// JSONL 后端：一行一条 JSON 追加写（改状态就追加新行），启动时读一遍建索引
// 量小、单进程够用；也是没配数据库时的默认后端，自测和回滚都靠它
const fs = require('fs')
const path = require('path')
const { newActivationCode: randomCode } = require('./code.js')

const DATA_DIR = process.env.DATA_DIR || path.join(__dirname, 'data')
const FILE = path.join(DATA_DIR, 'orders.jsonl')
const USERS_FILE = path.join(DATA_DIR, 'users.jsonl')
const SETTINGS_FILE = path.join(DATA_DIR, 'settings.json')

const orders = new Map() // outTradeNo -> 最新一条记录
const usedCodes = new Set()
const users = new Map() // openid -> 记录
const persistedSeen = new Map() // openid -> 最近一次落盘的活跃时间

function newActivationCode() {
  for (;;) {
    const code = randomCode()
    if (!usedCodes.has(code)) return code
  }
}

function load() {
  orders.clear()
  usedCodes.clear()
  users.clear()
  persistedSeen.clear()
  if (fs.existsSync(FILE)) {
    fs.readFileSync(FILE, 'utf8')
      .split('\n')
      .forEach((line) => {
        if (!line.trim()) return
        const record = JSON.parse(line)
        orders.set(record.outTradeNo, record) // 同一单号，后写的覆盖先写的
        if (record.code) usedCodes.add(record.code)
      })
  }
  if (fs.existsSync(USERS_FILE)) {
    fs.readFileSync(USERS_FILE, 'utf8')
      .split('\n')
      .forEach((line) => {
        if (!line.trim()) return
        const record = JSON.parse(line)
        users.set(record.openid, record)
        persistedSeen.set(record.openid, record.lastSeenAt)
      })
  }
}

load()

module.exports = {
  backend: 'jsonl',
  file: FILE,
  ready: async () => {},
  get: async (outTradeNo) => orders.get(outTradeNo) || null,

  // 全量落一条（新建、改状态、迁移导入都走它）
  saveOrder: async (record) => {
    fs.mkdirSync(DATA_DIR, { recursive: true })
    fs.appendFileSync(FILE, JSON.stringify(record) + '\n')
    orders.set(record.outTradeNo, record)
    if (record.code) usedCodes.add(record.code)
    return record
  },

  // 发货：生成激活码并绑定；已经有码就直接返回（幂等）
  assignCode: async (outTradeNo, extra) => {
    const record = orders.get(outTradeNo)
    if (!record) throw new Error('没有这笔业务单号：' + outTradeNo)
    if (record.code) return record
    return module.exports.saveOrder(
      Object.assign(
        {},
        record,
        { status: 'delivered', code: newActivationCode(), deliveredAt: Date.now(), notified: false },
        extra
      )
    )
  },

  markNotified: async (outTradeNo) => {
    const record = orders.get(outTradeNo)
    if (!record) return
    await module.exports.saveOrder(Object.assign({}, record, { notified: true }))
  },

  markRefunded: async (outTradeNo, refundOrderId) => {
    const record = orders.get(outTradeNo)
    if (!record) return
    await module.exports.saveOrder(Object.assign({}, record, { refunded: true, refundOrderId, refundedAt: Date.now() }))
  },

  listByOpenid: async (openid) =>
    Array.from(orders.values())
      .filter((o) => o.openid === openid && o.code && !o.refunded)
      .sort((a, b) => b.deliveredAt - a.deliveredAt),

  listPendingByOpenid: async (openid) =>
    Array.from(orders.values())
      .filter((o) => o.openid === openid && !o.refunded && (!o.code || !o.notified))
      .sort((a, b) => b.createdAt - a.createdAt),

  listPendingAll: async (since) =>
    Array.from(orders.values())
      .filter((o) => !o.refunded && (!o.code || !o.notified) && o.createdAt >= since)
      .sort((a, b) => a.createdAt - b.createdAt),

  listGoods: async () => [],

  getUser: async (openid) => {
    const record = users.get(openid)
    return record ? { openid, createdAt: record.createdAt, lastSeenAt: record.lastSeenAt, isAdmin: Boolean(record.isAdmin) } : null
  },

  // 文件后端：想改文案就在 data/settings.json 里写 {"buy.title": "xx"}
  getSettings: async () => {
    if (!fs.existsSync(SETTINGS_FILE)) return {}
    try {
      return JSON.parse(fs.readFileSync(SETTINGS_FILE, 'utf8'))
    } catch (err) {
      console.error('settings.json 解析失败：', err.message)
      return {}
    }
  },

  touchUser: async (openid, firstSeenAt) => {
    const now = Date.now()
    const existed = users.get(openid)
    const record = {
      openid,
      createdAt: existed ? existed.createdAt : firstSeenAt || now,
      lastSeenAt: now,
      isAdmin: existed ? existed.isAdmin : false,
    }
    users.set(openid, record)
    // 活跃时间最多每小时落一次盘，免得文件被刷爆
    if (!persistedSeen.has(openid) || now - persistedSeen.get(openid) > 3600000) {
      fs.mkdirSync(DATA_DIR, { recursive: true })
      fs.appendFileSync(USERS_FILE, JSON.stringify(record) + '\n')
      persistedSeen.set(openid, now)
    }
    return record
  },

  // 核对用：订单数、激活码数、未完成的单
  stats: async () => ({
    orders: orders.size,
    codes: Array.from(orders.values()).filter((o) => o.code).length,
    pending: Array.from(orders.values()).filter((o) => !o.refunded && (!o.code || !o.notified)).length,
    users: users.size,
  }),
}