'use strict'

const path = require('path')
const fs = require('fs')
const os = require('os')
const { spawn } = require('child_process')
const { DIRS } = require('./paths')
const { prefixPath, ensureUnifiedPrefix } = require('./prefixes')
const { prefixNameForGame } = require('./library')

// The fake Steam install used when no real Steam client is found. Both folders
// Proton links into its prefix have to exist, or the links dangle.
function ensureFakeSteam() {
  const fake = DIRS.FAKE_STEAM
  fs.mkdirSync(path.join(fake, 'steamapps'), { recursive: true })
  fs.mkdirSync(path.join(fake, 'appcache'), { recursive: true })
  return fake
}

// Proton needs the Steam client at STEAM_COMPAT_CLIENT_INSTALL_PATH or a Valve
// build dies in a "steamclient_main.c" assert; use a real client read-only,
// the empty fake otherwise (GE builds skip steam.exe entirely).
const STEAM_CLIENT_MARKERS = [
  ['legacycompat', 'steamclient.dll'],
  ['ubuntu12_32', 'steamclient.so']
]

function findSteamClientDir() {
  const home = os.homedir()
  const dataHome = process.env.XDG_DATA_HOME || path.join(home, '.local', 'share')
  const candidates = [
    process.env.STEAM_COMPAT_CLIENT_INSTALL_PATH,
    path.join(home, '.steam', 'steam'),
    path.join(home, '.steam', 'root'),
    path.join(dataHome, 'Steam'),
    // flatpak Steam keeps its install inside the sandbox's data dir
    path.join(home, '.var', 'app', 'com.valvesoftware.Steam', '.local', 'share', 'Steam')
  ]
  for (const dir of candidates) {
    if (!dir) continue
    for (const marker of STEAM_CLIENT_MARKERS) {
      if (fs.existsSync(path.join(dir, ...marker))) return dir
    }
  }
  return null
}

function steamClientDir() {
  return findSteamClientDir() || ensureFakeSteam()
}

// WINEDLLOVERRIDES: ';'-separated, '=' splits name/setting, ',' separates
// names. Guides write a trailing .dll; Wine strips it, so store the bare name.
function sanitizeDllName(name) {
  const clean = String(name || '').trim().replace(/\.dll$/i, '')
  return /^[^;=\s]+$/.test(clean) ? clean : ''
}

// Wine keeps the LAST entry per module: inherited overrides go first, the
// app's own after. An empty setting is Wine's "disabled" and stays as `name=`.
function dllOverridesFor(game, env) {
  const parts = []
  const inherited = String(env.WINEDLLOVERRIDES || '').trim().replace(/;+$/, '')
  if (inherited) parts.push(inherited)
  for (const entry of game.dllOverrides || []) {
    if (!entry) continue
    const dll = sanitizeDllName(entry.dll)
    if (!dll) continue
    const setting = String(entry.setting == null ? '' : entry.setting).trim()
    if (!/^[a-z,]*$/i.test(setting)) continue
    parts.push(`${dll}=${setting}`)
  }
  return parts.join(';')
}

// Repair only broken links (a resolvable absolute link would be synced out
// again). Once per prefix per launch.
const healedPrefixes = new Set()
async function healPrefixOnce(game) {
  const name = prefixNameForGame(game)
  const key = `${name}\u0000${DIRS.BUILD}`
  if (!name || healedPrefixes.has(key)) return 0
  healedPrefixes.add(key)
  try {
    return await require('./prefixes').healPrefix(name)
  } catch {
    return 0
  }
}

// Proton's STEAM_COMPAT_DATA_PATH must be a symlink to the launcher prefix;
// a real compat dir already sitting there is not ours to replace.
function linkPrefix(compatData, prefixDir) {
  try {
    fs.mkdirSync(path.dirname(compatData), { recursive: true })
  } catch {}
  try {
    if (!fs.lstatSync(compatData).isSymbolicLink()) return
    if (fs.readlinkSync(compatData) === prefixDir) return
    fs.unlinkSync(compatData)
  } catch {}
  try {
    fs.symlinkSync(prefixDir, compatData, 'dir')
  } catch {}
}

function buildEnv({ game, wine }) {
  const env = { ...process.env }
  const isProton = wine && wine.type === 'proton'
  // same fallback the games service uses, so in-use checks name this folder
  const prefixName = prefixNameForGame(game)
  // no pfx yet -> shared-link layout; an existing nested layout is left as is
  try {
    ensureUnifiedPrefix(prefixName)
  } catch {}
  const prefixDir = prefixPath(prefixName)

