<?php
/**
 * Database Singleton — PDO Connection
 */

require_once __DIR__ . '/../config.php';

class Database
{
    private static ?PDO $instance = null;

    private function __construct()
    {
        try {
            $dsn = sprintf(
                'mysql:host=%s;dbname=%s;charset=utf8mb4',
                DB_HOST,
                DB_NAME
            );

            self::$instance = new PDO($dsn, DB_USER, DB_PASS, [
                PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES   => false,
                PDO::MYSQL_ATTR_INIT_COMMAND => "SET time_zone = '+03:00'",
            ]);
        } catch (PDOException $e) {
            error_log('Database connection failed: ' . $e->getMessage());
            http_response_code(500);
            echo json_encode(['success' => false, 'message' => 'database_error']);
            exit;
        }
    }

    public static function getInstance(): PDO
    {
        if (self::$instance === null) {
            new self();
        }
        return self::$instance;
    }

    /** Prevent cloning */
    private function __clone() {}
    public function __wakeup()
    {
        throw new \Exception("Cannot unserialize singleton");
    }
}