<?php

namespace local_learnwise\local\OAuth2\ResponseType;

use local_learnwise\local\OAuth2\Storage\AuthorizationCodeInterface as AuthorizationCodeStorageInterface;

/**
 * @author Brent Shaffer <bshafs at gmail dot com>
 */
class AuthorizationCode implements AuthorizationCodeInterface
{
    protected $storage;
    protected $config;

    public function __construct(AuthorizationCodeStorageInterface $storage, array $config = array())
    {
        $this->storage = $storage;
        $this->config = array_merge(array(
            'enforce_redirect' => false,
            'auth_code_lifetime' => 30,
        ), $config);
    }

    public function getAuthorizeResponse($params, $user_id = null)
    {
        // build the URL to redirect to
        $result = array('query' => array());

        $params += array('scope' => null, 'state' => null, 'code_challenge' => null, 'code_challenge_method' => null);

        $result['query']['code'] = $this->createAuthorizationCode($params['client_id'], $user_id, $params['redirect_uri'], $params['scope'], $params['code_challenge'], $params['code_challenge_method']);

        if (isset($params['state'])) {
            $result['query']['state'] = $params['state'];
        }

        return array($params['redirect_uri'], $result);
    }

    /**
     * Handle the creation of the authorization code.
     *
     * @param $client_id
     * Client identifier related to the authorization code
     * @param $user_id
     * User ID associated with the authorization code
     * @param $redirect_uri
     * An absolute URI to which the authorization server will redirect the
     * user-agent to when the end-user authorization step is completed.
     * @param $scope
     * (optional) Scopes to be stored in space-separated string.
     *
     * @see http://tools.ietf.org/html/rfc6749#section-4
     * @ingroup oauth2_section_4
     */
    public function createAuthorizationCode($client_id, $user_id, $redirect_uri, $scope = null, $code_challenge = null, $code_challenge_method = null)
    {
        $code = $this->generateAuthorizationCode();
        $this->storage->setAuthorizationCode($code, $client_id, $user_id, $redirect_uri, time() + $this->config['auth_code_lifetime'], $scope, null, $code_challenge, $code_challenge_method);

        return $code;
    }

    /**
     * @return
     * TRUE if the grant type requires a redirect_uri, FALSE if not
     */
    public function enforceRedirect()
    {
        return $this->config['enforce_redirect'];
    }

    /**
     * Generates an unique auth code.
     *
     * Implementing classes may want to override this function to implement
     * other auth code generation schemes.
     *
     * @return
     * An unique auth code.
     *
     * @ingroup oauth2_section_4
     */
    protected function generateAuthorizationCode()
    {
        $tokenLen = 40;
        if (function_exists('random_bytes')) {
            $randomData = random_bytes(100);
        } elseif (function_exists('openssl_random_pseudo_bytes')) {
            $randomData = openssl_random_pseudo_bytes(100);
        } elseif (function_exists('mcrypt_create_iv')) {
            $randomData = mcrypt_create_iv(100, MCRYPT_DEV_URANDOM);
        } elseif (@file_exists('/dev/urandom')) { // Get 100 bytes of random data
            $randomData = file_get_contents('/dev/urandom', false, null, 0, 100) . uniqid(mt_rand(), true);
        } else {
            $randomData = mt_rand() . mt_rand() . mt_rand() . mt_rand() . microtime(true) . uniqid(mt_rand(), true);
        }

        return substr(hash('sha512', $randomData), 0, $tokenLen);
    }
}
