'use strict'

// Native Linux apps: the twin of runner.js. Same tracked spawn tail, but the
// program runs directly (no wine) with a redirected home and, when bubblewrap
// works, inside a namespace.

const crypto = require('crypto')
const fs = require('fs')
const os = require('os')
const path = require('path')
const { DIRS, readJson, writeJson } = require('./paths')
const { prefixPath, prefixLinuxRoot } = require('./prefixes')
const { prefixNameForGame } = require('./library')
const { spawnTracked, parseArgs } = require('./runner')
const { buildBwrapArgs, SHARE_ROOT } = require('./sandbox')

const DATA_DIRS = ['home', 'config', 'data', 'cache', 'state']

// host folder <-> in-sandbox XDG variable, so both backends set the same env
const XDG_LAYOUT = {
  XDG_CONFIG_HOME: ['config', '.config'],
  XDG_DATA_HOME: ['data', path.join('.local', 'share')],
  XDG_CACHE_HOME: ['cache', '.cache'],
  XDG_STATE_HOME: ['state', path.join('.local', 'state')]
}

// Write access is handed out to the folder the app was imported from and to
// nothing else outside its home: a portable app writes its logs and data next
// to itself (Prism Launcher refuses to start otherwise), while system trees
// must never come back writable.
const SYSTEM_DIRS = ['/bin', '/sbin', '/lib', '/lib32', '/lib64', '/libx32', '/usr', '/etc', '/boot', '/proc', '/sys', '/dev', '/run']

function writableAppDir(game) {
  const dir = (game && (game.path || (game.exePath && path.dirname(game.exePath)))) || ''
  // realpathSync('') would answer with the cwd - never hand that out
  if (!dir) return ''
  let real
  try {
    real = fs.realpathSync(dir)
    if (!fs.statSync(real).isDirectory()) return ''
  } catch {
    return ''
  }
  // launcher-owned folders: only an imported app may be written to
  if (real.startsWith(DIRS.FILES + path.sep)) {
    return real.startsWith(DIRS.APPS + path.sep) ? real : ''
  }
  if (real === '/') return ''
  for (const system of SYSTEM_DIRS) {
    if (real === system || real.startsWith(system + '/')) return ''
  }
  return real
}

function linuxUser() {
  try {
    return os.userInfo().username
  } catch {
    return process.env.USER || 'user'
  }
}

function copyFromHost(src, dst, { refresh = false } = {}) {
  try {
    if (!refresh && fs.existsSync(dst)) return false
    if (!fs.statSync(src).isFile()) return false
    fs.mkdirSync(path.dirname(dst), { recursive: true })
    fs.copyFileSync(src, dst)
    return true
  } catch {
    return false
  }
}

// PulseAudio looks for its cookie under $HOME/.config/pulse; with HOME
// redirected there is none, and sound dies for everything going through
// Pulse. Copied once - the app owns it afterwards.
function seedPulseCookie(root) {
  const dst = path.join(root, 'config', 'pulse', 'cookie')
  const seeded = copyFromHost(path.join(os.homedir(), '.config', 'pulse', 'cookie'), dst)
  if (seeded) {
    try {
      fs.chmodSync(dst, 0o600)
    } catch {}
  }
}

// The host's desktop preferences, not its data: a redirected home has no
// theme at all, and Qt/GTK then fall back to their built-in light look (KDE's
// dark palette lives in kdeglobals).
const DESKTOP_SEEDS = [
  'kdeglobals',
  'kdedefaults/kdeglobals',
  'gtk-3.0/settings.ini',
  'gtk-4.0/settings.ini',
  'qt5ct/qt5ct.conf',
  'qt6ct/qt6ct.conf',
  'Trolltech.conf',
  'user-dirs.dirs'
]

// The host's desktop *data* - fonts, icons, themes, colour schemes - is not
// copied but handed over read-only (see buildBwrapArgs), so it follows the
// host without an import.
const DATA_SHARES = ['fonts', 'icons', 'themes', 'color-schemes']

function hostShareDir() {
  return path.join(os.homedir(), '.local', 'share')
}

function dataShares() {
  return DATA_SHARES.map(name => path.join(hostShareDir(), name)).filter(dir => fs.existsSync(dir))
}

function hashOf(file) {
  try {
    return crypto.createHash('sha1').update(fs.readFileSync(file)).digest('hex')
  } catch {
    return ''
  }
}

function mtimeOf(file) {
  try {
    return fs.statSync(file).mtimeMs
  } catch {
    return 0
  }
}

