// 桌面端检查更新：拉取 /api/version/latest，应用内下载安装包并启动安装程序
const { app, BrowserWindow, dialog, net, ipcMain, shell } = require('electron')
const { spawn } = require('child_process')
const path = require('path')
const fs = require('fs')

const DOWNLOAD_TIMEOUT_MS = 15 * 60 * 1000

let deps = {
  getServerBase: () => '',
  getMainWindow: () => null,
  setQuitting: () => {},
}

let busy = false
let abortDownload = null

function init(next) {
  deps = { ...deps, ...next }
  ipcMain.handle('nlg:check-update', (_e, silent) => checkUpdate(!!silent))
  ipcMain.handle('nlg:cancel-update-download', () => {
    if (abortDownload) abortDownload()
    return true
  })
}

function compareVer(a, b) {
  const pa = String(a || '0').split('.').map((n) => parseInt(n, 10) || 0)
  const pb = String(b || '0').split('.').map((n) => parseInt(n, 10) || 0)
  const len = Math.max(pa.length, pb.length)
  for (let i = 0; i < len; i++) {
    const va = pa[i] || 0
    const vb = pb[i] || 0
    if (va > vb) return 1
    if (va < vb) return -1
  }
  return 0
}

function resolveDownloadUrl(url) {
  const base = String(deps.getServerBase() || '').replace(/\/+$/, '')
  if (!url) return ''
  try {
    const u = new URL(url, base + '/')
    const m = String(u.pathname || '').match(/\/(?:api\/)?download\/([^/]+)$/i)
    if (m) {
      return base + '/api/download/' + encodeURIComponent(decodeURIComponent(m[1]))
    }
    return u.href
  } catch {
    return url
  }
}

function formatBytes(n) {
  n = Number(n) || 0
  if (n < 1024) return n + ' B'
  if (n < 1024 * 1024) return (n / 1024).toFixed(1) + ' KB'
  return (n / 1024 / 1024).toFixed(1) + ' MB'
}

function headerVal(headers, key) {
  const raw = headers[key] || headers[key.toLowerCase()] || headers[key.toUpperCase()]
  return Array.isArray(raw) ? raw[0] : (raw || '')
}

function fetchLatestVersion() {
  return new Promise((resolve) => {
    const base = String(deps.getServerBase() || '').replace(/\/+$/, '')
    if (!base) return resolve({ ok: false, msg: '未配置服务器地址' })
    let settled = false
    const done = (v) => {
      if (settled) return
      settled = true
      resolve(v)
    }
    const req = net.request({
      method: 'GET',
      url: base + '/api/version/latest',
      redirect: 'follow',
    })
    let body = ''
    req.on('response', (resp) => {
      const code = resp.statusCode || 0
      if (code < 200 || code >= 300) {
        done({ ok: false, msg: '服务器返回 ' + code })
        return
      }
      resp.on('data', (chunk) => { body += chunk.toString('utf8') })
      resp.on('end', () => {
        try {
          const parsed = JSON.parse(body)
          if (parsed && typeof parsed.code === 'number' && parsed.code !== 0) {
            done({ ok: false, msg: parsed.msg || '检查更新失败' })
            return
          }
          const data = parsed && parsed.data ? parsed.data : parsed
          done({ ok: true, data })
        } catch {
          done({ ok: false, msg: '解析版本信息失败' })
        }
      })
    })
    req.on('error', (err) => done({ ok: false, msg: '网络错误：' + err.message }))
    const timer = setTimeout(() => {
      try { req.abort() } catch { /* ignore */ }
      done({ ok: false, msg: '请求超时' })
    }, 10000)
    req.on('close', () => clearTimeout(timer))
    req.end()
  })
}

function downloadInstaller(url, dest, onProgress) {
  return new Promise((resolve, reject) => {
    let settled = false
    const finish = (err, val) => {
      if (settled) return
      settled = true
      abortDownload = null
      if (err) reject(err)
      else resolve(val)
    }
    const req = net.request({ method: 'GET', url, redirect: 'follow' })
    abortDownload = () => {
      try { req.abort() } catch { /* ignore */ }
      const e = new Error('已取消')
      e.cancelled = true
      finish(e)
    }
    const timer = setTimeout(() => {
      try { req.abort() } catch { /* ignore */ }
      finish(new Error('下载超时，请检查网络后重试'))
    }, DOWNLOAD_TIMEOUT_MS)

