document.addEventListener('DOMContentLoaded', () => {
    // --- CONFIGURATION ---
    const API_BASE = "/api"; // Added for API calls

    // --- DOM ELEMENT REFERENCES ---
    const grid = document.getElementById('chambersGrid');
    const chamberTmpl = document.getElementById('chamberTemplate');
    const logTextArea = document.getElementById('instance-log');
    const connChip = document.getElementById('connection-status-chip');
    const stationNameEl = document.getElementById('station-name');
    const stationLocationEl = document.getElementById('station-location');
    const deviceIdEl = document.getElementById('device-id');
    const lastUpdateEl = document.getElementById('last-update-status');
    const stationDiagCodeEl = document.getElementById('station-diag-code');
    const backupPowerChip = document.getElementById('backup-power-chip');
    const diagFlagsGrid = document.getElementById('diag-flags-grid');
    const audioSelect = document.getElementById('audio-command-select');

    // Header Buttons
    const refreshBtn = document.getElementById('refreshBtn');
    const downloadBtn = document.getElementById('downloadBtn');
    const logoutBtn = document.getElementById('logout-btn');

    // --- STATE ---
    let selectedStation = null;
    let socket;
    let statusPollingInterval; // To hold our interval timer
     let chamberData = Array(9).fill({ batteryPresent: false });

    // The list of errors from your Python code
    const DIAGNOSTIC_ERRORS = [
        "Lock Power Cut", "Main Power Cut",
        "Relayboard CAN", "DB CAN Recv",
        "MB Can Recv",    "Smoke Alarm",
        "Water Alarm",    "Phase Failure",
        "Earth Leakage"
    ];

    // --- NEW: SWAP PROCESS ELEMENTS & LOGIC ---
    const swapIdleText = document.getElementById('swap-idle-text');
    const swapPairsList = document.getElementById('swap-pairs-list');
    const startSwapBtn = document.getElementById('start-swap-btn');
    const abortSwapBtn = document.getElementById('abort-swap-btn');
    const clearSwapBtn = document.getElementById('clear-swap-btn');
    const resetBtn = document.getElementById('station-reset-btn');
    
    let currentPair = [], swapPairs = [];

    // --- SWAP UI LOGIC ---
    function updateSwapUI() {
        const isBuilding = currentPair.length > 0 || swapPairs.length > 0;
        if (swapIdleText) swapIdleText.style.display = isBuilding ? 'none' : 'block';
        if (startSwapBtn) startSwapBtn.disabled = swapPairs.length === 0;

        const pairedOut = swapPairs.map(p => p[0]), pairedIn = swapPairs.map(p => p[1]);
        document.querySelectorAll('.chamber-card').forEach(card => {
            const n = parseInt(card.dataset.chamberId, 10);
            card.classList.remove('paired', 'pending');
            if (pairedOut.includes(n) || pairedIn.includes(n)) card.classList.add('paired');
            else if (currentPair.includes(n)) card.classList.add('pending');
        });

        if (swapPairsList) {
            swapPairsList.innerHTML = '';
            if (isBuilding) {
                swapPairs.forEach(p => {
                    const e = document.createElement('div');
                    e.className = 'text-sm font-semibold flex items-center justify-center gap-2 bg-black/20 rounded p-1.5';
                    e.innerHTML = `<span class="text-emerald-300">${p[0]}</span><span>→</span><span class="text-sky-300">${p[1]}</span>`;
                    swapPairsList.appendChild(e);
                });
                if (currentPair.length > 0) {
                    const e = document.createElement('div');
                    e.className = 'text-sm font-semibold flex items-center justify-center gap-2 bg-black/20 rounded p-1.5 ring-2 ring-sky-500';
                    e.innerHTML = `<span class="text-emerald-300 font-bold">${currentPair[0]}</span><span>→</span><span class="text-gray-400">?</span>`;
                    swapPairsList.appendChild(e);
                }
            }
        }
    }

    function handleChamberClick(num) {
        // Deselection logic
        if (currentPair.length === 1 && currentPair[0] === num) {
            currentPair = [];
            updateSwapUI();
            return;
        }
        const isAlreadyPaired = swapPairs.flat().includes(num);
        if (isAlreadyPaired) {
            swapPairs = swapPairs.filter(pair => !pair.includes(num));
            updateSwapUI();
            return;
        }

