<?php


class Auth extends Session
{
    /*
     * singleton pattern
     */
    private static $instance;
    private function __construct() {}
    public static function getInstance()
    {
        if (self::$instance)
            return self::$instance;
        self::$instance = new self();
        return self::$instance;
    }

    /*
     * Auth config settings
     */
    private $method;
    private $user_table;
    private $email_field_name;
    private $username_field_name;
    private $password_field_name;
    private $confirmation_password_field_name;
    public function setConfig($config) {
        $this->method = $config['method'];
        $this->user_table = $config['user_table'];
        $this->email_field_name = $config['email_field_name'];
        $this->username_field_name = $config['username_field_name'];
        $this->password_field_name = $config['password_field_name'];
        $this->confirmation_password_field_name = $config['confirmation_password_field_name'];
    }



    /*
     *  load queryBuilder and Request object
     */
    /** @var $query Query */
    private $query;
    private $request;
    private $errors = [];
    public function init(Query $query, Request $request)
    {
        parent::start();
        $this->query = $query;
        $this->request = $request;
    }


    /*
     * login
     */
    public function login()
    {
        if ($this->isUserLogged())
            return $this->getLoggedUser();

        $emailField = $this->email_field_name;
        $passwordField = $this->password_field_name;

        $password = $this->getUserCredentials($passwordField);
        $email = $this->getUserCredentials($emailField);

        //if credentials are not present return
        if (
            $email == null &&
            $password == null
        ) return false;

        //retrieve user by username
        $user = $this->getUserByEmail($email);
        if ( !$user )
            return false;

        //check password correctness
        if ( $this->verifyPassword($password, $user->$passwordField) ) {
            $this->completeLogin($user);
            return true;
        }
        return false;

    }


    protected function completeLogin($user)
    {
        $this->set('is_logged', true);
        $this->set('logged_user_id',$user->id);
        $this->set('logged_user_name', $user->username);
    }

    /*
     * logout
     */
    public function logout()
    {
        $this->delete('is_logged_in');
        $this->delete('logged_user_id');
        $this->delete('logged_user_name');
        parent::destroy();
    }



    /*
     * register
     */
    public function register()
    {
        if ($this->isUserLogged())
            $this->logout();

        $usernameField = $this->username_field_name;
        $emailField = $this->email_field_name;
        $passwordField = $this->password_field_name;
        $confirmationPasswordField = $this->confirmation_password_field_name;

        $username = $this->getUserCredentials($usernameField);
        $email = $this->getUserCredentials($emailField);
        $password = $this->getUserCredentials($passwordField);
        $confirmationPassword = $this->getUserCredentials($confirmationPasswordField);

        //check credentials
        if (
            $email == null ||
            $password == null ||
            $confirmationPassword == null ||
            $password !== $confirmationPassword
        ) return false;


        //vlidate credentials
        $errors = array_merge(
            $this->validateUsername($username),
            $this->validateEmail($email),
            $this->validatePassword($password)
        );
        if ( sizeof($errors) > 0 ) {
            $this->errors = $errors;
            return false;
        }


        $encryptedPassword = $this->encryptPassword($password);
        $this->query->insert($this->user_table, [
            $usernameField => $username,
            $emailField => $email,
            $passwordField => $encryptedPassword
        ]);
        return true;
    }





    /*
     * DB queries
     */
    protected function getUserByEmail($email)
    {
        $userTable = $this->user_table;
        $emailField = $this->email_field_name;
        $users = $this->query->selectWhere(
            $userTable,
            [$emailField => " = '$email'"]
        );
        return sizeof($users) == 1 ? $users[1] : null;
    }
    protected function getUserByUsername($username)
    {
        $userTable = $this->user_table;
        $usernameColumn = $this->username_field_name;
        $users = $this->query->selectWhere(
            $userTable,
            [$usernameColumn => " = '$username'"]
        );
        return sizeof($users) == 1 ? $users[1] : null;
    }
    protected function getUserById($id)
    {
        $userTable = $this->user_table;
        $users = $this->query->selectWhere(
            $userTable,
            ['id' => " = '$id'"]
        );
        return sizeof($users) == 1 ? $users[1] : null;
    }


    /*
     * utilities
     */
    protected function encryptPassword($password)
    {
        $passwordHash = password_hash($password, PASSWORD_BCRYPT, array('cost' => 12));
        return $passwordHash;
    }
    protected function getUserCredentials($key)
    {
        $method = $this->method;
        return $this->request->$method($key);
    }
    protected function verifyPassword($submittedPassword, $dbPassword)
    {
        $submittedPassword = $this->encryptPassword($submittedPassword);
        return $submittedPassword === $dbPassword;
    }
    public function getLoggedUser()
    {
        if ($this->isUserLogged()) {
            $id = $this->get('logged_user_id');
            return $this->getUserById($id);
        }
        return null;
    }

    protected function isUserLogged()
    {
        return $this->get('is_logged') ?? false;
    }

    public function getErrors()
    {
        return $this->errors;
    }


    protected function validateUsername($username)
    {
        $errors = [];
        if (strlen($username) < '3') {
            $errors[] = 'Username too short.';
        }
        if (strlen($username) > '50') {
            $errors[] = 'Username too long';
        }
        // Match a-z, A-Z, 1-9, -, _.
        if (!preg_match("/^[a-zA-Z\d-_]+$/i", $username)) {
            $errors[] = 'Disallowed characters';
        }
        return $errors;
    }

    protected function validatePassword($password)
    {
        $errors = [];
        if (strlen($password) < '8') {
            $errors[] = 'Password too short';
        }
        if (!preg_match("#[0-9]+#", $password)) {
            $errors[] = 'Password need numbers';
        }
        if (!preg_match("#[A-Z]+#", $password)) {
            $errors[] = 'Pasword need uppercase letters';
        }
        if (!preg_match("#[a-z]+#", $password)) {
            $errors[] = 'Pasword need lowercase letters';
        }
        return $errors;
    }

    protected function validateEmail($email)
    {
        $errors = [];
        // Remove all illegal characters from email
        $email = filter_var($email, FILTER_SANITIZE_EMAIL);
        // Validate e-mail
        if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
            $this->errors[] = 'E-mail address is not valid';
        }
        return $errors;
    }
}