if (server === undefined) return false
    disposer = installGuard(server, guard, { audit, loginPath, logoutPath })
    console.log('[panel-auth] guard installed: panel now requires a password')
    return true
  }
  if (!tryWrap()) {
    // Cold boot: webServer's node:http server is created in Service.init,
    // which may not have run when this row applies. Poll briefly.
    timer = setInterval(() => {
      if (!stopped && tryWrap()) clearInterval(timer)
    }, 50)
    timer.unref?.()
  }
}