const { query, transaction } = require('../config/database')
const crypto = require('crypto')
const { paginate } = require('../utils/pagination')
const { DEFAULT_PASSWORD } = require('../config/constants')
const { hashPassword, verifyPassword, needsRehash } = require('../utils/password')
const { signAccess, signRefresh, verifyToken, ACCESS_TTL, REFRESH_TTL } = require('../utils/jwt')
const { toLegacyToken } = require('../utils/legacy-token')
const { extractToken, getUserByToken } = require('../middleware/auth')

function generateToken() {
  return crypto.randomBytes(32).toString('hex')
}

async function issueTokenPair(user) {
  const access = signAccess(user)
  const refresh = signRefresh(user)
  const dbToken = generateToken()
  await query('UPDATE users SET token = ? WHERE id = ?', [dbToken, user.id])
  return { access, refresh, legacy: toLegacyToken(dbToken), accessTtl: ACCESS_TTL, refreshTtl: REFRESH_TTL }
}

function publicUser(user, tokenObj) {
  const base = {
    id: user.id,
    phone: user.phone,
    name: user.name,
    avatar: user.avatar,
    points: user.points,
    role: user.role
  }
  if (tokenObj) {
    return { ...base, token: tokenObj.access, accessToken: tokenObj.access, refreshToken: tokenObj.refresh, legacyToken: tokenObj.legacy, accessTtl: tokenObj.accessTtl, refreshTtl: tokenObj.refreshTtl }
  }
  return base
}

// 用户登录（支持双重身份）
async function login(ctx) {
  const { phone, password, loginType } = ctx.request.body

  if (!phone || !password) {
    ctx.body = { code: 400, message: '请输入手机号和密码' }
    return
  }

  const users = await query('SELECT * FROM users WHERE phone = ?', [phone])

  if (users.length === 0) {
    ctx.body = { code: 401, message: '用户不存在' }
    return
  }

  const user = users[0]

  if (user.status === 0) {
    ctx.body = { code: 401, message: '账号已被禁用' }
    return
  }

  if (!verifyPassword(password, user.password)) {
    ctx.body = { code: 401, message: '密码错误' }
    return
  }

  if (loginType === 'admin' && user.role !== 2) {
    ctx.body = { code: 401, message: '该账号不是管理员账号' }
    return
  }

  if (loginType === 'staff' && user.role !== 1) {
    ctx.body = { code: 401, message: '该账号不是店员账号' }
    return
  }

  if (loginType === 'customer' && user.role !== 0) {
    ctx.body = { code: 401, message: '该账号不是普通用户账号' }
    return
  }

  let tokenObj
  if (needsRehash(user.password)) {
    const upgraded = hashPassword(password)
    await query('UPDATE users SET password = ? WHERE id = ?', [upgraded, user.id])
  }
  tokenObj = await issueTokenPair(user)

  ctx.body = { code: 200, data: publicUser(user, tokenObj) }
}

// 用户注册（普通用户）
async function register(ctx) {
  const { phone, password, name } = ctx.request.body
  if (!phone || !password || !name) {
    ctx.body = { code: 400, message: '请填写完整信息' }
    return
  }

  if (password.length < 8) {
    ctx.body = { code: 400, message: '密码至少8位' }
    return
  }
  if (!/[a-zA-Z]/.test(password) || !/[0-9]/.test(password)) {
    ctx.body = { code: 400, message: '密码需包含字母和数字' }
    return
  }

  const existing = await query('SELECT * FROM users WHERE phone = ?', [phone])
  if (existing.length > 0) {
    ctx.body = { code: 400, message: '该手机号已注册' }
    return
  }

  const result = await query(
    'INSERT INTO users (phone, password, name, avatar, points, role) VALUES (?, ?, ?, ?, ?, ?)',
    [phone, hashPassword(password), name, '', 0, 0]
  )

  ctx.body = {
    code: 200,
    message: '注册成功',
    data: { id: result.insertId, phone, name, avatar: '', points: 0, role: 0 }
  }
}


async function requireAuth(ctx) {
  const user = await getUserByToken(extractToken(ctx))
  if (!user) {
    ctx.status = 401
    ctx.body = { code: 401, message: '未登录或登录已失效' }
    return null
  }
  return user
}

async function requireStaffAuth(ctx) {
  const user = await getUserByToken(extractToken(ctx))
  if (!user) {
    ctx.status = 401
    ctx.body = { code: 401, message: '未登录或登录已失效' }
    return null
  }
  if (user.role !== 1 && user.role !== 2) {
    ctx.status = 403
    ctx.body = { code: 403, message: '权限不足，仅店员或管理员可操作' }
    return null
  }
  return user
}