        // Selection logic
        if (swapPairs.length >= 4) return alert('Maximum of 4 swap pairs reached.');
        
        // Note: Live validation would go here. Removed for testing.
        
        currentPair.push(num);
        if (currentPair.length === 2) {
            swapPairs.push([...currentPair]);
            currentPair = [];
        }
        updateSwapUI();
    }

    function clearSelection() {
        currentPair = [];
        swapPairs = [];
        updateSwapUI();
    }


    // --- HELPER FUNCTIONS (Your original code is unchanged) ---

    const applyButtonFeedback = (button) => {
        if (!button) return;
        button.classList.add('btn-feedback');
        setTimeout(() => {
            button.classList.remove('btn-feedback');
        }, 150);
    };

    // And ensure your sendCommand function does NOT have the feedback logic
    const sendCommand = (command, data = null) => {
        if (!selectedStation || !socket || !socket.connected) {
            logToInstance(`Cannot send command '${command}', not connected.`, "error");
            return;
        }
        const payload = { station_id: selectedStation.id, command: command, data: data };
        socket.emit('rpc_request', payload);
        logToInstance(`Sent command: ${command}`, 'cmd');
    };

    const setChipStyle = (element, text, style) => {
        if (!element) return;
        const baseClass = element.className.split(' ')[0];
        element.textContent = text;
        element.className = `${baseClass} chip-${style}`;
    };
    const logToInstance = (message, type = 'info') => {
        if (!logTextArea) return;
        const timestamp = new Date().toLocaleTimeString();
        const typeIndicator = type === 'error' ? '[ERROR]' : type === 'cmd' ? '[CMD]' : '[INFO]';
        const newLog = `[${timestamp}] ${typeIndicator} ${message}\n`;
        logTextArea.value = newLog + logTextArea.value;
    };

    const updateChamberUI = (card, slot) => {
        if (!card || !slot) return;

        const filledState = card.querySelector('.filled-state');
        const emptyState = card.querySelector('.empty-state');
        const doorPill = card.querySelector('.door-pill');
        
        // Always update door status
        doorPill.textContent = slot.doorStatus ? 'OPEN' : 'CLOSED';
        doorPill.className = slot.doorStatus ? 'door-pill door-open' : 'door-pill door-close';
        
        const slotTempText = `${((slot.slotTemperature || 0) / 10).toFixed(1)} °C`;

        if (slot.batteryPresent) {
            filledState.style.display = 'flex';
            emptyState.style.display = 'none';
            
            // Update the detailed view
            card.querySelector('.slot-temp').textContent = slotTempText;
                        card.querySelector('.bat-id-big').textContent = slot.batteryIdentification || '—';
                card.querySelector('.soc').textContent = `${slot.soc || 0}%`;
                
                // --- Populate the detailed view ---
                card.querySelector('.bat-id-big').textContent = slot.batteryIdentification || '—';
                card.querySelector('.soc').textContent = `${slot.soc || 0}%`;
                card.querySelector('.voltage').textContent = `${((slot.voltage || 0) / 1000).toFixed(1)} V`;
                card.querySelector('.bat-temp').textContent = `${((slot.batteryMaxTemp || 0) / 10).toFixed(1)} °C`;
                card.querySelector('.bat-fault').textContent = slot.batteryFaultCode || '—';

                card.querySelector('.current').textContent = `${((slot.current || 0) / 1000).toFixed(1)} A`;
                card.querySelector('.slot-temp').textContent = `${((slot.slotTemperature || 0) / 10).toFixed(1)} °C`;
                card.querySelector('.chg-fault').textContent = slot.chargerFaultCode || '—';

                const batPill = card.querySelector('.battery-status-pill');
                batPill.innerHTML = `<span class="h-2 w-2 rounded-full bg-emerald-400 animate-pulseDot"></span> Present`;
                batPill.className = 'battery-status-pill chip chip-emerald';

                const chgPill = card.querySelector('.charger-status-pill');
                if (slot.chargerMode === 1) {
                    chgPill.innerHTML = `<span class="h-2 w-2 rounded-full bg-sky-400 animate-pulseDot"></span> Charging`;
                    chgPill.className = 'charger-status-pill chip chip-sky';
                } else {
                    chgPill.innerHTML = `<span class="h-2 w-2 rounded-full bg-slate-500"></span> Idle`;
                    chgPill.className = 'charger-status-pill chip chip-slate';
                }

