<?php
session_start();
header('Content-Type: application/json');

if (!isset($_SESSION["user_id"]) || ($_SESSION["user_role"] ?? '') !== 'Super User') {
    echo json_encode(['success' => false, 'error' => 'Unauthorized']);
    exit;
}

require_once '../db/config.php';
require_once '../db/backup_helper.php';

try {
    $db = db();
    
    // 1. Perform database backup before migrations
    $backup_info = backup_db();
    
    // 2. Ensure migration_history table exists
    $db->exec("CREATE TABLE IF NOT EXISTS migration_history (
        id INT AUTO_INCREMENT PRIMARY KEY,
        filename VARCHAR(255) NOT NULL UNIQUE,
        executed_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;");

    // 3. Scan migrations directory
    $migrations_dir = __DIR__ . '/../db/migrations/';
    $migration_files = glob($migrations_dir . '*.sql');
    sort($migration_files);

    // 4. Get list of already executed migrations
    $stmt = $db->query("SELECT filename FROM migration_history");
    $executed_migrations = $stmt->fetchAll(PDO::FETCH_COLUMN);

    $executed_count = 0;
    $skipped_count = 0;
    $new_migrations = [];

    foreach ($migration_files as $file_path) {
        $filename = basename($file_path);
        
        if (in_array($filename, $executed_migrations)) {
            $skipped_count++;
            continue;
        }

        $sql = file_get_contents($file_path);
        if ($sql) {
            // Execute migration
            $db->exec($sql);
            
            // Record migration in history
            $stmt = $db->prepare("INSERT INTO migration_history (filename) VALUES (?)");
            $stmt->execute([$filename]);
            
            $executed_count++;
            $new_migrations[] = $filename;
        }
    }

    echo json_encode([
        'success' => true, 
        'message' => "Backup and migration process complete.",
        'backup' => $backup_info['filename'],
        'executed' => $executed_count,
        'skipped' => $skipped_count,
        'new_migrations' => $new_migrations
    ]);
} catch (Exception $e) {
    echo json_encode([
        'success' => false, 
        'error' => 'Migration/Backup failed: ' . $e->getMessage()
    ]);
}