<?php

// Database configuration
define('DB_HOST', getenv('DB_HOST') ?: '127.0.0.1');
define('DB_PORT', getenv('DB_PORT') ?: '3306');
define('DB_NAME', getenv('DB_NAME') ?: 'main');
define('DB_USER', getenv('DB_USER') ?: 'admin');
define('DB_PASS', getenv('DB_PASS') ?: 'admin');

if (!function_exists('db')) {
    /**
     * Establishes a PDO database connection.
     *
     * @return PDO The PDO database connection object.
     * @throws PDOException If the connection fails.
     */
    function db(): PDO
    {
        static $pdo = null;

        if ($pdo === null) {
            $dsn = 'mysql:host=' . DB_HOST . ';port=' . DB_PORT . ';dbname=' . DB_NAME . ';charset=utf8mb4';
            $options = [
                PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES   => false,
            ];

            try {
                $pdo = new PDO($dsn, DB_USER, DB_PASS, $options);
            } catch (PDOException $e) {
                // In a real app, you would log this error and show a generic error page.
                // For development, it's okay to show the error.
                throw new PDOException($e->getMessage(), (int)$e->getCode());
            }
        }

        return $pdo;
    }
}