  if (isProton) {
    env.STEAM_COMPAT_DATA_PATH = path.join(DIRS.DATA, 'compat', game.id)
    env.STEAM_COMPAT_APP_ID = '0'
    env.SteamAppId = '0'
    env.SteamGameId = '0'
    // every Proton verb reads STEAM_COMPAT_CLIENT_INSTALL_PATH (a missing one
    // aborts with a KeyError). UMU run: real client; disableUmu: the fake.
    if (game.disableUmu) {
      delete env.UMU_ID
      env.STEAM_COMPAT_CLIENT_INSTALL_PATH = ensureFakeSteam()
    } else {
      env.STEAM_COMPAT_CLIENT_INSTALL_PATH = steamClientDir()
      // UMU_ID makes newer Protons run through umu.exe instead of steam.exe,
      // which needs the Steam client's DLLs (see steamClientDir).
      if (!env.UMU_ID) env.UMU_ID = 'umu-0'
    }
    env.WINEPREFIX = path.join(env.STEAM_COMPAT_DATA_PATH, 'pfx')
    env.PROTON_LOG_DIR = path.join(DIRS.DATA, 'logs')
    fs.mkdirSync(env.PROTON_LOG_DIR, { recursive: true })
    linkPrefix(env.STEAM_COMPAT_DATA_PATH, prefixDir)
    // no silent fallback: a real dir would orphan the prefix outside where
    // PLWL tracks it; only a missing path is refused
    if (!fs.existsSync(env.STEAM_COMPAT_DATA_PATH)) {
      throw new Error('prefix-link-failed')
    }
  } else {
    // plain wine (system or imported build)
    env.WINEPREFIX = prefixDir
  }

  const overrides = dllOverridesFor(game, env)
  if (overrides) env.WINEDLLOVERRIDES = overrides
  else delete env.WINEDLLOVERRIDES

  // 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, prefixDir }
}

// Proton verbs: 'run' goes through umu.exe/steam.exe, 'runinprefix' runs the
// build's wine directly and skips Proton's prefix setup (see game.disableUmu).
function protonVerb(game) {
  return game.disableUmu ? 'runinprefix' : 'run'
}

function parseArgs(args) {
  const out = []
  const re = /"([^"]*)"|'([^']*)'|(\S+)/g
  let m
  while ((m = re.exec(String(args || '')))) out.push(m[1] ?? m[2] ?? m[3])
  return out
}

// "Open with" handoff: the file reaches the app as a WINDOWS path (C:\ inside
// the prefix's drive, Z:\ for the rest).
function windowsPathFor(file, prefixDir) {
  let abs = String(file || '')
  try {
    abs = fs.realpathSync(abs)
  } catch {}
  try {
    const driveC = fs.realpathSync(path.join(prefixDir, 'drive_c'))
    const rel = path.relative(driveC, abs)
    if (rel && !rel.startsWith('..') && !path.isAbsolute(rel)) {
      return 'C:\\' + rel.split(path.sep).join('\\')
    }
  } catch {}
  return `Z:${abs.split(path.sep).join('\\')}`
}

const GRACE_MS = 60000
// A finished run may leave output in the pipes (or a grandchild holding them
// open): the log closes when its writers are done, at the latest this long
// after the exit.
const LOG_DRAIN_MS = 5000

// Live playtime: tiny file updated every 30s, totals mirrored to the registry
// on exit. `base` comes from the caller (live file, not the registry) so
// shared ids never mix playtime.
function startPlaytimeTicker({ game, startedAt, base }) {
  const library = require('./library')
  const timer = setInterval(() => {
    const counted = Math.max(0, Math.round((Date.now() - startedAt - GRACE_MS) / 1000))
    library.writePlaySeconds(game.id, base + counted)
  }, 30000)
  return () => clearInterval(timer)
}

function latestLogPath(gameId) {
  return path.join(DIRS.DATA, 'logs', `${gameId}-latest.log`)
}

function openLatestLog(gameId) {
  const logFile = latestLogPath(gameId)
  fs.mkdirSync(path.dirname(logFile), { recursive: true })
  // 'w' truncates, so every session starts with a fresh log
  return fs.createWriteStream(logFile, { flags: 'w' })
}

