// OTA 升级接口 (兼容 tauri-plugin-hotswap 服务端约定)
//   GET /api/ota/check/:current_sequence
//     - 客户端传当前 sequence, 服务端判断是否有更新
//     - 有: 200 + manifest JSON
//     - 无: 204 No Content
//   GET /api/ota/bundle/:filename
//     - 下载前端 bundle (tar.gz), 供 manifest.url 引用
//   GET /api/ota/manifest-web
//     - 给 Web 浏览器用的简化版 manifest (无签名, 仅展示用)
//
// 数据源: 环境变量 OTA_PACKAGE_DIR 指向的目录, 里面要放:
//   - latest.json   (由 scripts/build-ota.mjs 生成)
//     { sequence, version, min_binary_version, signature, notes, bundle, mandatory, pub_date, bundle_size }
//   - <filename>    (tar.gz 升级包)
import { Router } from 'express'
import fs from 'node:fs'
import path from 'node:path'

const router = Router()

function resolveOtaDir() {
  const dir = process.env.OTA_PACKAGE_DIR
    ? path.resolve(process.env.OTA_PACKAGE_DIR)
    : path.resolve(process.cwd(), 'ota-package')
  return dir
}

function readLatest() {
  const p = path.join(resolveOtaDir(), 'latest.json')
  if (!fs.existsSync(p)) return null
  try {
    return JSON.parse(fs.readFileSync(p, 'utf8'))
  } catch (e) {
    console.error('[ota] latest.json 解析失败:', e.message)
    return null
  }
}

// GET /api/ota/check/:current_sequence
//   客户端实际请求 URL 是 endpoint 中 {{current_sequence}} 替换后的形式
router.get('/ota/check/:current_sequence', (req, res) => {
  const currentSeq = Number(req.params.current_sequence)
  if (!Number.isFinite(currentSeq) || currentSeq < 0) {
    return res.status(400).json({ error: '无效的 sequence' })
  }
  const latest = readLatest()
  if (!latest) {
    // 无可用包, 按约定返回 204
    return res.status(204).end()
  }
  // 不新于当前则 204
  if (typeof latest.sequence === 'number' && latest.sequence <= currentSeq) {
    return res.status(204).end()
  }
  // 检查 binary_version 兼容性 (客户端会再校验一次, 这里只做参考过滤)
  // 客户端传 binary_version query: 暂不强制, 让客户端兜底
  const dir = resolveOtaDir()
  const base = process.env.OTA_PUBLIC_BASE || ''
  res.json({
    version: latest.version,
    sequence: latest.sequence,
    min_binary_version: latest.min_binary_version || '0.0.0',
    url: (base ? base : '') + '/api/ota/bundle/' + encodeURIComponent(latest.bundle),
    signature: latest.signature,
    notes: latest.notes || '',
    pub_date: latest.pub_date || new Date().toISOString(),
    mandatory: !!latest.mandatory,
    bundle_size: latest.bundle_size || 0,
  })
})

// GET /api/ota/bundle/:filename - 流式下载 bundle
router.get('/ota/bundle/:filename', (req, res) => {
  const dir = resolveOtaDir()
  // 防越界: 只取 basename
  const name = path.basename(req.params.filename)
  const p = path.join(dir, name)
  if (!fs.existsSync(p)) return res.status(404).json({ error: 'bundle 不存在' })
  const stat = fs.statSync(p)
  res.setHeader('Content-Type', 'application/gzip')
  res.setHeader('Content-Length', stat.size)
  res.setHeader('Content-Disposition', 'attachment; filename="' + name + '"')
  fs.createReadStream(p).pipe(res)
})

// GET /api/ota/manifest-web - Web 浏览器用的简化版
//   客户端会拿这个跟当前 build_id 比较, 有新版本就提示用户刷新
router.get('/ota/manifest-web', (_req, res) => {
  const latest = readLatest()
  if (!latest) return res.json({ available: false })
  res.json({
    available: true,
    version: latest.version,
    build_id: latest.build_id || latest.version,
    note: latest.notes || '',
    size: latest.bundle_size || 0,
  })
})

// GET /api/ota/info 已删除: 诊断接口会暴露服务器路径与签名, 且无调用方

export default router