/**
 * 构建机专用：下载 Windows 嵌入式 Python + FFmpeg，安装 requirements.txt。
 * 产物写入仓库根目录 python/ 与 tools/ffmpeg/，随 Electron 打包分发；最终用户无需联网。
 */
import fs from 'fs'
import path from 'path'
import { spawnSync } from 'child_process'
import { fileURLToPath } from 'url'

const __filename = fileURLToPath(import.meta.url)
const __dirname = path.dirname(__filename)
const electronRoot = path.resolve(__dirname, '..')
const backendRoot = path.resolve(electronRoot, '..')

const PY_VER = '3.12.8'
const PYTHON_ZIP = `https://www.python.org/ftp/python/${PY_VER}/python-${PY_VER}-embed-amd64.zip`
const GET_PIP = 'https://bootstrap.pypa.io/get-pip.py'
/** BtbN 静态构建，单 zip 内含 bin/ffmpeg.exe */
const FFMPEG_ZIP =
  'https://github.com/BtbN/FFmpeg-Builds/releases/download/latest/ffmpeg-master-latest-win64-gpl.zip'

const runtimeDir = path.join(backendRoot, 'python')
const embedExe = path.join(runtimeDir, 'python.exe')
const toolsFfmpegBin = path.join(backendRoot, 'tools', 'ffmpeg', 'bin')
const ffmpegExe = path.join(toolsFfmpegBin, 'ffmpeg.exe')
const requirementsTxt = path.join(backendRoot, 'requirements.txt')
const tmpDir = path.join(electronRoot, '.tmp-prepare-runtime')

function rmrf(p) {
  if (fs.existsSync(p)) fs.rmSync(p, { recursive: true, force: true })
}

function downloadFile(url, dest) {
  fs.mkdirSync(path.dirname(dest), { recursive: true })
  const u = url.replace(/'/g, "''")
  const d = dest.replace(/'/g, "''")
  const r = spawnSync(
    'powershell.exe',
    [
      '-NoProfile',
      '-Command',
      `$ProgressPreference='SilentlyContinue'; Invoke-WebRequest -Uri '${u}' -OutFile '${d}' -UseBasicParsing`,
    ],
    { stdio: 'inherit', windowsHide: true },
  )
  if (r.status !== 0) throw new Error(`下载失败: ${url}`)
}

function unzipWithPowerShell(zipPath, destDir) {
  fs.mkdirSync(destDir, { recursive: true })
  const ps = spawnSync(
    'powershell.exe',
    [
      '-NoProfile',
      '-Command',
      `Expand-Archive -LiteralPath '${zipPath.replace(/'/g, "''")}' -DestinationPath '${destDir.replace(/'/g, "''")}' -Force`,
    ],
    { stdio: 'inherit', windowsHide: true },
  )
  if (ps.status !== 0) throw new Error('Expand-Archive failed')
}

function enableEmbedSitePackages() {
  const pthFiles = fs.readdirSync(runtimeDir).filter((f) => f.endsWith('._pth'))
  for (const f of pthFiles) {
    const p = path.join(runtimeDir, f)
    const base = f.replace(/\._pth$/, '')
    const zipLine = `${base}.zip`
    // 嵌入式解释器必须显式启用 import site，Lib\\site-packages 才会进 sys.path（pip 才能用）
    fs.writeFileSync(p, `${zipLine}\n.\n..\n\nimport site\n`, 'utf8')
  }
}

function hasWorkingEmbedPython() {
  if (!fs.existsSync(embedExe)) return false
  if (fs.existsSync(path.join(runtimeDir, 'pyvenv.cfg'))) return false
  if (fs.existsSync(path.join(runtimeDir, 'Scripts', 'python.exe'))) return false
  enableEmbedSitePackages()
  const r = spawnSync(
    embedExe,
    [
      '-c',
      'import importlib.util,fastapi,uvicorn,requests,psutil,src; assert importlib.util.find_spec("web2")',
    ],
    {
      cwd: backendRoot,
      encoding: 'utf8',
      windowsHide: true,
      timeout: 60000,
    },
  )
  return r.status === 0
}

