// --- JWT Constants ---
const JWT_TOKEN_KEY = 'metrics_jwt_token';

// --- Server Stats Logic ---
async function getServerStats() {
    const statusElement = document.getElementById('server-status');
    const uptimeElement = document.getElementById('uptime');

    if (!statusElement || !uptimeElement) {
        return;
    }

    try {
        const response = await fetch('/stat/.server-stats.json'); 
        if (!response || !response.ok) {
            throw new Error(`Could not fetch server stats (status: ${response?.status})`);
        }
        const data = await response.json();

        let status = "green";
        const load1 = parseFloat(data.load_1min);
        const cores = parseInt(data.cores, 10) || 1;

        if (!isNaN(load1)) {
            if (load1 > (cores * 0.7)) status = "yellow";
            if (load1 > (cores * 0.9)) status = "red";
        } else {
            status = "yellow"; 
        }

        statusElement.className = `status-light ${status}`; // More direct class setting
        statusElement.title = status === "green" ? "Server running normally" : 
                             status === "yellow" ? "Server under medium load" :
                             status === "red" ? "Server under heavy load" : "Unknown status";

        uptimeElement.textContent = `Uptime: ${data.uptime || 'Unknown'} (Load: ${data.load_1min || '?'}, ${data.load_5min || '?'}, ${data.load_15min || '?'})`;

        // Store service status in a global variable for later use when metrics are displayed
        window.serviceStatusData = {
            http_status: data.service_http_status,
            ssh_status: data.service_ssh_status
        };
        
        // Update the service status if it's currently visible
        updateServiceStatusDisplay();
        
    } catch (error) {
        statusElement.className = 'status-light yellow';
        statusElement.title = "Status check failed - server may still be operational";
        uptimeElement.textContent = 'Status: Available (Stats unavailable)';
        
        // Clear service status data on error
        window.serviceStatusData = null;
    }
}

// Function to create/update service status display
function updateServiceStatusDisplay() {
    // Only update if metrics section is visible
    if (metricsSection && metricsSection.style.display === 'block' && window.serviceStatusData) {
        let serviceStatusElement = document.getElementById('service-status');
        
        // Create the element if it doesn't exist
        if (!serviceStatusElement) {
            serviceStatusElement = document.createElement('div');
            serviceStatusElement.id = 'service-status';
            serviceStatusElement.className = 'service-status';
            
            // Insert at the beginning of metrics section for better visibility
            if (metricsSection.firstChild) {
                metricsSection.insertBefore(serviceStatusElement, metricsSection.firstChild);
            } else {
                metricsSection.appendChild(serviceStatusElement);
            }
        }
        
        // Update the content
        const httpStatus = window.serviceStatusData.http_status === 1 ? "Up" : "Down";
        const sshStatus = window.serviceStatusData.ssh_status === 1 ? "Up" : "Down";
        
        const httpClass = window.serviceStatusData.http_status === 1 ? "green" : "red";
        const sshClass = window.serviceStatusData.ssh_status === 1 ? "green" : "red";
        
        serviceStatusElement.innerHTML = `
            <div class="service-item">
                <div class="status-light ${httpClass}"></div>
                <span>HTTP: ${httpStatus}</span>
            </div>
            <div class="service-item">
                <div class="status-light ${sshClass}"></div>
                <span>SSH: ${sshStatus}</span>
            </div>
        `;
    }
}

// --- Metrics Authentication & Display Logic ---
const viewMetricsBtn = document.getElementById('view-metrics-btn');
const passwordModal = document.getElementById('password-modal');
const passwordInput = document.getElementById('metrics-password');
const submitPasswordBtn = document.getElementById('submit-password');
const closeModalBtn = document.querySelector('.close-button');
const passwordError = document.getElementById('password-error');
const metricsSection = document.getElementById('metrics-section');
const metricsControls = document.getElementById('metrics-controls'); // Container for buttons

function getToken() {
    return localStorage.getItem(JWT_TOKEN_KEY);
}

function setToken(token) {
    localStorage.setItem(JWT_TOKEN_KEY, token);
}

function removeToken() {
    localStorage.removeItem(JWT_TOKEN_KEY);
}

function showMetrics() {
    if (!metricsSection) {
        return;
    }
    
    metricsSection.style.display = 'block';
    createOrShowHideButton(); 
    
