/**
 * Phase 2: 重构后的智能问答页面
 * 支持：通用对话、全文阅读、逐篇精读三种模式
 */

import { useState, useEffect } from 'react'
import { message as antdMessage } from 'antd'
import chatApi, { type GeneralMessage } from '../api/chatApi'
import { documentSelectionApi, documentApi } from '../api/knowledgeBaseApi'
import { useChatMode } from '../hooks/useChatMode'
import { useDeepReadState } from '../hooks/useDeepReadState'
import { ModeSelector } from '../components/chat/ModeSelector'
import { FullTextMode } from '../components/chat/FullTextMode'
import { DeepReadMode } from '../components/chat/DeepReadMode'
import { DocumentSelector } from '../components/chat/DocumentSelector'
import MessageList from '../components/chat/MessageList'
import MessageInput from '../components/chat/MessageInput'
import ModelSelector, { type ModelType } from '../components/chat/ModelSelector'
import { useKnowledgeBaseStore } from '../stores/useKnowledgeBaseStore'
import { ChatMessage } from '../types/chat'
import type { Document } from '../types/index'

const ChatPage = () => {
  const { knowledgeBases, fetchKnowledgeBases } = useKnowledgeBaseStore()
  
  // 聊天模式状态
  const {
    state: modeState,
    setBaseMode,
    selectKnowledgeBase,
    setKnowledgeBaseMode,
    loadFullTextMode,
    loadDeepReadMode,
  } = useChatMode()

  // 通用对话状态
  const [generalMessages, setGeneralMessages] = useState<GeneralMessage[]>([])
  const [selectedModel, setSelectedModel] = useState<ModelType>('deepseek-v3')
  const [sending, setSending] = useState(false)
  const [streamingContent, setStreamingContent] = useState('')
  const [currentConversationId, setCurrentConversationId] = useState<string>()

  // 逐篇精读状态
  const [deepReadState, setDeepReadState] = useState<ReturnType<typeof useDeepReadState> | null>(null)
  const [showDocSelector, setShowDocSelector] = useState(false)
  const [allDocuments, setAllDocuments] = useState<Document[]>([])

  // 加载知识库列表
  useEffect(() => {
    fetchKnowledgeBases()
  }, [fetchKnowledgeBases])

  // 当选择知识库时，加载文档选择结果（全文阅读模式）
  useEffect(() => {
    if (modeState.selectedKbId && modeState.kbMode === 'full_text') {
      loadFullTextData()
    }
  }, [modeState.selectedKbId, modeState.kbMode])

  // 当切换到逐篇精读模式时，显示文献选择器
  useEffect(() => {
    if (modeState.selectedKbId && modeState.kbMode === 'deep_read' && !modeState.deepReadState) {
      loadDocumentsForSelection()
    }
  }, [modeState.selectedKbId, modeState.kbMode])

  // 加载全文阅读模式数据
  const loadFullTextData = async () => {
    if (!modeState.selectedKbId) return

    try {
      const result = await documentSelectionApi.getSelection(modeState.selectedKbId)
      
      loadFullTextMode({
        loadedDocs: result.selectedDocuments || [],
        totalFiles: result.limits.maxFiles,
        selectedFiles: result.selection.selectedCount,
        totalTokens: result.limits.maxTokens,
        usedTokens: result.selection.selectedTokens,
        availableTokens: result.selection.availableTokens,
        reason: result.selection.reason,
      })
    } catch (error) {
      console.error('Failed to load document selection:', error)
      antdMessage.error('加载文档选择失败')
    }
  }

  // 加载文献列表供选择
  const loadDocumentsForSelection = async () => {
    if (!modeState.selectedKbId) return

    try {
      const result = await documentSelectionApi.getSelection(modeState.selectedKbId)
      setAllDocuments(result.selectedDocuments || [])
      setShowDocSelector(true)
    } catch (error) {
      console.error('Failed to load documents:', error)
      antdMessage.error('加载文献列表失败')
    }
  }

