simple login

account-t1.php

<?php
include 'accountfunctions.php';
requireUser('t1');

accountfunctions.php

<?php
function user($password, $tier) {
    return array($password, $tier);    
}
include 'accountlogins.php';
function getUser(){
    global $accounts;
    if (empty($_COOKIE["login"])){
        return false;
    }
    list($username, $encryptedPassword) = explode(',' , $_COOKIE["login"]);
    if(empty($accounts[$username])){
        return false;
    }
    if(encryptPassword($accounts[$username][0]) == $encryptedPassword){
        return $accounts[$username];
    }
    return false;
}
function requireUser($tier) {
    $user = getUser();
    if ($user == false){
        header("Location: login.php");
        die();
    }
    if ($user[1] != $tier){
        header("Location: account-". $user[1] . ".php");
        die();
    }
}
function loginUser($username, $password){
    global $accounts;
    if(empty($accounts[$username])) {
        return 'Username "'.$username.'" not found. Try again.';
    }
    if($accounts[$username][0] == $password){
        setcookie('login', $username . ',' . encryptPassword($password));
        header("Location: account-" . $accounts[$username][1] . ".php");
        die();
    }
    return 'Invalid password. Try again.';
}
function encryptPassword($password) {
    return hash('md5', $password . 'TLSrocks');
}

accountlogins.php

<?php
$accounts = array(
    
    'jim' => user('password', 't1'),
    'eric' => user('smile', 't2'),
);

login.php

<?php
    include 'accountfunctions.php';
    $msg = '';
    if (isset($_POST['uname']) && isset($_POST['pwd'])){
        $msg = loginUser($_POST['uname'],$_POST['pwd']);
    } else if (isset($_GET['logout'])){
        setcookie("login", "", time()-3600);
        $msg = "Goodbye.";
    }
?>


<?=$msg?>

<form action="login.php" method="post">
  Username: <input type="text" name="uname"><br>
  Password: <input type="password" name="pwd"><br>
  <input type="submit" value="Submit">
</form>