// Hashes of what we put in the prefix, so a host change can be followed while
// the app has not touched our copy. Kept in the prefix root: the app only
// ever sees home/config/data/cache/state.
const SEED_MARKER = '.seeded.json'

// Copies a preference in, then keeps following it for as long as we can prove
// the copy is still ours: an unusable theme is worse than a stale one, and an
// app's own edit is never overwritten.
function syncDesktopConfig(root) {
  const hostConfig = path.join(os.homedir(), '.config')
  const markerFile = path.join(root, SEED_MARKER)
  const marker = readJson(markerFile, {})
  let changed = false
  for (const rel of DESKTOP_SEEDS) {
    const src = path.join(hostConfig, rel)
    const dst = path.join(root, 'config', rel)
    const hostHash = hashOf(src)
    if (!hostHash) continue
    const known = marker[rel]
    if (fs.existsSync(dst)) {
      const current = hashOf(dst)
      if (known) {
        // the app owns it now, or there is nothing to do
        if (current !== known || current === hostHash) continue
      } else if (current !== hostHash && mtimeOf(dst) >= mtimeOf(src)) {
        // a prefix from an older launcher: an identical copy is ours, and so is
        // one the host's file has since outgrown. A copy that is not older than
        // the host's is the app's own - ties stay with the app
        continue
      }
    }
    // refresh: this is provably still our own copy
    if (copyFromHost(src, dst, { refresh: true })) {
      marker[rel] = hostHash
      changed = true
    }
  }
  if (changed) {
    try {
      writeJson(markerFile, marker)
    } catch {}
  }
}

// X11 access: XAUTHORITY usually lives in /run/user (bound), but a launcher
// started without it would leave X11 dead inside. Refreshed: a cookie is
// session state, not data.
function seedXauthority(root) {
  copyFromHost(path.join(os.homedir(), '.Xauthority'), path.join(root, 'home', '.Xauthority'), { refresh: true })
}

// Everything this module copies in from the host, prefix-relative: the one
// list a reset has to clear.
function seededRelPaths() {
  return [
    ...DESKTOP_SEEDS.map(rel => path.join('config', rel)),
    path.join('config', 'pulse', 'cookie'),
    path.join('home', '.Xauthority'),
    SEED_MARKER
  ]
}

// syncDesktopConfig only follows the host while the copy is provably ours, so
// an app that edited its own theme keeps it forever. The reset drops our
// copies (and the hashes that track them) and lets the next start seed clean
// ones - the app's own files in the same folders are never touched.
function resetSeededConfig(name) {
  const root = prefixLinuxRoot(name)
  const removed = []
  for (const rel of seededRelPaths()) {
    const file = path.join(root, rel)
    try {
      // lstat: a link pointing out of the prefix is none of our business
      if (!fs.lstatSync(file).isFile()) continue
      fs.rmSync(file, { force: true })
      removed.push(rel)
    } catch {}
  }
  // folders that exist only for a seed, and only while nothing else lives there
  const dirs = ['kdedefaults', 'gtk-3.0', 'gtk-4.0', 'qt5ct', 'qt6ct', 'pulse']
  for (const dir of dirs) {
    try {
      fs.rmdirSync(path.join(root, 'config', dir))
    } catch {}
  }
  return { ok: true, removed }
}

function ensureLinuxPfx(name) {
  const root = prefixLinuxRoot(name)
  fs.mkdirSync(path.join(root, 'home', '.local', 'share'), { recursive: true })
  for (const dir of DATA_DIRS) fs.mkdirSync(path.join(root, dir), { recursive: true })
  seedPulseCookie(root)
  seedXauthority(root)
  return root
}

// Wayland cannot carry a window icon and the compositor only guesses one from
// the app id; XWayland can, and GLFW/Qt/GTK all read these, so one flag moves
// the whole process tree (Prism and the Minecraft it launches) back to X11.
const X11_ENV = { XDG_SESSION_TYPE: 'x11', QT_QPA_PLATFORM: 'xcb', GDK_BACKEND: 'x11' }

// The theme data sits in front of the inherited list: on the host the user's
// own icons and fonts also win over the system ones.
function withHostShare(env, entries) {
  const own = entries.filter(Boolean)
  if (!own.length) return
  env.XDG_DATA_DIRS = [...own, env.XDG_DATA_DIRS].filter(Boolean).join(':')
}

