'use strict'

const path = require('path')
const fs = require('fs')
const { DIRS, readJson, writeJson } = require('./paths')
const { rewireSymlinks } = require('./symlinks')
const { removeTree, treeSize } = require('./fsutil')
const { normalizePathName } = require('./names')

// An app path stored relative to its prefix root ("drive_c/..." or
// "pfx/drive_c/..."); everything else is FILES-relative or absolute.
const PREFIX_REL_RE = /^(pfx[/\\])?drive_c([/\\]|$)/i
const isPrefixRel = v => typeof v === 'string' && PREFIX_REL_RE.test(v)

const REGISTRY = path.join(DIRS.DATA, 'prefixes.json')
const MAIN = 'Main'

function seed() {
  const defs = readJson(REGISTRY, null)
  if (!defs || !Array.isArray(defs.prefixes) || !defs.prefixes.length) {
    const seeded = { default: MAIN, prefixes: [{ name: MAIN, created: Date.now(), locked: true }] }
    if (!fs.existsSync(prefixPath(MAIN))) fs.mkdirSync(prefixPath(MAIN), { recursive: true })
    ensureUnifiedPrefix(MAIN)
    writeJson(REGISTRY, seeded)
  }
}

function listPrefixes() {
  seed()
  return readJson(REGISTRY, { default: MAIN, prefixes: [] })
}

function savePrefixes(defs) {
  writeJson(REGISTRY, defs)
}

function prefixPath(name) {
  return path.join(DIRS.PREFIXES, name)
}

// Native Linux apps keep their redirected home/config/cache in here, next to
// the Windows side of the same prefix.
const LINUX_PFX = 'linux_pfx'

function prefixLinuxRoot(name) {
  return path.join(prefixPath(name), LINUX_PFX)
}

function prefixExists(name) {
  try {
    fs.accessSync(prefixPath(name))
    return true
  } catch {
    return false
  }
}

// Every Windows C: drive a prefix has (top-level for plain wine, under pfx/
// for Proton); a unified prefix reports its single drive once.
function prefixDriveRoots(name) {
  const root = prefixPath(name)
  const found = []
  const seen = new Set()
  for (const base of [root, path.join(root, 'pfx')]) {
    try {
      const driveC = path.join(base, 'drive_c')
      if (!fs.statSync(driveC).isDirectory()) continue
      const real = fs.realpathSync(driveC)
      if (seen.has(real)) continue
      seen.add(real)
      found.push(driveC)
    } catch {}
  }
  return found
}

function lstatOrNull(p) {
  try {
    return fs.lstatSync(p)
  } catch {
    return null
  }
}

// Without a link, a prefix used with both wine kinds grows two C: drives;
// `pfx` -> prefix root collapses them. Only a prefix with no pfx at all gets
// the link - an existing layout is left exactly as it is.
function ensureUnifiedPrefix(name) {
  if (!name) return false
  const pfx = path.join(prefixPath(name), 'pfx')
  if (lstatOrNull(pfx)) return false
  try {
    fs.symlinkSync('.', pfx, 'dir')
    return true
  } catch {
    // the prefix folder may not exist yet - the link is added on creation
    return false
  }
}

// True when a path IS one of a prefix's own roots (folder, pfx/, drive_c):
// importing one would gut the prefix.
function isPrefixRoot(p) {
  if (!p) return false
  const abs = path.resolve(String(p))
  if (path.resolve(DIRS.PREFIXES) === abs) return true
  for (const entry of listPrefixes().prefixes) {
    const root = prefixPath(entry.name)
    if (abs === root || abs === path.join(root, 'pfx')) return true
    if (abs === path.join(root, 'drive_c') || abs === path.join(root, 'pfx', 'drive_c')) return true
    if (abs === path.join(root, LINUX_PFX) || abs === path.join(root, LINUX_PFX, 'home')) return true
  }
  return false
}

function createPrefix(name) {
  const clean = normalizePathName(name)
  if (!clean) return { ok: false, error: 'invalidName' }
  if (clean.toLowerCase() === MAIN.toLowerCase()) return { ok: false, error: 'alreadyExists' }
  if (fs.existsSync(prefixPath(clean))) return { ok: false, error: 'alreadyExists' }
  fs.mkdirSync(prefixPath(clean), { recursive: true })
  ensureUnifiedPrefix(clean)
  const defs = listPrefixes()
  defs.prefixes.push({ name: clean, created: Date.now() })
  if (!defs.prefixes.some(p => p.name === defs.default)) defs.default = clean
  savePrefixes(defs)
  return { ok: true, name: clean }
}

// Removal is measured (staging) so the UI shows a bar that moves.
async function deletePrefix(name, onProgress) {
  if (String(name).toLowerCase() === MAIN.toLowerCase()) return { ok: false, error: 'isMain' }
  const defs = listPrefixes()
  const emit = (phase, detail) => {
    if (onProgress) onProgress({ phase, label: name, ...detail })
  }
  emit('count', { files: 0, bytes: 0 })
  const total = await treeSize(prefixPath(name))
  await removeTree(prefixPath(name), p => emit('remove', { files: p.files, bytes: p.bytes, totalFiles: total.files, totalBytes: total.bytes }))
  // the registry forgets it only once the folder is gone, so an interrupted
  // delete stays visible and can be retried
  defs.prefixes = defs.prefixes.filter(p => p.name !== name)
  if (defs.default === name) defs.default = MAIN
  savePrefixes(defs)
  return { ok: true }
}

// Rewire absolute links to relative so a moved prefix keeps working.
async function healPrefix(name) {
  if (!name) return 0
  return rewireSymlinks(prefixPath(name), [DIRS.FILES])
}

// Rename moves the folder and follows the name through the registry.
function renamePrefix(oldName, newName) {
  const clean = normalizePathName(newName)
  if (!clean) return { ok: false, error: 'invalidName' }
  const defs = listPrefixes()
  const entry = defs.prefixes.find(p => p.name === oldName)
  if (!entry) return { ok: false, error: 'notFound' }
  if (entry.locked || String(oldName).toLowerCase() === MAIN.toLowerCase()) return { ok: false, error: 'isMain' }
  if (clean === oldName) return { ok: true, name: clean, games: 0 }
  if (defs.prefixes.some(p => p.name === clean) || fs.existsSync(prefixPath(clean))) return { ok: false, error: 'alreadyExists' }
  // a registered prefix without a folder yet can still be renamed
  if (fs.existsSync(prefixPath(oldName))) {
    try {
      fs.renameSync(prefixPath(oldName), prefixPath(clean))
    } catch (err) {
      return { ok: false, error: String((err && err.message) || err) }
    }
  }
  entry.name = clean
  if (defs.default === oldName) defs.default = clean
  savePrefixes(defs)
  const games = require('./library').renamePrefixRefs(oldName, clean)
  return { ok: true, name: clean, games }
}

function setDefaultPrefix(name) {
  const defs = listPrefixes()
  if (name && !defs.prefixes.some(p => p.name === name)) return { ok: false, error: 'notFound' }
  defs.default = name || ''
  savePrefixes(defs)
  return { ok: true }
}

module.exports = { isPrefixRel, PREFIX_REL_RE, LINUX_PFX, listPrefixes, savePrefixes, createPrefix, deletePrefix, renamePrefix, setDefaultPrefix, prefixPath, prefixLinuxRoot, prefixExists, prefixDriveRoots, isPrefixRoot, healPrefix, ensureUnifiedPrefix, MAIN }