        } else {
            // Show the empty view
            filledState.style.display = 'none';
            emptyState.style.display = 'flex';
            
            // --- DEBUGGING LOGIC ---
            const tempElement = card.querySelector('.slot-temp-empty');
            if (tempElement) {
                tempElement.textContent = slotTempText;
                // console.log(`Chamber ${slot.chamberNo}: Found .slot-temp-empty, setting text to: ${slotTempText}`);
            } else {
                // console.error(`Chamber ${slot.chamberNo}: Element .slot-temp-empty NOT FOUND! Check your HTML template.`);
            }
        }
        
        // Check if the icon library is loaded and then render the icons
        if (typeof lucide !== 'undefined') {
            lucide.createIcons();
        } else {
            console.error('Lucide icon script is not loaded. Please check dashboard.html');
        }
    };

    // --- NEW: Function to decode the SDC and update the UI ---
    const updateDiagnosticsUI = (sdcCode) => {
        if (!diagFlagsGrid) return;
        diagFlagsGrid.innerHTML = ''; // Clear previous statuses

        DIAGNOSTIC_ERRORS.forEach((errorText, index) => {
            // Use bitwise AND to check if the bit at this index is set
            const isActive = (sdcCode & (1 << index)) !== 0;

            const div = document.createElement('div');
            div.textContent = errorText;
            
            // Apply different styles based on whether the alarm is active
            if (isActive) {
                div.className = 'text-rose-300 text-center font-semibold';
            } else {
                div.className = 'text-slate-500 text-center';
            }
            diagFlagsGrid.appendChild(div);
        });
    };

    const resetDashboardUI = () => {
        grid.querySelectorAll('.chamber-card').forEach(card => {
            card.querySelector('.bat-id-big').textContent = 'Waiting...';
            card.querySelector('.soc').textContent = '—';
            card.querySelector('.voltage').textContent = '—';
            card.querySelector('.bat-temp').textContent = '—';
            card.querySelector('.bat-fault').textContent = '—';
            card.querySelector('.current').textContent = '—';
            card.querySelector('.slot-temp').textContent = '—';
            card.querySelector('.chg-fault').textContent = '—';
            
            // Show the "empty" view by default when resetting
            card.querySelector('.filled-state').style.display = 'none';
            card.querySelector('.empty-state').style.display = 'flex';
        });
        logToInstance("Station is offline. Clearing stale data.", "error");
    };

    // --- NEW: This function polls the API for the true station status ---
    const checkStationStatus = async () => {
        if (!selectedStation) return;
        try {
            const response = await fetch(`${API_BASE}/stations`);
            if (!response.ok) return;
            const stations = await response.json();
            const thisStation = stations.find(s => s.id === selectedStation.id);

            if (thisStation && connChip) {

                stationNameEl.textContent = thisStation.name;
                stationLocationEl.textContent = thisStation.location;

                if (thisStation.status === 'Online') {
                    connChip.innerHTML = `<span class="h-2 w-2 rounded-full bg-emerald-400 animate-pulseDot"></span> Online`;
                    connChip.className = 'cham_chip cham_chip-emerald';
                } else {
                    connChip.innerHTML = `<span class="h-2 w-2 rounded-full bg-rose-500"></span> Offline`;
                    connChip.className = 'cham_chip cham_chip-rose';
                    lastUpdateEl.textContent = "Waiting for data...";
                    resetDashboardUI();
                }
            }
        } catch (error) {
            console.error("Failed to fetch station status:", error);
        }
    };

