<?php
if(isset($_POST['submit_reg'])){
    $var=file("data.txt");
    $userData = $_POST['email'] . " " . $_POST['password'] . "rn";
    $lines=0;
        $db = fopen("data.txt", "a+");
        foreach($var as $key=>$value){
            $user = (explode(' ', $value));
            if ($_POST["password"] === $_POST["confirm_password"]) {
                    //print_r($value);
                if (trim($user[0]) == $_POST['email']) {
                    $lines++;
                }
                break;

            }
        }
            if($lines){
                    echo "The email is already exists ";
                }else{
                 fwrite($db,$userData."rn");
                 fclose($db);
                 echo "you are registered successfully ";
              }
}
?>

<?php
if (isset($_POST['submit_log'])) {
    $email =isset($_POST['email']);
    $password =isset($_POST['password']);
    $file = explode( PHP_EOL, file_get_contents( "data.txt" ));
    $auth = false;
 foreach( $file as $line ) {
    list($email, $password) = explode(" ", $line);

    if ($_POST['email'] == $email && $_POST['password'] == $password) {
        $auth =true;
        break;
    }
}
        if($auth) {
            echo "Login successfull!";
        } else {
            echo "Invalid username or password";
        }
    }
?>