<?php
/**
 * Database Connection Class
 * Uses PDO for secure MySQL connections
 */

class Database {
    private static $instance = null;
    private $conn;
    
    private function __construct() {
        try {
            $dsn = "mysql:host=" . DB_HOST . ";dbname=" . DB_NAME . ";charset=" . DB_CHARSET;
            $options = [
                PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES => false,
            ];
            
            $this->conn = new PDO($dsn, DB_USER, DB_PASS, $options);
        } catch (PDOException $e) {
            $this->handleError($e->getMessage());
        }
    }
    
    public static function getInstance() {
        if (self::$instance === null) {
            self::$instance = new self();
        }
        return self::$instance;
    }
    
    public function getConnection() {
        return $this->conn;
    }
    
    private function handleError($message) {
        if (DEBUG_MODE) {
            die(json_encode(['error' => 'Database Error: ' . $message]));
        } else {
            die(json_encode(['error' => 'Database connection failed']));
        }
    }
    
    // Prevent cloning
    private function __clone() {}
    
    // Prevent unserialization
    public function __wakeup() {
        throw new Exception("Cannot unserialize singleton");
    }
}