import React, { useState, useEffect, useCallback } from 'react'
import { View, Text, ScrollView } from '@tarojs/components'
import Taro from '@tarojs/taro'
import { pageShopUserCoupon, removeShopUserCoupon } from '@/api/shop/shopUserCoupon'
import type { ShopUserCoupon, ShopUserCouponParam } from '@/api/shop/shopUserCoupon/model'
import CouponCard from '@/components/business/CouponCard'
import EmptyState from '@/components/common/EmptyState'
import LoadMore from '@/components/common/LoadMore'

definePageConfig({
  navigationBarTitleText: '我的优惠券',
})

// Tab 配置
type CouponTab = 'available' | 'used' | 'expired'

const tabList: { title: string; key: CouponTab }[] = [
  { title: '未使用', key: 'available' },
  { title: '已使用', key: 'used' },
  { title: '已过期', key: 'expired' },
]

interface TabState {
  coupons: ShopUserCoupon[]
  page: number
  finished: boolean
  loading: boolean
  initialized: boolean
}

const CouponListPage: React.FC = () => {
  // 根据 URL 参数初始化 tab
  const { tab: initTab } = Taro.getCurrentInstance().router?.params || {}
  const getInitTabIndex = () => {
    switch (initTab) {
      case 'used': return 1
      case 'expired': return 2
      default: return 0
    }
  }
  const [tabIndex, setTabIndex] = useState(getInitTabIndex())

  // 每个 tab 独立维护状态
  const [tabStates, setTabStates] = useState<TabState[]>(
    tabList.map(() => ({
      coupons: [],
      page: 1,
      finished: false,
      loading: false,
      initialized: false,
    }))
  )

  const currentState = tabStates[tabIndex]

  const updateTabState = useCallback(
    (index: number, partial: Partial<TabState>) => {
      setTabStates(prev => {
        const next = [...prev]
        next[index] = { ...next[index], ...partial }
        return next
      })
    },
    []
  )

  const loadCoupons = useCallback(
    async (targetIndex: number, p: number) => {
      const state = tabStates[targetIndex]
      if (state.loading) return

      updateTabState(targetIndex, { loading: true })

      try {
        const tabKey = tabList[targetIndex].key
        const params: ShopUserCouponParam = { page: p, limit: 10 }

        // 根据 tab 设置筛选条件
        // status: 0=未使用, 1=已使用, 2=已过期
        switch (tabKey) {
          case 'available':
            params.status = 0
            break
          case 'used':
            params.status = 1
            break
          case 'expired':
            params.status = 2
            break
        }

        const res = await pageShopUserCoupon(params)
        const list = res?.list || []

        updateTabState(targetIndex, {
          coupons: p === 1 ? list : [...state.coupons, ...list],
          page: p,
          finished: list.length < 10,
          loading: false,
          initialized: true,
        })
      } catch {
        updateTabState(targetIndex, { loading: false, initialized: true })
      }
    },
    [tabStates, updateTabState]
  )

  // 切换 tab 时加载数据
  useEffect(() => {
    if (!tabStates[tabIndex].initialized) {
      loadCoupons(tabIndex, 1)
    }
  }, [tabIndex])

  // 加载更多
  const handleLoadMore = () => {
    if (!currentState.finished && !currentState.loading) {
      loadCoupons(tabIndex, currentState.page + 1)
    }
  }

  // 切换 tab
  const handleTabChange = (index: number) => {
    if (index !== tabIndex) {
      setTabIndex(index)
    }
  }

  // 删除优惠券
  const handleDelete = (id: string) => {
    Taro.showModal({
      title: '提示',
      content: '确定要删除该优惠券吗？',
      confirmColor: '#0e932e',
      success: async (res) => {
        if (res.confirm) {
          try {
            await removeShopUserCoupon(Number(id))
            // 从当前 tab 移除
            updateTabState(tabIndex, {
              coupons: tabStates[tabIndex].coupons.filter(c => c.id !== id)
            })
            Taro.showToast({ title: '删除成功', icon: 'success' })
          } catch {
            Taro.showToast({ title: '删除失败', icon: 'none' })
          }
        }
      }
    })
  }

  // 获取空状态文本
  const getEmptyText = () => {
    switch (tabList[tabIndex].key) {
      case 'available': return '暂无可用优惠券'
      case 'used': return '暂无已使用优惠券'
      case 'expired': return '暂无已过期优惠券'
    }
  }

  // 获取空状态操作
  const getEmptyAction = () => {
    if (tabList[tabIndex].key === 'available') {
      return {
        text: '去领取',
        action: () => Taro.switchTab({ url: '/pages/index/index' })
      }
    }
    return null
  }

  // 判断是否禁用
  const isDisabled = () => {
    const key = tabList[tabIndex].key
    return key === 'used' || key === 'expired'
  }

  return (
    <View className='min-h-screen bg-gray-50 flex flex-col'>
      {/* 自定义 Tabs 标题栏 */}
      <View className='bg-white flex flex-row items-center border-b border-gray-100'>
        {tabList.map((tab, index) => (
          <View
            key={tab.key}
            className='flex-1 flex flex-col items-center justify-center py-3'
            onClick={() => handleTabChange(index)}
          >
            <Text
              className='text-sm font-medium'
              style={{
                color: index === tabIndex ? '#ee0a24' : '#666',
              }}
            >
              {tab.title}
            </Text>
            {index === tabIndex && (
              <View
                className='mt-1 rounded-full'
                style={{
                  width: '20px',
                  height: '3px',
                  backgroundColor: '#ee0a24',
                }}
              />
            )}
          </View>
        ))}
      </View>

      {/* 内容区域 - 每个 tab 独立渲染 */}
      <View className='flex-1 relative'>
        {tabList.map((tab, idx) => (
          <View
            key={tab.key}
            className='absolute inset-0'
            style={{
              display: idx === tabIndex ? 'flex' : 'none',
              flexDirection: 'column',
            }}
          >
            <ScrollView
              scrollY
              className='flex-1'
              onScrollToLower={handleLoadMore}
              lowerThreshold={100}
            >
              <View className='p-3'>
                {tabStates[idx].coupons.length > 0 ? (
                  tabStates[idx].coupons.map(coupon => (
                    <CouponCard
                      key={coupon.id}
                      coupon={coupon}
                      disabled={isDisabled()}
                      showDelete={isDisabled()}
                      onDelete={() => handleDelete(coupon.id!)}
                    />
                  ))
                ) : tabStates[idx].initialized && !tabStates[idx].loading ? (
                  <EmptyState
                    text={getEmptyText()}
                    actionText={getEmptyAction()?.text}
                    onAction={getEmptyAction()?.action}
                  />
                ) : null}
                <LoadMore
                  loading={tabStates[idx].loading}
                  finished={tabStates[idx].finished}
                />
              </View>
            </ScrollView>
          </View>
        ))}
      </View>
    </View>
  )
}

export default CouponListPage