import { useState, useRef, useEffect, useCallback } from 'react'
import { Input, Button, Avatar, Spin, theme, Modal, Tooltip, Typography } from 'antd'
import {
  SendOutlined, RobotOutlined, UserOutlined, PlusOutlined,
  DeleteOutlined, StopOutlined, MessageOutlined,
} from '@ant-design/icons'
import { sendMessage } from '@/services/ai-chat'
import {
  listConversations, createConversation, deleteConversation,
  getMessages, updateConversation, type Conversation,
} from '@/services/conversation-api'
import Markdown from '@/components/Markdown'

const { Text } = Typography

interface Message {
  id: string
  role: 'user' | 'assistant'
  content: string
  timestamp: number
}

export default function TaskAssistant() {
  const [conversations, setConversations] = useState<Conversation[]>([])
  const [activeId, setActiveId] = useState<string | null>(null)
  const [messages, setMessages] = useState<Message[]>([])
  const [input, setInput] = useState('')
  const [loading, setLoading] = useState(false)
  const [editingId, setEditingId] = useState<string | null>(null)
  const [editTitle, setEditTitle] = useState('')
  const abortRef = useRef<AbortController | null>(null)
  const messagesEndRef = useRef<HTMLDivElement>(null)
  const editInputRef = useRef<any>(null)
  const { token } = theme.useToken()

  // Load conversations
  const loadConversations = useCallback(async () => {
    try { setConversations(await listConversations()) } catch { /* */ }
  }, [])
  useEffect(() => { loadConversations() }, [loadConversations])

  // Scroll to bottom
  useEffect(() => {
    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' })
  }, [messages])

  // Load messages when switching conversation
  const switchConversation = useCallback(async (id: string) => {
    if (loading) { abortRef.current?.abort(); setLoading(false) }
    setActiveId(id)
    setMessages([])
    try {
      const records = await getMessages(id)
      setMessages(records.map(m => ({
        id: m.id, role: m.role, content: m.content,
        timestamp: new Date(m.createdAt).getTime(),
      })))
    } catch { /* */ }
  }, [loading])

  // New conversation
  const handleNew = async () => {
    if (loading) { abortRef.current?.abort(); setLoading(false) }
    try {
      const conv = await createConversation()
      setConversations(prev => [conv, ...prev])
      setActiveId(conv.id)
      setMessages([])
      setInput('')
    } catch { /* */ }
  }

  // Delete conversation
  const handleDelete = async (id: string) => {
    Modal.confirm({
      title: '删除对话', content: '确定要删除这个对话吗？',
      okText: '删除', okType: 'danger', cancelText: '取消',
      onOk: async () => {
        await deleteConversation(id).catch(() => {})
        setConversations(prev => prev.filter(c => c.id !== id))
        if (activeId === id) { setActiveId(null); setMessages([]) }
      },
    })
  }

  // Start editing title
  const startEdit = (conv: Conversation) => {
    setEditingId(conv.id)
    setEditTitle(conv.title)
    setTimeout(() => editInputRef.current?.focus(), 50)
  }

  // Save title
  const saveTitle = async (id: string) => {
    const title = editTitle.trim()
    if (title && title !== conversations.find(c => c.id === id)?.title) {
      await updateConversation(id, title).catch(() => {})
      setConversations(prev => prev.map(c => c.id === id ? { ...c, title } : c))
    }
    setEditingId(null)
  }

