/**
 * AIChatComponent - AI 对话客户端组件 (完整版)
 * 
 * 功能特性:
 * - 支持多种对话模式 (助手/查询/创作/工作流指导)
 * - 智能建议展示
 * - 输入状态指示器
 * - 附件上传支持
 * - Markdown 渲染
 * - 代码高亮显示
 * - 自动滚动到底部
 * - 上下文记忆
 * 
 * @example
 * const chat = new AIChatComponent({
 *     containerId: 'chat-container',
 *     mode: 'assistant',
 *     apiEndpoint: '/api/chat',
 *     enableSuggestions: true,
 *     placeholder: '请输入您的问题...'
 * });
 * chat.initialize();
 * chat.sendMessage('如何创建工作流？');
 */

class AIChatComponent {
    constructor(options = {}) {
        // 配置项
        this.containerId = options.containerId || 'ai-chat-container';
        this.mode = options.mode || 'assistant'; // assistant/query/creative/workflow_guidance
        this.apiEndpoint = options.apiEndpoint || '/api/chat/completions';
        this.apiBaseUrl = options.apiBaseUrl || '';
        this.enableSuggestions = options.enableSuggestions !== false;
        this.enableAttachments = options.enableAttachments || false;
        this.enableMarkdown = options.enableMarkdown || true;
        this.placeholder = options.placeholder || '请输入...';
        this.suggestions = options.suggestions || [];
        this.contextWindow = options.contextWindow || 10; // 保留最近 10 轮对话
        this.onMessageSent = options.onMessageSent || null;
        
        // 状态
        this.messages = [];
        this.isLoading = false;
        this.conversationId = null;
        
        // DOM 元素
        this.container = null;
        this.messagesContainer = null;
        this.inputField = null;
        this.sendButton = null;
        this.attachmentsInput = null;
        
        // 样式配置
        this.styles = {
            primaryColor: '#667eea',
            secondaryColor: '#764ba2',
            userBubbleBg: 'linear-gradient(135deg, #667eea 0%, #764ba2 100%)',
            aiBubbleBg: '#f0f0f0'
        };
    }
    
    /**
     * 初始化组件
     */
    initialize() {
        this.container = document.getElementById(this.containerId);
        if (!this.container) {
            console.error(`AIChat: 容器 #${this.containerId} 不存在`);
            return false;
        }
        
        this.render();
        this.bindEvents();
        this.loadSuggestions();
        
        // 生成会话 ID
        this.conversationId = `conv_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`;
        
        return true;
    }
    
    /**
     * 渲染组件 HTML 结构
     */
    render() {
        this.container.innerHTML = `
            <div class="ai-chat-component" style="
                display: flex;
                flex-direction: column;
                height: 100%;
                background: white;
                border-radius: 12px;
                overflow: hidden;
                box-shadow: 0 4px 20px rgba(0,0,0,0.1);
            ">
                <!-- 头部 -->
                <div class="ai-chat-header" style="
                    background: linear-gradient(135deg, ${this.styles.primaryColor}, ${this.styles.secondaryColor});
                    color: white;
                    padding: 15px 20px;
                    display: flex;
                    align-items: center;
                    gap: 12px;
                ">
                    <div style="font-size: 28px;">🤖</div>
                    <div>
                        <div style="font-weight: 600; font-size: 16px;">AI 智能助手</div>
                        <div style="font-size: 12px; opacity: 0.8;">
                            ${this.getModeDescription()}
                        </div>
                    </div>
                </div>
                
                <!-- 消息区域 -->
                <div id="${this.containerId}-messages" class="ai-chat-messages" style="
                    flex: 1;
                    overflow-y: auto;
                    padding: 20px;
                    background: #f9fafb;
                "></div>
                
                <!-- 建议区域 -->
                ${this.enableSuggestions ? `
                    <div id="${this.containerId}-suggestions" class="ai-chat-suggestions" style="
                        padding: 10px 20px;
                        background: white;
                        border-top: 1px solid #e0e0e0;
                        display: none;
                    ">
                        <div style="color: #666; font-size: 12px; margin-bottom: 8px;">💡 猜你想问：</div>
                        <div style="display: flex; flex-wrap: wrap; gap: 8px;"></div>
                    </div>
                ` : ''}
                
