<?php
/**
 * Database Backup Helper
 * 
 * Provides functionality to back up the current database to the /backups directory.
 */

function backup_db() {
    // Determine path to backups directory (relative to db/config.php's folder)
    $backups_dir = realpath(__DIR__ . '/../backups');
    
    // Ensure the backups directory exists
    if (!$backups_dir) {
        $backups_dir = __DIR__ . '/../backups';
        if (!is_dir($backups_dir)) {
            if (!mkdir($backups_dir, 0775, true)) {
                throw new Exception("Could not create backups directory: $backups_dir");
            }
        }
        $backups_dir = realpath($backups_dir);
    }

    // Load DB config if not already loaded (might be called from various places)
    require_once __DIR__ . '/config.php';

    $timestamp = date('Y-m-d_H-i-s');
    $filename = "backup_{$timestamp}.sql";
    $filepath = "{$backups_dir}/{$filename}";

    // Use mysqldump to create the backup
    $command = sprintf(
        'mysqldump --host=%s --user=%s --password=%s %s > %s 2>&1',
        escapeshellarg(DB_HOST),
        escapeshellarg(DB_USER),
        escapeshellarg(DB_PASS),
        escapeshellarg(DB_NAME),
        escapeshellarg($filepath)
    );

    $output = [];
    $return_var = null;
    exec($command, $output, $return_var);

    if ($return_var !== 0) {
        $error_msg = implode("\n", $output);
        throw new Exception("Database backup failed with exit code {$return_var}: " . $error_msg);
    }

    // Automatic cleanup: keep only the last 5 backups
    cleanup_backups($backups_dir, 5);

    return [
        'filename' => $filename,
        'filepath' => $filepath,
        'size' => filesize($filepath)
    ];
}

/**
 * Cleanup old backups, keeping only the most recent $keep_count files.
 * 
 * @param string $backups_dir Path to backups directory
 * @param int $keep_count Number of backups to retain
 */
function cleanup_backups($backups_dir, $keep_count = 5) {
    $files = glob("{$backups_dir}/backup_*.sql");
    
    // Sort by modification time (newest first)
    usort($files, function($a, $b) {
        return filemtime($b) - filemtime($a);
    });

    // Remove files beyond the keep count
    if (count($files) > $keep_count) {
        $files_to_remove = array_slice($files, $keep_count);
        foreach ($files_to_remove as $file) {
            if (is_file($file)) {
                unlink($file);
            }
        }
    }
}