'use strict'

const fs = require('fs')
const fsp = fs.promises
const path = require('path')
const { DIRS, resolvePortablePath } = require('./paths')
const { newGame, newGameId, addGame } = require('./library')
const { extractIconFromExe } = require('./icons')
const { listPrefixes, prefixDriveRoots, isPrefixRoot } = require('./prefixes')
const { rewireSymlinks } = require('./symlinks')
const { copyTree, treeSize } = require('./fsutil')

// Directories that typically hold installers/redistributables, not the game.
const SKIPPED_DIRS = new Set(['redist', 'directx', '_commonredist', 'support', 'dotnet', 'vc'])

// The copy itself lives in fsutil.copyTree; moveFolder falls back to it
// across filesystems only.
function moveFolder(src, dst, onProgress) {
  const fallback = () => copyTree(src, dst, onProgress).then(() => fsp.rm(src, { recursive: true, force: true }))
  if (path.parse(src).root !== path.parse(dst).root) return fallback()
  return fsp.rename(src, dst).catch(fallback)
}

async function importGame(srcDir, mode, onProgress) {
  // a prefix (or its drive_c/pfx) is not an app folder
  if (isPrefixRoot(srcDir)) return { ok: false, error: 'prefix-root' }
  const name = path.basename(srcDir)
  // validate before touching anything: no .exe -> refuse
  const preExe = await findDefaultExe(srcDir)
  if (!preExe) return { ok: false, error: 'no-exe-found' }
  // the id doubles as the imported folder name
  const id = newGameId()
  let workdir = srcDir
  if (mode === 'copy' || mode === 'move') {
    const dst = path.join(DIRS.APPS, id)
    if (mode === 'copy') {
      // measured before it starts, so the bar can follow the bytes landing
      const emit = (phase, detail) => {
        if (onProgress) onProgress({ phase, label: name, ...detail })
      }
      emit('count', { files: 0, bytes: 0 })
      const total = await treeSize(srcDir)
      await copyTree(srcDir, dst, p => emit('copy', { files: p.done, bytes: p.bytes, totalFiles: total.files, totalBytes: total.bytes }))
    } else await moveFolder(srcDir, dst, onProgress)
    workdir = dst
    // in-data link targets become relative, so the import survives a move
    try {
      await rewireSymlinks(dst, [DIRS.FILES])
    } catch {}
  }
  const exePath = (await findDefaultExe(workdir)) || preExe
  if (!exePath) {
    return { ok: false, error: 'no-exe-found' }
  }
  const game = newGame({ id, name, exePath, workdir, mode })
  game.imported = mode === 'copy' || mode === 'move'
  // auto-picked exe -> grab its icon; a missing icon is not a failure
  const icon = path.join(DIRS.DATA, 'icons', id, 'icon.ico')
  if (extractIconFromExe(resolvePortablePath(exePath), icon).ok) {
    game.iconSource = icon
  }
  return addGame(game)
}

// Import from a prefix: the folder stays in place, paths stored prefix-relative.
async function importGameFromPrefix(prefix, srcDir, onProgress) {
  if (!listPrefixes().prefixes.some(p => p.name === prefix)) return { ok: false, error: 'prefix-not-found' }
  // the folder must live inside one of the prefix's C: drives
  const driveRoots = prefixDriveRoots(prefix)
  if (!driveRoots.length) return { ok: false, error: 'no-drive-c' }
  const src = path.resolve(String(srcDir))
  // realpath both sides: a unified prefix reaches drive_c through pfx too
  let realSrc
  try {
    realSrc = fs.realpathSync(src)
  } catch {
    return { ok: false, error: 'outside-drive-c' }
  }
  const insideDrive = driveRoots.some(root => {
    let realRoot
    try {
      realRoot = fs.realpathSync(root)
    } catch {
      return false
    }
    const rel = path.relative(realRoot, realSrc)
    return rel && !rel.startsWith('..') && !path.isAbsolute(rel)
  })
  if (!insideDrive) return { ok: false, error: 'outside-drive-c' }
  const preExe = await findDefaultExe(src)
  if (!preExe) return { ok: false, error: 'no-exe-found' }
  const id = newGameId()
  const game = newGame({ id, name: path.basename(src), exePath: preExe, workdir: src, mode: 'prefix' })
  game.importSource = 'prefix'
  game.prefix = prefix
  // auto-picked exe -> grab its icon; a missing icon is not a failure
  const icon = path.join(DIRS.DATA, 'icons', id, 'icon.ico')
  if (extractIconFromExe(resolvePortablePath(preExe), icon).ok) {
    game.iconSource = icon
  }
  return addGame(game)
}

// Largest .exe in the tree, skipping redistributable folders.
async function findDefaultExe(dir) {
  let best = ''
  let bestSize = -1
  const pending = []
  const consider = full => {
    const size = fsp.stat(full).then(st => st.size).catch(() => -1)
    pending.push(
      size.then(sz => {
        if (sz > bestSize) {
          best = full
          bestSize = sz
        }
      })
    )
  }
  const walk = async d => {
    let entries = []
    try {
      entries = await fsp.readdir(d, { withFileTypes: true })
    } catch {
      return
    }
    const subdirs = []
    for (const e of entries) {
      const full = path.join(d, e.name)
      if (e.isDirectory()) {
        if (!SKIPPED_DIRS.has(e.name.toLowerCase())) subdirs.push(full)
      } else if (e.name.toLowerCase().endsWith('.exe')) {
        consider(full)
      }
    }
    await Promise.all(subdirs.map(walk))
  }
  await walk(dir)
  await Promise.all(pending)
  return best
}

module.exports = { importGame, importGameFromPrefix, findDefaultExe, moveFolder }