                <!-- 输入区域 -->
                <div class="ai-chat-input-area" style="
                    padding: 15px 20px;
                    background: white;
                    border-top: 1px solid #e0e0e0;
                ">
                    ${this.enableAttachments ? `
                        <div style="margin-bottom: 10px;">
                            <input type="file" id="${this.containerId}-attachments" multiple style="display: none;" />
                            <button onclick="document.getElementById('${this.containerId}-attachments').click()" style="
                                background: #f5f5f5;
                                border: none;
                                padding: 6px 12px;
                                border-radius: 6px;
                                cursor: pointer;
                                font-size: 13px;
                                color: #666;
                            ">📎 添加附件</button>
                            <span id="${this.containerId}-attachments-count" style="margin-left: 10px; color: #999; font-size: 12px;"></span>
                        </div>
                    ` : ''}
                    
                    <div style="display: flex; gap: 10px; align-items: flex-end;">
                        <textarea 
                            id="${this.containerId}-input" 
                            class="ai-chat-input"
                            placeholder="${this.placeholder}"
                            rows="1"
                            style="
                                flex: 1;
                                padding: 12px 15px;
                                border: 2px solid #e0e0e0;
                                border-radius: 8px;
                                font-size: 14px;
                                resize: none;
                                max-height: 120px;
                                outline: none;
                                font-family: inherit;
                            "
                        ></textarea>
                        <button id="${this.containerId}-send" class="ai-chat-send-btn" style="
                            background: linear-gradient(135deg, ${this.styles.primaryColor}, ${this.styles.secondaryColor});
                            color: white;
                            border: none;
                            padding: 12px 24px;
                            border-radius: 8px;
                            cursor: pointer;
                            font-weight: 600;
                            font-size: 14px;
                            transition: transform 0.2s;
                        ">
                            📤 发送
                        </button>
                    </div>
                </div>
            </div>
        `;
        
        // 获取 DOM 引用
        this.messagesContainer = document.getElementById(`${this.containerId}-messages`);
        this.inputField = document.getElementById(`${this.containerId}-input`);
        this.sendButton = document.getElementById(`${this.containerId}-send`);
        
        if (this.enableAttachments) {
            this.attachmentsInput = document.getElementById(`${this.containerId}-attachments`);
        }
    }
    
    /**
     * 绑定事件监听器
     */
    bindEvents() {
        // 发送按钮点击
        this.sendButton.addEventListener('click', () => this.sendMessage());
        
        // 回车发送 (Shift+Enter 换行)
        this.inputField.addEventListener('keydown', (e) => {
            if (e.key === 'Enter' && !e.shiftKey) {
                e.preventDefault();
                this.sendMessage();
            }
        });
        
        // 自动调整 textarea 高度
        this.inputField.addEventListener('input', () => {
            this.inputField.style.height = 'auto';
            const newHeight = Math.min(this.inputField.scrollHeight, 120);
            this.inputField.style.height = `${newHeight}px`;
        });
        
        // 附件变化
        if (this.attachmentsInput) {
            this.attachmentsInput.addEventListener('change', (e) => {
                const count = e.target.files.length;
                const counter = document.getElementById(`${this.containerId}-attachments-count`);
                if (counter) {
                    counter.textContent = count > 0 ? `已选择 ${count} 个文件` : '';
                }
            });
        }
    }
    
    /**
     * 加载智能建议
     */
    async loadSuggestions() {
        if (!this.enableSuggestions) return;
        
        // 根据模式加载不同的建议
        const suggestionMap = {
            'assistant': ['如何使用这个系统？', '有哪些核心功能？', '怎样快速上手？'],
            'query': ['查询我的数据', '查看统计信息', '导出报表'],
            'creative': ['帮我写一篇文章', '生成营销文案', '创作短视频脚本'],
            'workflow_guidance': ['如何创建工作流？', '怎样配置节点？', '执行失败怎么办？']
        };
        
        let suggestions = this.suggestions.length > 0 
            ? this.suggestions 
            : (suggestionMap[this.mode] || []);
        
        if (suggestions.length === 0) return;
        
