import React, { useEffect, useState, useCallback, useRef } from 'react'
import { View, Text, Button, Input, ScrollView } from '@tarojs/components'
import Taro, { useReachBottom } from '@tarojs/taro'
import NavBar from '@/components/NavBar'
import LoadMore from '@/components/common/LoadMore'
import EmptyState from '@/components/common/EmptyState'
import { pageShopChatConversation, addShopChatConversation } from '@/api/shop/shopChatConversation'
import { pageShopChatMessage, addShopChatMessage } from '@/api/shop/shopChatMessage'
import type { ShopChatConversation, ShopChatConversationParam } from '@/api/shop/shopChatConversation/model'
import type { ShopChatMessage } from '@/api/shop/shopChatMessage/model'
import type { PageResult } from '@/api'

definePageConfig({
  navigationBarTitleText: '在线客服',
})

const SERVICE_ONLINE_HOURS = '9:00-21:00'
const SERVICE_HOTLINE = '400-888-8888'
const SERVICE_WECHAT = 'shop_service'

const CustomerServicePage: React.FC = () => {
  const [conversations, setConversations] = useState<ShopChatConversation[]>([])
  const [currentConversation, setCurrentConversation] = useState<ShopChatConversation | null>(null)
  const [messages, setMessages] = useState<ShopChatMessage[]>([])
  const [inputMessage, setInputMessage] = useState('')
  const [loading, setLoading] = useState(true)
  const [sending, setSending] = useState(false)
  const [loadingMore, setLoadingMore] = useState(false)
  const [hasMore, setHasMore] = useState(true)
  const [msgPage, setMsgPage] = useState(1)
  const [showHistory, setShowHistory] = useState(false)
  const scrollToBottom = useRef(false)

  const isOnline = () => {
    const now = new Date()
    const h = now.getHours()
    return h >= 9 && h < 21
  }

  // 加载会话列表
  const loadConversations = useCallback(async () => {
    setLoading(true)
    try {
      const params: ShopChatConversationParam = {
        page: 1,
        limit: 20,
        order: 'desc',
        sort: 'updateTime',
      }
      const result: PageResult<ShopChatConversation> = await pageShopChatConversation(params)
      if (result?.list) {
        setConversations(result.list)
        if (result.list.length > 0) {
          const latest = result.list[0]
          setCurrentConversation(latest)
          loadMessages(latest.id!, 1, false)
        }
      }
    } catch (e) {
      console.error('获取会话列表失败:', e)
      setConversations([])
    } finally {
      setLoading(false)
    }
  }, [])

  // 加载消息列表
  const loadMessages = useCallback(async (conversationId: number, pageNum: number = 1, isLoadMore = false) => {
    if (isLoadMore) setLoadingMore(true)
    try {
      const result = await pageShopChatMessage({
        conversationId,
        page: pageNum,
        limit: 20,
        order: 'asc',
        sort: 'createTime',
      } as any)
      if (result?.list) {
        if (isLoadMore) {
          setMessages(prev => [...result.list!, ...prev])
        } else {
          setMessages(result.list)
          scrollToBottom.current = true
        }
        setHasMore((result.list.length ?? 0) >= 20)
        setMsgPage(pageNum)
      }
    } catch (e) {
      console.error('获取消息列表失败:', e)
      if (!isLoadMore) setMessages([])
    } finally {
      setLoadingMore(false)
    }
  }, [])

  useEffect(() => {
    loadConversations()
  }, [loadConversations])

  useReachBottom(() => {
    if (hasMore && currentConversation && !loadingMore) {
      loadMessages(currentConversation.id!, msgPage + 1, true)
    }
  })

  // 创建新会话
  const ensureConversation = async (): Promise<ShopChatConversation | null> => {
    if (currentConversation) return currentConversation
    try {
      await addShopChatConversation({ type: 0 })
      // 重新拉取会话列表获取新会话
      const result = await pageShopChatConversation({ page: 1, limit: 20, order: 'desc', sort: 'updateTime' })
      if (result?.list && result.list.length > 0) {
        const conv = result.list[0]
        setConversations(result.list)
        setCurrentConversation(conv)
        return conv
      }
    } catch (e) {
      console.error('创建会话失败:', e)
    }
    return null
  }

  // 发送消息
  const handleSendMessage = async () => {
    const text = inputMessage.trim()
    if (!text) {
      Taro.showToast({ title: '请输入消息内容', icon: 'none' })
      return
    }

    setSending(true)
    setInputMessage('')
    try {
      const conv = await ensureConversation()
      if (!conv?.id) {
        Taro.showToast({ title: '无法创建会话，请稍后重试', icon: 'none' })
        setInputMessage(text)
        return
      }

      await addShopChatMessage({
        content: text,
        type: 'text',
        toUserId: 0, // 发送给客服（服务端路由）
      } as any)