async function requireAdminAuth(ctx) {
  const user = await getUserByToken(extractToken(ctx))
  if (!user) {
    ctx.status = 401
    ctx.body = { code: 401, message: '未登录或登录已失效' }
    return null
  }
  if (user.role !== 2) {
    ctx.status = 403
    ctx.body = { code: 403, message: '权限不足，仅管理员可操作' }
    return null
  }
  return user
}

async function createUser(phone, name, role) {
  const existing = await query('SELECT * FROM users WHERE phone = ?', [phone])
  if (existing.length > 0) return { conflict: true }

  const result = await query(
    'INSERT INTO users (phone, password, name, avatar, points, role) VALUES (?, ?, ?, ?, ?, ?)',
    [phone, hashPassword(DEFAULT_PASSWORD), name, '', 0, role]
  )

  return {
    conflict: false,
    data: {
      id: result.insertId,
      phone,
      name,
      avatar: '',
      points: 0,
      role
    }
  }
}

// 店员注册（需要管理员权限）
async function registerStaff(ctx) {
  const { phone, name } = ctx.request.body
  if (!phone || !name) {
    ctx.body = { code: 400, message: '请填写手机号和姓名' }
    return
  }

  const operator = await requireAdminAuth(ctx)
  if (!operator) return

  const result = await createUser(phone, name, 1)
  if (result.conflict) {
    ctx.body = { code: 400, message: '该手机号已注册' }
    return
  }

  ctx.body = {
    code: 200,
    message: `店员注册成功，默认密码为${DEFAULT_PASSWORD}`,
    data: result.data
  }
}

// 店员帮助用户注册（需要店员权限）
async function registerByStaff(ctx) {
  const { phone, name } = ctx.request.body
  if (!phone || !name) {
    ctx.body = { code: 400, message: '请填写手机号和姓名' }
    return
  }

  const operator = await requireStaffAuth(ctx)
  if (!operator) return

  const result = await createUser(phone, name, 0)
  if (result.conflict) {
    ctx.body = { code: 400, message: '该手机号已注册' }
    return
  }

  ctx.body = {
    code: 200,
    message: `用户注册成功，默认密码为${DEFAULT_PASSWORD}`,
    data: result.data
  }
}

// 获取用户信息
async function getUserInfo(ctx) {
  const userId = parseInt(ctx.query.id)
  
  if (!userId) {
    ctx.body = { code: 400, message: '缺少用户ID' }
    return
  }
  
  const users = await query('SELECT * FROM users WHERE id = ? AND status = 1', [userId])
  
  if (users.length > 0) {
    const user = users[0]
    ctx.body = {
      code: 200,
      data: {
        id: user.id,
        phone: user.phone,
        name: user.name,
        avatar: user.avatar,
        points: user.points,
        role: user.role
      }
    }
  } else {
    ctx.body = {
      code: 404,
      message: '用户不存在'
    }
  }
}

// 获取用户列表（管理员操作）
async function getUsers(ctx) {
  const operator = await requireAdminAuth(ctx)
  if (!operator) return

  let sql = 'SELECT id, phone, name, points, role, status, created_at FROM users WHERE status = 1'
  const params = []

  if (ctx.query.role !== undefined) {
    sql += ' AND role = ?'
    params.push(parseInt(ctx.query.role))
  }

  if (ctx.query.keyword) {
    sql += ' AND (phone LIKE ? OR name LIKE ?)'
    params.push(`%${ctx.query.keyword}%`, `%${ctx.query.keyword}%`)
  }

  sql += ' ORDER BY created_at DESC'

  const result = await paginate(query, sql, params, ctx.query.page, ctx.query.pageSize)

  ctx.body = {
    code: 200,
    ...result
  }
}

const USER_UPDATEABLE_FIELDS = ['name', 'avatar', 'points', 'status']

