document.addEventListener('DOMContentLoaded', () => {
    // --- CONFIGURATION ---
    const config = {
        // IMPORTANT: Paste your full and correct Cloudflare Worker URL here
        backendUrl: 'https://ar-city-explorer-backend.<your-subdomain>.workers.dev'
    };

    // --- GLOBAL STATE ---
    let poisData = []; // This will hold all our landmark data from the backend
    let arActive = false;

    // --- DOM ELEMENT SELECTORS ---
    const arToggle = document.getElementById('arToggle');
    const arViewport = document.getElementById('arViewport');
    const normalView = document.getElementById('normalView');
    const aiAssistant = document.getElementById('aiAssistant');
    const userInput = document.getElementById('userInput');
    const sendBtn = document.getElementById('sendBtn');
    const objectModal = document.getElementById('objectModal');
    const objectTitle = document.getElementById('objectTitle');
    const objectDescription = document.getElementById('objectDescription');
    const objectImage = document.getElementById('objectImage');
    const closeObjectModal = document.getElementById('closeObjectModal');

    // --- CORE FUNCTIONS ---

    function toggleARView(showAR) {
        arActive = showAR;
        if (arActive) {
            normalView.classList.add('hidden');
            arViewport.classList.remove('hidden');
            arToggle.innerHTML = '<i class="fas fa-times mr-1"></i> Exit AR';
            // Fetch data only if it hasn't been fetched yet
            if (poisData.length === 0) {
                fetchPoisAndCreateAREntities();
            }
        } else {
            arViewport.classList.add('hidden');
            normalView.classList.remove('hidden');
            arToggle.innerHTML = '<i class="fas fa-vr-cardboard mr-1"></i> AR Mode';
        }
    }

    function fetchPoisAndCreateAREntities() {
        console.log('Fetching POIs from backend...');
        fetch(`${config.backendUrl}/api/pois`)
            .then(response => {
                if (!response.ok) throw new Error(`Network error: ${response.statusText}`);
                return response.json();
            })
            .then(pois => {
                console.log('POIs received:', pois);
                poisData = pois; // Store the data globally
                const scene = document.querySelector('a-scene');
                if (!scene) return console.error('A-Frame scene not found!');

                pois.forEach(poi => {
                    const entity = document.createElement('a-entity');
                    entity.setAttribute('gps-new-entity-place', {
                        latitude: poi.latitude,
                        longitude: poi.longitude
                    });

                    const box = document.createElement('a-box');
                    box.setAttribute('material', 'color: red; opacity: 0.7;');
                    box.setAttribute('scale', '10 10 10');
                    box.setAttribute('position', '0 5 0');
                    box.setAttribute('data-poi-id', poi.id); // Set ID for click detection
                    entity.appendChild(box);

                    const text = document.createElement('a-text');
                    text.setAttribute('value', poi.name);
                    text.setAttribute('look-at', '[gps-new-camera]');
                    text.setAttribute('scale', '50 50 50');
                    text.setAttribute('position', '0 15 0');
                    entity.appendChild(text);
                    
                    scene.appendChild(entity);
                });
            })
            .catch(error => {
                console.error('Failed to load POIs:', error);
                alert('Could not load city data. Check your connection and the backend URL.');
                toggleARView(false);
            });
    }

    // --- MODAL AND UI FUNCTIONS ---
    
    function showObjectInfo(poiId) {
        const poi = poisData.find(p => p.id === poiId);
        if (!poi) return;
        objectTitle.textContent = poi.name;
        objectDescription.textContent = poi.description || "No description available.";
        objectImage.src = `https://via.placeholder.com/300x200?text=${encodeURIComponent(poi.name)}`;
        objectModal.classList.remove('hidden');
    }

    function addUserMessage(message) {
        const chatContainer = aiAssistant.querySelector('.flex-col');
        const msg = `<div class="ai-message user-message"><p>${message}</p></div>`;
        chatContainer.insertAdjacentHTML('beforeend', msg);
        aiAssistant.scrollTop = aiAssistant.scrollHeight;
    }

    function addAIMessage(message) {
        const chatContainer = aiAssistant.querySelector('.flex-col');
        const msg = `<div class="ai-message assistant-message"><div class="font-bold text-indigo-800 mb-1">AR Guide</div><p>${message}</p></div>`;
        chatContainer.insertAdjacentHTML('beforeend', msg);
        aiAssistant.scrollTop = aiAssistant.scrollHeight;
    }

    function handleSearch() {
        const searchTerm = userInput.value.trim();
        if (!searchTerm) return;
        addUserMessage(searchTerm);
        userInput.value = '';

        if (poisData.length === 0) {
            addAIMessage("I'm still loading location data. Please try again in a moment.");
            return;
        }

        const results = poisData.filter(poi =>
            poi.name.toLowerCase().includes(searchTerm.toLowerCase()) ||
            (poi.description && poi.description.toLowerCase().includes(searchTerm.toLowerCase()))
        );

        if (results.length > 0) {
            let response = `I found ${results.length} result(s):<ul>`;
            results.forEach(poi => { response += `<li class="mt-2 list-disc list-inside">${poi.name}</li>`; });
            response += "</ul>";
            addAIMessage(response);
        } else {
            addAIMessage(`Sorry, I couldn't find anything matching "${searchTerm}".`);
        }
    }
    
    // --- EVENT LISTENERS ---
    
    arToggle.addEventListener('click', () => toggleARView(!arActive));

    document.querySelector('a-scene').addEventListener('click', (event) => {
        if (event.target.hasAttribute('data-poi-id')) {
            const poiId = parseInt(event.target.getAttribute('data-poi-id'), 10);
            showObjectInfo(poiId);
        }
    });

    closeObjectModal.addEventListener('click', () => objectModal.classList.add('hidden'));
    
    sendBtn.addEventListener('click', handleSearch);
    userInput.addEventListener('keypress', (e) => {
        if (e.key === 'Enter') handleSearch();
    });

    // Initial fetch of data so the search bar works immediately
    fetchPoisAndCreateAREntities();
});