web/app/core/Database.php

<?php

// Encapsulates a single connection to a database
// TODO: refactor and add different driver implementations
class Database
{
    public PDO $conn;

    public function __construct(array $config)
    {
        if ($config['name'] !== 'mysql')
        {
            throw new Exception("Database error: ".$config['name']." is not implemented");
        }

        try {
            $this->conn = $this->connectWithMySQL($config['args']);
        } catch (PDOException $e) {
            throw new PDOException("Database error: " . $e->getMessage());
        }
    }

    private function connectWithMySQL(array $args): object 
    {
        $dsn = "mysql:host={$args['host']};dbname={$args['database']};charset={$args['charset']}";
        $options = [
            PDO::ATTR_PERSISTENT => true,
        ];
        return new PDO($dsn, $args['user'], $args['password'], $options);
    }
}