    req.on('response', (resp) => {
      const code = resp.statusCode || 0
      if (code < 200 || code >= 300) {
        clearTimeout(timer)
        finish(new Error('下载失败（HTTP ' + code + '）'))
        return
      }
      const ct = String(headerVal(resp.headers, 'content-type'))
      if (/text\/html/i.test(ct)) {
        clearTimeout(timer)
        finish(new Error('服务器返回了网页而不是安装包。请确认后台已上传安装包。'))
        return
      }
      const total = parseInt(headerVal(resp.headers, 'content-length'), 10) || 0
      fs.mkdirSync(path.dirname(dest), { recursive: true })
      const ws = fs.createWriteStream(dest)
      let loaded = 0
      resp.on('data', (chunk) => {
        loaded += chunk.length
        if (!ws.write(chunk) && typeof resp.pause === 'function') {
          resp.pause()
          ws.once('drain', () => { if (typeof resp.resume === 'function') resp.resume() })
        }
        if (onProgress) onProgress(loaded, total)
      })
      resp.on('end', () => { ws.end() })
      resp.on('error', (err) => {
        clearTimeout(timer)
        try { ws.destroy() } catch { /* ignore */ }
        finish(err)
      })
      ws.on('finish', () => {
        clearTimeout(timer)
        finish(null, { size: loaded, total })
      })
      ws.on('error', (err) => {
        clearTimeout(timer)
        finish(err)
      })
    })
    req.on('error', (err) => {
      clearTimeout(timer)
      finish(err)
    })
    req.end()
  })
}

function verifyInstaller(filePath, expectSize) {
  let st
  try {
    st = fs.statSync(filePath)
  } catch {
    return '安装包不存在'
  }
  // 网页被当成 exe 保存时通常只有几 KB；正式安装包约 100MB
  if (st.size < 64 * 1024) {
    return '文件过小，不是完整安装包（常见原因：下载地址被网站首页顶替）'
  }
  if (expectSize && Math.abs(st.size - expectSize) > 2048) {
    return `文件大小不符（已下 ${formatBytes(st.size)}，期望 ${formatBytes(expectSize)}）`
  }
  const ext = path.extname(filePath).toLowerCase()
  if (ext === '.exe') {
    const buf = Buffer.alloc(2)
    const fd = fs.openSync(filePath, 'r')
    fs.readSync(fd, buf, 0, 2, 0)
    fs.closeSync(fd)
    if (buf[0] !== 0x4d || buf[1] !== 0x5a) {
      return '安装包损坏（不是有效的 Windows 程序）'
    }
  }
  return ''
}

function launchInstaller(filePath) {
  return new Promise((resolve, reject) => {
    if (process.platform === 'win32') {
      // start 脱离本进程，避免 app.quit() 把安装程序一起带走
      const cmd = process.env.ComSpec || 'cmd.exe'
      const child = spawn(cmd, ['/c', 'start', '', filePath], {
        detached: true,
        stdio: 'ignore',
        windowsHide: true,
      })
      child.once('error', reject)
      child.unref()
      setTimeout(resolve, 400)
      return
    }
    shell.openPath(filePath).then((err) => {
      if (err) reject(new Error(err))
      else resolve()
    }).catch(reject)
  })
}

function openProgressWin(version) {
  const parent = deps.getMainWindow()
  const win = new BrowserWindow({
    width: 440,
    height: 230,
    parent: parent && !parent.isDestroyed() ? parent : undefined,
    modal: !!(parent && !parent.isDestroyed()),
    resizable: false,
    minimizable: false,
    maximizable: false,
    autoHideMenuBar: true,
    backgroundColor: '#12142a',
    title: '正在下载更新',
    webPreferences: {
      preload: path.join(__dirname, 'preload.cjs'),
      contextIsolation: true,
    },
  })
  const html = `<!DOCTYPE html><html lang="zh-CN"><head><meta charset="UTF-8"><title>下载更新</title>
<style>
  body{margin:0;background:#12142a;color:#e8e9f5;font:14px/1.6 "Microsoft YaHei",sans-serif;padding:22px 26px}
  h3{margin:0 0 10px;font-size:15px}
  .bar{height:8px;border-radius:99px;background:#262a52;overflow:hidden;margin:12px 0 8px}
  .bar i{display:block;height:100%;width:0;background:linear-gradient(135deg,#6d6ff0,#9b6df0);transition:width .15s}
  .msg{font-size:12px;color:#8d90b3;min-height:18px}
  .row{display:flex;justify-content:flex-end;margin-top:16px}
  button{border:0;border-radius:8px;padding:7px 18px;font-size:13px;cursor:pointer;background:#262a52;color:#c6c8e8}
</style></head><body>
  <h3>正在下载 ${String(version || '').replace(/[<>]/g, '')}</h3>
  <div class="bar"><i id="bar"></i></div>
  <div class="msg" id="msg">正在连接服务器…</div>
  <div class="row"><button id="cancel">取消</button></div>
  <script>
    window.__setProgress = (pct, text) => {
      document.getElementById('bar').style.width = Math.max(0, Math.min(100, pct)) + '%'
      if (text) document.getElementById('msg').textContent = text
    }
    document.getElementById('cancel').onclick = async () => {
      try { await window.desktop.cancelUpdateDownload() } catch (e) {}
      window.close()
    }
  </script>
</body></html>`
  win.loadURL('data:text/html;charset=utf-8,' + encodeURIComponent(html))
  return win
}

