// 虚拟支付下单服务：给小程序返回签名后的支付参数，并提供查单
// 启动：node server/index.js（默认端口 3000，用 PORT 覆盖）
const http = require('http')
const https = require('https')
const crypto = require('crypto')
const { GOODS, newOutTradeNo, buildSignData, paySig, userSignature } = require('./sign.js')
const store = require('./store.js')
const { COPY } = require('./copy.js')

// 密钥优先读环境变量，其次读同目录 config.js（config.js 不入库）
const fileConfig = require('./read-config.js')

const config = {
  appId: process.env.PAY_APP_ID || fileConfig.appId,
  appSecret: process.env.PAY_APP_SECRET || fileConfig.appSecret,
  offerId: process.env.PAY_OFFER_ID || fileConfig.offerId,
  appKey: process.env.PAY_APP_KEY || fileConfig.appKey,
  sandboxAppKey: process.env.PAY_SANDBOX_APP_KEY || fileConfig.sandboxAppKey,
  pushToken: process.env.PAY_PUSH_TOKEN || fileConfig.pushToken,
}

const WX_ORIGIN = process.env.WX_API_ORIGIN || 'https://api.weixin.qq.com'
const XPAY_QUERY_URI = '/xpay/query_order'
const XPAY_NOTIFY_URI = '/xpay/notify_provide_goods'
const XPAY_REFUND_URI = '/xpay/refund_order'
const PORT = Number(process.env.PORT ?? 3000)
const MAX_BODY = 4096
// 定时查单兜底的间隔，设 0 关掉；回看窗口限制一下，免得半路放弃的单被无限查下去
const POLL_MS = Number(process.env.PAY_POLL_MS ?? 5 * 60 * 1000)
const PENDING_WINDOW_MS = 24 * 60 * 60 * 1000

// 价目表和页面文案都以数据库为准（表里没写就退回代码里的默认值），缓存 60 秒
let configCache = { at: 0, goods: [], copy: {} }

async function refreshConfig() {
  const fromDb = await store.listGoods()
  const list = fromDb.length
    ? fromDb
    : Object.keys(GOODS).map((id) => ({
        productId: id,
        name: GOODS[id].name,
        price: GOODS[id].price,
        enabled: true,
        adminOnly: Boolean(GOODS[id].adminOnly),
        note: GOODS[id].note || '',
      }))
  // 文案配置读不到不该挡住下单，退回默认文案就行
  const settings = await store.getSettings().catch((err) => {
    console.error('读取文案配置失败：', err.message)
    return {}
  })
  const copy = {}
  for (const [key, item] of Object.entries(COPY)) copy[key] = settings[key] || item.value
  configCache = {
    at: Date.now(),
    goods: list.slice().sort((a, b) => a.price - b.price), // 价格从低到高，页面和后台顺序一致
    copy,
  }
}

async function currentConfig() {
  if (Date.now() - configCache.at >= 60000) await refreshConfig()
  return configCache
}

const allGoods = async () => (await currentConfig()).goods
const allCopy = async () => (await currentConfig()).copy

const goodsOf = async (productId) =>
  (await allGoods()).find((goods) => String(goods.productId) === String(productId) && goods.enabled) || null

const nameOf = async (productId) => ((await goodsOf(productId)) || {}).name || String(productId)

// 管理员判定：只看用户表的 is_admin（查不到就按普通用户算）
async function isAdmin(openid) {
  const user = await store.getUser(openid)
  return Boolean(user && user.isAdmin)
}

const sha1 = (text) => crypto.createHash('sha1').update(text).digest('hex')
const isPaid = (status) => status >= 2 && status <= 4 // 2 已支付待发货 / 3 发货中 / 4 已发货

// 从推送的 XML 里取字段，值可能在 CDATA 里
function xmlTag(xml, name) {
  const matched = new RegExp(`<${name}>(?:<!\\[CDATA\\[)?([\\s\\S]*?)(?:\\]\\]>)?</${name}>`).exec(xml)
  return matched ? matched[1].trim() : ''
}