// HOME and the XDG folders point at the prefix (plain run) or at the bind
// targets inside the sandbox - the two must agree or the app writes outside.
function buildLinuxEnv({ game, backend = 'env' }) {
  const prefixName = prefixNameForGame(game)
  const root = ensureLinuxPfx(prefixName)
  syncDesktopConfig(root)
  const sandboxed = backend === 'bwrap'
  const home = sandboxed ? `/home/${linuxUser()}` : path.join(root, 'home')
  const env = { ...process.env }
  env.HOME = home
  for (const [key, [hostDir, sandboxSub]] of Object.entries(XDG_LAYOUT)) {
    env[key] = sandboxed ? path.join(home, sandboxSub) : path.join(root, hostDir)
  }
  // XDG_RUNTIME_DIR stays the host's: Wayland, PipeWire and the session bus
  // live there. It weakens the isolation, and the UI says so.
  // The X session manager sits in the private /tmp, so its pointer would only
  // lead to a dead socket; clients skip it when it is absent.
  if (sandboxed) delete env.SESSION_MANAGER
  // the host's fonts/icons/themes: mounted read-only by buildBwrapArgs, or - in
  // a plain run, where nothing is hidden - just put on the search path
  if (dataShares().length) withHostShare(env, [sandboxed ? SHARE_ROOT : hostShareDir()])
  if (game.forceX11) Object.assign(env, X11_ENV)
  // the app's own environment comes last: it overrides everything above
  for (const [k, v] of Object.entries(game.env || {})) env[k] = v
  return { env, root, home, prefixName, prefixDir: prefixPath(prefixName) }
}

// bwrap when it works, plain run otherwise - unless the app demands a sandbox.
function pickBackend({ game, sandbox }) {
  const policy = (game && game.isolation) || 'auto'
  const status = sandbox && typeof sandbox.status === 'function' ? sandbox.status() : null
  const available = !!status && status.backend === 'bwrap'
  if (policy === 'off') return { ok: true, backend: 'env', policy, status }
  if (available) return { ok: true, backend: 'bwrap', policy, status }
  if (policy === 'require') return { ok: false, error: 'sandbox-required', policy, status }
  return { ok: true, backend: 'env', policy, status }
}

function isolationLine({ backend, status }) {
  if (backend === 'bwrap') return `[plwl] isolation: bwrap ${(status && status.version) || ''}`.trim()
  const reason = (status && status.reason) || 'missing'
  return `[plwl] isolation: env-only (reason: ${reason})`
}

// "Open with": a native app takes the file where it is (the sandbox sees /).
function linuxPathFor(file) {
  let abs = String(file || '')
  try {
    abs = fs.realpathSync(abs)
  } catch {}
  return abs
}

function bwrapSource() {
  const devices = ['/dev/shm', '/dev/dri', '/dev/snd', '/dev/input'].filter(d => fs.existsSync(d))
  const x11 = fs.existsSync('/tmp/.X11-unix') ? '/tmp/.X11-unix' : ''
  const runUser = `/run/user/${typeof process.getuid === 'function' ? process.getuid() : 0}`
  return {
    devices,
    x11,
    runUser: fs.existsSync(runUser) ? runUser : '',
    shares: dataShares(),
    user: linuxUser()
  }
}

async function runLinuxGame({ game, sandbox, onExit, openFile, handoff = false }) {
  const chosen = pickBackend({ game, sandbox })
  if (!chosen.ok) throw new Error(chosen.error)

  const exe = game.exePath
  const workdir = game.workdir || path.dirname(exe)
  const argList = parseArgs(game.args)
  if (openFile) argList.push(linuxPathFor(openFile))

  const { env, root } = buildLinuxEnv({ game, backend: chosen.backend })
  const header = [isolationLine(chosen)]
  if (game.forceX11) header.push('[plwl] x11 forced (XWayland)')

  let cmd = exe
  let args = argList
  if (chosen.backend === 'bwrap') {
    const source = bwrapSource()
    cmd = 'bwrap'
    args = [...buildBwrapArgs({ dataRoot: root, user: source.user, devices: source.devices, x11: source.x11, runUser: source.runUser, shares: source.shares, appDir: writableAppDir(game) }), '--', exe, ...argList]
    header.push(`[plwl] HOME=${env.HOME}`)
  }

  return spawnTracked({ game, cmd, args, cwd: workdir, env, handoff, header, onExit })
}

module.exports = {
  DATA_DIRS,
  XDG_LAYOUT,
  SYSTEM_DIRS,
  DESKTOP_SEEDS,
  DATA_SHARES,
  X11_ENV,
  writableAppDir,
  ensureLinuxPfx,
  resetSeededConfig,
  dataShares,
  syncDesktopConfig,
  buildLinuxEnv,
  pickBackend,
  isolationLine,
  linuxPathFor,
  runLinuxGame
}