import { nextTick, ref } from 'vue'
import { initialMessages, prompts } from '../data/requests.js'

export function useChat(activeView) {
  const messages = ref([...initialMessages])
  const draft = ref('')
  const uploadedFiles = ref([])
  const messageList = ref(null)
  const activeCase = ref(null)

  function agentReply(text) {
    const c = activeCase.value
    if (!c) return '建议先核对政策阈值和附件完整性，再决定通过、退回补件或转人工复核。'
    if (text.includes('审批')) return `${c.id} 建议审批意见：发票验真通过，费用归属与预算中心匹配；${c.risk} 已触发规则提示，建议保留业务说明后通过。`
    if (text.includes('补件')) return '补件优先级：业务目的说明、行程或客户名单、直属经理确认记录。'
    if (text.includes('拦截')) return `拦截原因是 ${c.risk}，该风险需要财务复核并留下制度依据。`
    if (text.includes('审计')) return `审计摘要：${c.person} 提交 ${c.amount} 报销，命中 ${c.risk}，系统已保留 AI 判断。`
    return '建议先核对政策阈值和附件完整性，再决定通过、退回补件或转人工复核。'
  }

  function scrollToBottom() {
    nextTick(() => messageList.value?.scrollTo({ top: messageList.value.scrollHeight, behavior: 'smooth' }))
  }

  function sendMessage() {
    const text = draft.value.trim()
    if (!text) return false
    messages.value.push({ id: Date.now(), role: 'user', text })
    draft.value = ''
    setTimeout(() => {
      messages.value.push({ id: Date.now() + 1, role: 'agent', text: agentReply(text) })
      scrollToBottom()
    }, 260)
    return true
  }

  function handleUpload(event) {
    uploadedFiles.value = Array.from(event.target.files ?? []).map((file) => ({
      name: file.name,
      size: file.size
    }))
    if (uploadedFiles.value.length) {
      const names = uploadedFiles.value.map((file) => file.name).join('、')
      messages.value.push({
        id: Date.now(),
        role: 'agent',
        text: `已接收 ${uploadedFiles.value.length} 个附件：${names}。我会优先核对发票验真、费用标准、预算归属和必备审批材料。`
      })
      scrollToBottom()
    }
  }

  function openChat(request) {
    activeCase.value = request
    activeView.value = 'chat'
    nextTick(() => messageList.value?.scrollTo({ top: messageList.value.scrollHeight }))
  }

  return {
    messages, draft, uploadedFiles, messageList, activeCase, prompts,
    sendMessage, handleUpload, openChat, scrollToBottom
  }
}