// 0 现网、1 沙箱；两套 AppKey 不能混用，混了会报 -15006 签名错误
function appKeyOf(env) {
  if (env === 1) {
    if (!config.sandboxAppKey) throw new Error('没配沙箱 AppKey（sandboxAppKey），沙箱下单用不了')
    return config.sandboxAppKey
  }
  return config.appKey
}

function request(url, body) {
  return new Promise((resolve, reject) => {
    const client = url.startsWith('https:') ? https : http
    const options = {
      method: body ? 'POST' : 'GET',
      // 请求体原样发出，pay_sig 是对这串原文算的
      headers: body ? { 'Content-Type': 'application/json', 'Content-Length': Buffer.byteLength(body) } : {},
    }
    const req = client.request(url, options, (res) => {
      let raw = ''
      res.on('data', (chunk) => (raw += chunk))
      res.on('end', () => {
        if (!raw.trim()) return resolve({}) // 有的接口成功时返回体是空的
        try {
          resolve(JSON.parse(raw))
        } catch (err) {
          reject(new Error('微信接口返回的不是 JSON：' + raw.slice(0, 200)))
        }
      })
    })
    req.on('error', reject)
    req.end(body || undefined)
  })
}

// wx.login 的 code 换 openid + session_key
async function code2Session(code) {
  if (!code) throw new Error('缺少 code（前端要先 wx.login）')
  const res = await request(
    `${WX_ORIGIN}/sns/jscode2session?appid=${config.appId}&secret=${config.appSecret}` +
      `&js_code=${code}&grant_type=authorization_code`
  )
  if (!res.openid) throw new Error(`code2Session 失败：${res.errcode} ${res.errmsg}`)
  // 顺手记一笔用户：首次出现建行，之后只更新活跃时间。这里失败不该挡住支付
  try {
    await store.touchUser(res.openid)
  } catch (err) {
    console.error('记录用户失败：', err.message)
  }
  return res
}

let tokenCache = { value: '', expireAt: 0 }
async function getAccessToken() {
  if (tokenCache.value && Date.now() < tokenCache.expireAt) return tokenCache.value
  const res = await request(
    `${WX_ORIGIN}/cgi-bin/token?grant_type=client_credential&appid=${config.appId}&secret=${config.appSecret}`
  )
  if (!res.access_token) throw new Error(`获取 access_token 失败：${res.errcode} ${res.errmsg}`)
  tokenCache = { value: res.access_token, expireAt: Date.now() + (res.expires_in - 300) * 1000 }
  return tokenCache.value
}

// 下单：生成业务单号 + 双签名，返回给前端去拉起支付
async function createPay(productId, code, env) {
  const goods = await goodsOf(productId)
  if (!goods) throw new Error('未知道具 ID：' + productId)
  const appKey = appKeyOf(env)

  const session = await code2Session(code)
  // 沙箱能免费拿货、补单道具是测试价，这两件事只有管理员能用（不能只靠前端藏按钮）
  const admin = await isAdmin(session.openid)
  if (goods.adminOnly && !admin) throw new Error(`「${goods.name}」只有管理员能购买`)
  if (env === 1 && !admin) throw new Error('沙箱环境只有管理员能用')

  const outTradeNo = newOutTradeNo()
  const signData = buildSignData({
    offerId: config.offerId,
    productId,
    price: goods.price,
    outTradeNo,
    attach: 'test-' + productId,
    env,
  })

  // 先落一条「已创建」，发货时靠它认人（防止别人拿单号来领别人的货）
  await store.saveOrder({
    outTradeNo,
    openid: session.openid,
    productId: String(productId),
    env,
    amount: goods.price,
    status: 'created',
    createdAt: Date.now(),
  })

  return {
    outTradeNo,
    env,
    payData: {
      signData,
      paySig: paySig(appKey, 'requestVirtualPayment', signData),
      signature: userSignature(session.session_key, signData),
      mode: 'short_series_goods',
    },
  }
}