      // 消息发送成功后刷新消息列表
      await loadMessages(conv.id, 1, false)

      // 同步更新会话列表 lastMessage
      setConversations(prev => prev.map(c =>
        c.id === conv.id ? { ...c, lastMessage: text, updateTime: new Date().toISOString() } : c
      ))
    } catch (e: any) {
      console.error('发送消息失败:', e)
      setInputMessage(text)
      Taro.showToast({ title: e?.message || '发送失败，请重试', icon: 'none' })
    } finally {
      setSending(false)
    }
  }

  // 拨打热线
  const handleCallHotline = () => {
    Taro.makePhoneCall({ phoneNumber: SERVICE_HOTLINE })
  }

  // 复制微信号
  const handleCopyWechat = () => {
    Taro.setClipboardData({
      data: SERVICE_WECHAT,
      success: () => Taro.showToast({ title: '已复制微信号', icon: 'success' }),
    })
  }

  // 跳转帮助中心
  const handleGoToHelp = () => {
    Taro.navigateTo({ url: '/pages/user/help-center' })
  }

  // 选择会话
  const handleSelectConversation = (conv: ShopChatConversation) => {
    setCurrentConversation(conv)
    setMessages([])
    setMsgPage(1)
    setHasMore(true)
    loadMessages(conv.id!, 1, false)
  }

  const formatTime = (timeStr?: string) => {
    if (!timeStr) return ''
    const date = new Date(timeStr)
    const m = String(date.getMonth() + 1).padStart(2, '0')
    const d = String(date.getDate()).padStart(2, '0')
    const h = String(date.getHours()).padStart(2, '0')
    const min = String(date.getMinutes()).padStart(2, '0')
    return `${m}-${d} ${h}:${min}`
  }

  const online = isOnline()

  return (
    <View className="flex flex-col min-h-screen bg-gray-100">
      <NavBar title="在线客服" />

      <ScrollView scrollY className="flex-1">
        {/* 客服状态栏 */}
        <View className="bg-white px-4 py-3 flex items-center justify-between">
          <View className="flex items-center gap-2">
            <View
              className="w-2 h-2 rounded-full"
              style={{ backgroundColor: online ? '#52c41a' : '#d1d5db' }}
            />
            <Text className="text-sm text-gray-700">{online ? '客服在线' : '客服离线'}</Text>
          </View>
          <Text className="text-xs text-gray-400">服务时间: {SERVICE_ONLINE_HOURS}</Text>
        </View>

        {/* 微信在线客服按钮 */}
        <View className="px-4 py-3 bg-white border-t border-gray-50">
          <Button
            openType="contact"
            className="w-full h-12 rounded-lg text-white font-medium text-base border-0"
            style={{ backgroundColor: '#07c160', lineHeight: '48px' }}
          >
            微信在线客服
          </Button>
        </View>

        {/* 消息记录入口 */}
        {!showHistory && (
          <View className="bg-white mx-4 mt-4 p-4 rounded-lg">
            <View
              className="flex items-center justify-between"
              onClick={() => setShowHistory(true)}
            >
              <View className="flex items-center gap-2">
                <Text className="text-lg">💬</Text>
                <Text className="text-sm text-gray-700">
                  历史消息记录 {conversations.length > 0 ? `（${conversations.length}条会话）` : ''}
                </Text>
              </View>
              <Text className="text-gray-400 text-sm">→</Text>
            </View>
          </View>
        )}

        {/* 历史会话与消息列表 */}
        {showHistory && (
          <View className="mx-4 mt-4">
            <View className="flex items-center justify-between mb-2">
              <Text className="text-sm font-medium text-gray-700">历史会话</Text>
              <Text
                className="text-sm"
                style={{ color: '#3b82f6' }}
                onClick={() => setShowHistory(false)}
              >
                收起
              </Text>
            </View>

            {loading ? (
              <LoadMore loading />
            ) : conversations.length === 0 ? (
              <EmptyState message="暂无历史会话" small />
            ) : (
              <View>
                {conversations.map(conv => (
                  <View
                    key={conv.id}
                    className="bg-white p-3 rounded-lg mb-2"
                    style={{ border: currentConversation?.id === conv.id ? '2px solid #10b981' : 'none' }}
                    onClick={() => handleSelectConversation(conv)}
                  >
                    <View className="flex justify-between items-center">
                      <Text className="text-sm text-gray-700" style={{ flex: 1, overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap' }}>
                        {conv.content || conv.lastMessage || '暂无消息'}
                      </Text>
                      <Text className="text-xs text-gray-400 ml-2">{formatTime(conv.updateTime)}</Text>
                    </View>
                  </View>
                ))}
              </View>
            )}