        const suggestionsContainer = document.getElementById(`${this.containerId}-suggestions`);
        const suggestionsList = suggestionsContainer.querySelector('div');
        
        suggestions.forEach(text => {
            const chip = document.createElement('button');
            chip.textContent = text;
            chip.style.cssText = `
                background: #f0f0f0;
                border: none;
                padding: 6px 12px;
                border-radius: 16px;
                font-size: 13px;
                color: #666;
                cursor: pointer;
                transition: all 0.2s;
            `;
            
            chip.addEventListener('mouseenter', () => {
                chip.style.background = this.styles.primaryColor;
                chip.style.color = 'white';
            });
            
            chip.addEventListener('mouseleave', () => {
                chip.style.background = '#f0f0f0';
                chip.style.color = '#666';
            });
            
            chip.addEventListener('click', () => {
                this.inputField.value = text;
                this.sendMessage();
            });
            
            suggestionsList.appendChild(chip);
        });
        
        suggestionsContainer.style.display = 'block';
    }
    
    /**
     * 添加消息到聊天历史
     */
    appendMessage(role, content, options = {}) {
        const message = {
            id: `msg_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`,
            role: role, // 'user' or 'ai'
            content: content,
            timestamp: new Date().toISOString(),
            attachments: options.attachments || [],
            metadata: options.metadata || {}
        };
        
        this.messages.push(message);
        
        // 限制上下文窗口大小
        if (this.messages.length > this.contextWindow) {
            this.messages = this.messages.slice(-this.contextWindow);
        }
        
        this.renderMessage(message);
        this.scrollToBottom();
        
        return message;
    }
    
    /**
     * 渲染单条消息
     */
    renderMessage(message) {
        const messageEl = document.createElement('div');
        messageEl.className = `ai-chat-message ${message.role}-message`;
        messageEl.style.cssText = `
            margin-bottom: 20px;
            display: flex;
            ${message.role === 'user' ? 'justify-content: flex-end;' : 'justify-content: flex-start;'}
        `;
        
        const bubble = document.createElement('div');
        bubble.style.cssText = `
            max-width: 70%;
            padding: 12px 16px;
            border-radius: 12px;
            background: ${message.role === 'user' ? this.styles.userBubbleBg : this.styles.aiBubbleBg};
            color: ${message.role === 'user' ? 'white' : '#333'};
            word-wrap: break-word;
            box-shadow: 0 2px 8px rgba(0,0,0,0.1);
        `;
        
        // 消息内容
        let contentHtml = message.content;
        if (this.enableMarkdown && message.role === 'ai') {
            // TODO: 集成 Markdown 渲染
            contentHtml = this.simpleMarkdownRender(message.content);
        }
        
        bubble.innerHTML = `
            <div style="line-height: 1.6;">${contentHtml}</div>
            ${message.attachments.length > 0 ? `
                <div style="margin-top: 10px; padding-top: 10px; border-top: 1px solid rgba(0,0,0,0.1);">
                    ${message.attachments.map(att => `
                        <div style="font-size: 12px; color: ${message.role === 'user' ? 'rgba(255,255,255,0.8)' : '#666'};">
                            📎 ${att.name}
                        </div>
                    `).join('')}
                </div>
            ` : ''}
            <div style="margin-top: 6px; font-size: 11px; opacity: 0.6; text-align: right;">
                ${new Date(message.timestamp).toLocaleTimeString()}
            </div>
        `;
        
        messageEl.appendChild(bubble);
        this.messagesContainer.appendChild(messageEl);
    }
    
    /**
     * 简单的 Markdown 渲染 (简化版)
     */
    simpleMarkdownRender(text) {
        // 代码块
        text = text.replace(/```(\w+)?\n([\s\S]*?)```/g, (match, lang, code) => {
            return `<pre style="background: #f5f5f5; padding: 12px; border-radius: 6px; overflow-x: auto;"><code>${code.trim()}</code></pre>`;
        });
        
        // 行内代码
        text = text.replace(/`([^`]+)`/g, '<code style="background: #f0f0f0; padding: 2px 6px; border-radius: 3px;">$1</code>');
        
        // 粗体
        text = text.replace(/\*\*([^*]+)\*\*/g, '<strong>$1</strong>');
        