  // Send message
  const handleSend = async () => {
    const text = input.trim()
    if (!text || loading) return

    const userMsg: Message = {
      id: Date.now().toString(), role: 'user', content: text, timestamp: Date.now(),
    }
    const newMessages = [...messages, userMsg]
    setMessages(newMessages)
    setInput('')
    setLoading(true)

    const controller = new AbortController()
    abortRef.current = controller

    try {
      const result = await sendMessage(
        newMessages.map(m => ({ role: m.role, content: m.content })),
        activeId ?? undefined, controller.signal,
      )

      const convId = result.conversationId || activeId
      if (convId && convId !== activeId) {
        setActiveId(convId)
        loadConversations()
      }

      const assistantMsg: Message = {
        id: (Date.now() + 1).toString(), role: 'assistant',
        content: result.content, timestamp: Date.now(),
      }
      setMessages(prev => [...prev, assistantMsg])
      loadConversations()
    } catch (err: any) {
      if (err.name === 'AbortError') return
      setMessages(prev => [...prev, {
        id: (Date.now() + 1).toString(), role: 'assistant',
        content: '请求失败：' + (err instanceof Error ? err.message : '未知错误'),
        timestamp: Date.now(),
      }])
    } finally {
      setLoading(false)
      abortRef.current = null
    }
  }

  const handleStop = () => { abortRef.current?.abort(); setLoading(false) }

  const handleKeyDown = (e: React.KeyboardEvent) => {
    if (e.key === 'Enter' && !e.shiftKey) { e.preventDefault(); handleSend() }
  }

  return (
    <div style={{ display: 'flex', height: 'calc(100vh - 112px)', gap: 12 }}>
      {/* Sidebar */}
      <div style={{
        width: 260, flexShrink: 0, display: 'flex', flexDirection: 'column',
        background: token.colorBgContainer, borderRadius: token.borderRadiusLG,
        border: `1px solid ${token.colorBorderSecondary}`, overflow: 'hidden',
      }}>
        <div style={{ padding: 12, borderBottom: `1px solid ${token.colorBorderSecondary}` }}>
          <Button type="primary" icon={<PlusOutlined />} block onClick={handleNew}>新对话</Button>
        </div>
        <div style={{ flex: 1, overflowY: 'auto', padding: '4px 8px' }}>
          {conversations.map(conv => (
            <div key={conv.id}
              onClick={() => activeId !== conv.id && switchConversation(conv.id)}
              style={{
                display: 'flex', alignItems: 'center', justifyContent: 'space-between',
                padding: '8px 10px', marginBottom: 2, borderRadius: 8, cursor: 'pointer',
                background: activeId === conv.id ? token.colorFillSecondary : 'transparent',
              }}>
              <MessageOutlined style={{ color: token.colorTextQuaternary, fontSize: 14, marginRight: 8, flexShrink: 0 }} />
              {editingId === conv.id ? (
                <Input
                  ref={editInputRef} size="small" value={editTitle}
                  onChange={e => setEditTitle(e.target.value)}
                  onBlur={() => saveTitle(conv.id)}
                  onPressEnter={() => saveTitle(conv.id)}
                  onClick={e => e.stopPropagation()}
                  style={{ flex: 1, fontSize: 13 }}
                />
              ) : (
                <Text
                  ellipsis
                  style={{ flex: 1, fontSize: 13, lineHeight: '28px' }}
                  onDoubleClick={e => { e.stopPropagation(); startEdit(conv) }}
                >{conv.title}</Text>
              )}
              <Tooltip title="删除">
                <DeleteOutlined
                  onClick={e => { e.stopPropagation(); handleDelete(conv.id) }}
                  style={{ fontSize: 12, color: token.colorTextQuaternary, marginLeft: 4, cursor: 'pointer' }}
                />
              </Tooltip>
            </div>
          ))}
          {conversations.length === 0 && (
            <div style={{ textAlign: 'center', padding: 24, color: token.colorTextQuaternary }}>
              <Text type="secondary" style={{ fontSize: 13 }}>暂无对话</Text>
              <br />
              <Text type="secondary" style={{ fontSize: 12, marginTop: 4 }}>双击标题可重命名</Text>
            </div>
          )}
        </div>
      </div>

