<?php

class Session
{
	private static $instance = null;

	private function __construct()
	{
		if (session_status() == PHP_SESSION_NONE)
			session_start();
	}

	public static function get()
	{
		if (self::$instance == null) {
			self::$instance = new Session();
		}

		return self::$instance;
	}

	public function sign_in(User $user)
	{
		$_SESSION['signed_in'] = true;
		$_SESSION['user_id'] = $user->id;
		$_SESSION['user_name'] = $user->name;
	}

	public function sign_out()
	{
		session_unset();
		session_destroy();
	}

	public function is_signed_in(): bool
	{
		return isset($_SESSION['signed_in']);
	}

	public function get_current_user()
	{
		// There is no current user
		if (!$this->is_signed_in()) {
			return null;
		}

		$result = new User();

		if (isset($_SESSION['user_id'])) {
			$result->get_by_id($_SESSION['user_id']);
		} else {
			$result = null;
		}

		return $result;
	}
}