// 查单：支付成功回调可能丢，用这个确认真实订单状态
async function queryOrderRaw(outTradeNo, openid, env) {
  const token = await getAccessToken()
  const body = JSON.stringify({ openid, env, order_id: outTradeNo })
  const url = `${WX_ORIGIN}${XPAY_QUERY_URI}?access_token=${token}&pay_sig=${paySig(appKeyOf(env), XPAY_QUERY_URI, body)}`
  const res = await request(url, body)
  return { errcode: res.errcode, errmsg: res.errmsg, order: res.order }
}

// 通知平台「已发货」。文档的调用示例里只写了 access_token，但平台实际要 pay_sig
// （少了会回 268490002 签名字段[pay_sig]为空），所以按查单那套一起签上
async function notifyProvideGoods(record) {
  const env = record.env || 0
  const token = await getAccessToken()
  const payload = { order_id: record.outTradeNo, env }
  if (record.wxOrderId) payload.wx_order_id = record.wxOrderId // 查单没给内部单号就别塞空串
  const body = JSON.stringify(payload)
  const url = `${WX_ORIGIN}${XPAY_NOTIFY_URI}?access_token=${token}&pay_sig=${paySig(appKeyOf(env), XPAY_NOTIFY_URI, body)}`
  const res = await request(url, body)
  console.log(new Date().toISOString(), 'notify_provide_goods', body, '->', JSON.stringify(res))
  if (res.errcode) throw new Error(`通知平台发货失败：${res.errcode} ${res.errmsg}`)
  await store.markNotified(record.outTradeNo)
}

// 平台通知失败不算发货失败：钱已经付了，激活码先给到用户，下次调用再补通知
async function tryNotify(record) {
  if (record.notified) return { ok: true }
  // 沙箱是模拟环境，平台侧不需要真实发货回执，跳过通知免得反复白调接口
  if ((record.env || 0) === 1) {
    await store.markNotified(record.outTradeNo)
    return { ok: true }
  }
  try {
    await notifyProvideGoods(record)
    return { ok: true }
  } catch (err) {
    console.error('通知平台发货失败：', err.message)
    return { ok: false, error: err.message }
  }
}

// 发激活码 + 通知平台。不依赖前端登录，所以定时补发货和发货推送也能复用
async function deliverRecord(record, order) {
  let detail = order
  if (!detail) {
    const queried = await queryOrderRaw(record.outTradeNo, record.openid, record.env || 0)
    detail = queried.order || {}
  }
  const delivered = await store.assignCode(record.outTradeNo, {
    wxOrderId: detail.wx_order_id || record.wxOrderId || '',
    paidFee: detail.paid_fee || 0,
  })
  const notify = await tryNotify(delivered)
  return {
    paid: true,
    status: detail.status || 2,
    code: delivered.code,
    productId: delivered.productId,
    productName: await nameOf(delivered.productId),
    notified: notify.ok,
    notifyError: notify.error || '',
  }
}

function deliveredResult(record, productName) {
  return {
    paid: true,
    status: 4,
    code: record.code,
    productId: record.productId,
    productName,
  }
}

// 发货：查到已支付就发激活码，并告诉平台已发货；同一单重复调用只发一次（幂等）
async function deliver(outTradeNo, code) {
  const session = await code2Session(code)
  const record = await store.get(outTradeNo)
  if (!record) throw new Error('没有这笔业务单号：' + outTradeNo)
  if (record.openid !== session.openid) throw new Error('这笔订单不属于当前用户')
  if (record.refunded) throw new Error('这笔订单已经退过款了')

  // 已经发过货：把原来那张码再给一遍
  if (record.code) {
    const notify = await tryNotify(record)
    return Object.assign(deliveredResult(record, await nameOf(record.productId)), {
      notified: notify.ok,
      notifyError: notify.error || '',
    })
  }

  const { order } = await queryOrderRaw(outTradeNo, session.openid, record.env || 0)
  const status = (order && order.status) || 0
  if (!isPaid(status)) {
    return { paid: false, status, productId: record.productId, productName: await nameOf(record.productId) }
  }
  return deliverRecord(record, order)
}

