<?php
// db/config.php

// --- Database Credentials ---
// Note: In a real application, these should be in a .env file or other secure storage.
define('DB_HOST', '127.0.0.1');
define('DB_NAME', 'lamp_app');
define('DB_USER', 'lamp_user');
define('DB_PASS', 'lamp_password');

/**
 * PDO Database Connection Helper
 *
 * Establishes a persistent PDO connection or returns the existing one.
 *
 * @return PDO|null Returns a PDO instance on success or null on failure.
 */
function db(): ?PDO
{
    static $pdo = null;

    if ($pdo !== null) {
        return $pdo;
    }

    $dsn = sprintf('mysql:host=%s;dbname=%s;charset=utf8mb4', DB_HOST, DB_NAME);
    $options = [
        PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
        PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
        PDO::ATTR_EMULATE_PREPARES   => false,
        PDO::ATTR_PERSISTENT         => true, // Use persistent connection
    ];

    try {
        // Create a new database if it doesn't exist
        $tempPdo = new PDO(sprintf('mysql:host=%s;charset=utf8mb4', DB_HOST), DB_USER, DB_PASS, $options);
        $tempPdo->exec("CREATE DATABASE IF NOT EXISTS " . DB_NAME);

        // Now connect to the specific database
        $pdo = new PDO($dsn, DB_USER, DB_PASS, $options);
        return $pdo;
    } catch (PDOException $e) {
        // In a real app, you'd log this error. For this demo, we'll just fail silently.
        // error_log('Database Connection Error: ' . $e->getMessage());
        return null;
    }
}