Database.php

<?php

class Database {
    private string $username;
    private string $password;
    private string $host;
    private string $database;
    private string $port;

    private ?PDO $conn = null;

    public function __construct(
        string $username,
        string $password,
        string $host,
        string $database,
        string $port
    ) {
        $this->username = $username;
        $this->password = $password;
        $this->host     = $host;
        $this->database = $database;
        $this->port     = $port;
    }

    public function connect() {
        if ($this->conn === NULL) {
            try {
                $this->conn = new PDO(
                    "pgsql:host=$this->host;port=$this->port;dbname=$this->database",
                    $this->username,
                    $this->password,
                    ["sslmode"  => "prefer"]
                );

                $this->conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
                return $this->conn;
            } catch(PDOException $e) {
                throw new RuntimeException('Could not connect to the database.', previous: $e);
            }
        }
        return $this->conn;
    }

    public function disconnect(): void {
        $this->conn = null;
    }
}