import React, { useState, useRef, KeyboardEvent } from 'react';
import { Input, Button, Space, Tooltip, Dropdown, Tag } from 'antd';
import { 
  SendOutlined, 
  PaperClipOutlined, 
  FileTextOutlined,
  CloseCircleOutlined
} from '@ant-design/icons';
import type { MenuProps } from 'antd';
import './MessageInput.css';

const { TextArea } = Input;

interface KnowledgeBase {
  id: string;
  name: string;
}

interface MessageInputProps {
  onSend: (content: string, knowledgeBaseIds: string[]) => void;
  loading?: boolean;
  knowledgeBases?: KnowledgeBase[];
  placeholder?: string;
}

const MessageInput: React.FC<MessageInputProps> = ({
  onSend,
  loading = false,
  knowledgeBases = [],
  placeholder = '输入你的问题...（Shift+Enter换行，Enter发送）',
}) => {
  const [content, setContent] = useState('');
  const [selectedKnowledgeBases, setSelectedKnowledgeBases] = useState<string[]>([]);
  const textAreaRef = useRef<any>(null);

  // 处理发送消息
  const handleSend = () => {
    const trimmedContent = content.trim();
    if (!trimmedContent || loading) return;

    onSend(trimmedContent, selectedKnowledgeBases);
    setContent('');
    setSelectedKnowledgeBases([]);
    
    // 重置输入框高度
    if (textAreaRef.current) {
      textAreaRef.current.resizableTextArea.textArea.style.height = 'auto';
    }
  };

  // 处理键盘事件
  const handleKeyDown = (e: KeyboardEvent<HTMLTextAreaElement>) => {
    // Enter发送，Shift+Enter换行
    if (e.key === 'Enter' && !e.shiftKey) {
      e.preventDefault();
      handleSend();
    }
  };

  // 添加知识库
  const handleSelectKnowledgeBase = (kbId: string) => {
    if (!selectedKnowledgeBases.includes(kbId)) {
      setSelectedKnowledgeBases([...selectedKnowledgeBases, kbId]);
    }
  };

  // 移除知识库
  const handleRemoveKnowledgeBase = (kbId: string) => {
    setSelectedKnowledgeBases(selectedKnowledgeBases.filter(id => id !== kbId));
  };

  // 知识库下拉菜单
  const knowledgeBaseMenuItems: MenuProps['items'] = knowledgeBases.map(kb => ({
    key: kb.id,
    label: kb.name,
    icon: <FileTextOutlined />,
    onClick: () => handleSelectKnowledgeBase(kb.id),
    disabled: selectedKnowledgeBases.includes(kb.id),
  }));

  // 获取选中的知识库名称
  const getKnowledgeBaseName = (kbId: string) => {
    const kb = knowledgeBases.find(k => k.id === kbId);
    return kb ? kb.name : kbId;
  };

  return (
    <div className="message-input-container">
      {/* 已选择的知识库标签 */}
      {selectedKnowledgeBases.length > 0 && (
        <div className="selected-knowledge-bases">
          <Space wrap>
            {selectedKnowledgeBases.map(kbId => (
              <Tag
                key={kbId}
                closable
                color="blue"
                onClose={() => handleRemoveKnowledgeBase(kbId)}
                closeIcon={<CloseCircleOutlined />}
              >
                <FileTextOutlined /> {getKnowledgeBaseName(kbId)}
              </Tag>
            ))}
          </Space>
        </div>
      )}

      {/* 输入框和工具栏 */}
      <div className="message-input-wrapper">
        <TextArea
          ref={textAreaRef}
          value={content}
          onChange={(e) => setContent(e.target.value)}
          onKeyDown={handleKeyDown}
          placeholder={placeholder}
          autoSize={{ minRows: 2, maxRows: 8 }}
          disabled={loading}
          className="message-textarea"
        />

        <div className="message-input-toolbar">
          <Space>
            {/* @知识库按钮 */}
            {knowledgeBases.length > 0 && (
              <Dropdown
                menu={{ items: knowledgeBaseMenuItems }}
                placement="topLeft"
                disabled={loading}
              >
                <Tooltip title="@知识库 - 基于知识库内容回答">
                  <Button
                    icon={<FileTextOutlined />}
                    type="text"
                    disabled={loading}
                  >
                    @知识库
                  </Button>
                </Tooltip>
              </Dropdown>
            )}

            {/* 上传附件按钮（预留） */}
            <Tooltip title="上传文档（即将上线）">
              <Button
                icon={<PaperClipOutlined />}
                type="text"
                disabled
              />
            </Tooltip>
          </Space>

          {/* 发送按钮 */}
          <Button
            type="primary"
            icon={<SendOutlined />}
            onClick={handleSend}
            loading={loading}
            disabled={!content.trim() || loading}
          >
            发送
          </Button>
        </div>
      </div>

      {/* 提示信息 */}
      <div className="message-input-hint">
        <span>Shift + Enter 换行，Enter 发送</span>
        {selectedKnowledgeBases.length > 0 && (
          <span className="kb-hint">
            · 已选择 {selectedKnowledgeBases.length} 个知识库
          </span>
        )}
      </div>
    </div>
  );
};

export default MessageInput;