class Validation
{
    private static $emailValidationRegex = '/^[^s@]+@[^s@]+.[^s@]+/';

    public static function fieldIsEmpty($field)
    {
        return empty($field);
    }

    public static function validateEmail($email)
    {
        return preg_match(self::$emailValidationRegex, $email);
    }

    public static function usernameExists($username)
    {
        if (UsersTable::getUserByUsername($username))
        {
            return true;
        }

        return false;
    }

    public static function emailExists($email)
    {
        if (UsersTable::getUserByEmail($email))
        {
            return true;
        }

        return false;
    }

    public static function redirectUser($validUser)
    {
        if ($validUser)
        {
            header('Location: ../index.php');
        }
        else
        {
            header('Location: ../login-page.php');
        }
    }

    public static function loginValidation($usernameOrEmail, $password)
    {
        $validUser = false;

        if (!self::fieldIsEmpty($usernameOrEmail) && !self::fieldIsEmpty($password))
        {
            $user = null;

            if (self::validateEmail($usernameOrEmail))
            {
                if (self::emailExists($usernameOrEmail))
                {
                    $user = UsersTable::getUserByEmail($usernameOrEmail);
                }
            }
            else
            {
                if (self::usernameExists($usernameOrEmail))
                {
                    $user = UsersTable::getUserByUsername($usernameOrEmail);
                }
            }

            if ($user !== null)
            {
                if (password_verify($password, $user['password']))
                {
                    $validUser = true;
                }
            }
        }

        self::redirectUser($validUser);
    }

    public static function signupValidation($email, $username, $password,
                                            $passwordConfirmation, $name)
    {
        echo 'Working so far!';
    }
}

class UsersTable
{
    public static function getAllUsers()
    {
        $statement = "SELECT * FROM `users`";
        $query = Database::query($statement);

        if ($query)
        {
            return $query->fetchAll(PDO::FETCH_ASSOC);
        }
    }

    public static function getUserByID($id)
    {
        $statement = "SELECT * FROM `users` WHERE `id` = '$id' "
                    . "LIMIT 1";
        $query = Database::query($statement);

        if ($query)
        {
            return $query->fetch(PDO::FETCH_ASSOC);
        }
    }

    public static function getUserByEmail($email)
    {
        $statement = "SELECT * FROM `users` WHERE `email` = '$email' "
                    . "LIMIT 1";
        $query = Database::query($statement);

        if ($query)
        {
            return $query->fetch(PDO::FETCH_ASSOC);
        }
    }

    public static function getUserByUsername($username)
    {
        $statement = "SELECT * FROM `users` WHERE `username` = '$username' "
                    . "LIMIT 1";
        $query = Database::query($statement);

        if ($query)
        {
            return $query->fetch(PDO::FETCH_ASSOC);
        }
    }

    public static function addUser($name, $email, $username, $password)
    {
        $hashedPassword = password_hash($password, PASSWORD_DEFAULT);

        $statement = "INSERT INTO `users` (`name`, `email`, `username`, "
                    . " `password`) VALUES ('$name', '$email', '$username', "
                    . "'$hashedPassword')";

        $query = Database::query($statement);
    }
}

require_once('../config.php');
require_once('database.php');
require_once('users-table.php');
require_once('validation.php');

Database::connect();

Validation::loginValidation($_POST['username-email'], $_POST['password']);