<?php

if (isset($_POST['submit'])) {
    require_once 'config.php';

    $firstname = mysqli_real_escape_string($connect, $_POST['firstname']);
    $lastname = mysqli_real_escape_string($connect, $_POST['lastname']);
    $email = mysqli_real_escape_string($connect, $_POST['email']);
    $username = mysqli_real_escape_string($connect, $_POST['username']);
    $password = mysqli_real_escape_string($connect, $_POST['password']);

    if (empty($firstname) || empty($lastname) || empty($email) || empty($username) || empty($password)) {
            header("Location: ../signup.php?signup=empty");
            exit();
    } else {

        if (!preg_match('/^[a-z]*$/i', $firstname) || !preg_match('/^[a-z]*$/i', $lastname) || !preg_match('/^[a-zd_]{4,20}$/i', $username)) {
            header("Location: ../signup.php?signup=invalid");
            exit();
        } else {
            if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
                header("Location: ../signup.php?signup=email_invalid");
                exit();
            } else {
                $sql = "SELECT * FROM users WHERE username='$username'";
                $search = mysqli_query($connect, $sql);
                $validate = mysqli_num_rows($search);

                if ($validate > 0) {
                    header("Location: ../signup.php?signup=username_already_taken");
                    exit();
                } else {
                    $hashed_password = password_hash($password, PASSWORD_DEFAULT);
                    $sql = "INSERT INTO users (firstname, lastname, email, username, password) VALUES ('$firstname', '$lastname', '$email', '$username', '$hashed_password')";
                    mysqli_query($connect, $sql);
                    $sql = $connect->query("SELECT * FROM users WHERE email='$email'");
                    $result = mysqli_fetch_assoc($sql);
                    $emailRecipient = $result["email"];
                    $subject = 'Welcome';
                    $message_body = 'You have successfully created an account '.$username.'! Welcome';
                    mail($emailRecipient, $subject, $message_body);
                    header("Location: ../index.php");
                    exit();
                }
            }
        }
    }

} else {
    header("Location: ../signup.php");
    exit();
}

?>

function validateInput()
{
     //assign values to array
     $user_input['firstname'] = mysqli_real_escape_string($connect, $_POST['firstname']);
     $user_input['lastname'] = mysqli_real_escape_string($connect, $_POST['lastname']);
     $user_input['email'] = mysqli_real_escape_string($connect, $_POST['email']);
     $user_input['username'] = mysqli_real_escape_string($connect, $_POST['username']);
     $user_input['password'] = mysqli_real_escape_string($connect, $_POST['password']);

    //loop through array to see if empty

    foreach($user_input as $field => $value){
         if(empty($value) || is_null($value){//check for empty
            //failed
         }
         if(($field === 'email') && !filter_var()){//check valid email
             //failed
         }
         if((!preg_match('/^[a-z]*$/i', $value) && ($field != 'username')){//check rules for all fields but username
            //failed
         }
         if((!preg_match('/^[a-zd_]{4,20}$/i', $value)&&($field === 'username')){
            //failed
        }
 }

if (isset($_POST['submit'])) {
    require_once 'config.php';
    validateInput();
    //continue on