document.addEventListener('DOMContentLoaded', () => {

    const API_URL = ''; // Use relative path for API calls

    // --- Application Elements ---
    const nasaSearchInput = document.getElementById('nasaSearchInput');
    const nasaSearchBtn = document.getElementById('nasaSearchBtn');
    const searchResultsList = document.getElementById('search-results-list');
    const trainChatbotBtn = document.getElementById('trainChatbotBtn');
    const chatHistory = document.getElementById('chat-history');
    const chatInput = document.getElementById('chat-input');
    const chatSendBtn = document.getElementById('chat-send');

    // --- Application State ---
    let currentSessionId = null;

    // --- Helper Functions ---
    function addChatMessage(sender, message, sources = []) {
        const messageElement = document.createElement('div');
        messageElement.classList.add('chat-message', sender.toLowerCase());
        messageElement.style.marginBottom = '12px';

        // Use innerText for safety, but replace newlines with <br> for rendering
        const formattedMessage = message.replace(/\n/g, '<br>');

        let sourcesHTML = '';
        if (sources.length > 0) {
            sourcesHTML = '<div class="sources" style="margin-top: 10px; font-size: 0.8rem; opacity: 0.7;"><strong>Sources:</strong><ul>';
            sources.forEach(source => {
                sourcesHTML += `<li style="margin-left: 20px;">${source}</li>`;
            });
            sourcesHTML += '</ul></div>';
        }

        messageElement.innerHTML = `
            <strong style="display: block; margin-bottom: 5px;">${sender}:</strong>
            <span>${formattedMessage}</span>
            ${sourcesHTML}
        `;

        chatHistory.appendChild(messageElement);
        chatHistory.scrollTop = chatHistory.scrollHeight;
    }

    // --- Event Listeners ---

    // 1. Search NASA Papers
    nasaSearchBtn.addEventListener('click', async () => {
        const keyword = nasaSearchInput.value.trim();
        if (!keyword) {
            alert('Please enter a search keyword.');
            return;
        }

        searchResultsList.innerHTML = '<p>Searching...</p>';
        trainChatbotBtn.style.display = 'none';
        nasaSearchBtn.disabled = true;
        nasaSearchBtn.textContent = 'Searching...';

        try {
            const response = await fetch(`${API_URL}/api/search`, {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ keyword }),
            });

            if (!response.ok) throw new Error(`HTTP error! status: ${response.status}`);
            const results = await response.json();
            displaySearchResults(results);
        } catch (error) {
            console.error('Search failed:', error);
            searchResultsList.innerHTML = `<p style="color: #ff5e00;">Search failed. Please check the console or try again.</p>`;
        } finally {
            nasaSearchBtn.disabled = false;
            nasaSearchBtn.textContent = 'Search';
        }
    });

    // 2. Display Search Results
    function displaySearchResults(results) {
        searchResultsList.innerHTML = '';
        if (results.length === 0) {
            searchResultsList.innerHTML = '<p>No papers with downloadable PDFs found for this keyword.</p>';
            return;
        }

        results.forEach(paper => {
            const paperElement = document.createElement('div');
            paperElement.classList.add('paper-item');
            paperElement.style.marginBottom = '15px';
            paperElement.innerHTML = `
                <label style="display: flex; align-items: flex-start; cursor: pointer;">
                    <input type="checkbox" class="paper-checkbox" data-pdf-url="${paper.pdfLink}" data-paper-id="${paper.id}" style="margin-top: 5px; margin-right: 10px;">
                    <div>
                        <strong style="color: #fff;">${paper.title}</strong>
                        <p style="font-size: 0.9rem; opacity: 0.7; margin-top: 5px;">${paper.abstract ? paper.abstract.substring(0, 150) + '...' : 'No abstract available.'}</p>
                    </div>
                </label>
            `;
            searchResultsList.appendChild(paperElement);
        });

        trainChatbotBtn.style.display = 'block';
    }

    // 3a. Poll for training status
    function pollTrainingStatus(jobId) {
        const interval = setInterval(async () => {
            try {
                const response = await fetch(`${API_URL}/api/train/status/${jobId}`);
                
                // Gracefully handle server restarts where the job is lost
                if (response.status === 404) {
                    clearInterval(interval);
                    throw new Error("Training process was interrupted on the server. Please try again.");
                }

                const result = await response.json();

                if (result.status === 'processing' || result.status === 'starting') {
                    addChatMessage('System', result.message);
                } else if (result.status === 'complete') {
                    clearInterval(interval);
                    currentSessionId = result.sessionId;
                    addChatMessage('Bot', result.message + " You can now ask me questions about them.");
                    trainChatbotBtn.disabled = false;
                    trainChatbotBtn.textContent = 'Train Chatbot on Selected Papers';
                } else if (result.status === 'error') {
                    clearInterval(interval);
                    throw new Error(result.message || 'Training job failed on the server.');
                }
            } catch (error) {
                clearInterval(interval);
                console.error('Polling failed:', error);
                addChatMessage('System', `Error during training: ${error.message}`);
                trainChatbotBtn.disabled = false;
                trainChatbotBtn.textContent = 'Train Chatbot on Selected Papers';
            }
        }, 3000); // Check every 3 seconds
    }