// 更新用户信息（管理员可改任意人；本人仅可改 name/avatar）
async function updateUser(ctx) {
  const operator = await requireAuth(ctx)
  if (!operator) return

  const userId = parseInt(ctx.params.id)
  const body = ctx.request.body

  let allowedFields = USER_UPDATEABLE_FIELDS
  if (operator.role !== 2) {
    if (userId !== operator.id) {
      ctx.body = { code: 403, message: '无权修改他人信息' }
      return
    }
    allowedFields = ['name', 'avatar']
  }

  const filtered = {}
  for (const key of allowedFields) {
    if (key in body) {
      filtered[key] = body[key]
    }
  }

  const { name, avatar, points, status } = filtered

  const updateFields = []
  const updateParams = []

  if (name !== undefined) {
    updateFields.push('name = ?')
    updateParams.push(name)
  }
  if (avatar !== undefined) {
    updateFields.push('avatar = ?')
    updateParams.push(avatar)
  }
  if (points !== undefined) {
    updateFields.push('points = ?')
    updateParams.push(parseInt(points))
  }
  if (status !== undefined) {
    updateFields.push('status = ?')
    updateParams.push(parseInt(status))
  }
  
  if (updateFields.length === 0) {
    ctx.body = {
      code: 400,
      message: '没有需要更新的字段'
    }
    return
  }
  
  updateParams.push(userId)
  
  const result = await query(`UPDATE users SET ${updateFields.join(', ')} WHERE id = ?`, updateParams)
  
  if (result.affectedRows > 0) {
    ctx.body = {
      code: 200,
      message: '更新成功'
    }
  } else {
    ctx.body = {
      code: 404,
      message: '用户不存在'
    }
  }
}

// 删除/禁用用户（管理员操作）
async function deleteUser(ctx) {
  const operator = await requireAdminAuth(ctx)
  if (!operator) return

  const userId = parseInt(ctx.params.id)

  if (userId === operator.id) {
    ctx.body = { code: 400, message: '不能禁用自己' }
    return
  }

  const result = await query('UPDATE users SET status = 0 WHERE id = ?', [userId])
  
  if (result.affectedRows > 0) {
    ctx.body = {
      code: 200,
      message: '禁用成功'
    }
  } else {
    ctx.body = {
      code: 404,
      message: '用户不存在'
    }
  }
}

// 修改密码
async function changePassword(ctx) {
  const { phone, oldPassword, newPassword } = ctx.request.body
  
  if (!phone || !oldPassword || !newPassword) {
    ctx.body = {
      code: 400,
      message: '请填写完整信息'
    }
    return
  }
  
  const users = await query('SELECT * FROM users WHERE phone = ? AND status = 1', [phone])
  
  if (users.length === 0) {
    ctx.body = {
      code: 404,
      message: '用户不存在'
    }
    return
  }
  
  const user = users[0]
  
  if (!verifyPassword(oldPassword, user.password)) {
    ctx.body = {
      code: 400,
      message: '原密码错误'
    }
    return
  }

  // 如果是旧版MD5哈希，登录时已自动升级；此处确保修改密码后使用scrypt
  await query('UPDATE users SET password = ? WHERE id = ?', [hashPassword(newPassword), user.id])
  
  ctx.body = {
    code: 200,
    message: '密码修改成功'
  }
}

// 重置密码（管理员操作）
async function resetPassword(ctx) {
  const operator = await requireAdminAuth(ctx)
  if (!operator) return

  const { userId } = ctx.request.body

  if (!userId) {
    ctx.body = {
      code: 400,
      message: '请指定用户ID'
    }
    return
  }

  const defaultPassword = DEFAULT_PASSWORD

  const result = await query('UPDATE users SET password = ? WHERE id = ?', [hashPassword(defaultPassword), userId])

  if (result.affectedRows > 0) {
    ctx.body = {
      code: 200,
      message: `密码已重置为${DEFAULT_PASSWORD}`
    }
  } else {
    ctx.body = {
      code: 404,
      message: '用户不存在'
    }
  }
}

// 调整积分（店员或管理员可操作）
async function addPoints(ctx) {
  const operator = await requireStaffAuth(ctx)
  if (!operator) return

  const { userId, points, description } = ctx.request.body

  if (!userId || points === undefined) {
    ctx.body = { code: 400, message: '请指定用户ID和积分变动值' }
    return
  }

  const pointsInt = parseInt(points)
  if (isNaN(pointsInt)) {
    ctx.body = { code: 400, message: '积分值无效' }
    return
  }

  const MAX_DELTA = 100000
  if (Math.abs(pointsInt) > MAX_DELTA) {
    ctx.body = { code: 400, message: `单次积分变动不能超过 ${MAX_DELTA}` }
    return
  }

  if (pointsInt === 0) {
    ctx.body = { code: 400, message: '积分变动值不能为0' }
    return
  }

  if (pointsInt < 0) {
    ctx.body = { code: 400, message: '不支持直接扣除积分，请使用专门的积分扣除接口' }
    return
  }

  const users = await query('SELECT * FROM users WHERE id = ? AND status = 1', [userId])
  if (users.length === 0) {
    ctx.body = { code: 404, message: '用户不存在' }
    return
  }

  const user = users[0]
  const newPoints = user.points + pointsInt

  await transaction(async (conn) => {
    await conn.execute('UPDATE users SET points = ? WHERE id = ?', [newPoints, userId])
    await conn.execute(
      'INSERT INTO points_logs (user_id, type, amount, description) VALUES (?, ?, ?, ?)',
      [userId, 'earn', Math.abs(pointsInt), description || '店员/管理员增加积分']
    )
  })

  ctx.body = {
    code: 200,
    message: '积分增加成功',
    data: { userId, oldPoints: user.points, newPoints, change: pointsInt }
  }
}

