import { useState, useMemo, useCallback, useRef, useEffect } from 'react'
import Taro, { useDidShow } from '@tarojs/taro'
import { View, Text, ScrollView, Input } from '@tarojs/components'
import { Icon } from '@antmjs/vantui'
import { chatList } from '@/mock/messages'
import { conversations } from '@/mock/conversations'
import type { ChatMessage } from '@/mock/conversations'
import './index.less'

/** 角色标签映射 */
const ROLE_LABEL: Record<string, string> = {
  rider: '骑手',
  merchant: '商家',
  user: '同学',
}

function getStatusBarH(): number {
  try { return Taro.getSystemInfoSync().statusBarHeight || 20 }
  catch { return 20 }
}

function getSafeBottom(): number {
  try {
    const info = Taro.getSystemInfoSync()
    return (info.screenHeight - info.safeArea!.bottom) || 0
  } catch { return 0 }
}

export default function ChatPage() {
  const id = String(Taro.getCurrentInstance().router?.params?.id || '')

  /* ---- 查找聊天对象 ---- */
  const partner = useMemo(() => chatList.find((c) => c.id === id), [id])

  /* ---- 对话消息 ---- */
  const [messages, setMessages] = useState<ChatMessage[]>([])
  const [inputValue, setInputValue] = useState('')

  const statusBarH = useMemo(getStatusBarH, [])
  const safeBottom = useMemo(getSafeBottom, [])

  // 初始化消息
  useDidShow(() => {
    if (id && conversations[id]) {
      setMessages(conversations[id])
    }
  })

  /* ---- 事件 ---- */
  const handleBack = useCallback(() => {
    Taro.navigateBack()
  }, [])

  const handleSend = useCallback(() => {
    const text = inputValue.trim()
    if (!text) return

    const now = new Date()
    const time = `${String(now.getHours()).padStart(2, '0')}:${String(now.getMinutes()).padStart(2, '0')}`

    const newMsg: ChatMessage = {
      id: `m${Date.now()}`,
      sender: 'me',
      content: text,
      time,
    }

    setMessages((prev) => [...prev, newMsg])
    setInputValue('')

    // 模拟对方自动回复（1.5 秒后）
    if (partner) {
      setTimeout(() => {
        const autoReply: ChatMessage = {
          id: `m${Date.now() + 1}`,
          sender: 'other',
          content: '好的，收到你的消息了～',
          time: `${String(now.getHours()).padStart(2, '0')}:${String(now.getMinutes() + 1).padStart(2, '0')}`,
        }
        setMessages((prev) => [...prev, autoReply])
      }, 1500)
    }
  }, [inputValue, partner])

  if (!partner) {
    return (
      <View className='chat-page'>
        <View className='chat-nav' style={{ paddingTop: `${statusBarH}px` }}>
          <View className='nav-content'>
            <View className='nav-back' onClick={handleBack}>
              <Icon name='arrow-left' size={22} color='#323233' />
            </View>
            <View className='nav-info'>
              <Text className='nav-name'>未知用户</Text>
            </View>
            <View className='nav-placeholder' />
          </View>
        </View>
        <View style={{ height: `${statusBarH + 44}px` }} />
        <View style={{ display: 'flex', alignItems: 'center', justifyContent: 'center', flex: 1 }}>
          <Text style={{ color: '#969799', fontSize: '30px' }}>对话不存在</Text>
        </View>
      </View>
    )
  }

  const roleLabel = partner.role ? ROLE_LABEL[partner.role] : ''

  return (
    <View className='chat-page'>
      {/* ===== 导航栏 ===== */}
      <View className='chat-nav' style={{ paddingTop: `${statusBarH}px` }}>
        <View className='nav-content'>
          <View className='nav-back' onClick={handleBack}>
            <Icon name='arrow-left' size={22} color='#323233' />
          </View>
          <View className='nav-info'>
            <Text className='nav-name'>{partner.name}</Text>
            {roleLabel && <Text className='nav-role'>{roleLabel}</Text>}
          </View>
          <View className='nav-placeholder' />
        </View>
      </View>
      <View style={{ height: `${statusBarH + 44}px` }} />

      {/* ===== 消息列表 ===== */}
      <ScrollView
        className='chat-scroll'
        scrollY
        enhanced
        showScrollbar={false}
        scrollTop={99999}
        scrollWithAnimation
      >
        <View className='message-list'>
          {messages.map((msg) => (
            <View
              key={msg.id}
              className={`message-item ${msg.sender === 'me' ? 'sent' : 'received'}`}
            >
              <Text className='bubble'>{msg.content}</Text>
              <Text className='msg-time'>{msg.time}</Text>
            </View>
          ))}
        </View>
        <View className='scroll-bottom-safe' />
      </ScrollView>

      {/* ===== 底部输入栏 ===== */}
      <View className='chat-input-bar' style={{ paddingBottom: `${safeBottom}px` }}>
        <View className='input-wrap'>
          <Input
            className='chat-input'
            value={inputValue}
            placeholder='输入消息...'
            placeholderStyle='color: #c8c9cc;'
            onInput={(e) => setInputValue(String(e.detail.value))}
            confirmType='send'
            onConfirm={handleSend}
          />
        </View>
        <View className='send-btn' onClick={handleSend}>
          <Text className='send-text'>发送</Text>
        </View>
      </View>
    </View>
  )
}