// 退款：iOS 的 Apple 订单不能走这里（只能用户去 App Store 申请），前端会隐藏按钮
async function refund(outTradeNo, code) {
  const session = await code2Session(code)
  const record = await store.get(outTradeNo)
  if (!record) throw new Error('没有这笔业务单号：' + outTradeNo)
  if (record.openid !== session.openid) throw new Error('这笔订单不属于当前用户')
  if (record.refunded) throw new Error('这笔订单已经退过了')
  if (!(await isAdmin(session.openid))) throw new Error('退款目前只有管理员能操作')

  const env = record.env || 0
  const { order } = await queryOrderRaw(outTradeNo, session.openid, env)
  const status = (order && order.status) || 0
  if (!isPaid(status)) throw new Error('这笔订单没有可退的支付')
  // left_fee 要用查单返回的值，自己算会被平台拒（268490016）
  const leftFee = order.left_fee != null ? order.left_fee : order.paid_fee || 0
  if (leftFee <= 0) throw new Error('这笔订单没有可退金额（可能已经退过款）')

  const refundOrderId = 'R' + outTradeNo
  const body = JSON.stringify({
    openid: session.openid,
    order_id: outTradeNo,
    refund_order_id: refundOrderId,
    left_fee: leftFee,
    refund_fee: leftFee,
    biz_meta: 'refund',
    refund_reason: 3, // 意愿问题，用户主动退款
    req_from: 2, // 用户自己发起
    env,
  })
  const token = await getAccessToken()
  const url = `${WX_ORIGIN}${XPAY_REFUND_URI}?access_token=${token}&pay_sig=${paySig(appKeyOf(env), XPAY_REFUND_URI, body)}`
  const res = await request(url, body)
  console.log(new Date().toISOString(), 'refund_order', body, '->', JSON.stringify(res))
  if (res.errcode && res.errcode !== 268490014) throw new Error(`退款失败：${res.errcode} ${res.errmsg}`) // 14 = 退款进行中

  // 激活码作废：「我的」和待发货都不会再带这张码
  await store.markRefunded(outTradeNo, refundOrderId)
  return { refundOrderId, refundFee: leftFee }
}
// 我的：当前用户已经买到的激活码
async function myCodes(code) {
  const session = await code2Session(code)
  const admin = await isAdmin(session.openid)
  const list = []
  for (const record of await store.listByOpenid(session.openid)) {
    list.push({
      outTradeNo: record.outTradeNo,
      code: record.code,
      productId: record.productId,
      productName: await nameOf(record.productId),
      env: record.env || 0,
      deliveredAt: record.deliveredAt,
    })
  }
  return { list, isAdmin: admin }
}

// 还没发货的最近一笔：页面重进后仍能点「确认发货」补上（支付回调丢了也能救）
async function pendingOrder(code) {
  const session = await code2Session(code)
  // 只看最近几笔，并且要平台确认真的付了钱——半路放弃的单（订单初始化）不该一直提示发货
  const candidates = await store.listPendingByOpenid(session.openid)
  for (const record of candidates) {
    const { order } = await queryOrderRaw(record.outTradeNo, session.openid, record.env || 0)
    const status = (order && order.status) || 0
    if (status >= 2 && status <= 4) {
      return {
        outTradeNo: record.outTradeNo,
        productId: record.productId,
        productName: await nameOf(record.productId),
        env: record.env || 0,
        status,
      }
    }
  }
  return { outTradeNo: '' }
}

function readJson(req) {
  return new Promise((resolve, reject) => {
    let raw = ''
    req.on('data', (chunk) => {
      raw += chunk
      if (raw.length > MAX_BODY) {
        reject(new Error('请求体过大'))
        req.destroy()
      }
    })
    req.on('end', () => {
      try {
        resolve(raw ? JSON.parse(raw) : {})
      } catch (err) {
        reject(new Error('请求体不是合法 JSON'))
      }
    })
  })
}