            {/* 当前会话的消息 */}
            {currentConversation && messages.length > 0 && (
              <View className="bg-white rounded-lg p-3 mb-4">
                <Text className="text-xs text-gray-400 mb-3 block">消息记录</Text>
                {loadingMore && <LoadMore loading />}
                {messages.map(msg => (
                  <View
                    key={msg.id}
                    className={`flex mb-3 ${msg.formUserId === currentConversation.userId ? 'justify-end' : 'justify-start'}`}
                  >
                    <View
                      className="px-3 py-2 rounded-lg max-w-xs"
                      style={{
                        backgroundColor: msg.formUserId === currentConversation.userId ? '#10b981' : '#f3f4f6',
                        maxWidth: '70%',
                      }}
                    >
                      <Text
                        className="text-sm"
                        style={{ color: msg.formUserId === currentConversation.userId ? '#fff' : '#374151' }}
                      >
                        {msg.content}
                      </Text>
                      <Text
                        className="text-xs block mt-1"
                        style={{ color: msg.formUserId === currentConversation.userId ? 'rgba(255,255,255,0.7)' : '#9ca3af' }}
                      >
                        {formatTime(msg.createTime)}
                      </Text>
                    </View>
                  </View>
                ))}
              </View>
            )}
          </View>
        )}

        {/* 其他联系方式 */}
        <View className="bg-white mx-4 mt-4 p-4 rounded-lg">
          <Text className="text-base font-medium text-gray-800 mb-3 block">其他联系方式</Text>
          <View
            className="flex items-center justify-between py-3 border-b border-gray-50"
            onClick={handleCallHotline}
          >
            <View className="flex items-center gap-2">
              <Text className="text-lg">📞</Text>
              <View>
                <Text className="text-sm text-gray-700 block">客服热线</Text>
                <Text className="text-xs text-gray-400">{SERVICE_HOTLINE}</Text>
              </View>
            </View>
            <Text className="text-xs" style={{ color: '#3b82f6' }}>拨打</Text>
          </View>
          <View
            className="flex items-center justify-between py-3"
            onClick={handleCopyWechat}
          >
            <View className="flex items-center gap-2">
              <Text className="text-lg">💬</Text>
              <View>
                <Text className="text-sm text-gray-700 block">微信号</Text>
                <Text className="text-xs text-gray-400">{SERVICE_WECHAT}</Text>
              </View>
            </View>
            <Text className="text-xs" style={{ color: '#3b82f6' }}>复制</Text>
          </View>
        </View>

        {/* 帮助中心入口 */}
        <View className="bg-white mx-4 mt-4 p-4 rounded-lg mb-4">
          <Text className="text-base font-medium text-gray-800 mb-3 block">常见问题</Text>
          <View
            className="flex items-center justify-between py-2"
            onClick={handleGoToHelp}
          >
            <Text className="text-sm text-gray-700">查看帮助中心</Text>
            <Text className="text-gray-400 text-sm">→</Text>
          </View>
        </View>

        {/* 留言（离线时） */}
        {!online && (
          <View className="bg-white mx-4 mb-4 p-4 rounded-lg">
            <Text className="text-base font-medium text-gray-800 mb-3 block">离线留言</Text>
            <Text className="text-sm text-gray-400 block">
              客服暂时不在线，可在下方输入框留言，客服上线后会尽快回复您。
            </Text>
          </View>
        )}
      </ScrollView>

      {/* 消息输入区 - 始终显示，支持发送留言 */}
      <View className="bg-white border-t border-gray-200 px-4 py-3 flex items-center gap-2">
        <Input
          className="flex-1 border border-gray-200 rounded-full text-sm"
          style={{ paddingLeft: '16px', paddingRight: '16px', height: '40px', lineHeight: '40px' }}
          placeholder={online ? '输入消息...' : '留言给客服...'}
          value={inputMessage}
          onInput={(e: any) => setInputMessage(e.detail.value)}
          onConfirm={handleSendMessage}
          disabled={sending}
        />
        <View
          className="rounded-full flex items-center justify-center"
          style={{
            width: '72px',
            height: '40px',
            backgroundColor: sending ? '#d1d5db' : '#10b981',
          }}
          onClick={sending ? undefined : handleSendMessage}
        >
          <Text className="text-sm text-white">{sending ? '发送中' : '发送'}</Text>
        </View>
      </View>
    </View>
  )
}

export default CustomerServicePage