document.addEventListener('DOMContentLoaded', () => {
    // --- DOM ELEMENTS ---
    const stationsGrid = document.getElementById('stations-grid');
    const stationTemplate = document.getElementById('stationCardTemplate');
    const errorMessage = document.getElementById('error-message');
    const stationCountEl = document.getElementById('station-count');
    // Note: SocketIO is not needed on this page anymore
    
    let allStations = []; // To store the master list of stations

    // --- AUTHENTICATION & USER INFO (Your existing code is perfect) ---
    const user = JSON.parse(localStorage.getItem('user'));
    if (!user) {
        window.location.href = 'index.html'; // Redirect if not logged in
        return;
    }
    
    // User info and logout button logic... (omitted for brevity, no changes needed)
    
    // --- ADMIN FEATURES (Your existing code is perfect) ---
    // Admin button and add station card logic... (omitted for brevity, no changes needed)


    // --- HELPER FUNCTIONS ---
    const getStatusAttributes = (status) => {
        switch (status) {
            case 'Online': return { color: 'text-green-500', bgColor: 'bg-green-100/60 dark:bg-green-500/10', icon: 'power' };
            case 'Offline': return { color: 'text-red-500', bgColor: 'bg-red-100/60 dark:bg-red-500/10', icon: 'power-off' };
            default: return { color: 'text-gray-500', bgColor: 'bg-gray-100/60 dark:bg-gray-500/10', icon: 'help-circle' };
        }
    };
    
    const handleStationSelect = (stationId) => {
        window.location.href = `dashboard.html?station_id=${stationId}`;
    };

    // This function now only renders the initial grid
    const renderStations = (stations) => {
        stationsGrid.innerHTML = '';
        stationCountEl.textContent = `${stations.length} stations found. Select one to monitor.`;

        stations.forEach(station => {
            const status = getStatusAttributes(station.status);
            const card = document.createElement('div');
            card.className = "group bg-gray-900/60 backdrop-blur-xl rounded-2xl shadow-lg border border-gray-700 transition-transform duration-300 ease-out cursor-pointer flex flex-col justify-between hover:-translate-y-1.5 hover:border-emerald-400/60 hover:shadow-[0_0_0_1px_rgba(16,185,129,0.25),0_20px_40px_rgba(0,0,0,0.45)]";
            card.id = `station-${station.id}`;
            card.onclick = () => handleStationSelect(station.id);

            card.innerHTML = `
                <div class="p-5">
                    <div class="flex justify-between items-start">
                        <h3 class="text-lg font-bold text-white pr-2">${station.name}</h3>
                        <div class="status-badge flex items-center text-xs font-semibold px-3 py-1 rounded-full ${status.bgColor} ${status.color}">
                            <i data-lucide="${status.icon}" class="w-4 h-4 mr-1.5"></i>
                            <span class="status-text">${station.status}</span>
                        </div>
                    </div>
                    <p class="text-sm text-gray-400 mt-1">${station.id}</p>
                </div>
            `;
            stationsGrid.appendChild(card);
        });
        lucide.createIcons();
    };

    // --- NEW: Function to update statuses without redrawing everything ---
    const updateStationStatuses = (stations) => {
        stations.forEach(station => {
            const card = document.getElementById(`station-${station.id}`);
            if (card) {
                const status = getStatusAttributes(station.status);
                const statusBadge = card.querySelector('.status-badge');
                const statusText = card.querySelector('.status-text');
                const statusIcon = card.querySelector('i[data-lucide]');

                if (statusBadge && statusText && statusIcon) {
                    statusBadge.className = `status-badge flex items-center text-xs font-semibold px-3 py-1 rounded-full ${status.bgColor} ${status.color}`;
                    statusText.textContent = station.status;
                    statusIcon.setAttribute('data-lucide', status.icon);
                }
            }
        });
        lucide.createIcons(); // Re-render icons if any changed
    };

    // --- DATA FETCHING & STATUS POLLING ---
    const loadAndPollStations = async () => {
        try {
            const response = await fetch('http://localhost:5000/api/stations');
            if (!response.ok) throw new Error('Failed to fetch stations');
            const stations = await response.json();
            
            // Check if this is the first time loading data
            if (allStations.length === 0) {
                allStations = stations;
                renderStations(allStations); // Initial full render
            } else {
                allStations = stations;
                updateStationStatuses(allStations); // Subsequent, efficient updates
            }

        } catch (error) {
            console.error(error);
            stationCountEl.textContent = 'Could not load stations. Is the backend running?';
            // Stop polling on error
            if (pollingInterval) clearInterval(pollingInterval);
        }
    };

    // --- INITIALIZATION ---
    loadAndPollStations(); // Load immediately on page start
    // Then, set an interval to refresh the statuses every 10 seconds
    const pollingInterval = setInterval(loadAndPollStations, 10000); 
});