    // Display the service status when metrics are shown
    updateServiceStatusDisplay();
    
    // Initialize metrics UI if not already initialized
    if (!chartsInitialized) {
        initializeMetricsUI();
    } else {
        startDataUpdates();
    }
}

function hideMetrics() {
    if (!metricsSection) return;
    metricsSection.style.display = 'none';
    removeHideButton();
    
    // Remove the service status element when metrics are hidden
    const serviceStatusElement = document.getElementById('service-status');
    if (serviceStatusElement) {
        serviceStatusElement.remove();
    }
    
    if (typeof stopDataUpdates === 'function') {
        stopDataUpdates();
    }
}

function createOrShowHideButton() {
    if (!metricsControls) return;
    let hideBtn = document.getElementById('hide-metrics-btn');
    if (!hideBtn) {
        hideBtn = document.createElement('button');
        hideBtn.id = 'hide-metrics-btn';
        hideBtn.className = 'button';
        hideBtn.textContent = 'Hide Server Metrics';
        hideBtn.style.marginLeft = '10px';
        hideBtn.addEventListener('click', () => {
            removeToken(); // Optionally clear token on hide
            hideMetrics();
        });
        metricsControls.appendChild(hideBtn);
    } 
    hideBtn.style.display = 'inline-block'; // Ensure it's visible
}

function removeHideButton() {
    const hideBtn = document.getElementById('hide-metrics-btn');
    if (hideBtn) {
        hideBtn.remove();
    }
}

function openPasswordModal() {
    if (!passwordModal || !passwordInput || !passwordError) return;
    passwordInput.value = '';
    passwordError.textContent = '';
    passwordError.style.opacity = 0;
    passwordModal.style.display = 'block';
    setTimeout(() => {
        passwordModal.classList.add('show');
        passwordInput.focus();
    }, 10);
}

function closePasswordModal() {
    if (!passwordModal) return;
    passwordModal.classList.remove('show');
    setTimeout(() => {
        passwordModal.style.display = 'none';
    }, 300);
}

async function login() {
    if (!passwordInput || !passwordError) return;
    const password = passwordInput.value;
    if (!password) {
        showPasswordError('Please enter a password');
        return;
    }

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

        if (response.ok) {
            const data = await response.json();
            if (data.token) {
                setToken(data.token); // Store JWT
                closePasswordModal();
                showMetrics();
            } else {
                showPasswordError('Login failed: No token received.');
            }
        } else {
            const errorData = await response.json().catch(() => ({ error: 'Unknown login error' }));
            showPasswordError(`Login failed: ${errorData.error || response.statusText}`);
            passwordInput.value = '';
        }
    } catch (error) {
        showPasswordError('Login request error. Check connection.');
    }
}

function showPasswordError(message) {
    if (!passwordError || !passwordInput) return;
    passwordError.textContent = message;
    passwordError.style.opacity = 1;
    passwordInput.classList.add('shake');
    setTimeout(() => { passwordInput.classList.remove('shake'); }, 500);
}

// --- SNMP Charts Logic ---
const API_ENDPOINT = '/api/metrics';
const UPDATE_INTERVAL = 10000;
const CHART_HISTORY = 60;
let charts = {};
let chartsInitialized = false;
let updateIntervalId;
let metricsDefinitions = {};

const chartColors = {
    networkIn: '#88B7B5', 
    networkOut: '#FDCFF3', 
    cpu: '#88B7B5',
    memory: '#FDCFF3', 
    system: '#88B7B5', 
    generic: '#88B7B5',
    // New colors for application performance metrics
    appResponse: '#4CAF50',  // Green for response time
    appError: '#F44336',     // Red for error rate
    appRequests: '#2196F3',  // Blue for request count
    serviceStatus: '#FF9800' // Orange for service status
};

