import { useCallback, useMemo, useRef, useState } from 'react'
import Taro, { useDidShow, useReachBottom } from '@tarojs/taro'
import { View, Text, Image } from '@tarojs/components'
import { Grid, GridItem, Icon, Search, Swiper, SwiperItem } from '@antmjs/vantui'
import useCartStore from '@/stores/cart/useCartStore'
import { getHomeConfigApi } from '@/services/home'
import type { HomeConfig } from '@/services/home'
import { getSpecialListApi, normalizeSpecialCart } from '@/services/special'
import { getProductCover } from '@/types/product'
import type { Product, ProductCartPatch } from '@/types/product'
import { getToken } from '@/utils/request'
import CartBall from '@/components/CartBall'
import CartStepper from '@/components/CartStepper'
import {formatRetailPrice, formatSpec} from '@/utils/format'
import './index.less'
import CustomTabBar from "@/components/CustomTabBar";

/** 首页 → 商品页的本地存储传参 key（switchTab 无法带参） */
const PENDING_CATEGORY_KEY = 'product_category_id'
const PENDING_KEYWORD_KEY = 'product_keyword'

/** 特价推荐每页条数 */
const SPECIAL_PAGE_SIZE = 10

/** tabBar 页面路径（link 跳转需改用 switchTab） */
const TAB_PATHS = [
  'pages/index/index',
  'pages/product/index',
  'pages/cart/index',
  'pages/message/index',
  'pages/profile/index',
]

/** 宫格导航无图时的兜底色块配色（生鲜红橙系） */
const NAV_COLORS = ['#ee0a24', '#ff7a1a', '#07c160', '#1989fa', '#8a5cf6', '#ff976a', '#00b8d9', '#f56c6c']

/** 获取状态栏高度（H5 端为 0） */
function getStatusBarHeight(): number {
  try {
    const info = typeof Taro.getWindowInfo === 'function' ? Taro.getWindowInfo() : Taro.getSystemInfoSync()
    return info.statusBarHeight || 0
  } catch {
    return 0
  }
}

export default function IndexPage() {
  const addItem = useCartStore(s => s.addItem)
  const setSummary = useCartStore(s => s.setSummary)

  /** 首页配置（轮播图 / 宫格导航 / 促销卡片） */
  const [config, setConfig] = useState<HomeConfig>({ banners: [], navs: [], promos: [] })
  /** 特价推荐商品（后台「客户端配置 → 特价推荐」标记，价格为登录门店的等级价） */
  const [specials, setSpecials] = useState<Product[]>([])
  /** 特价推荐分页 */
  const [specialPage, setSpecialPage] = useState(1)
  const [specialHasMore, setSpecialHasMore] = useState(false)
  /** 加载更多中（首屏重置不展示，避免已渲染列表下方闪烁） */
  const [specialLoading, setSpecialLoading] = useState(false)
  /** 特价推荐请求序号（返回 tab 重置与上拉加载并发时，仅采用最后一次响应） */
  const specialSeqRef = useRef(0)
  /** 是否有「加载更多」请求进行中 */
  const specialLoadingRef = useRef(false)
  /** 搜索框输入 */
  const [keyword, setKeyword] = useState('')

  const statusBarHeight = useMemo(() => getStatusBarHeight(), [])

  useDidShow(() => {
    loadHomeConfig()
    loadSpecials(1, true)
  })

  /** 上拉加载更多特价推荐 */
  useReachBottom(() => {
    if (!specialHasMore) return
    loadSpecials(specialPage + 1, false)
  })

  /** 首页配置聚合数据（响应附带悬浮球汇总） */
  const loadHomeConfig = useCallback(async () => {
    try {
      const res = await getHomeConfigApi()
      setConfig(res.data)
      // 旧版本后端可能未返回 cart 块
      if (res.data.cart) setSummary(res.data.cart)
    } catch {
      // 错误已由 request 层 toast
    }
  }, [setSummary])

  /**
   * 特价推荐商品（reset 时回到第一页整体替换）。
   * 行结构与 /mini/product/list 一致；响应附带悬浮球汇总
   */
  const loadSpecials = useCallback(
    async (pageNum: number, reset: boolean) => {
      if (!reset && specialLoadingRef.current) return
      const seq = ++specialSeqRef.current
      specialLoadingRef.current = true
      if (!reset) setSpecialLoading(true)
      try {
        const res = await getSpecialListApi({ page: pageNum, pageSize: SPECIAL_PAGE_SIZE })
        if (seq !== specialSeqRef.current) return // 已有更新的请求，丢弃本次响应
        const { data, total, cart } = res.data
        setSpecials(prev => (reset ? data : [...prev, ...data]))
        setSpecialPage(pageNum)
        setSpecialHasMore(pageNum * SPECIAL_PAGE_SIZE < total)
        // 列表响应附带悬浮球汇总（旧版本后端可能未返回）
        const summary = normalizeSpecialCart(cart)
        if (summary) setSummary(summary)
      } catch {
        // 错误已由 request 层 toast
      } finally {
        if (seq === specialSeqRef.current) {
          specialLoadingRef.current = false
          setSpecialLoading(false)
        }
      }
    },
    [setSummary],
  )

