<?php

session_start();

/* Log the user out if requested */
if(isset($_GET['act']) && $_GET['act'] == 'logout')
{
    /* Check for CSRF */
    if(isset($_GET['token']) && $_GET['token'] == $_SESSION['token'])
    {
        session_destroy();
        header("Location: " . $_SERVER['PHP_SELF']);
    }
    else
    {
        exit("Token key incorrect. Possible hacking attempt.");
    }
}

/* Check if user is already logged in */
if(!isset($_SESSION['id']))
{
    /* Connect to the database */
    $conn = mysql_connect("localhost", "root", "removedforpastebin");
    mysql_select_db("one_page_login", $conn);

    /* Check if they attempted to login */
    if(isset($_POST['submit']))
    {
        /* Prepare data for query */
        $user = mysql_real_escape_string($_POST['user'], $conn);
        $pass = sha1($_POST['pass']);

        /* Select user id and password from database */
        $result = mysql_query("SELECT `id`, `password` FROM `users` WHERE `username`='" . $user . "'", $conn);

        /* Check that a user actually exists by that name */
        if(mysql_num_rows($result) != 0)
        {
            /* Check if password is correct */
            $array = mysql_fetch_assoc($result);
            if($array['password'] == $pass)
            {
                $_SESSION['id'] = $array['id'];
                $_SESSION['token'] = md5(microtime());

                header("Location: " . $_SERVER['PHP_SELF']);
            }
            else
            {
                echo "The password you entered was invalid!";
            }
        }
        else
        {
            echo "No user exists by that username!";
        }
    }
    else
    {
        /* Build the form */
        ?>
        <form name='login' method='post' action=''>
            <table>
            <tr>
                <td>Username</td>
                <td><input type='text' name='user' value='' /></td>
            </tr>
            <tr>
                <td>Password</td>
                <td><input type='password' name='pass' value='' /></td>
            </tr>
            <tr>
                <td colspan='2'><input type='submit' name='submit' value='Login!' /></td>
            </tr>
        </form>
        <?php
    }
}
else
{
    echo "You are already logged in! <a href='?act=logout&token=" . $_SESSION['token'] . "'>Logout?</a>";
}