// formatBytes, formatTime, calculateRates - Keep these utility functions as they were
function formatBytes(bytes, decimals = 2) {
    if (bytes === undefined || bytes === null || bytes === 0) return '0 Bytes';
    const k = 1024, dm = decimals < 0 ? 0 : decimals, sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB'];
    const i = Math.floor(Math.log(Math.abs(bytes)) / Math.log(k));
    return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
}

function formatTime(centiseconds) {
    if (!centiseconds || centiseconds < 0) return '0s';
    const totalSeconds = Math.floor(centiseconds / 100);
    const days = Math.floor(totalSeconds / 86400), hours = Math.floor((totalSeconds % 86400) / 3600);
    const minutes = Math.floor((totalSeconds % 3600) / 60), seconds = totalSeconds % 60;
    if (days > 0) return `${days}d ${hours}h ${minutes}m`;
    if (hours > 0) return `${hours}h ${minutes}m ${seconds}s`;
    if (minutes > 0) return `${minutes}m ${seconds}s`;
    return `${seconds}s`;
}

function calculateRates(data) {
    if (!data || data.length < 2) {
        return [];
    }
    
    const rates = [];
    for (let i = 1; i < data.length; i++) {
        const timeDiff = (data[i].timestamp - data[i-1].timestamp) / 1000;
        const valueDiff = data[i].value - data[i-1].value;
        if (timeDiff < 0.001) continue;
        
        // Detect counter wrap/reset (when a counter resets to 0)
        const rate = valueDiff >= 0 ? 
                      valueDiff / timeDiff : 
                      (4294967295 + valueDiff) / timeDiff;
        
        rates.push({ timestamp: data[i].timestamp, value: rate });
    }
    
    return rates;
}

function createChartContainers(metrics) {
    const metricGrid = document.querySelector('.metric-grid');
    if (!metricGrid) {
        return;
    }
    
    metricGrid.innerHTML = ''; // Clear previous
    charts = {}; // Clear chart objects
    
    // Group the metrics into two sections
    const networkAndSystemMetrics = {};
    const appPerformanceMetrics = {};
    const serviceStatusMetrics = {};
    
    // First categorize the metrics
    for (const [metricName, definition] of Object.entries(metrics)) {
        // Skip system_uptime and memory metrics (as requested)
        if (metricName === 'system_uptime' || 
            metricName.includes('memory_total') || 
            metricName === 'memory_size') {
            continue;
        }
        
        // Categorize based on metric name
        if (metricName.startsWith('app_')) {
            appPerformanceMetrics[metricName] = definition;
        } else if (metricName.startsWith('service_')) {
            serviceStatusMetrics[metricName] = definition;
        } else {
            networkAndSystemMetrics[metricName] = definition;
        }
    }
    
    // Create section headers and containers
    if (Object.keys(networkAndSystemMetrics).length > 0) {
        const sectionHeader = document.createElement('h4');
        sectionHeader.textContent = 'Network & System Metrics';
        sectionHeader.className = 'metric-section-header';
        metricGrid.appendChild(sectionHeader);
        
        // Create containers for network & system metrics
        for (const [metricName, definition] of Object.entries(networkAndSystemMetrics)) {
            createMetricCard(metricGrid, metricName, definition);
        }
    }
    
    // Application Performance section
    if (Object.keys(appPerformanceMetrics).length > 0) {
        const sectionHeader = document.createElement('h4');
        sectionHeader.textContent = 'Application Performance';
        sectionHeader.className = 'metric-section-header';
        metricGrid.appendChild(sectionHeader);
        
