import { useState } from 'react'
import { View, Text } from '@tarojs/components'
import { useDidShow } from '@tarojs/taro'
import { useAppDispatch, useAppSelector } from '@/store/hooks'
import { setAuth } from '@/store/authSlice'
import { performWxLogin, completeUserInfoLogin, getLoginSubState } from './wxLoginFlow'
import { useToast } from '@/hooks/useToast'
import { ROUTES } from '@/constants/routes'
import { reLaunch } from '@/utils/navigation'
import { storage } from '@/utils/storage'
import { WX_OPENID_STORAGE_KEY } from '@/constants/auth'
import styles from './index.module.scss'

export default function Login() {
  const dispatch = useAppDispatch()
  const toast = useToast()
  const token = useAppSelector((s) => s.auth.token)
  const [loading, setLoading] = useState(false)
  // 注册中间态：needUserInfo（待用户资料授权）→ null（初始/完成）
  const [needAuth, setNeedAuth] = useState(false)
  const [openId, setOpenId] = useState('')

  // 已有 token 直接进首页（本期不做 checkLogin 校验，spec D5）
  useDidShow(() => {
    if (token && !loading) reLaunch(ROUTES.HOME)
  })

  // 完整登录态校验与落地；未完成时推进授权态
  const applyResult = async (result: Awaited<ReturnType<typeof performWxLogin>>) => {
    const state = getLoginSubState(result)
    if (state !== 'complete') {
      console.log('[login-page] 注册未完成，推进到', state)
      if (state === 'noMobile') {
        // 手机号授权暂缓（后端字段未定）：提示并保持当前态，等后端确认后接续
        throw new Error('后端要求绑定手机号，该流程暂未开通')
      }
      // openId 兜底链：响应 openId → 本地缓存（needUserInfo 首次已写入）→ 当前 state
      const openIdNext =
        result.openId ?? storage.get<string>(WX_OPENID_STORAGE_KEY) ?? openId
      if (!openIdNext) throw new Error('响应缺少 openId，无法继续授权')
      setOpenId(openIdNext)
      setNeedAuth(true)
      setLoading(false)
      return
    }
    if (!result.code || !result.userInfo) throw new Error('登录响应缺少凭证')
    console.log('[login-page] 登录完成，token 已落地')
    setNeedAuth(false)
    dispatch(setAuth({ token: result.code, userInfo: result.userInfo }))
    await reLaunch(ROUTES.HOME)
  }

  const handleWxLogin = async () => {
    if (loading) return
    setLoading(true)
    try {
      applyResult(await performWxLogin())
    } catch (e) {
      // code 失效/已用等场景：toast 后端 Message，用户重按按钮重新 Taro.login（code 一次性，重试安全）
      console.error('[login-page] performWxLogin 失败', e)
      toast.error(e instanceof Error && e.message ? e.message : '登录失败')
      setLoading(false)
    }
  }

  // needUserInfo：getUserInfo 授权用户资料（后端文档约定的授权接口）
  const handleAuthUserInfo = async () => {
    if (loading || !openId) return
    setLoading(true)
    try {
      applyResult(await completeUserInfoLogin(openId))
    } catch (e) {
      // 授权失败/取消：保留待授权态，用户可重试
      console.error('[login-page] completeUserInfoLogin 失败', e)
      toast.error(e instanceof Error && e.message ? e.message : '授权失败')
      setLoading(false)
    }
  }

  return (
    <View className={styles.page}>
      <View className={styles.hero}>
        <View className={styles.logo}>
          <Text className={styles.logoText}>智</Text>
        </View>
        <Text className={styles.productName}>智慧养老</Text>
        <Text className={styles.slogan}>一起守护家人</Text>
      </View>
      <View className={styles.form}>
        <View
          className={styles.submit}
          onClick={needAuth ? handleAuthUserInfo : handleWxLogin}
        >
          <Text className={styles.submitText}>
            {loading ? '登录中...' : needAuth ? '授权用户信息，继续' : '微信一键登录'}
          </Text>
        </View>
      </View>
    </View>
  )
}