<?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/>.

/**
 * This file adds support to rss feeds generation
 *
 * @package mod-forum
 * @copyright 2001 Eloy Lafuente (stronk7) http://contiento.com
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

    /**
     * This function is the main entry point to forum rss feeds generation.
     * Foreach site forum with rss enabled build one XML rss structure.
     */
    function forum_rss_feeds() {

        global $CFG, $DB;

        $status = true;

        //Check CFG->enablerssfeeds
        if (empty($CFG->enablerssfeeds)) {
            debugging('DISABLED (admin variables)');
        //Check CFG->forum_enablerssfeeds
        } else if (empty($CFG->forum_enablerssfeeds)) {
            debugging('DISABLED (module configuration)');
        //It's working so we start...
        } else {
            //Iterate over all forums
            if ($forums = $DB->get_records("forum")) {
                foreach ($forums as $forum) {
                    if (!empty($forum->rsstype) && !empty($forum->rssarticles) && $status) {

                        $filename = rss_file_name('forum', $forum);  // RSS file

                        //First let's make sure there is work to do by checking existing files
                        if (file_exists($filename)) {
                            if ($lastmodified = filemtime($filename)) {
                                if (!forum_rss_newstuff($forum, $lastmodified)) {
                                    continue;
                                }
                            }
                        }

                        //Ignore hidden forums
                        if (!instance_is_visible('forum',$forum)) {
                            if (file_exists($filename)) {
                                @unlink($filename);
                            }
                            continue;
                        }

                        mtrace("Updating RSS feed for ".format_string($forum->name,true).", ID: $forum->id");

                        //Get the XML contents
                        $result = forum_rss_feed($forum);
                        //Save the XML contents to file
                        if (!empty($result)) {
                            $status = rss_save_file("forum",$forum,$result);
                        }
                        if (debugging()) {
                            if (empty($result)) {
                                echo "ID: $forum->id-> (empty) ";
                            } else {
                                if (!empty($status)) {
                                    echo "ID: $forum->id-> OK ";
                                } else {
                                    echo "ID: $forum->id-> FAIL ";
                                }
                            }
                        }
                    }
                }
            }
        }
        return $status;
    }


    /**
     * Given a forum object, deletes the RSS file
     *
     * @param 0object $forum
     * @return bool
     */
    function forum_rss_delete_file($forum) {
        global $CFG;
        $rssfile = rss_file_name('forum', $forum);
        if (file_exists($rssfile)) {
            return unlink($rssfile);
        } else {
            return true;
        }
    }


    /**
     * If there is new stuff in the forum since $time then this returns
     * true.  Otherwise it returns false.
     *
     * @param object $forum
     * @param int $time
     * @return bool
     */
    function forum_rss_newstuff($forum, $time) {
        if ($forum->rsstype == 1) {
            $items = forum_rss_feed_discussions($forum, $time);
        } else {
            $items = forum_rss_feed_posts($forum, $time);
        }
        return (!empty($items));
    }

    /**
     * This function return the XML rss contents about the forum record passed as parameter
     * It returns false if something is wrong
     *
     * @param object $forum
     * @param bool
     */
    function forum_rss_feed($forum) {

        global $CFG;

        $status = true;

        //Check CFG->enablerssfeeds
        if (empty($CFG->enablerssfeeds)) {
            debugging("DISABLED (admin variables)");
        //Check CFG->forum_enablerssfeeds
        } else if (empty($CFG->forum_enablerssfeeds)) {
            debugging("DISABLED (module configuration)");
        //It's working so we start...
        } else {
            //Check the forum has rss activated
            if (!empty($forum->rsstype) && !empty($forum->rssarticles)) {
                //Depending of the forum->rsstype, we are going to execute, different sqls
                if ($forum->rsstype == 1) {    //Discussion RSS
                    $items = forum_rss_feed_discussions($forum);
                } else {                //Post RSS
                    $items = forum_rss_feed_posts($forum);

                }
                //Now, if items, we begin building the structure
                if (!empty($items)) {
                    //First all rss feeds common headers
                    $header = rss_standard_header(strip_tags(format_string($forum->name,true)),
                                                  $CFG->wwwroot."/mod/forum/view.php?f=".$forum->id,
                                                  format_string($forum->intro,true)); // TODO: fix format
                    //Now all the rss items
                    if (!empty($header)) {
                        $articles = rss_add_items($items);
                    }
                    //Now all rss feeds common footers
                    if (!empty($header) && !empty($articles)) {
                        $footer = rss_standard_footer();
                    }
                    //Now, if everything is ok, concatenate it
                    if (!empty($header) && !empty($articles) && !empty($footer)) {
                        $status = $header.$articles.$footer;
                    } else {
                        $status = false;
                    }
                } else {
                    $status = false;
                }
            }
        }
        return $status;
    }