    // --- DOWNLOAD MODAL LOGIC ---
    const showDownloadModal = () => {
        const modalOverlay = document.createElement('div');
        modalOverlay.className = "fixed inset-0 bg-black/70 backdrop-blur-sm flex items-center justify-center z-50";
        
        modalOverlay.innerHTML = `
            <div class="bg-slate-800 border border-slate-700 rounded-lg shadow-xl p-6 w-full max-w-md">
                <h3 class="text-lg font-bold text-white mb-4">Export Logs</h3>
                <div class="space-y-4">
                    <div>
                        <label class="block text-sm font-medium text-gray-300 mb-2">Quick Time Ranges</label>
                        <div class="grid grid-cols-3 gap-2">
                            <button data-range="1" class="time-range-btn btn btn-ghost !py-1.5">Last Hour</button>
                            <button data-range="6" class="time-range-btn btn btn-ghost !py-1.5">Last 6 Hours</button>
                            <button data-range="24" class="time-range-btn btn btn-ghost !py-1.5">Last 24 Hours</button>
                            <button data-range="today" class="time-range-btn btn btn-ghost !py-1.5">Today</button>
                            <button data-range="yesterday" class="time-range-btn btn btn-ghost !py-1.5">Yesterday</button>
                        </div>
                    </div>
                    <div>
                        <label for="log-type" class="block text-sm font-medium text-gray-300">Log Type</label>
                        <select id="log-type" class="mt-1 block w-full bg-slate-700 border-slate-600 rounded-md p-2 text-white">
                            <option value="PERIODIC">Periodic Data</option>
                            <option value="EVENT">Events & RPC</option>
                        </select>
                    </div>
                    <div>
                        <label for="start-datetime" class="block text-sm font-medium text-gray-300">Start Date & Time</label>
                        <input type="text" id="start-datetime" class="mt-1 block w-full bg-slate-700 border-slate-600 rounded-md p-2 text-white">
                    </div>
                    <div>
                        <label for="end-datetime" class="block text-sm font-medium text-gray-300">End Date & Time</label>
                        <input type="text" id="end-datetime" class="mt-1 block w-full bg-slate-700 border-slate-600 rounded-md p-2 text-white">
                    </div>
                </div>
                <div class="mt-6 flex justify-end gap-3">
                    <button id="cancel-download" class="btn btn-ghost px-4 py-2">Cancel</button>
                    <button id="confirm-download" class="btn btn-primary px-4 py-2">Download CSV</button>
                </div>
            </div>
        `;
        document.body.appendChild(modalOverlay);

        const startInput = document.getElementById('start-datetime');
        const endInput = document.getElementById('end-datetime');

        // --- NEW: Initialize flatpickr on the inputs ---
        const fpConfig = {
            enableTime: true,
            dateFormat: "Y-m-d\\TH:i", // Format needed by the backend
            time_24hr: true
        };
        const fpStart = flatpickr(startInput, fpConfig);
        const fpEnd = flatpickr(endInput, fpConfig);
        
        // --- (The rest of the function is the same) ---
        const now = new Date();
        const oneHourAgo = new Date(now.getTime() - 3600 * 1000);
        fpStart.setDate(oneHourAgo, true);
        fpEnd.setDate(now, true);

        modalOverlay.querySelectorAll('.time-range-btn').forEach(button => {
            button.addEventListener('click', () => {
                const range = button.dataset.range;
                const now = new Date();
                let start = new Date();

                if (range === 'today') {
                    start.setHours(0, 0, 0, 0);
                } else if (range === 'yesterday') {
                    start.setDate(start.getDate() - 1);
                    start.setHours(0, 0, 0, 0);
                    now.setDate(now.getDate() - 1);
                    now.setHours(23, 59, 59, 999);
                } else {
                    start.setHours(now.getHours() - parseInt(range, 10));
                }
                
                fpStart.setDate(start, true);
                fpEnd.setDate(now, true);
            });
        });

    document.getElementById('cancel-download').onclick = () => document.body.removeChild(modalOverlay);
        
    document.getElementById('confirm-download').onclick = async () => {
        const logType = document.getElementById('log-type').value;
        const startDateStr = document.getElementById('start-datetime').value;
        const endDateStr = document.getElementById('end-datetime').value;
        const confirmBtn = document.getElementById('confirm-download');

        if (!startDateStr || !endDateStr) {
            alert('Please select both a start and end date/time.');
            return;
        }