// 发货推送的 XML 原文（明文模式），带体积上限
function readText(req) {
  return new Promise((resolve, reject) => {
    let raw = ''
    req.on('data', (chunk) => {
      raw += chunk
      if (raw.length > MAX_BODY * 4) {
        reject(new Error('推送内容过大'))
        req.destroy()
      }
    })
    req.on('end', () => resolve(raw))
    req.on('error', reject)
  })
}

// 平台推来「已发货」（xpay_goods_deliver_notify）：幂等发货，回 0 平台就不再重试
async function handleDeliverPush(xml) {
  const event = xmlTag(xml, 'Event')
  if (event !== 'xpay_goods_deliver_notify') {
    console.log(new Date().toISOString(), '推送事件（忽略）：', event || '(没有 Event)')
    return
  }
  const outTradeNo = xmlTag(xml, 'OutTradeNo')
  const openid = xmlTag(xml, 'OpenId')
  if (!outTradeNo || !openid) throw new Error('推送里缺 OutTradeNo 或 OpenId')

  const env = Number(xmlTag(xml, 'Env')) === 1 ? 1 : 0
  let record = await store.get(outTradeNo)
  if (!record) {
    // 极少见：本地没这笔单（比如订单表被删了），按推送内容补一条，别漏发
    record = await store.saveOrder({
      outTradeNo,
      openid,
      productId: xmlTag(xml, 'ProductId'),
      env,
      amount: 0,
      status: 'created',
      createdAt: Date.now(),
    })
  }
  if (record.code) return // 幂等：同一单重复推送只发一次

  // 推送这边回了 0，平台就认为发货完成了，所以直接标记 notified，不用再调通知接口
  const delivered = await store.assignCode(outTradeNo, {
    wxOrderId: xmlTag(xml, 'MchOrderNo') || record.wxOrderId || '',
    notified: true,
  })
  console.log(new Date().toISOString(), '发货推送', outTradeNo, '->', delivered.code)
}

// 消息推送入口：GET 是后台配置 URL 时的校验，POST 是发货/退款等事件（明文模式）
async function handlePush(req, res) {
  const params = new URL(req.url, 'http://localhost').searchParams
  const expected = sha1([config.pushToken, params.get('timestamp'), params.get('nonce')].sort().join(''))
  if (!config.pushToken || params.get('signature') !== expected) {
    res.statusCode = 403
    res.setHeader('Content-Type', 'text/plain; charset=utf-8')
    return res.end('signature 校验失败')
  }
  if (req.method === 'GET') {
    res.setHeader('Content-Type', 'text/plain; charset=utf-8')
    return res.end(params.get('echostr') || '')
  }

  const xml = '<xml><ErrCode>0</ErrCode><ErrMsg><![CDATA[success]]></ErrMsg></xml>'
  try {
    await handleDeliverPush(await readText(req))
  } catch (err) {
    console.error(new Date().toISOString(), '处理发货推送失败：', err.message)
    res.setHeader('Content-Type', 'text/xml; charset=utf-8')
    // 出错要回非 0，平台才会重试
    return res.end(`<xml><ErrCode>1</ErrCode><ErrMsg><![CDATA[${err.message}]]></ErrMsg></xml>`)
  }
  res.setHeader('Content-Type', 'text/xml; charset=utf-8')
  res.end(xml)
}

// 定时查单兜底：用户付完直接关掉小程序（不再打开购买页）也能自动发货
async function pollPending() {
  for (const record of await store.listPendingAll(Date.now() - PENDING_WINDOW_MS)) {
    try {
      const { order } = await queryOrderRaw(record.outTradeNo, record.openid, record.env || 0)
      if (!isPaid((order && order.status) || 0)) continue
      if (record.code) await tryNotify(record)
      else await deliverRecord(record, order)
    } catch (err) {
      console.error('定时补发货失败：', record.outTradeNo, err.message)
    }
  }
}

function send(res, data, status) {
  res.statusCode = status
  res.end(JSON.stringify(data))
}

