index.php

<?php
include('User.php');
if (isset($_POST['register'])) {
    header('Location: inscription.php');
}
session_start();
if (isset($_SESSION['login'])) {
    header('Location: mainPage.php');
}
if (!isset($_SESSION['login'])) {
    if (isset($_POST['login']) && isset($_POST['password'])) {
        $user = User::login_email_pwd($_POST['login'], $_POST['password']);
        if ($user) {
            $_SESSION['login'] = $_POST['login'];
            header('Location: mainPage.php');
        } else {
            echo('Invalid fields');
        }
    }
}
?>

<html>
    <head>
        <title>420 px</title>
    </head>
    <body>
        <?
            echo '<form name="login" method="post" action="login.php">';
            echo 'Login : <input type = "texte" name="login"> <br />';
            echo 'Password : <input type = "password" name="password"> <br />';
            echo '<input type = "submit" name="connexion" value = "connexion">';

            echo '<form name="register" method="post" action="login.php">';
            echo '<input type = "submit" name="register" value="inscription">'
        ?>
    </body>
</html>