        // Create containers for app performance metrics
        for (const [metricName, definition] of Object.entries(appPerformanceMetrics)) {
            createMetricCard(metricGrid, metricName, definition);
        }
    }
    
    // Service Status section (not displayed as a chart - we already added it to server stats)
    // We skip adding charts for service_* metrics
}

function createMetricCard(container, metricName, definition) {
    const displayName = definition.label || metricName;
    const metricCard = document.createElement('div');
    metricCard.className = 'metric-card';
    metricCard.innerHTML = `<h5>${displayName}</h5><div class="chart-container"><canvas id="${metricName}Chart"></canvas></div>`;
    container.appendChild(metricCard);
}

function startDataUpdates() {
    if (updateIntervalId) {
        return;  // Don't start if already running
    }
    
    updateCharts(); 
    updateIntervalId = setInterval(updateCharts, UPDATE_INTERVAL);
}

function stopDataUpdates() {
    if (updateIntervalId) {
        clearInterval(updateIntervalId);
        updateIntervalId = null;
    }
}

async function fetchWithAuth(url, options = {}) {
    const token = getToken();
    const headers = { ...options.headers };
    if (token) {
        headers['Authorization'] = `Bearer ${token}`;
    }
    
    try {
        const response = await fetch(url, { ...options, headers });
        
        if (response.status === 401) {
            // Unauthorized - Token is invalid or expired
            removeToken();
            hideMetrics(); // Hide metrics section
            openPasswordModal(); // Prompt for login
            throw new Error('Unauthorized'); // Prevent further processing
        }
        
        return response;
    } catch (error) {
        throw error;
    }
}

function initCharts(metrics) {
    // Common options are reused from previous logic
    const commonOptions = {
        responsive: true, 
        maintainAspectRatio: false, 
        animation: { duration: 300 },
        scales: {
            x: { 
                type: 'time', 
                time: { unit: 'minute', tooltipFormat: 'HH:mm:ss' }, 
                grid: { color: 'rgba(255, 255, 255, 0.1)' }, 
                ticks: { color: '#E8F1F2', maxTicksLimit: 5 } 
            },
            y: { 
                beginAtZero: true, 
                grid: { color: 'rgba(255, 255, 255, 0.1)' }, 
                ticks: { color: '#E8F1F2' } 
            }
        },
        plugins: {
            legend: { 
                display: true,
                labels: { color: '#E8F1F2', font: { family: "'IBM Plex Sans', sans-serif" } } 
            },
            tooltip: { 
                enabled: true,
                mode: 'index', 
                intersect: false, 
                backgroundColor: 'rgba(17, 17, 17, 0.8)', 
                titleColor: '#FDCFF3', 
                bodyColor: '#E8F1F2', 
                borderColor: '#333', 
                borderWidth: 1 
            }
        }
    };

    for (const [metricName, definition] of Object.entries(metrics)) {
        // Skip system_uptime and memory metrics (as requested)
        if (metricName === 'system_uptime' || 
            metricName.includes('memory_total') || 
            metricName === 'memory_size') {
            continue;
        }
        
        // Skip service status metrics - they're shown in the server stats
        if (metricName.startsWith('service_')) {
            continue;
        }
        
        const canvas = document.getElementById(`${metricName}Chart`);
        if (!canvas) {
            continue;
        }
        
        const ctx = canvas.getContext('2d');
        if (!ctx) {
            continue;
        }
        
        let chartOptions = JSON.parse(JSON.stringify(commonOptions)); // Deep clone options
        let datasets = [];
        let label = definition.label || metricName;
        let color = chartColors.generic;

