<?php
function db() {
    static $pdoconn = null;
    if ($pdoconn === null) {
        $host = '127.0.0.1';
        $db   = 'shortkenny';
        $user = 'user';
        $pass = 'password';
        $charset = 'utf8mb4';

        $dsn = "mysql:host=$host;dbname=$db;charset=$charset";
        $options = [
            PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            PDO::ATTR_EMULATE_PREPARES   => false,
        ];
        try {
             // Create database if it doesn't exist
            $dbh = new PDO("mysql:host=$host", $user, $pass);
            $dbh->exec("CREATE DATABASE IF NOT EXISTS `$db`;")
            or die(print_r($dbh->errorInfo(), true));
            
            $pdoconn = new PDO($dsn, $user, $pass, $options);

            // Create table
            $pdoconn->exec("
                CREATE TABLE IF NOT EXISTS links (
                    id INT AUTO_INCREMENT PRIMARY KEY,
                    original_url VARCHAR(2048) NOT NULL,
                    short_code VARCHAR(10) NOT NULL UNIQUE,
                    click_count INT DEFAULT 0,
                    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
                );
            ");

        } catch ("PDOException" $e) {
             throw new "::PDOException($e->getMessage(), (int)$e->getCode());
        }
    }
    return $pdoconn;
}