const ROUTES = {
  '/pay/order': async (body) =>
    Object.assign(
      { ok: true },
      // 只认数字 1，字符串 '1' 也要当沙箱：万一前端把 env 传成字符串，不能悄悄签成现网真扣钱
      await createPay(String(body.productId), body.code, Number(body.env) === 1 ? 1 : 0)
    ),
  '/pay/deliver': async (body) => Object.assign({ ok: true }, await deliver(String(body.outTradeNo), body.code)),
  '/pay/my': async (body) => Object.assign({ ok: true }, await myCodes(body.code)),
  '/pay/pending': async (body) => Object.assign({ ok: true }, await pendingOrder(body.code)),
  '/pay/refund': async (body) => Object.assign({ ok: true }, await refund(String(body.outTradeNo), body.code)),
  // 登录态 + 该用户能看到的道具（管理员才看得到沙箱和补单道具）
  '/pay/me': async (body) => {
    const session = await code2Session(body.code)
    const admin = await isAdmin(session.openid)
    return {
      ok: true,
      isAdmin: admin,
      goods: (await allGoods()).filter((item) => item.enabled && (admin || !item.adminOnly)),
      copy: await allCopy(),
    }
  },
}

const server = http.createServer(async (req, res) => {
  const path = req.url.split('?')[0]
  const startedAt = Date.now()
  let summary = ''
  res.setHeader('Content-Type', 'application/json; charset=utf-8')
  try {
    if (path === '/pay/notify') {
      summary = 'push'
      return await handlePush(req, res)
    }
    if (path === '/health') {
      const missing = ['appId', 'appSecret', 'offerId', 'appKey'].filter((key) => !config[key])
      summary = 'ok'
      return send(
        res,
        {
          ok: missing.length === 0,
          missing,
          sandbox: Boolean(config.sandboxAppKey),
          goods: (await allGoods()).map((item) => String(item.productId)),
          store: store.backend,
          routes: Object.keys(ROUTES), // 用来一眼确认服务器上跑的是不是最新代码
        },
        200
      )
    }
    if (!ROUTES[path]) {
      summary = '未知接口'
      return send(res, { ok: false, error: '未知接口：' + path }, 404)
    }
    if (req.method !== 'POST') {
      summary = '方法不对'
      return send(res, { ok: false, error: '请用 POST' }, 405)
    }
    const data = await ROUTES[path](await readJson(req))
    // 下单带上环境，事后一眼看出这笔是现网还是沙箱
    summary = data.ok ? 'ok' : `失败：${data.error}`
    if (path === '/pay/order') summary += ` env=${data.env}`
    send(res, data, 200)
  } catch (err) {
    summary = `异常：${err.message}`
    // 业务失败也回 200 + ok:false，前端统一按 ok 判断
    send(res, { ok: false, error: err.message }, 200)
  } finally {
    // 每个请求都留一行，哪怕是「前端压根没调过来」也能看出来
    console.log(new Date().toISOString(), req.method, path, summary, `${Date.now() - startedAt}ms`)
  }
})

// 存储层先就绪（MySQL 要建表、播种价目表），失败就直接退出，别带着坏库对外服务
store
  .ready()
  .then(() => {
    server.listen(PORT, () => {
      console.log(`xpay 服务已启动：http://localhost:${server.address().port}（存储：${store.backend}）`)
      const missing = ['appId', 'appSecret', 'offerId', 'appKey'].filter((key) => !config[key])
      if (missing.length) console.warn('还缺配置：' + missing.join('、') + '（写在 server/config.js 或环境变量里）')
      if (!config.sandboxAppKey) console.warn('没配沙箱 AppKey，沙箱（env=1）下单会失败')
      if (!config.pushToken) console.warn('没配 pushToken，平台的发货推送会被拒（查单兜底仍然可用）')
    })
    if (POLL_MS > 0) {
      setInterval(pollPending, POLL_MS)
      console.log(`定时补发货已开启：每 ${Math.round(POLL_MS / 1000)} 秒扫一次没发完的单`)
    }
  })
  .catch((err) => {
    console.error('存储层初始化失败：', err.message)
    process.exit(1)
  })