    /**
     * This function returns "items" record array to be used to build the rss feed
     * for a Type=discussions forum
     *
     * @param object $forum
     * @param int $newsince
     */
    function forum_rss_feed_discussions($forum, $newsince=0) {

        global $CFG, $DB;

        $items = array();

        if ($newsince) {
            $newsince = " AND p.modified > '$newsince'";
        } else {
            $newsince = "";
        }

        if ($recs = $DB->get_records_sql ("SELECT d.id AS discussionid,
                                             d.name AS discussionname,
                                             u.id AS userid,
                                             u.firstname AS userfirstname,
                                             u.lastname AS userlastname,
                                             p.message AS postmessage,
                                             p.created AS postcreated,
                                             p.messageformat AS postformat,
                                             p.messagetrust AS posttrust
                                      FROM {forum_discussions} d,
                                           {forum_posts} p,
                                           {user} u
                                      WHERE d.forum = '$forum->id' AND
                                            p.discussion = d.id AND
                                            p.parent = 0 AND
                                            u.id = p.userid $newsince
                                      ORDER BY p.created desc",
                                      array($forum->id, $newsince), 0, $forum->rssarticles)) {

            $item = NULL;
            $user = NULL;

            $formatoptions = new object;
            $formatoptions->trusted = $rec->posttrust;

            foreach ($recs as $rec) {
                unset($item);
                unset($user);
                $item->title = format_string($rec->discussionname);
                $user->firstname = $rec->userfirstname;
                $user->lastname = $rec->userlastname;
                $item->author = fullname($user);
                $item->pubdate = $rec->postcreated;
                $item->link = $CFG->wwwroot."/mod/forum/discuss.php?d=".$rec->discussionid;
                $item->description = format_text($rec->postmessage,$rec->postformat,$formatoptions,$forum->course);
                $items[] = $item;
            }
        }
        return $items;
    }

    /**
     * This function returns "items" record array to be used to build the rss feed
     * for a Type=posts forum
     *
     * @param object $forum
     * @param int $newsince
     */
    function forum_rss_feed_posts($forum, $newsince=0) {

        global $CFG, $DB;

        $items = array();

        if ($newsince) {
            $newsince = " AND p.modified > '$newsince'";
        } else {
            $newsince = "";
        }

        if ($recs = $DB->get_records_sql ("SELECT p.id AS postid,
                                             d.id AS discussionid,
                                             d.name AS discussionname,
                                             u.id AS userid,
                                             u.firstname AS userfirstname,
                                             u.lastname AS userlastname,
                                             p.subject AS postsubject,
                                             p.message AS postmessage,
                                             p.created AS postcreated,
                                             p.messageformat AS postformat,
                                             p.messagetrust AS posttrust
                                      FROM {forum_discussions} d,
                                           {forum_posts} p,
                                           {user} u
                                      WHERE d.forum = ? AND
                                            p.discussion = d.id AND
                                            u.id = p.userid $newsince
                                      ORDER BY p.created desc", array($forum->id), 0, $forum->rssarticles)) {

            $item = NULL;
            $user = NULL;

            $formatoptions = new object;
            $formatoptions->trusted = $rec->posttrust;

            foreach ($recs as $rec) {
                unset($item);
                unset($user);
                $item->category = $rec->discussionname;
                $item->title = $rec->postsubject;
                $user->firstname = $rec->userfirstname;
                $user->lastname = $rec->userlastname;
                $item->author = fullname($user);
                $item->pubdate = $rec->postcreated;
                $item->link = $CFG->wwwroot."/mod/forum/discuss.php?d=".$rec->discussionid."&parent=".$rec->postid;
                $item->description = format_text($rec->postmessage,$rec->postformat,$formatoptions,$forum->course);


                $post_file_area_name = str_replace('//', '/', "$forum->course/$CFG->moddata/forum/$forum->id/$rec->postid");
                $post_files = get_directory_list("$CFG->dataroot/$post_file_area_name");

                if (!empty($post_files)) {
                    $item->attachments = array();
                    //TODO: rewrite attachment handling
                }

                $items[] = $item;
            }
        }
        return $items;
    }