  /**
   * 后台配置的 link 统一跳转：
   * - 空字符串不跳转
   * - tabBar 页面用 switchTab，其余用 navigateTo
   */
  const handleLink = useCallback((link: string) => {
    if (!link) return
    const path = link.split('?')[0].replace(/^\//, '')
    if (TAB_PATHS.includes(path)) {
      Taro.switchTab({ url: `/${path}` })
    } else {
      Taro.navigateTo({ url: link })
    }
  }, [])

  /** 跳转商品页并带上关键词 */
  const goProduct = useCallback((kw?: string) => {
    try {
      if (kw !== undefined) Taro.setStorageSync(PENDING_KEYWORD_KEY, kw)
      Taro.removeStorageSync(PENDING_CATEGORY_KEY)
    } catch {
      // noop
    }
    Taro.switchTab({ url: '/pages/product/index' })
  }, [])

  /** 跳转商品详情 */
  const goDetail = useCallback((id: number) => {
    Taro.navigateTo({ url: `/pages/product-detail/index?id=${id}` })
  }, [])

  /** 搜索框聚焦/提交 → 商品页搜索 */
  const handleSearchFocus = useCallback(() => {
    goProduct(keyword.trim())
  }, [goProduct, keyword])

  /** 行内加减购确认后回写特价商品项的购物车字段 */
  const handleRowSync = useCallback((productId: number, patch: ProductCartPatch) => {
    setSpecials(prev => prev.map(p => (p.id === productId ? { ...p, ...patch } : p)))
  }, [])

  /** 快捷加购（用返回的购物车行回写，卡片随即展示加减器） */
  const handleQuickAdd = useCallback(
    async (product: Product, e: any) => {
      e.stopPropagation()
      try {
        const res = await addItem(product.id, 1)
        handleRowSync(product.id, { cart_id: res.id, cart_quantity: res.quantity })
        Taro.showToast({ title: '已加入购物车', icon: 'success' })
      } catch {
        // 错误（未设等级价等）已由 request 层 toast
      }
    },
    [addItem, handleRowSync],
  )

  /** 无价格时点击：未登录引导登录，已登录但未设等级价提示原因 */
  const handlePriceGuide = useCallback((e: any) => {
    e.stopPropagation()
    if (getToken()) {
      Taro.showToast({ title: '该商品暂未设置等级价', icon: 'none' })
    } else {
      Taro.navigateTo({ url: '/pages/login/index' })
    }
  }, [])

  return (
    <View className='home-page'>
      {/* ========== 自定义顶部导航栏 ========== */}
      <View className='home-header' style={{ paddingTop: `${statusBarHeight}px` }}>
        <View className='home-header__bar'>
          <View className='home-header__brand'>
            <Text className='home-header__title'>鲜采直供</Text>
            <Text className='home-header__slogan'>产地直采 · 新鲜直达</Text>
          </View>
          <View className='home-header__notice' onClick={() => Taro.switchTab({ url: '/pages/message/index' })}>
            <Icon name='bell' size='44rpx' color='#ffffff' />
          </View>
        </View>
        <View className='home-header__search'>
          <Search
            value={keyword}
            placeholder='搜索商品名称/规格'
            shape='round'
            background='transparent'
            onChange={e => setKeyword(String(e.detail))}
            onFocus={handleSearchFocus}
            onSearch={handleSearchFocus}
          />
        </View>
      </View>

      {/* ========== 轮播图 ========== */}
      <View className='home-banner'>
        <Swiper
          className='home-banner__swiper'
          height='300rpx'
          autoPlay={3000}
          loop
          paginationVisible
          paginationColor='#ffffff'
        >
          {config.banners.length > 0 ? (
            config.banners.map(banner =>
              banner.image_url ? (
                <SwiperItem key={banner.id}>
                  <Image
                    className='home-banner__image'
                    src={banner.image_url}
                    mode='aspectFill'
                    onClick={() => handleLink(banner.link)}
                  />
                </SwiperItem>
              ) : null,
            )
          ) : (
            <SwiperItem>
              <View className='home-banner__placeholder'>
                <Text className='home-banner__placeholder-title'>新鲜直采</Text>
                <Text className='home-banner__placeholder-sub'>每日凌晨采货 · 天亮前到店</Text>
              </View>
            </SwiperItem>
          )}
        </Swiper>
      </View>

