<?php

namespace App\Classes;

use OTPHP\TOTP;
use OTPHP\Factory;
use Assert\AssertionFailedException;

class OTP
{

    /**
     * Generate a TOTP
     *
     * @param  \App\TwoFAccount  $twofaccount
     * @param  Boolean $isPreview   Prevent updating storage in case of HOTP preview
     * @return an array that represent the totp code
     */
    public static function generate($uri, $isPreview = false)
    {
        
        $otp = OTP::get($uri);

        if( get_class($otp) === 'OTPHP\TOTP' ) {

            $currentPosition = time();
            $PeriodCount = floor($currentPosition / $otp->getPeriod()); //nombre de période de x s depuis T0 (x=30 par défaut)
            $currentPeriodStartAt = $PeriodCount * $otp->getPeriod();
            $positionInCurrentPeriod = $currentPosition - $currentPeriodStartAt;

            // For memo :
            // $nextOtpAt = ($PeriodCount+1)*$period
            // $remainingTime = $nextOtpAt - time()

            return $totp = [
                'otp' => $otp->now(),
                'position' => $positionInCurrentPeriod
            ];
        }
        else {
            // It's a HOTP
            $hotp = [
                'otp' => $otp->at($otp->getCounter()),
                'counter' => $otp->getCounter()
            ];

            // now we update the counter for the next OTP generation
            $otp->setParameter( 'counter', $otp->getcounter() + 1 );
            $hotp['nextUri'] = urldecode($otp->getProvisioningUri());

            if( !$isPreview ) {
                $twofaccount = \App\TwoFAccount::where('uri', $uri)->first();
                $twofaccount->uri = $hotp['nextUri'];
                $twofaccount->save();
            }

            return $hotp;
        }

    }


    /**
     * check if the provided uri is a valid OTP uri
     *
     * @param  \App\TwoFAccount  $twofaccount
     * @return \Illuminate\Http\Response
     */
    public static function get(String $uri) {

        try {
            return Factory::loadFromProvisioningUri($uri);
        }
        catch (AssertionFailedException $exception) {
            $error = \Illuminate\Validation\ValidationException::withMessages([
                'qrcode' => __('errors.response.no_valid_totp')
            ]);

            throw $error;
        }

    }


}