        // Configure chart based on metric type
        if (metricName === 'network_in' || metricName === 'network_out') {
            chartOptions.scales.y.title = { display: true, text: 'Bytes/sec', color: '#E8F1F2' };
            chartOptions.scales.y.ticks.callback = function(value) { return formatBytes(value, 0); };
            label = metricName === 'network_in' ? 'In' : 'Out';
            color = metricName === 'network_in' ? chartColors.networkIn : chartColors.networkOut;
        } else if (metricName === 'cpu_load') {
            chartOptions.scales.y.title = { display: true, text: 'Load/Usage', color: '#E8F1F2' };
            label = 'CPU'; color = chartColors.cpu;
        } else if (metricName === 'system_processes') {
            chartOptions.scales.y.title = { display: true, text: 'Count', color: '#E8F1F2' };
            label = 'Processes'; color = chartColors.system;
        } 
        // New application performance metrics
        else if (metricName === 'app_response_time_avg') {
            chartOptions.scales.y.title = { display: true, text: 'Time (ms)', color: '#E8F1F2' };
            label = 'Response Time';
            color = chartColors.appResponse;
        } else if (metricName === 'app_error_rate') {
            chartOptions.scales.y.title = { display: true, text: 'Error Rate (%)', color: '#E8F1F2' };
            label = 'Error Rate';
            color = chartColors.appError;
        } else if (metricName === 'app_request_count') {
            chartOptions.scales.y.title = { display: true, text: 'Requests', color: '#E8F1F2' };
            label = 'Request Count';
            color = chartColors.appRequests;
        } else {
            chartOptions.scales.y.title = { display: true, text: 'Value', color: '#E8F1F2' };
        }

        datasets = [{
            label: label,
            borderColor: color, 
            backgroundColor: `${color}33`, 
            borderWidth: 2,
            data: [], 
            pointRadius: 0, 
            fill: true
        }];
        
        // Destroy existing chart if it exists to prevent memory leaks
        if (charts[metricName]) {
            try {
                charts[metricName].destroy();
            } catch (e) {
                // Silent error handling
            }
        }
        
        try {
            charts[metricName] = new Chart(ctx, { 
                type: 'line', 
                data: { datasets }, 
                options: chartOptions 
            });
        } catch (error) {
            // Silent error handling
        }
    }
    
    chartsInitialized = true;
}

// Modified to handle sparse data better
async function updateCharts() {
    // Only run if metrics section is visible
    if (!metricsSection || metricsSection.style.display === 'none') return;
    
    try {
        const response = await fetchWithAuth(API_ENDPOINT);
        if (!response.ok) {
            return; 
        }
        const data = await response.json();
        
        // Combine metrics from both regular metrics and app performance metrics
        const allMetrics = { ...data.metrics };
        
        // Update chart data for each metric
        for (const [metricName, metricData] of Object.entries(allMetrics)) {
            // Skip metrics we're not displaying
            if (!charts[metricName]) {
                continue;
            }
            
            if (!metricData || !Array.isArray(metricData) || metricData.length === 0) {
                continue;
            }
            
            // Process the data
            let chartData;
            
            // For network metrics, try to calculate rates, but fall back to actual values if needed
            if (metricName === 'network_in' || metricName === 'network_out') {
                chartData = calculateRates(metricData);
                
                // If rate calculation failed due to insufficient data, use the raw values directly
                if (!chartData || chartData.length === 0) {
                    chartData = [...metricData];
                }
            } else {
                // For other metrics, use the data directly
                chartData = [...metricData];
            }
            
            if (!chartData || !Array.isArray(chartData) || chartData.length === 0) {
                continue;
            }
            
            // Map the data to chart format
            const formattedData = chartData.map(point => {
                if (!point || typeof point !== 'object' || point.timestamp === undefined || point.value === undefined) {
                    return null;
                }
                
                let value = point.value;
                if (typeof value === 'string') {
                    const match = value.match(/[\d.]+/); // Allow decimals
                    value = match ? parseFloat(match[0]) : 0;
                } else if (typeof value !== 'number') {
                    value = 0;
                }
                
                return { x: point.timestamp, y: value };
            }).filter(point => point !== null);
            
            if (formattedData.length === 0) {
                continue;
            }
            
            // Update the chart - wrap in try/catch to prevent errors from breaking all charts
            try {
                charts[metricName].data.datasets[0].data = formattedData;
                charts[metricName].update('none'); // Use 'none' mode for better performance
            } catch (e) {
                // Silent error handling
            }
        }
    } catch (error) {
        if (error.message !== 'Unauthorized') {
            // Silent error handling
        }
    }
}

