<?php

defined("AUTH_SESSION_VAR_NAME") || define("AUTH_SESSION_VAR_NAME", "user");


if (!isset($_REQUEST["nosess"]))
    session_start();

class Auth {
    /*
     * The Authenticator v3.0 by Gydo194
     * Date: 1611171716
     * Author: Gydo194
     * Description: Simple and efficient authentication mechanism with both session and sessionless mode support.
     */

    /**
     *  The user's username
     * @var string username
     */
    private static $username = "";

    /**
     *
     * @var type string the user's password
     */
    private static $password = "";

    /**
     * Dual purpose; both serves as the user's access level and as an
     * indicator whether the user is logged in.
     *
     * @var int the user's access level
     */
    private static $accessLevel = 0;

    //getters

    public static function getUserName(): string {
        return self::$username;
    }

    public static function getPassword(): string {
        return self::$password;
    }

    public static function getAccessLevel(): int {
        return self::$accessLevel;
    }

    //no public setters on purpose.
    //these vars have to be set by the authentication mechanism itself.

    private static function setUserName(string $user) {
        self::$username = $user;
    }

    private static function setPassword(string $pass) {
        self::$password = $pass;
    }

    private static function setAccessLevel(int $accessLevel) {
        self::$accessLevel = $accessLevel;
    }

    //state getters
    public static function isLoggedIn(): bool {
        return self::$accessLevel > 0 ? true : false;
    }






    /**
     * Gets a request parameter value
     *
     * @param string $param the parameter to get
     * @return string the value of the parameter, "" if not set.
     */
    private static function getRequestParameter(string $param): string {
        switch ($_SERVER["REQUEST_METHOD"]) {
            case "GET":
                if (isset($_GET[$param]))
                    return filter_input(INPUT_GET, $param);
                else
                    return "";
                break;
            case "POST":
                if (isset($_POST[$param]))
                    return filter_input(INPUT_POST, $param);
                else
                    return "";
                break;
        }
        return "";
    }



    //session login handling functions

    /**
     * check if the session hold user data.
     * @return bool
     */
    private static function hasSessionLogin(): bool {
        if (session_id()) {
            if (isset($_SESSION[AUTH_SESSION_VAR_NAME]["access"])) {
                if ($_SESSION[AUTH_SESSION_VAR_NAME] > 0)
                    return true;
            }
        }
        return false;
    }


    private static function getSessionLogin(): void {
        if(!session_id()) return;
        self::setUserName($_SESSION[AUTH_SESSION_VAR_NAME]["user"]);
        self::setPassword($_SESSION[AUTH_SESSION_VAR_NAME]["pass"]);
        self::setAccessLevel($_SESSION[AUTH_SESSION_VAR_NAME]["access"]);
    }

    private static function saveSessionLogin(): void {
        if(!session_id()) return;
        $_SESSION[AUTH_SESSION_VAR_NAME]["user"] = self::getUserName();
        $_SESSION[AUTH_SESSION_VAR_NAME]["pass"] = self::getPassword();
        $_SESSION[AUTH_SESSION_VAR_NAME]["access"] = self::getAccessLevel();
    }





    //credential validating

    private static function validateCredentials(string $user, string $pass): bool {
        //function to be extended
        if ($user === "ADMIN" && $pass === "admin") {
            self::setAccessLevel(2);
            return true;
        }

        if ($user === "USER" && $pass === "user") {
            self::setAccessLevel(1);
            return true;
        }

        return false;
    }
















     public static function login(string $user, string $pass): void {
        if (self::validateCredentials($user, $pass)) {
            self::setUserName($user);
            self::setPassword($pass);
        }
    }





    public static function autoLogin(): void {
        if(self::hasSessionLogin()) { self::getSessionLogin(); return; }
        //nope no session login
        $user = self::getRequestParameter("user");
        $pass = self::getRequestParameter("pass");
        if (self::validateCredentials($user, $pass)) {
            self::setUserName($user);
            self::setPassword($pass);
            self::saveSessionLogin(); //save login to session
        }
    }




}

/*
 * TESTING
 */


/*
  echo Auth::isLoggedIn() ? "true" : "false";
  echo "<br>Logging in<br>";
 */

Auth::autoLogin(); // <-- login using ONE function call!!



$access = Auth::getAccessLevel();
$user = Auth::getUserName();
$pass = Auth::getPassword();
$login = Auth::isLoggedIn();

if ($login) {
    echo "Welcome, <b>$user</b>! Your access level is <b>$access</b>, and your password is <b>$pass</b>.<br>";
} else {
    echo "Nope that doesn't work.<br>";
}