<?php
function db() {
    static $p;
    if ($p) return $p;

    // Read credentials from environment variables
    $dbName = getenv('DB_NAME') ?: 'my_database';
    $dbHost = getenv('DB_HOST') ?: '127.0.0.1';
    $dbPort = getenv('DB_PORT') ?: '3306';
    $dbUser = getenv('DB_USER') ?: 'user';
    $dbPass = getenv('DB_PASS') ?: 'password';

    $dsn = "mysql:host={$dbHost};port={$dbPort};dbname={$dbName};charset=utf8mb4";

    try {
        $p = new PDO($dsn, $dbUser, $dbPass, [
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            PDO::ATTR_EMULATE_PREPARES => false,
        ]);
        return $p;
    } catch (PDOException $e) {
        // In a real app, you'd log this error and show a generic message
        throw new PDOException($e->getMessage(), (int)$e->getCode());
    }
}