<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * rss/file.php - entry point to serve rss streams
 * 
 * This script simply checks the parameters to construct a $USER
 * then finds and calls a function in the relevant component to 
 * actually check security and create the RSS stream
 *
 * @package   moodlecore
 * @copyright 1999 onwards Martin Dougiamas  http://moodle.com
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */


// Disable moodle specific debug messages and any errors in output
define('NO_DEBUG_DISPLAY', true);//comment this out to see any error messages during RSS generation

// Sessions not used here, we recreate $USER every time we are called
define('NO_MOODLE_COOKIES', true);

require_once('../config.php');
require_once($CFG->libdir.'/filelib.php');
require_once($CFG->libdir.'/rsslib.php');

// RSS feeds must be enabled site-wide
if (empty($CFG->enablerssfeeds)) {
    debugging('DISABLED (admin variables)');
    rss_error();
}


// All the arguments are in the path
$relativepath = get_file_argument();
if (!$relativepath) {
    rss_error();
}


// Extract relative path components into variables
$args = explode('/', trim($relativepath, '/'));
if (count($args) < 5) {
    rss_error();
}

$contextid   = (int)$args[0];
$token  = $args[1];
$componentname = clean_param($args[2], PARAM_FILE);


// Authenticate the user from the token
$userid = rss_get_userid_from_token($token);
if (!$userid) {
    rss_error('rsserrorauth');
}

$user = get_complete_user_data('id', $userid);
session_set_user($user); //for login and capability checks


// Check the context actually exists
$context = get_context_instance_by_id($contextid);
if (!$context) {
    rss_error();
}
$PAGE->set_context($context);


// Work out which component in Moodle we want (from the frankenstyle name)
$componentdir = get_component_directory($componentname);
list($type, $plugin) = normalize_component($componentname);


// Call the component to check/update the feed and tell us the path to the cached file
$pathname = null;

if (file_exists($componentdir)) {
    require_once("$componentdir/rsslib.php");
    $functionname = $plugin.'_rss_get_feed';

    if (function_exists($functionname)) {
        // $pathname will be null if there was a problem (eg user doesn't have the necessary capabilities)
        // NOTE:the component providing the feed must do its own capability checks and security
        $pathname = $functionname($context, $args);
    }
}


// Check that file exists
if (empty($pathname) || !file_exists($pathname)) {
    rss_error();
}

// Send the RSS file to the user!
send_file($pathname, 'rss.xml', 3600);   // Cached by browsers for 1 hour


/*
 * Sends an error formatted as an rss file and then dies
 */
function rss_error($error='rsserror', $filename='rss.xml', $lifetime=0) {
    send_file(rss_geterrorxmlfile($error), $filename, $lifetime, false, true);
    exit;
}