import React, { useState, useEffect, useRef } from 'react';
import SvgIcon from '../../components/SvgIcon';

export default function ChatWindow({ chatId, knowledgeBaseId }) {
    const [messages, setMessages] = useState([]);
    const [inputMessage, setInputMessage] = useState('');
    const [isLoading, setIsLoading] = useState(false);
    const [knowledgeBase, setKnowledgeBase] = useState(null);
    const messagesEndRef = useRef(null);

    // Fetch knowledge base details
    useEffect(() => {
        // In a real app, you would fetch the knowledge base details from the API
        const mockKnowledgeBases = [
            {
                id: '1',
                title: '产品开发知识库',
                description: '产品开发流程及规范说明文档',
            },
            {
                id: '2',
                title: '市场分析知识库',
                description: '2025年Q1市场分析总结',
            },
            {
                id: '3',
                title: '财务知识库',
                description: '月度财务分析报告',
            },
            {
                id: '4',
                title: '技术架构知识库',
                description: '系统架构设计文档',
            },
            {
                id: '5',
                title: '用户研究知识库',
                description: '用户调研和反馈分析',
            },
        ];

        const kb = mockKnowledgeBases.find((kb) => kb.id === knowledgeBaseId);
        setKnowledgeBase(kb);

        // In a real app, you would fetch the chat messages from the API
        // For now, we'll just add a welcome message
        if (kb) {
            setMessages([
                {
                    id: '1',
                    sender: 'bot',
                    content: `欢迎使用 ${kb.title}，有什么可以帮助您的？`,
                    timestamp: new Date().toISOString(),
                },
            ]);
        }
    }, [chatId, knowledgeBaseId]);

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

    const handleSendMessage = (e) => {
        e.preventDefault();

        if (!inputMessage.trim()) return;

        // Add user message
        const userMessage = {
            id: Date.now().toString(),
            sender: 'user',
            content: inputMessage,
            timestamp: new Date().toISOString(),
        };

        setMessages((prev) => [...prev, userMessage]);
        setInputMessage('');
        setIsLoading(true);

        // Simulate bot response after a delay
        setTimeout(() => {
            const botMessage = {
                id: (Date.now() + 1).toString(),
                sender: 'bot',
                content: `这是来自 ${knowledgeBase?.title} 的回复：${inputMessage}`,
                timestamp: new Date().toISOString(),
            };

            setMessages((prev) => [...prev, botMessage]);
            setIsLoading(false);
        }, 1000);
    };

    return (
        <div className='chat-window d-flex flex-column h-100'>
            {/* Chat header */}
            <div className='p-3 border-bottom'>
                <h5 className='mb-0'>{knowledgeBase?.title || 'Loading...'}</h5>
                <small className='text-muted'>{knowledgeBase?.description}</small>
            </div>

            {/* Chat messages */}
            <div className='flex-grow-1 p-3 overflow-auto' >
                <div className='container'>
                    {messages.map((message) => (
                        <div
                            key={message.id}
                            className={`d-flex ${
                                message.sender === 'user' ? 'justify-content-end' : 'justify-content-start'
                            } mb-3`}
                        >
                            <div
                                className={`p-3 rounded-3 ${
                                    message.sender === 'user' ? 'bg-primary text-white' : 'bg-white border'
                                }`}
                                style={{ maxWidth: '75%' }}
                            >
                                {message.content}
                            </div>
                        </div>
                    ))}

                    {isLoading && (
                        <div className='d-flex justify-content-start mb-3'>
                            <div className='p-3 rounded-3 bg-white border'>
                                <div className='spinner-border spinner-border-sm text-secondary' role='status'>
                                    <span className='visually-hidden'>Loading...</span>
                                </div>
                            </div>
                        </div>
                    )}

                    <div ref={messagesEndRef} />
                </div>
            </div>

            {/* Chat input */}
            <div className='p-3 border-top'>
                <form onSubmit={handleSendMessage} className='d-flex gap-2'>
                    <input
                        type='text'
                        className='form-control'
                        placeholder='输入你的问题...'
                        value={inputMessage}
                        onChange={(e) => setInputMessage(e.target.value)}
                        disabled={isLoading}
                    />
                    <button
                        type='submit'
                        className='btn btn-dark d-flex align-items-center justify-content-center gap-2'
                        disabled={isLoading || !inputMessage.trim()}
                    >
                        <SvgIcon className='send' color='#ffffff' />
                        <span className='ms-1' style={{ minWidth: 'fit-content' }}>发送</span>
                    </button>
                </form>
            </div>
        </div>
    );
}