<?php
/**
 * 数据库：PDO 单例。
 * 只依赖 config.php 里的 db 配置，方言差异集中在这里。
 */

declare(strict_types=1);

namespace App;

use PDO;

final class Database
{
    /** @var PDO|null */
    private static $pdo = null;

    public static function get(): PDO
    {
        if (self::$pdo instanceof PDO) {
            return self::$pdo;
        }
        $c = $GLOBALS['config']['db'];
        $dsn = sprintf(
            'mysql:host=%s;port=%d;dbname=%s;charset=%s',
            $c['host'],
            $c['port'],
            $c['name'],
            $c['charset']
        );
        self::$pdo = new PDO($dsn, $c['user'], $c['pass'], [
            PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            PDO::ATTR_EMULATE_PREPARES   => false,
        ]);
        return self::$pdo;
    }

    /** 表是否存在（安装判定用，不依赖异常） */
    public static function hasTables(): bool
    {
        try {
            $st = self::get()->prepare(
                'SELECT COUNT(*) FROM information_schema.tables
                 WHERE table_schema = DATABASE() AND table_name IN
                 (\'families\',\'persons\',\'accounts\',\'settings\')'
            );
            $st->execute();
            return (int)$st->fetchColumn() === 4;
        } catch (\Throwable $e) {
            return false;
        }
    }
}