/**
 * Common Utilities for OpenVPN Monitor
 */

// --- Global Variables ---
var currentTheme = localStorage.getItem('theme') || 'light';

// --- Theme Functions ---
function initTheme() {
    document.documentElement.setAttribute('data-theme', currentTheme);
    const icon = document.getElementById('themeIcon');
    if (icon) {
        if (currentTheme === 'dark') {
            // In dark mode we want Sun icon (to switch to light)
            if (icon.classList.contains('fa-moon')) icon.classList.replace('fa-moon', 'fa-sun');
            else icon.classList = 'fas fa-sun';
        } else {
            // In light mode we want Moon icon (to switch to dark)
            if (icon.classList.contains('fa-sun')) icon.classList.replace('fa-sun', 'fa-moon');
            else icon.classList = 'fas fa-moon';
        }
    }
}

function toggleTheme(callback = null) {
    currentTheme = currentTheme === 'light' ? 'dark' : 'light';
    localStorage.setItem('theme', currentTheme);
    initTheme();
    if (callback) callback();
}

// --- Formatting Functions ---
function formatBytes(bytes, decimals = 2) {
    if (bytes === 0) return '0 B';
    const k = 1024;
    const dm = decimals < 0 ? 0 : decimals;
    const sizes = ['B', 'KB', 'MB', 'GB', 'TB'];
    const i = Math.floor(Math.log(bytes) / Math.log(k));
    return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
}

function formatRate(rate) {
    return parseFloat(rate).toFixed(3) + ' Mbps';
}

function parseServerDate(dateStr) {
    if (!dateStr) return null;
    let isoStr = dateStr.replace(' ', 'T');
    if (!isoStr.endsWith('Z') && !isoStr.includes('+')) {
        isoStr += 'Z';
    }
    return new Date(isoStr);
}

function formatCertDate(dateString) {
    if (!dateString || dateString === 'N/A') return 'N/A';

    try {
        // Handle OpenSSL date format: "Jun  9 08:37:28 2024 GMT"
        if (dateString.includes('GMT')) {
            const months = {
                'Jan': '01', 'Feb': '02', 'Mar': '03', 'Apr': '04',
                'May': '05', 'Jun': '06', 'Jul': '07', 'Aug': '08',
                'Sep': '09', 'Oct': '10', 'Nov': '11', 'Dec': '12'
            };

            const parts = dateString.split(' ');
            const month = months[parts[0]];
            const day = parts[1].padStart(2, '0');
            const year = parts[3];
            const time = parts[2];

            return `${day}-${month}-${year} ${time}`;
        }

        // Try to parse as ISO date or other format
        const date = new Date(dateString);
        if (!isNaN(date.getTime())) {
            return date.toLocaleDateString('en-GB', {
                day: '2-digit',
                month: 'short',
                year: 'numeric',
                hour: '2-digit',
                minute: '2-digit',
                hour12: false
            }).replace(',', '');
        }

        return dateString;
    } catch (error) {
        console.log('Date formatting error:', error, 'for date:', dateString);
        return dateString;
    }
}