        // --- Validation Logic ---
        const selectedStartDate = new Date(startDateStr);
        const selectedEndDate = new Date(endDateStr);
        const currentDate = new Date();

        if (selectedStartDate > currentDate) {
            alert('Error: The start date cannot be in the future.');
            return; 
        }
        if (selectedEndDate > currentDate) {
            alert('Error: The end date cannot be in the future.');
            return;
        }
        if (selectedStartDate >= selectedEndDate) {
            alert('Error: The start date must be earlier than the end date.');
            return;
        }

        // --- Fetch and Download Logic ---
        confirmBtn.textContent = 'Fetching...';
        confirmBtn.disabled = true;

        const downloadUrl = `${API_BASE}/logs/export?station_id=${selectedStation.id}&start_datetime=${startDateStr}&end_datetime=${endDateStr}&log_type=${logType}`;
        
        try {
            const response = await fetch(downloadUrl);
            
            if (response.ok) { // Status 200, CSV file received
                const blob = await response.blob();
                const url = window.URL.createObjectURL(blob);
                const a = document.createElement('a');
                a.style.display = 'none';
                a.href = url;
                
                const logType = document.getElementById('log-type').value;
                const dateStr = startDateStr.split('T')[0]; // Get just the date part
                let filename = `${selectedStation.name || selectedStation.id}_${logType}_${dateStr}.csv`; 
                
                const disposition = response.headers.get('Content-Disposition');
                if (disposition && disposition.indexOf('attachment') !== -1) {
                    const filenameMatch = disposition.match(/filename="(.+?)"/);
                    if (filenameMatch && filenameMatch.length === 2) {
                        filename = filenameMatch[1];
                    }
                }
                a.download = filename;
                
                document.body.appendChild(a);
                a.click();
                window.URL.revokeObjectURL(url);
                document.body.removeChild(a);
                document.body.removeChild(modalOverlay);

            } else { // Status 404, no data found
                const errorData = await response.json();
                alert(`Could not download: ${errorData.message}`);
            }
        } catch (error) {
            alert('An unexpected error occurred. Please check the console.');
            console.error('Download error:', error);
        } finally {
            confirmBtn.textContent = 'Download CSV';
            confirmBtn.disabled = false;
        }
    };
    };

    // --- MAIN LOGIC (Your original code is unchanged) ---
   const initializeDashboard = () => {
        try {
            selectedStation = JSON.parse(localStorage.getItem('selected_station'));
            if (!selectedStation || !selectedStation.id) {
                window.location.href = './index.html';
            }
            stationNameEl.textContent = selectedStation.name || 'Unknown Station';
            stationLocationEl.textContent = selectedStation.location || 'No location';
            deviceIdEl.textContent = selectedStation.id;
        } catch (e) {
            document.body.innerHTML = `<div class="text-center p-8 text-rose-400">${e.message} <a href="./station_selection.html" class="underline">Go Back</a></div>`;
            return;
        }

        grid.innerHTML = '';
        for (let i = 1; i <= 9; i++) {
            const node = chamberTmpl.content.cloneNode(true);
            const card = node.querySelector('.chamber-card');
            card.dataset.chamberId = i;
            card.querySelector('.slotNo').textContent = i;
            grid.appendChild(node);
        }

        logToInstance(`Dashboard initialized for station: ${selectedStation.name} (${selectedStation.id})`);

        // --- EVENT LISTENERS ---

        // NEW: A single, global click listener for all button feedback
        document.addEventListener('click', (event) => {
            const button = event.target.closest('.btn');
            if (button) {
                applyButtonFeedback(button);
            }
        });

        // Chamber Card and Swap Selection
        document.querySelectorAll('.chamber-card').forEach(card => {
            // Listener for swap selection
            card.addEventListener('click', () => handleChamberClick(parseInt(card.dataset.chamberId, 10)));
            
            // Listeners for command buttons inside the card
            card.querySelectorAll('.btn').forEach(btn => {
                btn.addEventListener('click', (e) => {
                    e.stopPropagation();
                    const commandText = e.currentTarget.textContent.trim();
                    const command = commandText.replace(' ', '_');
                    const chamberNum = parseInt(e.currentTarget.closest('.chamber-card').dataset.chamberId, 10);

                    if (command === 'OPEN') {
                        if (confirm(`Are you sure you want to open door for Chamber ${chamberNum}?`)) {
                            sendCommand(command, chamberNum);
                        } else {
                            logToInstance(`Open Door command for Chamber ${chamberNum} cancelled.`);
                        }
                    } else {
                        sendCommand(command, chamberNum);
                    }
                });
            });
        });

