<?php
    session_start();
    $username = "";
    $email = "";
    $errors = array();

    $db = mysqli_connect('localhost','root','','registration');

    if(isset($_POST['register'])){
        $username = mysqli_real_escape_string($db,$_POST['username']);
        $email = mysqli_real_escape_string($db,$_POST['email']);
        $password = mysqli_real_escape_string($db,$_POST['password']);
        $password2 = mysqli_real_escape_string($db,$_POST['password2']);

        if(empty($username)){
            array_push($errors, "Username is required");
        }
        if(empty($email)){
            array_push($errors, "Email is required");
        }
        if(empty($password)){
            array_push($errors, "Password is required");
        }

        if($password != $password2){
            array_push($errors, "The two password do not match");
        }
        if(count($errors) == 0){
            $sql = "INSERT INTO users (username, email, password) VALUES ('$username','$email','$password')";
            mysqli_query($db, $sql);
            $_SESSION['username'] = $username;
            $_SESSION['success'] = "You are now logged in";
            header('location:index.php');
        }

        }

        if(isset($_POST['login'])){
            $username = mysqli_real_escape_string($db,$_POST['username']);
            $password = mysqli_real_escape_string($db,$_POST['password']);

            if(empty($username)){
                array_push($errors, "Username is required");
            }
            if(empty($password)){
                array_push($errors, "Password is required");
            }
            if(count($errors) == 0){
                $query = "SELECT * FROM users WHERE username ='$username' AND password ='$password'";
                $result = mysqli_query($db, $query);
                if(mysqli_num_rows($result) > 0){
                    header('location:add.php');

                } else{
                    array_push($errors, "wrong username or password");
                }
            }
        }

        if(isset($_GET['logout'])){
            session_destroy();
            unset($_SESSION['username']);
            header('location: login.php');

    }

?>