<?php
/*
 * Copyright (c) 2011 Le Lag 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

namespace OTPHP {
    /**
     * TOTP - One time password generator
     *
     * The TOTP class allow for the generation
     * and verification of one-time password using
     * the TOTP specified algorithm.
     *
     * This class is meant to be compatible with
     * Google Authenticator
     *
     * This class was originally ported from the rotp
     * ruby library available at https://github.com/mdp/rotp
     */
    class TOTP extends OTP {
        /**
         * The interval in seconds for a one-time password timeframe
         * Defaults to 30
         * @var integer
         */
        public $interval;

        public function __construct($s, $opt = Array()) {
            $this->interval = isset($opt['interval']) ? $opt['interval'] : 30;
            parent::__construct($s, $opt);
        }

        /**
         *  Get the password for a specific timestamp value
         *
         *  @param integer $timestamp the timestamp which is timecoded and
         *  used to seed the hmac hash function.
         *  @return integer the One Time Password
         */
        public function at($timestamp) {
            return $this->generateOTP($this->timecode($timestamp));
        }

        /**
         *  Get the password for the current timestamp value
         *
         *  @return integer the current One Time Password
         */
        public function now() {
            return $this->generateOTP($this->timecode(time()));
        }

        /**
         * Verify if a password is valid for a specific counter value
         *
         * @param integer $otp the one-time password
         * @param integer $timestamp the timestamp for the a given time, defaults to current time.
         * @return  bool true if the counter is valid, false otherwise
         */
        public function verify($otp, $timestamp = null) {
            if($timestamp === null)
                $timestamp = time();
            return ($otp == $this->at($timestamp));
        }

        /**
         * Returns the uri for a specific secret for totp method.
         * Can be encoded as a image for simple configuration in
         * Google Authenticator.
         *
         * @param string $name the name of the account / profile
         * @return string the uri for the hmac secret
         */
        public function provisioning_uri($name) {
            return "otpauth://totp/".urlencode($name)."?secret={$this->secret}";
        }

        /**
         * Transform a timestamp in a counter based on specified internal
         *
         * @param integer $timestamp
         * @return integer the timecode
         */
        protected function timecode($timestamp) {
            return (int)( (((int)$timestamp * 1000) / ($this->interval * 1000)));
        }
    }

}