// Escape for safe HTML text content (prevents XSS when inserting into HTML)
function escapeHtml(text) {
    if (text == null) return '';
    const s = String(text);
    return s
        .replace(/&/g, '&')
        .replace(/</g, '&lt;')
        .replace(/>/g, '&gt;')
        .replace(/"/g, '&quot;')
        .replace(/'/g, '&#39;');
}

// Format bytes to GB (matches Django convert_bytes filter default)
function formatBytes(bytes, targetUnit = 'GB') {
    if (bytes == null || isNaN(Number(bytes))) return '0';
    const b = Number(bytes);
    const factors = { B: 1, KB: 1024, MB: 1024 * 1024, GB: 1024 ** 3, TB: 1024 ** 4 };
    const unit = (targetUnit || 'GB').toUpperCase();
    const factor = factors[unit] || factors.GB;
    return (b / factor).toFixed(1);
}

// Color utilities
const getCSSVar = (varName) => {
    return getComputedStyle(document.documentElement).getPropertyValue(varName).trim();
}
function getColorWithOpacity(className) {
    const element = document.createElement('div');
    element.className = className;
    element.style.opacity = '1'; // Force opacity
    element.textContent = '.';
    
    document.body.appendChild(element);
    const computedColor = window.getComputedStyle(element).color;
    document.body.removeChild(element);
    
    return computedColor;
}
// Format audit date for display (ISO string -> short date, e.g. "Feb 1")
function formatAuditDate(isoString) {
    if (!isoString) return '';
    try {
        return new Date(isoString).toLocaleDateString('en-US', { month: 'short', day: 'numeric' });
    } catch (e) {
        return '';
    }
}

// Utility function to calculate mean and standard deviation
function calculateStats(data) {
    if (!data || data.length === 0) return { mean: 0, std: 0 };
    
    const mean = data.reduce((a, b) => a + b, 0) / data.length;
    const variance = data.reduce((a, b) => a + Math.pow(b - mean, 2), 0) / data.length;
    const std = Math.sqrt(variance);
    
    return { mean, std };
}