/**
 * Thing Extension - 后台 Service Worker
 *
 * 职责：
 * 1. 接管浏览器下载，转发到 aria2
 * 2. 与本应用（可选）通过 JSON-RPC 通信
 * 3. 提供右键菜单"使用 aria2 下载链接"
 * 4. 预留资源嗅探能力（webRequest 监听）
 *
 * 注：Service Worker 是短生命周期的，配置需持久化到 chrome.storage
 */

// ===== 默认配置 =====
const DEFAULT_CONFIG = {
  rpcUrl: 'http://127.0.0.1:6800/jsonrpc',
  rpcSecret: '',
  // 是否拦截浏览器原生下载
  interceptDownload: true,
  // 文件大小阈值（字节），超过才转 aria2。0 = 全部转
  minSize: 0,
  // 排除的域名（这些域名的下载走浏览器原生）
  excludeDomains: [],
  // 是否显示桌面通知
  showNotifications: true
}

// ===== 配置读取 =====
async function getConfig() {
  const stored = await chrome.storage.local.get('config')
  return { ...DEFAULT_CONFIG, ...(stored.config || {}) }
}

async function saveConfig(config) {
  await chrome.storage.local.set({ config })
}

// ===== aria2 JSON-RPC 调用 =====
async function aria2Call(method, params = []) {
  const config = await getConfig()
  const rpcParams = []
  if (config.rpcSecret) {
    rpcParams.push(`token:${config.rpcSecret}`)
  }
  rpcParams.push(...params)

  const resp = await fetch(config.rpcUrl, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      jsonrpc: '2.0',
      id: Date.now().toString(),
      method,
      params: rpcParams
    })
  })
  if (!resp.ok) {
    throw new Error(`aria2 RPC HTTP ${resp.status}`)
  }
  const data = await resp.json()
  if (data.error) {
    throw new Error(`aria2 RPC error: ${data.error.message} (${data.error.code})`)
  }
  return data.result
}

/**
 * 添加 URI 下载任务到 aria2
 * @returns {string} gid
 */
async function aria2AddUri(url, filename, referer, cookies) {
  const options = {}
  if (filename) options.out = filename
  if (referer) options.referer = referer
  if (cookies) options.header = [`Cookie: ${cookies}`]
  // User-Agent 用浏览器默认值更兼容
  options['user-agent'] = navigator.userAgent
  return aria2Call('aria2.addUri', [[url], options])
}

// ===== 下载拦截 =====
async function shouldIntercept(downloadItem) {
  const config = await getConfig()
  if (!config.interceptDownload) return false
  // 大小阈值
  if (config.minSize > 0 && downloadItem.fileSize > 0 && downloadItem.fileSize < config.minSize) {
    return false
  }
  // 域名排除
  try {
    const url = new URL(downloadItem.finalUrl || downloadItem.url)
    if (config.excludeDomains.some(d => url.hostname.includes(d))) {
      return false
    }
  } catch { /* ignore */ }
  return true
}

async function handleDownloadCreated(downloadItem) {
  if (!await shouldIntercept(downloadItem)) return

  // 立即取消浏览器原生下载
  try {
    await chrome.downloads.cancel(downloadItem.id)
    await chrome.downloads.erase({ id: downloadItem.id })
  } catch { /* ignore */ }

  const url = downloadItem.finalUrl || downloadItem.url
  const filename = downloadItem.filename || ''

  try {
    const gid = await aria2AddUri(url, filename, downloadItem.referrer, '')
    await notify('已添加到 aria2', `${filename || url}\nGID: ${gid}`)
  } catch (e) {
    await notify('aria2 添加失败', `${filename || url}\n${e.message}`)
    // 失败时把 URL 重新交给浏览器下载
    try { await chrome.downloads.download({ url }) } catch { /* ignore */ }
  }
}

// ===== 通知 =====
async function notify(title, message) {
  const config = await getConfig()
  if (!config.showNotifications) return
  try {
    await chrome.notifications.create({
      type: 'basic',
      iconUrl: 'icons/icon-128.png',
      title,
      message
    })
  } catch { /* ignore */ }
}

// ===== 右键菜单 =====
chrome.runtime.onInstalled.addListener(() => {
  chrome.contextMenus.create({
    id: 'thing-download-link',
    title: '使用 aria2 下载此链接',
    contexts: ['link']
  })
  chrome.contextMenus.create({
    id: 'thing-download-page',
    title: '使用 aria2 下载当前页面资源',
    contexts: ['page']
  })
})

chrome.contextMenus.onClicked.addListener(async (info, tab) => {
  if (info.menuItemId === 'thing-download-link') {
    const url = info.linkUrl
    const filename = url.split('/').pop()?.split('?')[0] || ''
    try {
      const gid = await aria2AddUri(url, filename, info.pageUrl, '')
      await notify('已添加到 aria2', `${filename || url}\nGID: ${gid}`)
    } catch (e) {
      await notify('aria2 添加失败', `${e.message}`)
    }
  }
})

// ===== 下载事件监听 =====
chrome.downloads.onCreated.addListener(handleDownloadCreated)

// ===== 资源嗅探（预留，仅日志，不拦截）=====
// 后续可启用：监听页面媒体资源，提供"嗅探到的资源"列表
chrome.webRequest.onBeforeRequest.addListener(
  (details) => {
    // 预留：识别视频/音频流等可下载资源
    // 当前不处理，仅保留权限和入口
    return undefined
  },
  { urls: ['<all_urls>'] },
  []
)

// ===== 来自 popup 的消息 =====
chrome.runtime.onMessage.addListener((msg, _sender, sendResponse) => {
  if (msg.type === 'getConfig') {
    getConfig().then(sendResponse)
    return true
  }
  if (msg.type === 'saveConfig') {
    saveConfig(msg.config).then(() => sendResponse({ ok: true })).catch(e => sendResponse({ ok: false, error: e.message }))
    return true
  }
  if (msg.type === 'testConnection') {
    aria2Call('aria2.getVersion', [])
      .then(res => sendResponse({ ok: true, version: res.version }))
      .catch(e => sendResponse({ ok: false, error: e.message }))
    return true
  }
})