    // 3b. Display selected papers and hide search results
    function showSelectedPapers(papers) {
        const searchPanel = document.getElementById('search-panel');
        const selectedPapersPanel = document.getElementById('selected-papers-panel');
        const selectedPapersList = document.getElementById('selected-papers-list');

        selectedPapersList.innerHTML = ''; // Clear previous list
        papers.forEach(paper => {
            const paperElement = document.createElement('div');
            paperElement.innerHTML = `
                <a href="${paper.url}" target="_blank" rel="noopener noreferrer" class="selected-paper-link" style="display: block; padding: 10px; border-radius: 5px; text-decoration: none; color: #fff; background: rgba(255,255,255,0.05); margin-bottom: 10px; transition: background 0.3s;">
                    ${paper.title}
                </a>
            `;
            selectedPapersList.appendChild(paperElement);
        });

        searchPanel.style.display = 'none';
        selectedPapersPanel.style.display = 'block';
    }

    // 3. Train Chatbot
    trainChatbotBtn.addEventListener('click', async () => {
        const selectedCheckboxes = document.querySelectorAll('.paper-checkbox:checked');
        const papers = Array.from(selectedCheckboxes).map(cb => ({
            id: cb.dataset.paperId,
            url: cb.dataset.pdfUrl,
            title: cb.closest('.paper-item').querySelector('strong').textContent,
        }));

        if (papers.length === 0) {
            alert('Please select at least one paper to train the chatbot.');
            return;
        }

        addChatMessage('System', `Training chatbot on ${papers.length} paper(s)... This may take a moment.`);
        trainChatbotBtn.disabled = true;
        trainChatbotBtn.textContent = 'Training...';

        // Show the selected papers list and hide the search results
        showSelectedPapers(papers);

        // Activate the three-column layout for the knowledge map
        document.getElementById('main-app-container').classList.add('knowledge-map-active');

        try {
            const response = await fetch(`${API_URL}/api/train`, {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ papers }),
            });

            const result = await response.json();
            if (response.status === 202) { // 202 Accepted
                addChatMessage('System', result.message);
                pollTrainingStatus(result.jobId); // Start polling for status
            } else {
                throw new Error(result.error || 'Failed to start training job.');
            }
        } catch (error) {
            console.error('Training failed:', error);
            addChatMessage('System', `Error during training: ${error.message}`);
        }
    });

    // 4. Handle Chat Messages
    async function handleSendMessage() {
        const query = chatInput.value.trim();
        if (!query) return;

        if (!currentSessionId) {
            addChatMessage('System', 'Error: No active training session. Please train the chatbot first.');
            return;
        }

        addChatMessage('You', query);
        chatInput.value = '';
        chatSendBtn.disabled = true;

        try {
            const response = await fetch(`${API_URL}/api/ask`, {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ query, sessionId: currentSessionId }),
            });

            const result = await response.json();
            if (!response.ok) throw new Error(result.error || 'Failed to get an answer.');

            addChatMessage('Bot', result.answer, result.sources);
        } catch (error) {
            console.error('Ask failed:', error);
            addChatMessage('System', `Error: ${error.message}`);
        } finally {
            chatSendBtn.disabled = false;
        }
    }

    chatSendBtn.addEventListener('click', handleSendMessage);
    chatInput.addEventListener('keypress', (e) => {
        if (e.key === 'Enter') {
            handleSendMessage();
        }
    });

    // --- Original Theme JavaScript ---
    // (The existing code for particles, menu, text rotation, etc., goes here)

    // Create floating particles
        function createParticles() {
            const particlesContainer = document.getElementById('particles');
            const particleCount = 30;

            for (let i = 0; i < particleCount; i++) {
                const particle = document.createElement('div');
                particle.className = 'particle';
                particle.style.left = Math.random() * 100 + '%';
                particle.style.animationDelay = Math.random() * 15 + 's';
                particle.style.animationDuration = (Math.random() * 10 + 15) + 's';
                
                // Randomly assign orange or blue color
                if (Math.random() > 0.5) {
                    particle.style.setProperty('--particle-color', '#00B2FF');
                    const before = particle.style.getPropertyValue('--particle-color');
                    particle.style.background = '#00B2FF';
                }
                
                particlesContainer.appendChild(particle);
            }
        }

        // Mobile menu toggle
        const menuToggle = document.getElementById('menuToggle');
        const navLinks = document.getElementById('navLinks');

        menuToggle.addEventListener('click', () => {
            menuToggle.classList.toggle('active');
            navLinks.classList.toggle('active');
        });