// The tail every tracked run shares (wine and native Linux alike): spawn
// detached, tee output into the app's latest log, tick playtime, stamp
// lastPlayed, report the exit. `header` lines land right after the launch line.
function spawnTracked({ game, cmd, args, cwd, env, handoff = false, header = [], onExit }) {
  const library = require('./library')
  fs.mkdirSync(DIRS.DATA, { recursive: true })
  return new Promise((resolve, reject) => {
    let child
    try {
      child = spawn(cmd, args, {
        cwd,
        env,
        // a handoff is untracked: its pipes drain so the app never blocks
        stdio: handoff ? 'ignore' : ['ignore', 'pipe', 'pipe'],
        detached: true
      })
    } catch (err) {
      return reject(err)
    }
    // spawn() resolves before the process exists; a missing binary only
    // surfaces as an 'error' event, so wait for the real 'spawn'.
    let started = false
    child.once('error', err => {
      if (!started) reject(err)
    })
    child.once('spawn', () => {
      started = true
      // a handoff writes no log or playtime: the tracked run owns both
      if (handoff) {
        child.unref()
        return resolve({ pid: child.pid, logFile: null })
      }
      const logFile = latestLogPath(game.id)
      const ws = openLatestLog(game.id)
      // a launch line first, so the log answers "which prefix/overrides/run"
      ws.write(`[plwl] ${cmd} ${args.join(' ')}\n`)
      for (const line of header) ws.write(line + '\n')
      // two pipes feed one log, so neither may end it: pipe() would close the
      // stream on the first EOF, and the second writer then kills the process
      // with ERR_STREAM_WRITE_AFTER_END (an unhandled WriteStream 'error')
      child.stdout.pipe(ws, { end: false })
      child.stderr.pipe(ws, { end: false })
      let openPipes = 2
      const endLog = () => {
        if (--openPipes <= 0) ws.end()
      }
      child.stdout.once('end', endLog)
      child.stderr.once('end', endLog)
      // an unwritable log (full disk, file removed) must not take us down
      ws.on('error', () => {})
      child.unref()
      const startedAt = Date.now()
      // read the LIVE playtime file, not the registry (shared ids)
      const basePlaySeconds = library.readPlaySeconds(game.id) ?? (game.playSeconds || 0)
      const stopTicker = startPlaytimeTicker({ game, startedAt, base: basePlaySeconds })
      // stamp "last played" once at start, even if we crash later
      library.updateGame(game.id, { lastPlayed: startedAt })
      child.on('exit', (code, signal) => {
        stopTicker()
        // nothing may outlive the run: end the log once the buffered output had
        // its chance, even if something else still holds the pipes
        const drain = setTimeout(() => ws.end(), LOG_DRAIN_MS)
        if (drain.unref) drain.unref()
        const counted = Math.max(0, Math.round((Date.now() - startedAt - GRACE_MS) / 1000))
        library.updateGame(game.id, {
          lastPlayed: startedAt,
          playSeconds: basePlaySeconds + counted
        })
        if (onExit) onExit(code, signal)
      })
      resolve({ pid: child.pid, logFile })
    })
  })
}

async function runGame({ game, wine, systemWine, onExit, openFile, handoff = false }) {
  await healPrefixOnce(game)
  const isProton = wine && wine.type === 'proton'
  const { env, prefixDir } = buildEnv({ game, wine })
  const exe = game.exePath
  const workdir = game.workdir || path.dirname(exe)
  const argList = parseArgs(game.args)
  // an opened file is an argument to the exe, exactly like Windows' "Open with"
  if (openFile) argList.push(windowsPathFor(openFile, prefixDir))

  let cmd
  let base
  if (isProton) {
    cmd = wine.wineBin || path.join(wine.path, 'proton')
    base = [protonVerb(game), exe, ...argList]
  } else {
    cmd = systemWine ? 'wine' : wine.wineBin
    base = [exe, ...argList]
  }

  const header = [`[plwl] WINEPREFIX=${env.WINEPREFIX}`]
  if (env.WINEDLLOVERRIDES) header.push(`[plwl] WINEDLLOVERRIDES=${env.WINEDLLOVERRIDES}`)
  if (isProton) header.push(`[plwl] proton launcher: ${game.disableUmu ? 'direct wine (no UMU, no Steam)' : `umu.exe (UMU_ID=${env.UMU_ID})`}`)
  return spawnTracked({ game, cmd, args: base, cwd: workdir, env, handoff, header, onExit })
}

async function runTool({ game, wine, tool, args, systemWine }) {
  await healPrefixOnce(game)
  const isProton = wine && wine.type === 'proton'
  const { env } = buildEnv({ game, wine })
  const exe = game.exePath
  const workdir = game.workdir || path.dirname(exe)
  const argList = parseArgs(args)

  let cmd
  let base
  if (isProton) {
    cmd = wine.wineBin || path.join(wine.path, 'proton')
    base = [protonVerb(game), tool, ...argList]
  } else if (systemWine) {
    cmd = tool
    base = argList
  } else {
    cmd = wine.wineBin
    base = [tool, ...argList]
  }
  return new Promise((resolve, reject) => {
    const child = spawn(cmd, base, { cwd: workdir, env, stdio: 'ignore', detached: true })
    child.on('error', reject)
    child.unref()
    resolve({ pid: child.pid })
  })
}

// Ad-hoc launch ("Open with PLWL"): the runGame pipeline under the shared
// `openwith` id; no library entry is created. `prefix` is the picker's
// choice ('' = launcher default).
function runAdHoc({ openPath, wine, systemWine, prefix, onExit }) {
  const game = require('./openwith').makeTarget(openPath, 'default', prefix || '')
  return runGame({ game, wine, systemWine, onExit })
}

module.exports = { buildEnv, runGame, runTool, runAdHoc, parseArgs, latestLogPath, windowsPathFor, spawnTracked }