        // Swap Panel Buttons
        if (clearSwapBtn) clearSwapBtn.addEventListener('click', clearSelection);
        if (startSwapBtn) {
            startSwapBtn.addEventListener('click', () => {
                if (swapPairs.length > 0) {
                    const formattedPairs = swapPairs.map(p => `[${p[0]},${p[1]}]`).join(',');
                    sendCommand('START_SWAP', formattedPairs);
                    clearSelection();
                }
            });
        }
        if (abortSwapBtn) abortSwapBtn.addEventListener('click', () => sendCommand('ABORT_SWAP'));
        if (resetBtn) {
            resetBtn.addEventListener('click', () => { 
                if (confirm('Are you sure you want to reset the station?')) {
                    sendCommand('STATION_RESET');
                }
            });
        }
        
        // Header Buttons
        if (refreshBtn) refreshBtn.addEventListener('click', () => window.location.reload());
        if (logoutBtn) {
            logoutBtn.addEventListener('click', () => {
                localStorage.clear(); 
                window.location.href = './index.html';
            });
        }
        if (downloadBtn) downloadBtn.addEventListener('click', showDownloadModal);
        
        // Audio Command Button (assuming it exists in your HTML)
        const sendAudioBtn = document.getElementById('send-audio-btn');
        if (sendAudioBtn) {
            sendAudioBtn.addEventListener('click', () => {
                const language = document.getElementById('audio-command-select').value;
                sendCommand('LANGUAGE_UPDATE', language);
            });
        }

        updateSwapUI();
        connectSocket();
        checkStationStatus();
        statusPollingInterval = setInterval(checkStationStatus, 10000);
    };

    const connectSocket = () => {
        socket = io();

        // --- CHANGED: No longer sets status to "Online" on its own ---
        socket.on('connect', () => {
            logToInstance("Successfully connected to the backend WebSocket.");
            socket.emit('join_station_room', { station_id: selectedStation.id });
        });

        // --- CHANGED: Sets status to "Offline" correctly on disconnect ---
        socket.on('disconnect', () => {
            logToInstance("Disconnected from the backend WebSocket.", "error");
            connChip.innerHTML = `<span class="h-2 w-2 rounded-full bg-rose-500"></span> Offline`;
            connChip.className = 'cham_chip cham_chip-rose';
        });
        
        socket.on('dashboard_update', (message) => {
            // console.log("DEBUG: Received 'dashboard_update' message:", message);
            const { stationId, data } = message;

            if (stationId !== selectedStation.id) {
                console.warn(`Ignoring message for wrong station. Expected ${selectedStation.id}, got ${stationId}`);
                return;
            }

            lastUpdateEl.textContent = `Last Recv ${new Date().toLocaleTimeString()}`;
            stationDiagCodeEl.textContent = data.stationDiagnosticCode || '—';
            
            // Show/hide the backup power chip based on the payload data
            if (data.backupSupplyStatus === 1) {
                backupPowerChip.textContent = 'On Backup';
                backupPowerChip.className = 'cham_chip w-full justify-center mt-3 cham_chip-amber';
            } else {
                backupPowerChip.textContent = 'On Mains Power';
                backupPowerChip.className = 'cham_chip w-full justify-center mt-3 cham_chip-emerald';
            }
            
            lastUpdateEl.textContent = new Date().toLocaleTimeString();
            stationDiagCodeEl.textContent = data.stationDiagnosticCode || '—';

            // --- NEW: Call the function to update the diagnostics grid ---
            updateDiagnosticsUI(data.stationDiagnosticCode || 0);
            
            if (data.slotLevelPayload && Array.isArray(data.slotLevelPayload)) {
                data.slotLevelPayload.forEach((slotData, index) => {
                    const slotId = index + 1;
                    chamberData[slotId - 1] = slotData; // Keep live data in sync
                    const card = grid.querySelector(`.chamber-card[data-chamber-id="${slotId}"]`);
                    if (card) {
                        updateChamberUI(card, slotData);
                    }
                });
            }
        });

    };
    // --- SCRIPT EXECUTION ---
    initializeDashboard();
});