        // Close mobile menu when clicking a link
        document.querySelectorAll('.nav-links a').forEach(link => {
            link.addEventListener('click', () => {
                menuToggle.classList.remove('active');
                navLinks.classList.remove('active');
            });
        });

        // Active navigation highlighting
        const sections = document.querySelectorAll('section');
        const navItems = document.querySelectorAll('.nav-link');

        function updateActiveNav() {
            const scrollPosition = window.pageYOffset + 100;

            sections.forEach((section, index) => {
                const sectionTop = section.offsetTop;
                const sectionHeight = section.offsetHeight;

                if (scrollPosition >= sectionTop && scrollPosition < sectionTop + sectionHeight) {
                    navItems.forEach(item => item.classList.remove('active'));
                    const currentNav = document.querySelector(`.nav-link[href="#${section.id}"]`);
                    if (currentNav) currentNav.classList.add('active');
                }
            });
        }

        // Navbar scroll effect
        window.addEventListener('scroll', function() {
            const navbar = document.getElementById('navbar');
            if (window.scrollY > 50) {
                navbar.classList.add('scrolled');
            } else {
                navbar.classList.remove('scrolled');
            }
            updateActiveNav();
        });

        // Initial active nav update
        updateActiveNav();

        // Smooth scrolling for navigation links
        document.querySelectorAll('a[href^="#"]').forEach(anchor => {
            anchor.addEventListener('click', function (e) {
                e.preventDefault();
                const target = document.querySelector(this.getAttribute('href'));
                if (target) {
                    target.scrollIntoView({
                        behavior: 'smooth',
                        block: 'start'
                    });
                }
            });
        });


        // Feature tabs functionality
        const tabs = document.querySelectorAll('.tab-item');
        const panels = document.querySelectorAll('.content-panel');

        tabs.forEach(tab => {
            tab.addEventListener('click', () => {
                const tabId = tab.getAttribute('data-tab');
                // Remove active class from all tabs and panels
                tabs.forEach(t => t.classList.remove('active'));
                panels.forEach(p => p.classList.remove('active'));
                // Add active class to clicked tab and corresponding panel
                tab.classList.add('active');
                document.getElementById(tabId).classList.add('active');
            });
        });

        // Form submission
        document.getElementById('contactForm').addEventListener('submit', function(e) {
            e.preventDefault();
            // Add your form submission logic here
            alert('Message sent! We\'ll get back to you soon.');
            this.reset();
        });

        // Initialize particles
        createParticles();

        // Text rotation with character animation
        const textSets = document.querySelectorAll('.text-set');
        let currentIndex = 0;
        let isAnimating = false;

        function wrapTextInSpans(element) {
            const text = element.textContent;
            element.innerHTML = text.split('').map((char, i) => 
                `<span class="char" style="animation-delay: ${i * 0.05}s">${char === ' ' ? '&nbsp;' : char}</span>`
            ).join('');
        }

        function animateTextIn(textSet) {
            const glitchText = textSet.querySelector('.glitch-text');
            const subtitle = textSet.querySelector('.subtitle');
            
            // Wrap text in spans for animation
            wrapTextInSpans(glitchText);
            
            // Update data attribute for glitch effect
            glitchText.setAttribute('data-text', glitchText.textContent);
            
            // Show subtitle after main text
            setTimeout(() => {
                subtitle.classList.add('visible');
            }, 800);
        }

        function animateTextOut(textSet) {
            const chars = textSet.querySelectorAll('.char');
            const subtitle = textSet.querySelector('.subtitle');
            
            // Animate characters out
            chars.forEach((char, i) => {
                char.style.animationDelay = `${i * 0.02}s`;
                char.classList.add('out');
            });
            
            // Hide subtitle
            subtitle.classList.remove('visible');
        }

        function rotateText() {
            if (isAnimating) return;
            isAnimating = true;

            const currentSet = textSets[currentIndex];
            const nextIndex = (currentIndex + 1) % textSets.length;
            const nextSet = textSets[nextIndex];

            // Animate out current text
            animateTextOut(currentSet);

            // After out animation, switch sets
            setTimeout(() => {
                currentSet.classList.remove('active');
                nextSet.classList.add('active');
                animateTextIn(nextSet);
                
                currentIndex = nextIndex;
                isAnimating = false;
            }, 600);
        }

        // Initialize first text set
        textSets[0].classList.add('active');
        animateTextIn(textSets[0]);

        // Start rotation after initial display
        setTimeout(() => {
            setInterval(rotateText, 5000); // Change every 5 seconds
        }, 4000);

        // Add random glitch effect
        setInterval(() => {
            const glitchTexts = document.querySelectorAll('.glitch-text');
            glitchTexts.forEach(text => {
                if (Math.random() > 0.95) {
                    text.style.animation = 'none';
                    setTimeout(() => {
                        text.style.animation = '';
                    }, 200);
                }
            });
        }, 3000);
});