  // 确认文献选择（逐篇精读模式）
  const handleConfirmDocSelection = (selectedDocs: Document[]) => {
    const deepRead = useDeepReadState(selectedDocs)
    setDeepReadState(deepRead as any)
    
    loadDeepReadMode({
      selectedDocs,
      currentDocId: selectedDocs[0].id,
      conversationPerDoc: new Map(selectedDocs.map(doc => [doc.id, []])),
      totalTokens: selectedDocs.reduce((sum, doc) => sum + (doc.tokensCount || 0), 0),
    })
    
    setShowDocSelector(false)
  }

  // 发送消息（通用对话）
  const handleSendGeneralMessage = async (content: string, knowledgeBaseIds: string[]) => {
    if (sending) return

    setSending(true)
    setStreamingContent('')

    const userMessage: GeneralMessage = {
      id: `temp-${Date.now()}`,
      conversationId: currentConversationId || 'temp',
      role: 'user',
      content,
      createdAt: new Date().toISOString(),
    }
    setGeneralMessages(prev => [...prev, userMessage])

    try {
      let fullContent = ''

      await chatApi.sendMessageStream(
        {
          content,
          modelType: selectedModel,
          knowledgeBaseIds,
          conversationId: currentConversationId,
        },
        (chunk) => {
          fullContent += chunk
          setStreamingContent(fullContent)
        },
        (conversationId) => {
          if (!currentConversationId && conversationId) {
            setCurrentConversationId(conversationId)
          }

          const assistantMessage: GeneralMessage = {
            id: `temp-assistant-${Date.now()}`,
            conversationId: conversationId || currentConversationId || 'temp',
            role: 'assistant',
            content: fullContent,
            model: selectedModel,
            createdAt: new Date().toISOString(),
          }
          setGeneralMessages(prev => [...prev, assistantMessage])
          setStreamingContent('')
          setSending(false)
        },
        (error) => {
          console.error('Send failed:', error)
          antdMessage.error('发送消息失败：' + error.message)
          setStreamingContent('')
          setSending(false)
        }
      )
    } catch (err) {
      console.error('Send message exception:', err)
      antdMessage.error('发送消息失败')
      setStreamingContent('')
      setSending(false)
    }
  }

  // 发送消息（逐篇精读模式）
  const handleSendDeepReadMessage = async (content: string) => {
    if (!deepReadState || !deepReadState.currentDoc) return

    setSending(true)
    
    // 添加用户消息
    const userMsg: ChatMessage = {
      id: `temp-${Date.now()}`,
      role: 'user',
      content,
      timestamp: new Date(),
    }
    deepReadState.addMessage(userMsg)

    try {
      // TODO: 调用实际的API（支持documentIds参数）
      // 当前先使用通用API
      let fullContent = ''
      
      await chatApi.sendMessageStream(
        {
          content: `[当前文献: ${deepReadState.currentDoc.filename}]\n\n${content}`,
          modelType: selectedModel,
          knowledgeBaseIds: modeState.selectedKbId ? [modeState.selectedKbId] : [],
        },
        (chunk) => {
          fullContent += chunk
          setStreamingContent(fullContent)
        },
        () => {
          const assistantMsg: ChatMessage = {
            id: `temp-assistant-${Date.now()}`,
            role: 'assistant',
            content: fullContent,
            timestamp: new Date(),
          }
          deepReadState.addMessage(assistantMsg)
          setStreamingContent('')
          setSending(false)
        },
        (error) => {
          console.error('Send failed:', error)
          antdMessage.error('发送消息失败')
          setStreamingContent('')
          setSending(false)
        }
      )
    } catch (error) {
      console.error('Send error:', error)
      antdMessage.error('发送消息失败')
      setSending(false)
    }
  }

  // 渲染内容区域
  const renderContent = () => {
    const kb = knowledgeBases.find(k => k.id === modeState.selectedKbId)
    const kbName = kb?.name || '未选择'

