<?php

/**
 * Create a timestamped backup of a zonefile.
 *
 * Backup format:
 *   /var/named/chroot/var/named/backups/<zone>_YYYYMMDD_HHMMSS.hosts
 *
 * @param string $zoneDir   Base zone directory
 * @param string $zone      Zone name (example.com)
 * @return string|null      Path to backup file or null on failure
 */
function backup_zonefile(string $zoneDir, string $zone): ?string {
    $backupDir = $zoneDir . '/backups';

    // Ensure backup directory exists
    if (!is_dir($backupDir)) {
        if (!mkdir($backupDir, 0755, true) && !is_dir($backupDir)) {
            return null;
        }
    }

    $timestamp = date('Ymd_His');
    $src       = "$zoneDir/$zone.hosts";
    $dst       = "$backupDir/{$zone}_{$timestamp}.hosts";

    // Source must exist
    if (!file_exists($src)) {
        return null;
    }

    // Copy backup
    if (!copy($src, $dst)) {
        return null;
    }

    return $dst;
}

/**
 * Get the latest backup file for a zone.
 *
 * @param string $zoneDir
 * @param string $zone
 * @return string|null
 */
function get_latest_backup(string $zoneDir, string $zone): ?string {
    $backupDir = $zoneDir . '/backups';
    $pattern   = "{$backupDir}/{$zone}_*.hosts";

    $files = glob($pattern);
    if (!$files) {
        return null;
    }

    sort($files);
    return end($files);
}