<?php
require_once __DIR__ . "/config.php";

function db() {
    static $pdo = null;
    if ($pdo === null) {
        $dsn = "mysql:host=" . DB_HOST . ";dbname=" . DB_NAME . ";charset=" . DB_CHARSET;
        try {
            $pdo = new PDO($dsn, DB_USER, DB_PASS, [
                PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES => false,
            ]);
        } catch (PDOException $e) {
            die("数据库连接失败: " . htmlspecialchars($e->getMessage()));
        }
    }
    return $pdo;
}