import { Router, Request, Response } from 'express'
import { createHmac } from 'crypto'
import pool from '../db/connection'

const router = Router()

const APPID = process.env.WX_APPID || ''
const SECRET = process.env.WX_SECRET || ''
const TOKEN_SECRET = process.env.TOKEN_SECRET || 'xiaocai-token-secret-change-in-production'

/** 启动时检查 TOKEN_SECRET 是否为默认占位符，是则拒绝启动 */
export function checkTokenSecret(): void {
  const defaults = [
    'xiaocai-token-secret-change-in-production',
    'change-me-to-a-secure-random-string',
  ]
  if (defaults.includes(TOKEN_SECRET)) {
    console.error('[Auth] FATAL: TOKEN_SECRET is using a default placeholder. Set a secure TOKEN_SECRET in .env before starting the server.')
    process.exit(1)
  }
}

export function signToken(userId: number): string {
  const payload = `${userId}:${Date.now()}`
  const signature = createHmac('sha256', TOKEN_SECRET).update(payload).digest('hex')
  return Buffer.from(`${payload}:${signature}`).toString('base64')
}

// H5 演示登录 — 创建/复用演示用户
router.post('/demo-login', async (_req: Request, res: Response) => {
  try {
    const demoOpenid = 'h5_demo_user'
    const [result] = await pool.query(
      'INSERT INTO users (openid, session_key) VALUES (?, ?) ON DUPLICATE KEY UPDATE session_key = ?, id = LAST_INSERT_ID(id)',
      [demoOpenid, 'demo', 'demo']
    )
    const userId = (result as any).insertId

    // 首个用户自动设为管理员
    await autoSetAdmin(userId)

    const token = signToken(userId)
    const [userRows] = await pool.query('SELECT nickname, avatar_url, role FROM users WHERE id = ?', [userId])
    const userInfo = (userRows as any[])[0]
    res.json({ code: 0, data: { token, userId, nickname: userInfo?.nickname || '小菜', avatar_url: userInfo?.avatar_url || '', role: userInfo?.role || 'user' } })
  } catch (err: any) {
    console.error('[Auth] Demo login failed:', err)
    res.status(500).json({ code: 50000, message: '服务器错误' })
  }
})

router.post('/login', async (req: Request, res: Response) => {
  try {
    const { code } = req.body
    if (!code || typeof code !== 'string' || code.length > 128 || !/^[a-zA-Z0-9_-]+$/.test(code)) {
      return res.status(400).json({ code: 40001, message: 'code参数无效' })
    }

    // 调用微信 code2session 接口
    const url = `https://api.weixin.qq.com/sns/jscode2session?appid=${APPID}&secret=${SECRET}&js_code=${code}&grant_type=authorization_code`
    const wxRes = await fetch(url)
    const wxData = await wxRes.json() as any

    if (wxData.errcode) {
      console.error('[Auth] WeChat API error:', wxData.errcode, wxData.errmsg)
      return res.status(400).json({ code: 40002, message: '微信登录失败' })
    }

    const { openid, session_key } = wxData

    // 查找或创建用户 (atomic: handles race condition)
    const [result] = await pool.query(
      'INSERT INTO users (openid, session_key) VALUES (?, ?) ON DUPLICATE KEY UPDATE session_key = ?, id = LAST_INSERT_ID(id)',
      [openid, session_key, session_key]
    )
    const userId = (result as any).insertId

    // 首个用户自动设为管理员
    await autoSetAdmin(userId)

    // HMAC signed token with expiry
    const token = signToken(userId)
    const [userRows] = await pool.query('SELECT nickname, avatar_url, role FROM users WHERE id = ?', [userId])
    const userInfo = (userRows as any[])[0]
    res.json({ code: 0, data: { token, userId, nickname: userInfo?.nickname || '小菜', avatar_url: userInfo?.avatar_url || '', role: userInfo?.role || 'user' } })
  } catch (err: any) {
    console.error('[Auth] Login failed:', err)
    res.status(500).json({ code: 50000, message: '服务器错误' })
  }
})

/** 首个用户自动设为管理员 */
async function autoSetAdmin(userId: number) {
  const [adminCount] = await pool.query('SELECT COUNT(*) as count FROM users WHERE role = ?', ['admin'])
  if ((adminCount as any[])[0].count === 0) {
    await pool.query('UPDATE users SET role = ? WHERE id = ?', ['admin', userId])
    console.log(`[Auth] User ${userId} auto-promoted to admin`)
  }
}

export default router