function hasFfmpeg() {
  return fs.existsSync(ffmpegExe)
}

function installEmbeddablePython() {
  console.log('[prepare:runtime] 安装嵌入式 Python ' + PY_VER + ' …')
  rmrf(tmpDir)
  fs.mkdirSync(tmpDir, { recursive: true })
  const zipPath = path.join(tmpDir, 'python-embed.zip')
  downloadFile(PYTHON_ZIP, zipPath)
  rmrf(runtimeDir)
  fs.mkdirSync(runtimeDir, { recursive: true })
  unzipWithPowerShell(zipPath, runtimeDir)
  enableEmbedSitePackages()

  const getPipPath = path.join(tmpDir, 'get-pip.py')
  downloadFile(GET_PIP, getPipPath)
  let pip = spawnSync(embedExe, [getPipPath, '--no-warn-script-location'], {
    cwd: runtimeDir,
    stdio: 'inherit',
    windowsHide: true,
    env: { ...process.env, PYTHONPATH: '' },
  })
  if (pip.status !== 0) throw new Error('get-pip failed')

  pip = spawnSync(embedExe, ['-m', 'pip', 'install', '--upgrade', 'pip', 'setuptools', 'wheel'], {
    cwd: backendRoot,
    stdio: 'inherit',
    windowsHide: true,
  })
  if (pip.status !== 0) throw new Error('pip upgrade failed')

  if (!fs.existsSync(requirementsTxt)) throw new Error('Missing requirements.txt')
  pip = spawnSync(embedExe, ['-m', 'pip', 'install', '-r', requirementsTxt], {
    cwd: backendRoot,
    stdio: 'inherit',
    windowsHide: true,
  })
  if (pip.status !== 0) throw new Error('pip install -r requirements.txt failed')
  console.log('[prepare:runtime] 嵌入式 Python + 依赖已就绪。')
}

function installFfmpeg() {
  console.log('[prepare:runtime] 下载 FFmpeg（win64）…')
  rmrf(tmpDir)
  fs.mkdirSync(tmpDir, { recursive: true })
  const zipPath = path.join(tmpDir, 'ffmpeg.zip')
  downloadFile(FFMPEG_ZIP, zipPath)
  const extractRoot = path.join(tmpDir, 'ff')
  unzipWithPowerShell(zipPath, extractRoot)
  const dirs = fs.readdirSync(extractRoot)
  const top = dirs.length === 1 ? path.join(extractRoot, dirs[0]) : extractRoot
  const binSrc = path.join(top, 'bin')
  if (!fs.existsSync(path.join(binSrc, 'ffmpeg.exe'))) {
    throw new Error('ffmpeg zip layout unexpected: missing bin/ffmpeg.exe')
  }
  rmrf(path.join(backendRoot, 'tools', 'ffmpeg'))
  fs.mkdirSync(toolsFfmpegBin, { recursive: true })
  for (const name of fs.readdirSync(binSrc)) {
    fs.copyFileSync(path.join(binSrc, name), path.join(toolsFfmpegBin, name))
  }
  console.log('[prepare:runtime] FFmpeg 已安装到 tools/ffmpeg/bin/')
}

try {
  if (!hasWorkingEmbedPython()) {
    if (fs.existsSync(path.join(runtimeDir, 'pyvenv.cfg'))) {
      console.log('[prepare:runtime] 移除旧 venv，改用嵌入式 Python …')
      rmrf(runtimeDir)
    }
    installEmbeddablePython()
  } else {
    console.log('[prepare:runtime] 已存在可用的嵌入式 Python，跳过下载。')
  }

  if (!hasFfmpeg()) {
    installFfmpeg()
  } else {
    console.log('[prepare:runtime] 已存在 tools/ffmpeg/bin/ffmpeg.exe，跳过下载。')
  }

  rmrf(tmpDir)
  console.log('[prepare:runtime] 全部完成。')
} catch (e) {
  console.error('[prepare:runtime] 失败:', e)
  process.exit(1)
}