      {/* Chat area */}
      <div style={{ flex: 1, display: 'flex', flexDirection: 'column', minWidth: 0 }}>
        {/* Messages */}
        <div style={{
          flex: 1, overflowY: 'auto', background: token.colorBgContainer,
          borderRadius: `${token.borderRadiusLG}px ${token.borderRadiusLG}px 0 0`,
          padding: '20px 24px',
          border: `1px solid ${token.colorBorderSecondary}`, borderBottom: 'none',
        }}>
          {messages.length === 0 && (
            <div style={{
              display: 'flex', flexDirection: 'column', alignItems: 'center',
              justifyContent: 'center', height: '100%', color: token.colorTextQuaternary,
            }}>
              <RobotOutlined style={{ fontSize: 48, marginBottom: 16 }} />
              <Text type="secondary" style={{ fontSize: 16 }}>
                {activeId ? '开始新对话' : '点击左侧「新对话」开始'}
              </Text>
              <Text type="secondary" style={{ fontSize: 13, marginTop: 8 }}>
                Hermes Agent 通过 DeepSeek 提供回答
              </Text>
            </div>
          )}

          {messages.map(msg => (
            <div key={msg.id} style={{
              display: 'flex', gap: 12, marginBottom: 20,
              flexDirection: msg.role === 'user' ? 'row-reverse' : 'row',
            }}>
              <Avatar size={32}
                icon={msg.role === 'user' ? <UserOutlined /> : <RobotOutlined />}
                style={{
                  backgroundColor: msg.role === 'user' ? token.colorPrimary : token.colorSuccess,
                  flexShrink: 0,
                }}
              />
              <div style={{
                maxWidth: '75%', padding: '12px 16px', borderRadius: 12,
                background: msg.role === 'user' ? token.colorPrimary : token.colorFillAlter,
                color: msg.role === 'user' ? '#fff' : token.colorText,
                lineHeight: 1.8, wordBreak: 'break-word',
              }}>
                {msg.role === 'assistant' ? <Markdown content={msg.content} /> : msg.content}
              </div>
            </div>
          ))}

          {loading && (
            <div style={{ display: 'flex', gap: 12, marginBottom: 20 }}>
              <Avatar size={32} icon={<RobotOutlined />}
                style={{ backgroundColor: token.colorSuccess, flexShrink: 0 }} />
              <div style={{
                maxWidth: '75%', padding: '12px 16px', borderRadius: 12,
                background: token.colorFillAlter,
              }}>
                <Spin size="small" /> <Text type="secondary">Hermes 思考中...</Text>
              </div>
            </div>
          )}
          <div ref={messagesEndRef} />
        </div>

        {/* Input area — redesigned */}
        <div style={{
          background: token.colorBgContainer, borderTop: 'none',
          border: `1px solid ${token.colorBorderSecondary}`,
          borderRadius: `0 0 ${token.borderRadiusLG}px ${token.borderRadiusLG}px`,
          padding: '16px 20px',
        }}>
          <div style={{
            display: 'flex', alignItems: 'flex-end', gap: 10,
            background: token.colorFillTertiary, borderRadius: 12,
            padding: '8px 8px 8px 14px', border: `1px solid ${token.colorBorderSecondary}`,
          }}>
            <Input.TextArea
              value={input}
              onChange={e => setInput(e.target.value)}
              onKeyDown={handleKeyDown}
              placeholder={activeId ? '输入消息，Enter 发送，Shift+Enter 换行' : '请先新建或选择对话'}
              autoSize={{ minRows: 1, maxRows: 5 }}
              disabled={loading || !activeId}
              variant="borderless"
              style={{ flex: 1, resize: 'none', padding: '4px 0', fontSize: 14 }}
            />
            {loading ? (
              <Button
                danger type="primary" icon={<StopOutlined />} onClick={handleStop}
                style={{ borderRadius: 8, height: 34, minWidth: 72 }}>
                停止
              </Button>
            ) : (
              <Button
                type="primary" icon={<SendOutlined />} onClick={handleSend}
                disabled={!input.trim() || !activeId}
                style={{ borderRadius: 8, height: 34, minWidth: 72 }}>
                发送
              </Button>
            )}
          </div>
        </div>
      </div>
    </div>
  )
}