<?php
/**
 * StatusNet, the distributed open-source microblogging tool
 *
 * Issue temporary OAuth credentials (a request token)
 *
 * PHP version 5
 *
 * LICENCE: This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @category  API
 * @package   StatusNet
 * @author    Zach Copley <zach@status.net>
 * @copyright 2010 StatusNet, Inc.
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
 * @link      http://status.net/
 */

if (!defined('STATUSNET')) {
    exit(1);
}

/**
 * Issue temporary OAuth credentials (a request token)
 *
 * @category API
 * @package  StatusNet
 * @author   Zach Copley <zach@status.net>
 * @license  http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
 * @link     http://status.net/
 */
class ApiOAuthRequestTokenAction extends ApiOAuthAction
{
    /**
     * Take arguments for running
     *
     * @param array $args $_REQUEST args
     *
     * @return boolean success flag
     */
    function prepare(array $args = array())
    {
        parent::prepare($args);

        // XXX: support "force_login" parameter like Twitter? (Forces the user to enter
        // their credentials to ensure the correct users account is authorized.)

        return true;
    }

    /**
     * Handle a request for temporary OAuth credentials
     *
     * Make sure the request is kosher, then emit a set of temporary
     * credentials -- AKA an unauthorized request token.
     *
     * @param array $args array of arguments
     *
     * @return void
     */
    function handle()
    {
        parent::handle();

        $datastore   = new ApiGNUsocialOAuthDataStore();
        $server      = new OAuthServer($datastore);
        $hmac_method = new OAuthSignatureMethod_HMAC_SHA1();

        $server->add_signature_method($hmac_method);

        try {

            $req = OAuthRequest::from_request();

            // verify callback
            if (!$this->verifyCallback($req->get_parameter('oauth_callback'))) {
                throw new OAuthException(
                    "You must provide a valid URL or 'oob' in oauth_callback.",
                    400
                );
            }

            // check signature and issue a new request token
            $token = $server->fetch_request_token($req);

            common_log(
                LOG_INFO,
                sprintf(
                    "API OAuth - Issued request token %s for consumer %s with oauth_callback %s",
                    $token->key,
                    $req->get_parameter('oauth_consumer_key'),
                    "'" . $req->get_parameter('oauth_callback') ."'"
                )
            );

            // return token to the client
            $this->showRequestToken($token);

        } catch (OAuthException $e) {
            common_log(LOG_WARNING, 'API OAuthException - ' . $e->getMessage());

            // Return 401 for for bad credentials or signature problems,
            // and 400 for missing or unsupported parameters

            $code = $e->getCode();
            $this->clientError($e->getMessage(), empty($code) ? 401 : $code, 'text');
        }
    }

    /*
     * Display temporary OAuth credentials
     */
    function showRequestToken($token)
    {
        header('Content-Type: application/x-www-form-urlencoded');
        print $token;
        print '&oauth_callback_confirmed=true';
    }

    /* Make sure the callback parameter contains either a real URL
     * or the string 'oob'.
     *
     * @todo Check for evil/banned URLs here
     *
     * @return boolean true or false
     */
    function verifyCallback($callback)
    {
        if ($callback == "oob") {
            common_debug("OAuth request token requested for out of band client.");

            // XXX: Should we throw an error if a client is registered as a
            // web application but requests the pin based workflow? For now I'm
            // allowing the workflow to proceed and issuing a pin. --Zach

            return true;
        } else {
            return filter_var($callback, FILTER_VALIDATE_URL);
        }
    }
}