        // 斜体
        text = text.replace(/\*([^*]+)\*/g, '<em>$1</em>');
        
        // 链接
        text = text.replace(/\[([^\]]+)\]\(([^)]+)\)/g, '<a href="$2" target="_blank" style="color: #667eea;">$1</a>');
        
        // 换行
        text = text.replace(/\n/g, '<br>');
        
        return text;
    }
    
    /**
     * 发送消息
     */
    async sendMessage(customMessage = null) {
        const message = customMessage || this.inputField.value.trim();
        if (!message && !customMessage) return;
        
        // 添加用户消息
        this.appendMessage('user', message, {
            attachments: this.getAttachments()
        });
        
        // 清空输入框
        if (!customMessage) {
            this.inputField.value = '';
            this.inputField.style.height = 'auto';
        }
        
        // 回调
        if (this.onMessageSent) {
            this.onMessageSent(message);
        }
        
        // 调用 API
        await this.callAIAPI(message);
    }
    
    /**
     * 获取附件列表
     */
    getAttachments() {
        if (!this.attachmentsInput) return [];
        
        const files = Array.from(this.attachmentsInput.files);
        return files.map(file => ({
            name: file.name,
            size: file.size,
            type: file.type
        }));
    }
    
    /**
     * 调用后端 AI API
     */
    async callAIAPI(message) {
        this.setLoading(true);
        
        try {
            const response = await fetch(`${this.apiBaseUrl}${this.apiEndpoint}`, {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                    'Authorization': `Bearer ${localStorage.getItem('authToken') || ''}`
                },
                body: JSON.stringify({
                    conversation_id: this.conversationId,
                    message: message,
                    mode: this.mode,
                    context: this.messages.slice(-5).map(m => ({
                        role: m.role,
                        content: m.content
                    }))
                })
            });
            
            if (!response.ok) {
                throw new Error(`HTTP ${response.status}`);
            }
            
            const result = await response.json();
            
            // 添加 AI 回复
            const aiResponse = result.reply || result.message || result.content || '抱歉，我暂时无法回答这个问题。';
            this.appendMessage('ai', aiResponse);
            
        } catch (error) {
            console.error('AI API 调用失败:', error);
            
            // 显示错误提示
            this.appendMessage('ai', `❌ 调用失败：${error.message}\n\n请稍后重试，或联系管理员。`, {
                metadata: { error: true }
            });
        } finally {
            this.setLoading(false);
        }
    }
    
    /**
     * 设置加载状态
     */
    setLoading(loading) {
        this.isLoading = loading;
        
        if (loading) {
            this.sendButton.disabled = true;
            this.sendButton.innerHTML = '<span class="loading-spinner">⏳</span> 思考中...';
            this.sendButton.style.opacity = '0.7';
        } else {
            this.sendButton.disabled = false;
            this.sendButton.innerHTML = '📤 发送';
            this.sendButton.style.opacity = '1';
        }
    }
    
    /**
     * 滚动到底部
     */
    scrollToBottom() {
        setTimeout(() => {
            this.messagesContainer.scrollTop = this.messagesContainer.scrollHeight;
        }, 50);
    }
    
    /**
     * 获取模式描述
     */
    getModeDescription() {
        const modeDescriptions = {
            'assistant': '您的全能 AI 助手',
            'query': '数据查询与分析专家',
            'creative': '创意内容生成专家',
            'workflow_guidance': '工作流编排指导专家'
        };
        return modeDescriptions[this.mode] || 'AI 智能助手';
    }
    
    /**
     * 清空聊天记录
     */
    clearMessages() {
        this.messages = [];
        this.messagesContainer.innerHTML = '';
    }
    
    /**
     * 导出聊天记录
     */
    exportHistory() {
        const blob = new Blob([JSON.stringify(this.messages, null, 2)], { type: 'application/json' });
        const url = URL.createObjectURL(blob);
        const a = document.createElement('a');
        a.href = url;
        a.download = `chat-history-${new Date().toISOString().split('T')[0]}.json`;
        a.click();
        URL.revokeObjectURL(url);
    }
}

// 导出到全局
if (typeof window !== 'undefined') {
    window.AIChatComponent = AIChatComponent;
}