    // 通用对话模式
    if (modeState.baseMode === 'general') {
      return (
        <div style={{ flex: 1, display: 'flex', flexDirection: 'column', overflow: 'hidden' }}>
          <div style={{ flex: 1, display: 'flex', flexDirection: 'column', minHeight: 0, overflow: 'hidden' }}>
            {generalMessages.length === 0 && !sending ? (
              <div style={{ 
                flex: 1, 
                display: 'flex', 
                alignItems: 'center', 
                justifyContent: 'center', 
                background: '#fafafa' 
              }}>
                <div style={{ textAlign: 'center', color: '#999' }}>
                  <div style={{ fontSize: 48, marginBottom: 16 }}>💬</div>
                  <div style={{ fontSize: 18, fontWeight: 500, marginBottom: 8 }}>
                    与AI自由对话
                  </div>
                  <div style={{ fontSize: 14 }}>
                    直接提问，或使用@知识库引用文献
                  </div>
                </div>
              </div>
            ) : (
              <MessageList
                messages={generalMessages}
                loading={sending}
                streamingContent={streamingContent}
              />
            )}
          </div>

          <MessageInput
            onSend={handleSendGeneralMessage}
            loading={sending}
            knowledgeBases={knowledgeBases}
            placeholder="输入你的问题...（Shift+Enter换行，Enter发送）"
          />
        </div>
      )
    }

    // 全文阅读模式
    if (modeState.baseMode === 'knowledge_base' && modeState.kbMode === 'full_text') {
      if (!modeState.fullTextState) {
        return (
          <div style={{ flex: 1, display: 'flex', alignItems: 'center', justifyContent: 'center' }}>
            <div>加载中...</div>
          </div>
        )
      }

      return (
        <FullTextMode
          state={modeState.fullTextState}
          kbName={kbName}
          kbId={modeState.selectedKbId!}
          onSendMessage={(content) => handleSendGeneralMessage(content, [modeState.selectedKbId!])}
          messages={generalMessages}
          loading={sending}
          streamingContent={streamingContent}
        />
      )
    }

    // 逐篇精读模式
    if (modeState.baseMode === 'knowledge_base' && modeState.kbMode === 'deep_read') {
      if (!modeState.deepReadState || !deepReadState) {
        return (
          <div style={{ flex: 1, display: 'flex', alignItems: 'center', justifyContent: 'center' }}>
            <div>请选择要精读的文献...</div>
          </div>
        )
      }

      return (
        <DeepReadMode
          state={{
            selectedDocs: deepReadState.selectedDocs,
            currentDoc: deepReadState.currentDoc,
            currentConversation: deepReadState.currentConversation,
          } as any}
          kbName={kbName}
          onSwitch={deepReadState.switchDocument}
          onSendMessage={handleSendDeepReadMessage}
          loading={sending}
          streamingContent={streamingContent}
        />
      )
    }

    return null
  }

  return (
    <div style={{ height: '100%', display: 'flex' }}>
      {/* 左侧模式选择器 */}
      <ModeSelector
        state={modeState}
        onModeChange={setBaseMode}
        onKbSelect={selectKnowledgeBase}
        onKbModeChange={setKnowledgeBaseMode}
      />

      {/* 主内容区 */}
      <div style={{ flex: 1, display: 'flex', flexDirection: 'column' }}>
        {/* 顶部工具栏 */}
        <div style={{ 
          padding: '12px 24px',
          background: '#fff',
          borderBottom: '1px solid #e8e8e8',
          display: 'flex',
          alignItems: 'center',
          justifyContent: 'flex-end',
          flexShrink: 0,
        }}>
          {/* 模型选择器 */}
          <ModelSelector
            value={selectedModel}
            onChange={setSelectedModel}
            disabled={sending}
          />
        </div>

        {/* 内容区域 */}
        {renderContent()}
      </div>

      {/* 文献选择器弹窗 */}
      {showDocSelector && (
        <DocumentSelector
          documents={allDocuments}
          maxSelection={5}
          onConfirm={handleConfirmDocSelection}
          onCancel={() => setShowDocSelector(false)}
        />
      )}
    </div>
  )
}

export default ChatPage