function setProgressUI(win, pct, text) {
  if (!win || win.isDestroyed()) return
  const js = `window.__setProgress && window.__setProgress(${Number(pct) || 0}, ${JSON.stringify(text)})`
  win.webContents.executeJavaScript(js).catch(() => {})
}

async function downloadAndInstall({ version, url, size, filename }) {
  const destName = (filename && path.basename(String(filename))) || ('PixelArcade-Setup-' + version + '.exe')
  const dest = path.join(app.getPath('temp'), destName)
  try { fs.unlinkSync(dest) } catch { /* ignore */ }

  const win = openProgressWin(version)
  win.on('closed', () => {
    if (abortDownload) abortDownload()
  })

  try {
    setProgressUI(win, 0, '正在连接服务器…')
    const onProg = (loaded, total) => {
      const t = total || size || 0
      const pct = t ? Math.min(99, Math.round((loaded / t) * 100)) : 0
      setProgressUI(win, pct, `已下载 ${formatBytes(loaded)}${t ? ' / ' + formatBytes(t) : ''}`)
    }
    let r
    try {
      r = await downloadInstaller(url, dest, onProg)
    } catch (e) {
      if (e && e.cancelled) throw e
      const alt = String(url).replace('/api/download/', '/download/')
      if (alt === url) throw e
      setProgressUI(win, 0, '正在尝试备用下载地址…')
      r = await downloadInstaller(alt, dest, onProg)
    }
    setProgressUI(win, 99, '正在校验安装包…')
    const bad = verifyInstaller(dest, size || r.total || 0)
    if (bad) throw new Error(bad)
    setProgressUI(win, 100, '下载完成，即将启动安装程序…')
    await launchInstaller(dest)
    deps.setQuitting(true)
    app.quit()
  } catch (e) {
    try { if (!win.isDestroyed()) win.close() } catch { /* ignore */ }
    if (e && e.cancelled) return
    try { fs.unlinkSync(dest) } catch { /* ignore */ }
    const parent = deps.getMainWindow()
    const { response } = await dialog.showMessageBox(parent && !parent.isDestroyed() ? parent : undefined, {
      type: 'error',
      title: '下载更新失败',
      message: '无法下载或安装更新',
      detail: (e && e.message) || String(e),
      buttons: ['在浏览器中打开', '确定'],
      defaultId: 0,
      cancelId: 1,
      noLink: true,
    })
    if (response === 0 && url) shell.openExternal(url)
  }
}

async function checkUpdate(silent = false) {
  if (busy) return
  const local = app.getVersion()
  const parent = () => {
    const w = deps.getMainWindow()
    return w && !w.isDestroyed() ? w : undefined
  }
  const r = await fetchLatestVersion()
  if (!r.ok) {
    if (!silent) dialog.showErrorBox('检查更新失败', r.msg || '无法连接服务器')
    return
  }
  const { version, download_url, release_notes: notes, force, size, filename } = r.data || {}
  if (compareVer(version, local) <= 0) {
    if (!silent) {
      dialog.showMessageBox(parent(), {
        type: 'info',
        title: '已是最新版本',
        message: '当前已是最新版本',
        detail: `版本 ${local}`,
      })
    }
    return
  }
  const url = resolveDownloadUrl(download_url)
  const buttons = url ? ['立即更新', force ? '确定' : '稍后提醒'] : [force ? '确定' : '稍后提醒']
  const { response } = await dialog.showMessageBox(parent(), {
    type: force ? 'warning' : 'info',
    title: '发现新版本',
    message: `发现新版本 ${version}`,
    detail: notes || '将下载安装包并启动安装程序，安装时请先关闭本应用。',
    buttons,
    defaultId: 0,
    cancelId: buttons.length - 1,
    noLink: true,
  })
  if (response === 0 && url) {
    busy = true
    try {
      await downloadAndInstall({ version, url, size, filename })
    } finally {
      busy = false
    }
  }
}

module.exports = { init, checkUpdate, compareVer, resolveDownloadUrl }