// Modified initializeMetricsUI to better handle edge cases
function initializeMetricsUI() {
    if (chartsInitialized) {
        startDataUpdates();
        return;
    }
    
    // Ensure we are authenticated before trying to fetch
    if (!getToken()) {
        openPasswordModal();
        return;
    }
    
    // Fetch metrics data
    fetchWithAuth(API_ENDPOINT)
        .then(response => {
            if (!response.ok) {
                return Promise.reject(new Error(`HTTP error: ${response.status}`));
            }
            return response.json();
        })
        .then(data => {
            if (!data || typeof data !== 'object') {
                return Promise.reject(new Error("Invalid metrics data format"));
            }
            
            if (!data.metrics || !data.definitions) {
                // Create empty objects if missing rather than failing
                data.metrics = data.metrics || {};
                data.definitions = data.definitions || {};
            }
            
            // Store definitions
            metricsDefinitions = data.definitions || {};
            
            // Check specifically for app performance metrics
            const appMetrics = Object.keys(metricsDefinitions)
                .filter(key => key.startsWith('app_'));
            
            if (appMetrics.length === 0) {
                // Add placeholder definitions if they don't exist
                if (!metricsDefinitions['app_response_time_avg']) {
                    metricsDefinitions['app_response_time_avg'] = {
                        label: 'Avg Response Time (ms)',
                        type: 'calculated'
                    };
                }
                
                if (!metricsDefinitions['app_error_rate']) {
                    metricsDefinitions['app_error_rate'] = {
                        label: 'Error Rate (%)',
                        type: 'calculated'
                    };
                }
                
                if (!metricsDefinitions['app_request_count']) {
                    metricsDefinitions['app_request_count'] = {
                        label: 'Request Count',
                        type: 'calculated'
                    };
                }
            }
            
            // Create UI
            createChartContainers(metricsDefinitions);
            initCharts(metricsDefinitions);
            
            // Start updates
            startDataUpdates();
        })
        .catch(error => {
            if (error.message === 'Unauthorized') {
                openPasswordModal();
            } else {
                alert('Error loading metrics. Please try again.');
            }
        });
}

// --- Initial Load Logic ---
document.addEventListener('DOMContentLoaded', function() {
    // Start server stats check immediately and then interval
    getServerStats();
    setInterval(getServerStats, 30000);

    // Style the submit button
    if (submitPasswordBtn) submitPasswordBtn.classList.add('submit-button');
    
    // Event listeners for authentication
    if (viewMetricsBtn) {
        viewMetricsBtn.addEventListener('click', () => {
            // Authenticate and show metrics
            const token = getToken();
            if (token) {
                // Try to initialize/show metrics, fetchWithAuth will handle invalid tokens
                showMetrics(); 
            } else {
                openPasswordModal();
            }
        });
    }
    if (submitPasswordBtn) {
        submitPasswordBtn.addEventListener('click', login);
    }
    if (passwordInput) {
        passwordInput.addEventListener('keyup', (event) => {
            if (event.key === 'Enter') login();
        });
    }
    if (closeModalBtn) {
        closeModalBtn.addEventListener('click', closePasswordModal);
    }
    window.addEventListener('click', (event) => {
        if (event.target === passwordModal) closePasswordModal();
    });

    // Check token on load - attempt to show metrics if token exists
    // initializeMetricsUI() will handle token validation via fetchWithAuth
    if (getToken()) {
        showMetrics();
    } else {
        // Ensure metrics are hidden if no token
        hideMetrics(); 
    }
});