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<!DOCTYPE html>
    <html lang="en">
<head>
<title>loggin in tutorial</title>
    <meta charset="utf-8" />
    <link href='http://fonts.googleapis.com/css?family=questrial' rel='stylesheet' type='text/css'>
</head>
<body>
<div class="header">
<nav class="row">
<div id ="logo">
</div>
</div>
<hr></hr>
<div id="login">
<form action="index.php" method="post">
    <th>Username:<input type="text" name="username" placeholder="Username"></th>
    <th>Password:<input type="password" name="password" placeholder="Password"></th>
    <input type="submit" value="login">
    </form>
</div>
    </body>
</html>
<?php

    if (empty($_POST) === false) {
        $username = $_POST['username'];
        $password = $_POST['password'];
        // error checking

        if (empty($username) == true || empty($password) == true) {
            $errors[] = 'You need to enter a username and password';
            header("location: login.php");
        } else
        if (user_exists($username) == false) {
            $errors[] = 'Username does not exist';
            header("location: login.php");
        } else {
            // call login function with submitted data
            $login = login($username, $password);

            if ($login == false) {
                $errors[] = 'Username and password combination is incorrect';
                header("location: login.php");
            } else {
                // set the user session and login
                $_SESSION['username'] = $login;
                header('Location: index.php');
                exit();
            }

        }

    } else {
        $errors[] = 'No data recieved';
    }

    // Output

    if (empty($errors) == false) {
    }

    ?>