// DOM Elements
    const messagesContainer = document.getElementById('messages');
    const messageInput = document.getElementById('message-input');
    const sendButton = document.getElementById('send-button');
    const emptyChat = document.getElementById('empty-chat');
    const chatContainer = document.getElementById('chat-container');
    const sourcesContainer = document.getElementById('sources-container');
    const noSources = document.getElementById('no-sources');
    const scrapeBtn = document.getElementById('scrape-btn');
    const refreshBtn = document.getElementById('refresh-btn');

    // State
    let messages = [];
    let sources = [];

    // Initialize
    document.addEventListener('DOMContentLoaded', () => {
        // Enable/disable send button based on input
        messageInput.addEventListener('input', () => {
            sendButton.disabled = !messageInput.value.trim();
        });
        
        // Send message on button click
        sendButton.addEventListener('click', sendMessage);
        
        // Send message on Enter key
        messageInput.addEventListener('keypress', (e) => {
            if (e.key === 'Enter') {
                sendMessage();
            }
        });
        
        // Admin buttons
        scrapeBtn.addEventListener('click', triggerScrape);
        refreshBtn.addEventListener('click', triggerRefreshIndex);
    });

    // Format date
    function formatDate() {
        return new Date().toLocaleString();
    }

    // Create message element
    function createMessageElement(message) {
        const messageEl = document.createElement('div');
        messageEl.className = `message ${message.role}`;
    
        const bubble = document.createElement('div');
        bubble.className = 'bubble';
        bubble.innerHTML = marked.parse(message.content); // parse Markdown to HTML
    
        const meta = document.createElement('div');
        meta.className = 'meta';
        meta.textContent = formatDate();
    
        messageEl.appendChild(bubble);
        messageEl.appendChild(meta);
    
        return messageEl;
    }

    // Update sources panel
    function updateSources(sources) {
        sourcesContainer.innerHTML = '';
    
        // Filter sources with score > -8
        const filteredSources = sources.filter(source => source.score > -8);
    
        if (filteredSources.length === 0) {
            sourcesContainer.appendChild(noSources);
            return;
        }
    
        filteredSources.forEach(source => {
            const card = document.createElement('div');
            card.className = 'source-card';
    
            const title = document.createElement('h4');
            title.textContent = source.title;
    
            const link = document.createElement('a');
            link.className = 'link';
            link.href = source.url;
            link.target = '_blank';
            link.innerHTML = `View source <i class="fas fa-external-link-alt"></i>`;
    
            const score = document.createElement('div');
            score.className = 'score';
            score.textContent = `Relevance: ${source.score.toFixed(2)}`;
    
            card.appendChild(title);
            card.appendChild(link);
            card.appendChild(score);
    
            sourcesContainer.appendChild(card);
        });
    }

    // Send message
    async function sendMessage() {
        const content = messageInput.value.trim();
        if (!content) return;
        
        // Hide empty chat if visible
        if (emptyChat.style.display !== 'none') {
            emptyChat.style.display = 'none';
        }
        
        // Add user message
        const userMessage = { role: 'user', content };
        messages.push(userMessage);
        messagesContainer.appendChild(createMessageElement(userMessage));
        
        // Clear input
        messageInput.value = '';
        sendButton.disabled = true;
        
        // Show thinking message
        const thinkingEl = document.createElement('div');
        thinkingEl.className = 'message assistant';
        
        const thinkingBubble = document.createElement('div');
        thinkingBubble.className = 'bubble';
        thinkingBubble.textContent = 'Thinking...';
        
        thinkingEl.appendChild(thinkingBubble);
        messagesContainer.appendChild(thinkingEl);
        
        // Scroll to bottom
        chatContainer.scrollTop = chatContainer.scrollHeight;
        
        try {
            // Call API
            const response = await fetch('/api/ask', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                },
                body: JSON.stringify({
                    query: content,
                    k: 5
                }),
            });
            
            if (!response.ok) {
                throw new Error('API request failed');
            }
            
            const data = await response.json();
            
            // Remove thinking message
            messagesContainer.removeChild(thinkingEl);
            
            // Add assistant message
            const assistantMessage = { role: 'assistant', content: data.response };
            messages.push(assistantMessage);
            messagesContainer.appendChild(createMessageElement(assistantMessage));
            
            // Update sources
            sources = data.sources;
            updateSources(sources);
            
            // Scroll to bottom
            chatContainer.scrollTop = chatContainer.scrollHeight;
            
        } catch (error) {
            console.error('Error:', error);
            
            // Remove thinking message
            messagesContainer.removeChild(thinkingEl);
            
            // Add error message
            const errorMessage = { 
                role: 'assistant', 
                content: "I'm sorry, I encountered an error. Please try again later or contact UB International Student Services directly."
            };
            messages.push(errorMessage);
            messagesContainer.appendChild(createMessageElement(errorMessage));
            
            // Scroll to bottom
            chatContainer.scrollTop = chatContainer.scrollHeight;
        }
    }

    // Quick questions
    async function askQuickQuestion(question) {
        // Set the question in the input field
        messageInput.value = question;
        
        // Send the message
        await sendMessage();
    }

    // Admin functions
    async function triggerScrape() {
        scrapeBtn.disabled = true;
        scrapeBtn.textContent = 'Scraping...';
        
        try {
            const response = await fetch('/api/scrape', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                },
                body: JSON.stringify({
                    seed_url: 'https://www.buffalo.edu/international-student-services.html',
                    max_pages: 100
                }),
            });
            
            if (!response.ok) {
                throw new Error('API request failed');
            }
            
            const data = await response.json();
            alert(`${data.message}`);
            
        } catch (error) {
            console.error('Error:', error);
            alert('Error starting scraper. Please check console for details.');
            
        } finally {
            scrapeBtn.disabled = false;
            scrapeBtn.textContent = 'Scrape New Content';
        }
    }

    async function triggerRefreshIndex() {
        refreshBtn.disabled = true;
        refreshBtn.textContent = 'Refreshing...';
        
        try {
            const response = await fetch('/api/refresh-index', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                },
            });
            
            if (!response.ok) {
                throw new Error('API request failed');
            }
            
            const data = await response.json();
            alert(`${data.message}`);
            
        } catch (error) {
            console.error('Error:', error);
            alert('Error refreshing index. Please check console for details.');
            
        } finally {
            refreshBtn.disabled = false;
            refreshBtn.textContent = 'Refresh Index';
        }
    }