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

const { Text } = Typography
const { TextArea } = Input

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

interface Conversation {
  id: string
  title: string
  updatedAt: string
}

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 abortRef = useRef<AbortController | null>(null)
  const messagesEndRef = useRef<HTMLDivElement>(null)
  const { token } = theme.useToken()

  // Load conversations
  useEffect(() => {
    listConversations().then(setConversations).catch(() => {})
  }, [])

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

  // Switch conversation
  const switchConversation = useCallback((id: string) => {
    if (loading) {
      abortRef.current?.abort()
      setLoading(false)
    }
    setActiveId(id)
    setMessages([])
    setInput('')
  }, [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 { /* ignore */ }
  }

  // Delete conversation
  const handleDelete = async (id: string, e: React.MouseEvent) => {
    e.stopPropagation()
    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([])
        }
      },
    })
  }

  // 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,
      )

      // Use returned conversationId if this was auto-created
      if (result.conversationId && !activeId) {
        setActiveId(result.conversationId)
        const conv = await createConversation(
          newMessages[newMessages.length - 1]?.content?.slice(0, 30)
        ).catch(() => null)
        if (conv) setConversations(prev => [conv, ...prev])
      }

      const assistantMsg: Message = {
        id: (Date.now() + 1).toString(),
        role: 'assistant',
        content: result.content,
        timestamp: Date.now(),
      }
      setMessages(prev => [...prev, assistantMsg])

      // Refresh conversation list for updated timestamps
      listConversations().then(setConversations).catch(() => {})
    } catch (err: any) {
      if (err.name === 'AbortError') return
      const errorMsg: Message = {
        id: (Date.now() + 1).toString(),
        role: 'assistant',
        content: '请求失败：' + (err instanceof Error ? err.message : '未知错误'),
        timestamp: Date.now(),
      }
      setMessages(prev => [...prev, errorMsg])
    } finally {
      setLoading(false)
      abortRef.current = null
    }
  }

  // Stop generation
  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: 16 }}>
      {/* 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: '12px 16px', 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: 4 }}>
          {conversations.map(conv => (
            <div
              key={conv.id}
              onClick={() => switchConversation(conv.id)}
              style={{
                display: 'flex', alignItems: 'center', justifyContent: 'space-between',
                padding: '8px 12px', margin: '2px 0', borderRadius: 8, cursor: 'pointer',
                background: activeId === conv.id ? token.colorFillSecondary : 'transparent',
                transition: 'background 0.2s',
              }}
              onMouseEnter={e => (e.currentTarget.style.background = token.colorFillSecondary)}
              onMouseLeave={e => {
                if (activeId !== conv.id) e.currentTarget.style.background = 'transparent'
              }}
            >
              <Space style={{ overflow: 'hidden', flex: 1 }}>
                <MessageOutlined style={{ color: token.colorTextQuaternary, fontSize: 14 }} />
                <Text ellipsis style={{ fontSize: 13, maxWidth: 160 }}>{conv.title}</Text>
              </Space>
              <Tooltip title="删除">
                <DeleteOutlined
                  onClick={e => handleDelete(conv.id, e)}
                  style={{ fontSize: 12, color: token.colorTextQuaternary, opacity: 0, transition: 'opacity 0.2s' }}
                  className="conv-delete-icon"
                />
              </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>
            </div>
          )}
        </div>
      </div>

      {/* Chat area */}
      <div style={{ flex: 1, display: 'flex', flexDirection: 'column', minWidth: 0 }}>
        <div style={{
          flex: 1, overflowY: 'auto', background: token.colorBgContainer,
          borderRadius: token.borderRadiusLG, padding: '20px 24px', marginBottom: 12,
          border: `1px solid ${token.colorBorderSecondary}`,
        }}>
          {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 */}
        <div style={{
          padding: '12px 16px', background: token.colorBgContainer,
          borderRadius: token.borderRadiusLG, border: `1px solid ${token.colorBorderSecondary}`,
        }}>
          <Space.Compact style={{ width: '100%' }}>
            <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: 4 }}
              disabled={loading || !activeId}
              style={{ resize: 'none' }}
            />
            {loading ? (
              <Button danger icon={<StopOutlined />} onClick={handleStop} style={{ height: 'auto' }}>
                停止
              </Button>
            ) : (
              <Button type="primary" icon={<SendOutlined />} onClick={handleSend}
                disabled={!input.trim() || !activeId} style={{ height: 'auto' }}>
                发送
              </Button>
            )}
          </Space.Compact>
        </div>
      </div>

      {/* CSS for delete icon hover */}
      <style>{`
        .conv-delete-icon { opacity: 0; }
        div:hover > .conv-delete-icon { opacity: 1 !important; }
      `}</style>
    </div>
  )
}