// 退出登录（使服务端 token 失效）
async function logout(ctx) {
  const user = await getUserByToken(extractToken(ctx))
  if (user) {
    await query('UPDATE users SET token = NULL WHERE id = ?', [user.id])
  }
  ctx.body = { code: 200, message: '已退出登录' }
}

// 刷新 access token
async function refreshToken(ctx) {
  const { refreshToken: token } = ctx.request.body
  if (!token) {
    ctx.status = 400
    ctx.body = { code: 400, message: '缺少 refreshToken' }
    return
  }
  const payload = verifyToken(token)
  if (!payload || payload.type !== 'refresh') {
    ctx.status = 401
    ctx.body = { code: 401, message: 'refreshToken 无效或已过期' }
    return
  }
  const users = await query('SELECT * FROM users WHERE id = ? AND status = 1', [payload.sub])
  if (users.length === 0) {
    ctx.status = 401
    ctx.body = { code: 401, message: '账号不存在或已禁用' }
    return
  }
  const user = users[0]
  const tokenObj = await issueTokenPair(user)
  ctx.body = { code: 200, data: publicUser(user, tokenObj) }
}

// 获取积分记录
async function getPointsLogs(ctx) {
  const userId = parseInt(ctx.query.userId)
  
  if (!userId) {
    ctx.body = {
      code: 400,
      message: '请指定用户ID'
    }
    return
  }
  
  const logs = await query(
    'SELECT * FROM points_logs WHERE user_id = ? ORDER BY created_at DESC',
    [userId]
  )
  
  ctx.body = {
    code: 200,
    data: logs
  }
}

// 微信一键登录
async function wechatLogin(ctx) {
  const { code } = ctx.request.body
  if (!code) {
    ctx.body = { code: 400, message: '缺少微信登录code' }
    return
  }

  const fetch = require('node-fetch')
  const APPID = process.env.WECHAT_APPID
  const SECRET = process.env.WECHAT_SECRET

  if (!APPID || !SECRET) {
    ctx.body = { code: 500, message: '微信登录未配置' }
    return
  }

  try {
    // 调用微信接口获取 openid 和 session_key
    const res = await fetch(
      `https://api.weixin.qq.com/sns/jscode2session?appid=${APPID}&secret=${SECRET}&js_code=${code}&grant_type=authorization_code`
    )
    const data = await res.json()

    if (data.errcode) {
      ctx.body = { code: 400, message: `微信登录失败: ${data.errmsg}` }
      return
    }

    const { openid } = data

    // 查找是否已有绑定该 openid 的用户
    const users = await query('SELECT * FROM users WHERE openid = ? AND status = 1', [openid])

    if (users.length > 0) {
      // 已有用户，直接登录
      const user = users[0]
      const tokenObj = await issueTokenPair(user)
      ctx.body = { code: 200, data: publicUser(user, tokenObj) }
    } else {
      // 新用户，自动注册
      const phone = `wx_${openid.slice(0, 10)}`
      const name = `微信用户`
      const result = await query(
        'INSERT INTO users (phone, password, name, avatar, points, role, openid) VALUES (?, ?, ?, ?, ?, ?, ?)',
        [phone, hashPassword(Math.random().toString(36)), name, '', 0, 0, openid]
      )
      const newUser = { id: result.insertId, phone, name, avatar: '', points: 0, role: 0, openid }
      const tokenObj = await issueTokenPair(newUser)
      ctx.body = { code: 200, data: publicUser(newUser, tokenObj), isNewUser: true }
    }
  } catch (err) {
    console.error('微信登录异常:', err)
    ctx.body = { code: 500, message: '微信登录失败' }
  }
}

module.exports = {
  requireAuth,
  requireStaffAuth,
  requireAdminAuth,
  login,
  wechatLogin,
  register,
  registerStaff,
  registerByStaff,
  getUserInfo,
  getUsers,
  updateUser,
  deleteUser,
  changePassword,
  resetPassword,
  addPoints,
  getPointsLogs,
  logout,
  refreshToken
}