      {/* ========== 宫格导航（一行四个） ========== */}
      {config.navs.length > 0 && (
        <View className='home-menu'>
          <Grid columnNum={4} border={false} iconSize={88}>
            {config.navs.map((nav, idx) => (
              <GridItem
                key={nav.id}
                text={nav.name}
                onClick={() => handleLink(nav.link)}
                renderIcon={
                  nav.image_url ? (
                    <Image className='menu-icon__image' src={nav.image_url} mode='aspectFit' />
                  ) : (
                    <View className='menu-icon' style={{ background: NAV_COLORS[idx % NAV_COLORS.length] }}>
                      <Text className='menu-icon__text'>{nav.name.slice(0, 1)}</Text>
                    </View>
                  )
                }
              />
            ))}
          </Grid>
        </View>
      )}

      {/* ========== 促销推荐卡片 ========== */}
      {config.promos.length > 0 && (
        <View className='home-promo'>
          {config.promos.map(promo => (
            <View key={promo.id} className='promo-card' onClick={() => handleLink(promo.link)}>
              {promo.image_url && (
                <Image className='promo-card__bg' src={promo.image_url} mode='aspectFill' lazyLoad />
              )}
              {promo.title && <View className='promo-card__mask' />}
              <View className='promo-card__content'>
                <Text className='promo-card__title'>{promo.title}</Text>
                {promo.sub_title && <Text className='promo-card__sub'>{promo.sub_title}</Text>}
              </View>
            </View>
          ))}
        </View>
      )}

      {/* ========== 特价推荐 ========== */}
      <View className='home-recommend'>
        <View className='home-recommend__header'>
          <View className='home-recommend__title-wrap'>
            <View className='home-recommend__title-bar' />
            <Text className='home-recommend__title'>特价推荐</Text>
          </View>
          <Text className='home-recommend__more' onClick={() => goProduct()}>查看更多 ›</Text>
        </View>

        { specials.length === 0 ? (
          <View className='home-recommend__empty'>
            <Text className='home-recommend__empty-text'>暂无特价商品</Text>
          </View>
        ) : (
          <>
            <View className='product-grid'>
              {specials.map(product => (
                <View key={product.id} className='product-card' onClick={() => goDetail(product.id)}>
                  <Image
                    className='product-card__image'
                    src={getProductCover(product) || 'https://img.yzcdn.cn/vant/cat.jpeg'}
                    mode='aspectFill'
                    lazyLoad
                  />
                  <View className='product-card__info'>
                    <Text className='product-card__name'>{product.name}</Text>
                    <View className='product-card__spec'>
                      {formatSpec(product.spec, product.unit)}{'  '}
                      {product.price !== null && <>
                        单价：{formatRetailPrice(product.price, product.spec)} {product.price_unit}
                      </>}
                    </View>
                    <View className='product-card__bottom'>
                      {product.price !== null ? (
                        <Text className='product-card__price'>￥{product.price}</Text>
                      ) : (
                        <Text
                          className='product-card__price product-card__price--none'
                          onClick={handlePriceGuide}
                        >
                          登录后查看价格
                        </Text>
                      )}
                      {/* 已加购展示行内加减器，否则展示快捷加购按钮 */}
                      {Number(product.cart_quantity ?? 0) > 0 ? (
                        <CartStepper product={product} onSync={handleRowSync} />
                      ) : (
                        <View className='product-card__add' onClick={e => handleQuickAdd(product, e)}>
                          <Text className='product-card__add-icon'>＋</Text>
                        </View>
                      )}
                    </View>
                  </View>
                </View>
              ))}
            </View>
            {/* 加载更多状态 */}
            {specialLoading && (
              <View className='home-recommend__loading'>
                <Text className='home-recommend__loading-text'>加载中…</Text>
              </View>
            )}
            {!specialHasMore && specialPage > 1 && (
              <View className='home-recommend__loading'>
                <Text className='home-recommend__loading-text'>已加载全部特价商品</Text>
              </View>
            )}
          </>
        )}
      </View>

      {/* ========== 购物车悬浮球 ========== */}
      <CartBall />
      {process.env.TARO_ENV === 'h5' && <CustomTabBar />}
    </View>
  )
}